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2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death

A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society
Published:October 30, 2017DOI:https://doi.org/10.1016/j.hrthm.2017.10.036

      Keywords

      ACC/AHA Task Force Members

      Glenn N. Levine, MD, FACC, FAHA, Chair
      Patrick T. O’Gara, MD, MACC, FAHA, Chair-Elect
      Jonathan L. Halperin, MD, FACC, FAHA, Immediate Past Chair
      Former Task Force member; current member during the writing effort.
      Sana M. Al-Khatib, MD, MHS, FACC, FAHA
      Joshua A. Beckman, MD, MS, FAHA
      Kim K. Birtcher, MS, PharmD, AACC
      Biykem Bozkurt, MD, PhD, FACC, FAHA
      Former Task Force member; current member during the writing effort.
      Ralph G. Brindis, MD, MPH, MACC
      Former Task Force member; current member during the writing effort.
      Joaquin E. Cigarroa, MD, FACC
      Anita Deswal, MD, MPH, FACC, FAHA
      Lesley H. Curtis, PhD, FAHA
      Former Task Force member; current member during the writing effort.
      Lee A. Fleisher, MD, FACC, FAHA
      Federico Gentile, MD, FACC
      Samuel Gidding, MD, FAHA
      Former Task Force member; current member during the writing effort.
      Zachary D. Goldberger, MD, MS, FACC, FAHA
      Mark A. Hlatky, MD, FACC, FAHA
      John Ikonomidis, MD, PhD, FAHA
      José A. Joglar, MD, FACC, FAHA
      Laura Mauri, MD, MSc, FAHA
      Barbara Riegel, PhD, RN, FAHA
      Susan J. Pressler, PhD, RN, FAHA
      Former Task Force member; current member during the writing effort.
      Duminda N. Wijeysundera, MD, PhD

      Preamble

      Since 1980, the American College of Cardiology (ACC) and American Heart Association (AHA) have translated scientific evidence into clinical practice guidelines with recommendations to improve cardiovascular health. These guidelines, which are based on systematic methods to evaluate and classify evidence, provide a cornerstone for quality cardiovascular care. The ACC and AHA sponsor the development and publication of guidelines without commercial support, and members of each organization volunteer their time to the writing and review efforts. Guidelines are official policy of the ACC and AHA.

       Intended Use

      Practice guidelines provide recommendations applicable to patients with or at risk of developing cardiovascular disease. The focus is on medical practice in the United States, but guidelines developed in collaboration with other organizations may have a global impact. Although guidelines may be used to inform regulatory or payer decisions, their intent is to improve patients’ quality of care and align with patients’ interests. Guidelines are intended to define practices meeting the needs of patients in most, but not all, circumstances and should not replace clinical judgment.

       Clinical Implementation

      Guideline-recommended management is effective only when followed by healthcare providers and patients. Adherence to recommendations can be enhanced by shared decision-making between healthcare providers and patients, with patient engagement in selecting interventions based on individual values, preferences, and associated conditions and comorbidities.

       Methodology and Modernization

      The ACC/AHA Task Force on Clinical Practice Guidelines (Task Force) continuously reviews, updates, and modifies guideline methodology on the basis of published standards from organizations including the Institute of Medicine (
      Committee on Standards for Developing Trustworthy Clinical Practice GuidelinesInstitute of Medicine (U.S.)
      Clinical Practice Guidelines We Can Trust.
      ,
      Committee on Standards for Systematic Reviews of Comparative Effectiveness ResearchInstitute of Medicine (U.S.)
      Finding What Works in Health Care: Standards for Systematic Reviews.
      ) and on the basis of internal reevaluation. Similarly, the presentation and delivery of guidelines are reevaluated and modified on the basis of evolving technologies and other factors to facilitate optimal dissemination of information at the point of care to healthcare professionals.
      Toward this goal, this guideline heralds the introduction of an evolved format of presenting guideline recommendations and associated text called the “modular knowledge chunk format”. Each modular “chunk” includes a table of related recommendations, a brief synopsis, recommendation-specific supportive text and, when appropriate, flow diagrams or additional tables. References are provided within the modular chunk itself to facilitate quick review. This format also will facilitate seamless updating of guidelines with focused updates as new evidence is published, and content tagging for rapid electronic retrieval of related recommendations on a topic of interest. This evolved format was instituted when this guideline was near completion; therefore, the current document represents a transitional formatting that best suits the text as written. Future guidelines will fully implement this format, including provisions for limiting the amount of text in a guideline.
      Recognizing the importance of cost–value considerations in certain guidelines, when appropriate and feasible, an analysis of the value of a medication, device, or intervention may be performed in accordance with the ACC/AHA methodology (
      • Anderson J.L.
      • Heidenreich P.A.
      • Barnett P.G.
      • et al.
      ACC/AHA statement on cost/value methodology in clinical practice guidelines and performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures and Task Force on Practice Guidelines.
      ).
      To ensure that guideline recommendations remain current, new data are reviewed on an ongoing basis, with full guideline revisions commissioned in approximately 6-year cycles. Publication of new, potentially practice-changing study results that are relevant to an existing or new medication, device, or management strategy will prompt evaluation by the Task Force, in consultation with the relevant guideline writing committee, to determine whether a focused update should be commissioned. For additional information and policies regarding guideline development, we encourage readers to consult the ACC/AHA guideline methodology manual (

      ACCF/AHA Task Force on Practice Guidelines. Methodology Manual and Policies From the ACCF/AHA Task Force on Practice Guidelines. American College of Cardiology and American Heart Association, 2010. Available at: http://assets.cardiosource.com/Methodology_Manual_for_ACC_AHA_Writing_Committees.pdf and http://professional.heart.org/idc/groups/ahamah-public/@wcm/@sop/documents/downloadable/ucm_319826.pdf. Accessed October 1, 2017.

      ) and other methodology articles (
      • Arnett D.K.
      • Goodman R.A.
      • Halperin J.L.
      • et al.
      AHA/ACC/HHS strategies to enhance application of clinical practice guidelines in patients with cardiovascular disease and comorbid conditions: from the American Heart Association, American College of Cardiology, and U.S. Department of Health and Human Services.
      ,
      • Halperin J.L.
      • Levine G.N.
      • Al-Khatib S.M.
      • et al.
      Further evolution of the ACC/AHA clinical practice guideline recommendation classification system: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Clinical Practice Guidelines.
      ,
      • Jacobs A.K.
      • Anderson J.L.
      • Halperin J.L.
      The evolution and future of ACC/AHA clinical practice guidelines: a 30-year journey: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
      ,
      • Jacobs A.K.
      • Kushner F.G.
      • Ettinger S.M.
      • et al.
      ACCF/AHA clinical practice guideline methodology summit report: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
      ).

       Selection of Writing Committee Members

      The Task Force strives to avoid bias by selecting experts from a broad array of backgrounds. Writing committee members represent different geographic regions, sexes, ethnicities, races, intellectual perspectives/biases, and scopes of clinical practice. The Task Force may also invite organizations and professional societies with related interests and expertise to participate as partners, collaborators, or endorsers.

       Relationships With Industry and Other Entities

      The ACC and AHA have rigorous policies and methods to ensure that guidelines are developed without bias or improper influence. The complete relationships with industry and other entities (RWI) policy can be found online. Appendix 1 of the current document lists writing committee members’ relevant RWI. For the purposes of full transparency, writing committee members’ comprehensive disclosure information is available online, as is the comprehensive disclosure information for the Task Force.

       Evidence Review and Evidence Review Committees

      When developing recommendations, the writing committee uses evidence-based methodologies that are based on all available data (

      ACCF/AHA Task Force on Practice Guidelines. Methodology Manual and Policies From the ACCF/AHA Task Force on Practice Guidelines. American College of Cardiology and American Heart Association, 2010. Available at: http://assets.cardiosource.com/Methodology_Manual_for_ACC_AHA_Writing_Committees.pdf and http://professional.heart.org/idc/groups/ahamah-public/@wcm/@sop/documents/downloadable/ucm_319826.pdf. Accessed October 1, 2017.

      ,
      • Arnett D.K.
      • Goodman R.A.
      • Halperin J.L.
      • et al.
      AHA/ACC/HHS strategies to enhance application of clinical practice guidelines in patients with cardiovascular disease and comorbid conditions: from the American Heart Association, American College of Cardiology, and U.S. Department of Health and Human Services.
      ,
      • Halperin J.L.
      • Levine G.N.
      • Al-Khatib S.M.
      • et al.
      Further evolution of the ACC/AHA clinical practice guideline recommendation classification system: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Clinical Practice Guidelines.
      ,
      • Jacobs A.K.
      • Anderson J.L.
      • Halperin J.L.
      The evolution and future of ACC/AHA clinical practice guidelines: a 30-year journey: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
      ). Literature searches focus on randomized controlled trials (RCTs) but also include registries, nonrandomized comparative and descriptive studies, case series, cohort studies, systematic reviews, and expert opinion. Only key references are cited.
      An independent evidence review committee (ERC) is commissioned when there are ≥1 questions deemed of utmost clinical importance that merit formal systematic review. This systematic review will strive to determine which patients are most likely to benefit from a test, medication, device, or treatment strategy and to what degree. Criteria for commissioning an ERC and formal systematic review include: a) the absence of a current authoritative systematic review; b) the feasibility of defining the benefit and risk in a time frame consistent with the writing of a guideline; c) the relevance to a substantial number of patients; and d) the likelihood that the findings can be translated into actionable recommendations. ERC members may include methodologists, epidemiologists, healthcare providers, and biostatisticians. When a formal systematic review has been commissioned, the recommendations developed by the writing committee on the basis of the systematic review are marked with “SR”.

       Guideline-Directed Management and Therapy

      The term guideline-directed management and therapy (GDMT) encompasses clinical evaluation, diagnostic testing, and pharmacological and procedural treatments. For these and all recommended medication treatment regimens, the reader should confirm the dosage by reviewing product insert material and evaluate the treatment regimen for contraindications and interactions. The recommendations are limited to medications, devices, and treatments approved for clinical use in the United States.

       Class of Recommendation and Level of Evidence

      The Class of Recommendation (COR) indicates the strength of the recommendation, encompassing the estimated magnitude and certainty of benefit in proportion to risk. The Level of Evidence (LOE) rates the quality of scientific evidence that supports the intervention on the basis of the type, quantity, and consistency of data from clinical trials and other sources (Table 1) (

      ACCF/AHA Task Force on Practice Guidelines. Methodology Manual and Policies From the ACCF/AHA Task Force on Practice Guidelines. American College of Cardiology and American Heart Association, 2010. Available at: http://assets.cardiosource.com/Methodology_Manual_for_ACC_AHA_Writing_Committees.pdf and http://professional.heart.org/idc/groups/ahamah-public/@wcm/@sop/documents/downloadable/ucm_319826.pdf. Accessed October 1, 2017.

      ,
      • Halperin J.L.
      • Levine G.N.
      • Al-Khatib S.M.
      • et al.
      Further evolution of the ACC/AHA clinical practice guideline recommendation classification system: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Clinical Practice Guidelines.
      ,
      • Jacobs A.K.
      • Kushner F.G.
      • Ettinger S.M.
      • et al.
      ACCF/AHA clinical practice guideline methodology summit report: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
      ).
      Table 1Applying Class of Recommendation and Level of Evidence to Clinical Strategies, Interventions, Treatments, or Diagnostic Testing in Patient Care* (Updated August 2015)
      Glenn N. Levine, MD, FACC, FAHA Chair, ACC/AHA Task Force on Clinical Practice Guidelines

      1. Introduction

      1.1 Methodology and Evidence Review

      The recommendations listed in this clinical practice guideline are, whenever possible, evidence-based. An initial extensive evidence review, which included literature derived from research involving human subjects, published in English, and indexed in MEDLINE (through PubMed), EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline, was conducted from April 2016 to September 2016. Key search words included, but were not limited, to the following: sudden cardiac death, ventricular tachycardia, ventricular fibrillation, premature ventricular contractions, implantable cardioverter-defibrillator, subcutaneous implantable cardioverter-defibrillator, wearable cardioverter-defibrillator, and catheter ablation. Additional relevant studies published through March 2017, during the guideline writing process, were also considered by the writing committee, and added to the evidence tables when appropriate. The final evidence tables are included in the Online Data Supplement and summarize the evidence used by the writing committee to formulate recommendations. Additionally, the writing committee reviewed documents related to ventricular arrhythmias (VA) and sudden cardiac death (SCD) previously published by the ACC, AHA, and the Heart Rhythm Society (HRS). References selected and published in this document are representative and not all-inclusive.
      As noted in the Preamble, an independent ERC was commissioned to perform a formal systematic review of 2 important clinical questions for which clear literature and prior guideline consensus were felt to be lacking or limited (Table 2). The results of the ERC review were considered by the writing committee for incorporation into this guideline. Concurrent with this process, writing committee members evaluated other published data relevant to the guideline. The findings of the ERC and the writing committee members were formally presented and discussed, then guideline recommendations were developed. The “Systematic Review for the 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death” is published in conjunction with this guideline (
      • Kusumoto F.M.
      • Bailey K.R.
      • Chaouki A.S.
      • et al.
      Systematic review for the 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.
      ).
      Table 2Systematic Review Questions on SCD Prevention
      Question NumberQuestionSection Number
      1For asymptomatic patients with Brugada syndrome, what is the association between an abnormal programmed ventricular stimulation study and SCD and other arrhythmia endpoints?7.9.1.3
      2What is the impact of ICD implantation for primary prevention in older patients and patients with significant comorbidities?10.3
      ICD = implantable cardioverter-defibrillator; SCD = sudden cardiac death.
      The ACC and AHA have acknowledged the importance of value in health care and have called for eventual development of a Level of Value for clinical practice recommendations (
      • Anderson J.L.
      • Heidenreich P.A.
      • Barnett P.G.
      • et al.
      ACC/AHA statement on cost/value methodology in clinical practice guidelines and performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures and Task Force on Practice Guidelines.
      ). Available cost-effectiveness data were determined to be sufficient to support 2 specific recommendations in this guideline (see Sections 7.1.1 and 7.1.2). As a result, a Level of Value was assigned to those 2 recommendations on the basis of the “ACC/AHA Statement on Cost/Value Methodology in Clinical Practice Guidelines and Performance Measures,” as shown in Table 3 (
      • Anderson J.L.
      • Heidenreich P.A.
      • Barnett P.G.
      • et al.
      ACC/AHA statement on cost/value methodology in clinical practice guidelines and performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures and Task Force on Practice Guidelines.
      ). Available quality of life (QoL) data were deemed to be insufficient to support specific recommendations in this guideline.
      Table 3Proposed Integration of Level of Value Into Clinical Practice Guideline Recommendations
      Dollar amounts used in this table are based on U.S. GDP data from 2012 and were obtained from WHO-CHOICE Cost-Effectiveness Thresholds (S1.4-3).
      Level of Value
      High value: Better outcomes at lower cost or ICER <$50,000 per QALY gained

      Intermediate value: $50,000 to <$150,000 per QALY gained

      Low value: ≥$150,000 per QALY gained

      Uncertain value: Value examined but data are insufficient to draw a conclusion because of no studies, low-quality studies, conflicting studies, or prior studies that are no longer relevant

      Not assessed: Value not assessed by the writing committee
      Proposed abbreviations for each value recommendation:

      Level of Value: H to indicate high value; I, intermediate value; L, low value; U, uncertain value; and NA, value not assessed
      GDP = gross domestic product; ICER = incremental cost-effectiveness ratio; QALY = quality-adjusted life-years; WHO-CHOICE = World Health Organization Choosing Interventions that are Cost-Effective. Reproduced from Anderson et al.
      • Anderson J.L.
      • Heidenreich P.A.
      • Barnett P.G.
      • et al.
      ACC/AHA statement on cost/value methodology in clinical practice guidelines and performance measures: a report of the American College of Cardiology/American Heart Association Task Force on Performance Measures and Task Force on Practice Guidelines.
      .
      Dollar amounts used in this table are based on U.S. GDP data from 2012 and were obtained from WHO-CHOICE Cost-Effectiveness Thresholds

      World Health Organization. CHOosing Interventions that are Cost Effective (WHO-CHOICE): cost-effectiveness thresholds. Available at: http://www.who.int/choice/en/. Accessed March 26, 2013.

      .

      1.2 Organization of the Writing Committee

      The writing committee consisted of cardiac electrophysiologists (including those specialized in pediatrics), general adult and pediatric cardiologists (including those specialized in critical care and acute coronary syndromes [ACS], genetic cardiology, heart failure, and cost-effectiveness analyses), a geriatrician with expertise in terminal care and shared decision-making, and a lay representative, in addition to representatives from the ACC, AHA, HRS, and the Heart Failure Society of America (HFSA).

      1.3 Document Review and Approval

      This document was reviewed by 2 official reviewers nominated by the ACC, AHA, and HRS; 1 official lay reviewer nominated by the AHA; 1 organizational reviewer nominated by the HFSA; and 28 individual content reviewers. Reviewers’ RWI information was distributed to the writing committee and is published in this document (Appendix 2).
      This document was approved for publication by the governing bodies of the ACC, the AHA, and the HRS; and endorsed by the HFSA.

      1.4 Scope of the Guideline

      The purpose of this AHA/ACC/HRS document is to provide a contemporary guideline for the management of adults who have VA or who are at risk for SCD, including diseases and syndromes associated with a risk of SCD from VA. This guideline supersedes the “ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death” (
      • Zipes D.P.
      • Camm A.J.
      • Borggrefe M.
      • et al.
      ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society.
      ). It also supersedes some sections of the “ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities” (
      • Epstein A.E.
      • DiMarco J.P.
      • Ellenbogen K.A.
      • et al.
      ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices). Developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons.
      ), specifically those sections on indications for the implantable cardioverter-defibrillator (ICD); and, it updates the SCD prevention recommendations in the “2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy” (
      • Gersh B.J.
      • Maron B.J.
      • Bonow R.O.
      • et al.
      2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons.
      ). Some recommendations from the earlier guidelines have been updated as warranted by new evidence or a better understanding of existing evidence, and irrelevant or overlapping recommendations were deleted or modified.
      In the current guideline, sudden cardiac arrest (SCA) is defined as the “sudden cessation of cardiac activity so that the victim becomes unresponsive, with no normal breathing and no signs of circulation” (
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology).
      ). If corrective measures are not taken rapidly, this condition progresses to SCD. Cardiac arrest is used to signify an event that can be reversed, usually by cardiopulmonary resuscitation (CPR), administration of medications and/or defibrillation or cardioversion. SCA and SCD can result from causes other than VA, such as bradyarrhythmias, electromechanical dissociation, pulmonary embolism, intracranial hemorrhage, and aortic dissection; however, the scope of this document includes only SCA and SCD due to VA.
      This guideline includes indications for ICDs for the treatment of VA and prevention of SCD, but it does not delve into details on individual device selection and programming, including considerations relevant to cardiac resynchronization therapy (CRT), bradycardia pacing, and hemodynamic monitoring. These important aspects of ICD management have been covered in an HRS expert consensus statement (
      • Wilkoff B.L.
      • Fauchier L.
      • Stiles M.K.
      • et al.
      2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing.
      ). An AHA science advisory discusses the use of wearable cardioverter-defibrillators (
      • Piccini Sr., J.P.
      • Allen L.A.
      • Kudenchuk P.J.
      • et al.
      Wearable cardioverter-defibrillator therapy for the prevention of sudden cardiac death: a science advisory from the American Heart Association.
      ). The findings of that document were reviewed; however, recommendations on this topic were developed independently of that document. This guideline includes indications for catheter ablation of VA, but does not provide recommendations on specific techniques or ablation technologies, which were beyond the scope of this document.
      Recommendations for interventional therapies, including ablation and the implantation of devices, apply only if these therapies can be implemented by qualified clinicians, such that outcomes consistent with published literature are a reasonable expectation. The writing committee agreed that a high degree of expertise was particularly important for performance of catheter ablation of VA, and this point is further emphasized in relevant sections. In addition, all recommendations related to ICDs require that meaningful survival of >1 year is expected; meaningful survival means that a patient has a reasonable quality of life and functional status.
      Although this document is aimed at the adult population (≥18 years of age) and offers no specific recommendations for pediatric patients, some of the literature on pediatric patients was examined. In some cases, the data from pediatric patients beyond infancy helped to inform this guideline.
      The writing committee recognized the importance of shared decision-making and patient-centered care and, when possible, it endeavored to formulate recommendations relevant to these important concepts. The importance of a shared decision-making process in which the patient, family, and clinicians discuss risks and benefits of diagnostic and treatment options and consider the patients’ personal preferences is emphasized (see Section 15).
      In developing this guideline, the writing committee reviewed previously published guidelines and related statements. Table 4 contains a list of guidelines and statements deemed pertinent to this writing effort and is intended for use as a resource, obviating repetition of existing guideline recommendations.
      Table 4Associated Guidelines and Statements
      TitleOrganizationPublication Year (Reference)
      Guidelines
      SyncopeACC/AHA/HRS2017
      • Shen W.K.
      • Sheldon R.S.
      • Benditt D.G.
      • et al.
      2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.
      Heart failureACCF/AHA2017
      • Yancy C.W.
      • Jessup M.
      • Bozkurt B.
      • et al.
      2017 ACC/AHA/HFSA focused update of the 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Failure Society of America.
      2016
      • Yancy C.W.
      • Jessup M.
      • Bozkurt B.
      • et al.
      2016 ACC/AHA/HFSA focused update on new pharmacological therapy for heart failure: an update of the 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Failure Society of America.
      , and 2013
      • Yancy C.W.
      • Jessup M.
      • Bozkurt B.
      • et al.
      2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
      Valvular heart diseaseAHA/ACC2017
      • Nishimura R.A.
      • Otto C.M.
      • Bonow R.O.
      • et al.
      2017 AHA/ACC focused update of the 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines.
      and 2014
      • Nishimura R.A.
      • Otto C.M.
      • Bonow R.O.
      • et al.
      2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
      Supraventricular tachycardiaACC/AHA/HRS2015
      • Page R.L.
      • Joglar J.A.
      • Caldwell M.A.
      • et al.
      2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.
      Ventricular arrhythmias and the prevention of sudden cardiac deathESC2015
      • Priori S.G.
      • Blomstrom-Lundqvist C.
      • Mazzanti A.
      • et al.
      2015 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. The Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology.
      Guidelines for cardiopulmonary resuscitation and emergency cardiovascular careAHA2015
      • Perkins G.D.
      • Jacobs I.G.
      • Nadkarni V.M.
      • et al.
      Cardiac arrest and cardiopulmonary resuscitation outcome reports: update of the Utstein Resuscitation Registry Templates for Out-of-Hospital Cardiac Arrest: a statement for healthcare professionals from a task force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian and New Zealand Council on Resuscitation, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Southern Africa, Resuscitation Council of Asia); and the American Heart Association Emergency Cardiovascular Care Committee and the Council on Cardiopulmonary, Critical Care, Perioperative and Resuscitation.
      Atrial fibrillationAHA/ACC/HRS2014
      • January C.T.
      • Wann L.S.
      • Alpert J.S.
      • et al.
      2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society.
      Non–ST-elevation acute coronary syndromesAHA/ACC2014
      • Amsterdam E.A.
      • Wenger N.K.
      • Brindis R.G.
      • et al.
      2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
      Assessment of cardiovascular riskACC/AHA2013
      • Andrus B.
      • Lacaille D.
      2013 ACC/AHA guideline on the assessment of cardiovascular risk.
      ST-elevation myocardial infarctionACCF/AHA2013
      • O’Gara P.T.
      • Kushner F.G.
      • Ascheim D.D.
      • et al.
      2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
      Acute myocardial infarction in patients presenting with ST-segment elevationESC2012
      • Steg P.G.
      • James S.K.
      • Atar D.
      • et al.
      ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation.
      Device-based therapies for cardiac rhythm abnormalitiesACCF/AHA/HRS2012
      • Tracy C.M.
      • Epstein A.E.
      • Darbar D.
      • et al.
      2012 ACCF/AHA/HRS focused update of the 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
      Coronary artery bypass graft surgeryACCF/AHA2011
      • Hillis L.D.
      • Smith P.K.
      • Anderson J.L.
      • et al.
      2011 ACCF/AHA guideline for coronary artery bypass graft surgery. a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with the American Association for Thoracic Surgery, Society of Cardiovascular Anesthesiologists, and Society of Thoracic Surgeons.
      Hypertrophic cardiomyopathyACCF/AHA2011
      • Gersh B.J.
      • Maron B.J.
      • Bonow R.O.
      • et al.
      2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons.
      Percutaneous coronary interventionACCF/AHA/SCAI2011
      • Levine G.N.
      • Bates E.R.
      • Blankenship J.C.
      • et al.
      2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions.
      Secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular diseaseAHA/ACCF2011
      • Smith Jr., S.C.
      • Benjamin E.J.
      • Bonow R.O.
      • et al.
      AHA/ACCF secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular disease: 2011 update: a guideline from the American Heart Association and American College of Cardiology Foundation.
      Scientific Statements
      Wearable cardioverter-defibrillator therapy for the prevention of sudden cardiac deathAHA2016
      • Piccini Sr., J.P.
      • Allen L.A.
      • Kudenchuk P.J.
      • et al.
      Wearable cardioverter-defibrillator therapy for the prevention of sudden cardiac death: a science advisory from the American Heart Association.
      Optimal implantable cardioverter defibrillator programming and testingHRS/EHRA/APHRS/SOLAECE2016
      • Wilkoff B.L.
      • Fauchier L.
      • Stiles M.K.
      • et al.
      2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing.
      Treatment of cardiac arrest: current status and future directions: strategies to improve cardiac arrest survivalIOM2015
      Institute of Medicine
      Committee on the Treatment of Cardiac Arrest: Current Status and Future Directions: Strategies to improve cardiac arrest survival: a time to act.
      Eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalitiesACC/AHA2015
      • Link M.S.
      • Myerburg R.J.
      • Estes 3rd, N.A.
      Eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalities: Task Force 12: emergency action plans, resuscitation, cardiopulmonary resuscitation, and automated external defibrillators: a scientific statement from the American Heart Association and American College of Cardiology.
      Ventricular arrhythmiasEHRA/HRS/APHRS2014
      • Pedersen C.T.
      • Kay G.N.
      • Kalman J.
      • et al.
      EHRA/HRS/APHRS expert consensus on ventricular arrhythmias.
      Arrhythmias in adult congenital heart diseasePACES/HRS2014
      • Khairy P.
      • Van Hare G.F.
      • Balaji S.
      • et al.
      PACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease: developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS).
      Implantable cardioverter-defibrillator therapy in patients who are not included or not well represented in clinical trialsHRS/ACC/AHA2014
      • Kusumoto F.M.
      • Calkins H.
      • Boehmer J.
      • et al.
      HRS/ACC/AHA expert consensus statement on the use of implantable cardioverter-defibrillator therapy in patients who are not included or not well represented in clinical trials.
      Cardiac sarcoidosisHRS2014
      • Birnie D.H.
      • Sauer W.H.
      • Bogun F.
      • et al.
      HRS expert consensus statement on the diagnosis and management of arrhythmias associated with cardiac sarcoidosis.
      Inherited primary arrhythmia syndromesHRS/EHRA/APHRS2013
      • Priori S.G.
      • Wilde A.A.
      • Horie M.
      • et al.
      HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes.
      ACC = American College of Cardiology; ACCF = American College of Cardiology Foundation; AHA = American Heart Association; APHRS = Asia Pacific Heart Rhythm Society; EHRA = European Heart Rhythm Association; ESC = European Society of Cardiology; HRS = Heart Rhythm Society; PACES = Pediatric and Congenital Electrophysiology Society; SCAI = Society for Cardiovascular Angiography and Interventions; SOLAECE = Sociedad Latinoamericana de Estimulación Cardíaca y Electrofisiología.
      During final production review of the guidelines, several recommendations were refined to better reflect the data and current recommended medical practice. These refinements were reviewed and approved by the writing committee, the Task Force, and ACC, AHA, and HRS organizational leadership. These recommendations were:
      • Section 7.1.1., recommendation 1
      • Section 7.1.3., recommendation 2
      • Section 7.2.1., recommendation 1
      • Section 7.9.1.4., recommendation 2
      • Section 10.8., recommendation 6
      Readers should refer to these sections for the updated text.

      1.5 Abbreviations

      Tabled 1
      AbbreviationMeaning/Phrase
      ACSacute coronary syndromes
      AEDautomated external defibrillator
      AMIacute myocardial infarction
      BNPB-type natriuretic peptide
      CABGcoronary artery bypass graft
      CKDchronic kidney disease
      CPRcardiopulmonary resuscitation
      CRTcardiac resynchronization therapy
      CTcomputed tomography
      ECGelectrocardiogram
      ERCevidence review committee
      ESRDend-stage renal disease
      GDMTguideline-directed management and therapy
      HCMhypertrophic cardiomyopathy
      HFheart failure
      HFpEFheart failure with preserved ejection fraction
      HFrEFheart failure with reduced ejection fraction
      ICDimplantable cardioverter-defibrillator
      LVleft ventricular
      LVADleft ventricular assist device
      LVEFleft ventricular ejection fraction
      MImyocardial infarction
      NICMnonischemic cardiomyopathy
      NSVTnonsustained ventricular tachycardia
      PETpositron emission tomography
      PCIpercutaneous coronary intervention
      PVCpremature ventricular complex
      QoLquality of life
      RCTrandomized controlled trial
      RVright ventricular
      RVOTright ventricular outflow tract
      SCAsudden cardiac arrest
      SCDsudden cardiac death
      SVTsupraventricular tachycardia
      TOFtetralogy of Fallot
      VAventricular arrhythmia
      VTventricular tachycardia

      2. Epidemiology

      2.1 General Concepts

      Table 5
      Table 5Table of Definitions of Commonly Used Terms in this Document
      TermDefinition or Description
      Ventricular tachycardia
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      Cardiac arrhythmia of ≥3 consecutive complexes originating in the ventricles at a rate >100 bpm (cycle length: <600 ms). Types of VT:
      • Sustained: VT >30 s or requiring termination due to hemodynamic compromise in <30 s.
      • Nonsustained/unsustained: ≥3 beats, terminating spontaneously.
      • Monomorphic: Stable single QRS morphology from beat to beat.
      • Polymorphic: Changing or multiform QRS morphology from beat to beat.
      • Bidirectional: VT with a beat-to-beat alternation in the QRS frontal plane axis, often seen in the setting of digitalis toxicity or catecholaminergic polymorphic VT
      Monomorphic VT

      Polymorphic VT

      Bidirectional VT

      Torsades de pointes
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      Torsades de pointes is polymorphic VT that occurs in the setting of a long QT interval and is characterized by a waxing and waning QRS amplitude. It often has a long-short initiating sequence with a long coupling interval to the first VT beat and may present with salvos of NSVT. The twisting of the points, although characteristic, may not always be seen, especially if the episode is nonsustained or if only a limited number of leads are available. Torsades de pointes can result from bradycardia including high-grade AV block that leads to a long-short sequence initiating torsades de pointes.

      Ventricular flutter
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      A regular VA ≈300 bpm (cycle length: 200 ms) with a sinusoidal, monomorphic appearance; no isoelectric interval between successive QRS complexes.

      Ventricular fibrillation
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      Rapid, grossly irregular electrical activity with marked variability in electrocardiographic waveform, ventricular rate usually >300 bpm (cycle length: <200 ms).

      Sudden cardiac arrest
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      SCA is the sudden cessation of cardiac activity such that the victim becomes unresponsive, with either persisting gasping respirations or absence of any respiratory movements, and no signs of circulation as manifest by the absence of a perceptible pulse. An arrest is presumed to be of cardiac etiology unless it is known or likely to have been caused by trauma, drowning, respiratory failure or asphyxia, electrocution, drug overdose, or any other noncardiac cause.
      Sudden cardiac death
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      Sudden and unexpected death occurring within an hour of the onset of symptoms, or occurring in patients found dead within 24 h of being asymptomatic and presumably due to a cardiac arrhythmia or hemodynamic catastrophe.
      VT/VF storm
      • Sapp J.L.
      • Wells G.A.
      • Parkash R.
      • et al.
      Ventricular tachycardia ablation versus escalation of antiarrhythmic drugs.
      VT/VF storm (electrical storm or arrhythmic storm) refers to a state of cardiac electrical instability that is defined by ≥3 episodes of sustained VT, VF, or appropriate shocks from an ICD within 24 h.
      Primary prevention ICD
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      ICD placement with the intention of preventing SCD in a patient who has not had sustained VT or SCA but who is at an increased risk for these events.
      Secondary prevention ICD 
      • Buxton A.E.
      • Calkins H.
      • Callans D.J.
      • et al.
      ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards.
      ICD placement in a patient with prior SCA, sustained VT, or syncope caused by VA.
      Structural heart disease
      The definition of this term may differ across publications. Refer to the entry for the definition used in this document.
      This term encompasses IHD, all types of cardiomyopathy, valvular heart disease, and adult congenital heart disease.
      Cardiac channelopathy
      • Priori S.G.
      • Wilde A.A.
      • Horie M.
      • et al.
      HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes.
      Arrhythmogenic disease due to a genetic abnormality that results in dysfunction of a cardiac ion channel (e.g., long QT syndrome, catecholaminergic polymorphic VT).
      AV = atrioventricular; ICD = implantable cardioverter-defibrillator; IHD = ischemic heart disease; NSVT = nonsustained ventricular tachycardia; SCA = sudden cardiac arrest; SCD = sudden cardiac death; VA = ventricular arrhythmia; VF = ventricular fibrillation; VT = ventricular tachycardia.
      The definition of this term may differ across publications. Refer to the entry for the definition used in this document.
      VA include a spectrum that ranges from premature ventricular complex (PVC) to ventricular fibrillation (VF), with a clinical presentation that ranges from a total lack of symptoms to cardiac arrest. Most life-threatening VA are associated with ischemic heart disease, particularly in older patients (
      • Myerburg R.J.
      • Junttila M.J.
      Sudden cardiac death caused by coronary heart disease.
      ). The risks of VA and SCD vary in specific populations with different underlying cardiac conditions, and with specific family history and genetic variants, and this variation has important implications for studying and applying therapies.

      2.1.1 Premature Ventricular Complexes and Nonsustained VT

      PVCs are common and increase in frequency with age. Although PVCs were found in a healthy military population in only 0.6% of those <20 years of age and 2.7% of those >50 years of age (
      • Hiss R.G.
      • Lamb L.E.
      Electrocardiographic findings in 122,043 individuals.
      ) on 12-lead ECGs, longer term monitoring shows PVCs in about 50% of all people with or without heart disease (
      • Brodsky M.
      • Wu D.
      • Denes P.
      • et al.
      Arrhythmias documented by 24 hour continuous electrocardiographic monitoring in 50 male medical students without apparent heart disease.
      ). The presence of PVCs on 2 minutes of monitoring of middle-aged patients in the ARIC (Atherosclerosis Risk In Communities) study was associated with increased risk of both ischemic heart disease events and mortality, with or without prevalent ischemic heart disease (
      • Massing M.W.
      • Simpson Jr., R.J.
      • Rautaharju P.M.
      • et al.
      Usefulness of ventricular premature complexes to predict coronary heart disease events and mortality (from the Atherosclerosis Risk In Communities cohort).
      ,
      • Ofoma U.
      • He F.
      • Shaffer M.L.
      • et al.
      Premature cardiac contractions and risk of incident ischemic stroke.
      ). In the general population, frequent PVCs, which are defined as the presence of at least 1 PVC on a 12-lead ECG or >30 PVCs per hour, are associated with increased cardiovascular risk and increased mortality (
      • Ataklte F.
      • Erqou S.
      • Laukkanen J.
      • et al.
      Meta-analysis of ventricular premature complexes and their relation to cardiac mortality in general populations.
      ). In a study from Taiwan of patients without sustained VT or structural heart disease who had 24-hour Holter monitoring for clinical evaluation, multifocal PVCs were associated with increased risk of death and nonfatal cardiovascular adverse outcomes (
      • Lin C.Y.
      • Chang S.L.
      • Lin Y.J.
      • et al.
      Long-term outcome of multiform premature ventricular complexes in structurally normal heart.
      ). In the same population, nonsustained ventricular tachycardia (NSVT) was independently associated with increased risk of death and other cardiovascular adverse outcomes, including stroke (
      • Lin C.Y.
      • Chang S.L.
      • Chung F.P.
      • et al.
      Long-term outcome of non-sustained ventricular tachycardia in structurally normal hearts.
      ). An association of PVCs with increased risk of stroke was also seen in the ARIC population (
      • Ofoma U.
      • He F.
      • Shaffer M.L.
      • et al.
      Premature cardiac contractions and risk of incident ischemic stroke.
      ).
      Because some studies have shown an association of PVCs with adverse outcomes, the detection of PVCs, particularly if multifocal and frequent, is generally considered a risk factor for adverse cardiovascular outcomes, and such patients are generally evaluated to ensure they do not have underlying conditions (e.g., ischemic heart disease, left ventricular [LV] dysfunction) that warrant further treatment to reduce risk. PVC and NSVT in patients with cardiovascular disease are common and have been associated with adverse outcomes (
      • Ruberman W.
      • Weinblatt E.
      • Goldberg J.D.
      • et al.
      Ventricular premature complexes and sudden death after myocardial infarction.
      ,
      • Ruberman W.
      • Weinblatt E.
      • Goldberg J.D.
      • et al.
      Ventricular premature beats and mortality after myocardial infarction.
      ). In CAST (Cardiac Arrhythmia Suppression Trials), treatment of patients with post-myocardial infarction (MI) who took antiarrhythmic medications (e.g., flecainide, encainide, moricizine) increased the risk of death despite suppression of VA (
      The Cardiac Arrhythmia Suppression Trial II Investigators
      Effect of the antiarrhythmic agent moricizine on survival after myocardial infarction. The Cardiac Arrhythmia Suppression Trial II Investigators.
      ,
      • Echt D.S.
      • Liebson P.R.
      • Mitchell L.B.
      • et al.
      Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial.
      ). Treatment of PVCs with antiarrhythmic medications has not been shown to reduce mortality and, in the post- MI population, treatment with class I sodium channel–blocking medications (e.g., quinidine, flecainide) increases the risk of death (
      • Echt D.S.
      • Liebson P.R.
      • Mitchell L.B.
      • et al.
      Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial.
      ,
      • Morganroth J.
      • Goin J.E.
      Quinidine-related mortality in the short-to-medium-term treatment of ventricular arrhythmias. A meta-analysis.
      ). Likewise, in patients with a reduced LVEF class I, sodium channel–blocking medications and d-sotalol increase the risk of death (
      • Morganroth J.
      • Goin J.E.
      Quinidine-related mortality in the short-to-medium-term treatment of ventricular arrhythmias. A meta-analysis.
      ,
      • Waldo A.L.
      • Camm A.J.
      • deRuyter H.
      • et al.
      Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival With Oral d-Sotalol.
      ). Beta blockers, nondihydropyridines calcium channel blockers, and some antiarrhythmic medications may relieve symptoms of palpitations (
      • Ling Z.
      • Liu Z.
      • Su L.
      • et al.
      Radiofrequency ablation versus antiarrhythmic medication for treatment of ventricular premature beats from the right ventricular outflow tract: prospective randomized study.
      ).
      PVCs that occur during an exercise test are associated with a higher risk of death (
      • Jouven X.
      • Zureik M.
      • Desnos M.
      • et al.
      Long-term outcome in asymptomatic men with exercise-induced premature ventricular depolarizations.
      ). In 1 study, PVCs that occur during recovery are a stronger predictor of death than PVCs occurring only during exercise (
      • Frolkis J.P.
      • Pothier C.E.
      • Blackstone E.H.
      • et al.
      Frequent ventricular ectopy after exercise as a predictor of death.
      ). However, PVCs are common in trained athletes who have palpitations, in whom there does not appear to be increased risk of death based on studies of small numbers of athletes, at least in those without other cardiovascular abnormalities (
      • Biffi A.
      • Pelliccia A.
      • Verdile L.
      • et al.
      Long-term clinical significance of frequent and complex ventricular tachyarrhythmias in trained athletes.
      ,
      • Heidbüchel H.
      • Hoogsteen J.
      • Fagard R.
      • et al.
      High prevalence of right ventricular involvement in endurance athletes with ventricular arrhythmias: role of an electrophysiologic study in risk stratification.
      ). Complex PVCs may not represent a benign finding in endurance athletes. An electrophysiological study may be needed to assess patients’ arrhythmogenic risk (
      • Heidbüchel H.
      • Hoogsteen J.
      • Fagard R.
      • et al.
      High prevalence of right ventricular involvement in endurance athletes with ventricular arrhythmias: role of an electrophysiologic study in risk stratification.
      ). Very frequent PVCs, >10,000 to 20,000 a day, can be associated with depressed LV function in some patients that is reversible with control of the PVCs, and has been referred to as PVC-induced cardiomyopathy (
      • Kanei Y.
      • Friedman M.
      • Ogawa N.
      • et al.
      Frequent premature ventricular complexes originating from the right ventricular outflow tract are associated with left ventricular dysfunction.
      ,
      • Lee G.K.
      • Klarich K.W.
      • Grogan M.
      • et al.
      Premature ventricular contraction-induced cardiomyopathy: a treatable condition.
      ). (See also Section 8.5. PVC-Induced Cardiomyopathy.) Very rarely, idiopathic PVCs from the outflow tract may trigger malignant VA in patients without structural heart disease (
      • Viskin S.
      • Rosso R.
      • Rogowski O.
      • et al.
      The “short-coupled” variant of right ventricular outflow ventricular tachycardia: a not-so-benign form of benign ventricular tachycardia?.
      ,
      • Noda T.
      • Shimizu W.
      • Taguchi A.
      • et al.
      Malignant entity of idiopathic ventricular fibrillation and polymorphic ventricular tachycardia initiated by premature extrasystoles originating from the right ventricular outflow tract.
      ).

      2.1.2 VT and VF During ACS

      Approximately half of patients with out-of-hospital cardiac arrest with the first rhythm identified as VF and who survive to hospital admission have evidence of acute MI (AMI) (
      • Dumas F.
      • Cariou A.
      • Manzo-Silberman S.
      • et al.
      Immediate percutaneous coronary intervention is associated with better survival after out-of-hospital cardiac arrest: insights from the PROCAT (Parisian Region Out of hospital Cardiac ArresT) registry.
      ). Of all out-of-hospital cardiac arrests, >50% will have significant coronary artery lesions on acute coronary angiography (
      • Dumas F.
      • Cariou A.
      • Manzo-Silberman S.
      • et al.
      Immediate percutaneous coronary intervention is associated with better survival after out-of-hospital cardiac arrest: insights from the PROCAT (Parisian Region Out of hospital Cardiac ArresT) registry.
      ). Of patients hospitalized with AMI, 5% to 10% have VF or sustained VT prior to hospital presentation, and another 5% will have VF or sustained VT after hospital arrival, most within 48 hours of admission. A study of patients with non–ST-elevation ACS who underwent cardiac catheterization within 48 hours found VT/VF in 7.6% of patients, with 60% of those events within 48 hours of admission (
      • Gupta S.
      • Pressman G.S.
      • Figueredo V.M.
      Incidence of, predictors for, and mortality associated with malignant ventricular arrhythmias in non-ST elevation myocardial infarction patients.
      ). Accelerated idioventricular rhythm is a common arrhythmia in patients with acute MI, including patients with ST-segment elevation MI undergoing primary percutaneous coronary intervention (PCI). Accelerated idioventricular rhythm is more closely related to the extent of infarction than to reperfusion itself (
      • Terkelsen C.J.
      • Sorensen J.T.
      • Kaltoft A.K.
      • et al.
      Prevalence and significance of accelerated idioventricular rhythm in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention.
      ).
      Sustained VA that occurs in the setting of an ACS is more often polymorphic VT or VF than monomorphic VT. Risk factors for VT/VF include prior history of hypertension, prior MI, ST-segment changes at presentation, and chronic obstructive pulmonary disease (
      • Al-Khatib S.M.
      • Granger C.B.
      • Huang Y.
      • et al.
      Sustained ventricular arrhythmias among patients with acute coronary syndromes with no ST-segment elevation: incidence, predictors, and outcomes.
      ). A nationwide Danish study found that 11.6% of patients with ST-segment elevation MI who underwent PCI had VF prior to the PCI, and that VF was associated with alcohol consumption, preinfarction angina, anterior infarct location, and complete coronary occlusion at the time of coronary angiography (
      • Jabbari R.
      • Engstrom T.
      • Glinge C.
      • et al.
      Incidence and risk factors of ventricular fibrillation before primary angioplasty in patients with first ST-elevation myocardial infarction: a nationwide study in Denmark.
      ). In a select group of patients undergoing primary PCI in a clinical trial, 5.7% developed sustained VT or VF, with two thirds of these events occurring prior to the end of the catheterization, and 90% within 48 hours from the procedure. VT or VF after primary PCI was associated with lower blood pressure, higher heart rate, poor coronary flow at the end of the procedure, and incomplete resolution of ST elevation (
      • Mehta R.H.
      • Starr A.Z.
      • Lopes R.D.
      • et al.
      Incidence of and outcomes associated with ventricular tachycardia or fibrillation in patients undergoing primary percutaneous coronary intervention.
      ). Importantly, and in contrast to some earlier studies, VT or VF at any time was associated with a substantially higher risk of death within 90 days. Late VT or VF (after 48 hours of hospital presentation) was associated with a higher risk of death than early VT or VF (within 48 hours of hospital presentation) (
      • Volpi A.
      • Cavalli A.
      • Franzosi M.G.
      • et al.
      One-year prognosis of primary ventricular fibrillation complicating acute myocardial infarction. The GISSI (Gruppo Italiano per lo Studio della Streptochinasi nell’Infarto miocardico) investigators.
      ).

      2.1.3 Sustained VT and VF Not Associated With ACS

      Patients with structural heart disease are at an increased risk for sustained VT and VF. Sustained VT that is not associated with an ACS is often monomorphic as it is usually due to scar-related reentry, but it may degenerate to VF (
      • El-Sherif N.
      • Smith R.A.
      • Evans K.
      Canine ventricular arrhythmias in the late myocardial infarction period. 8. Epicardial mapping of reentrant circuits.
      ). The risk and predictors of VT in patients with structural heart disease depend on the type, severity, and duration of structural heart disease, increasing with the severity of ventricular dysfunction and the presence of symptomatic HF. Monomorphic VT occurring in the absence of structural heart disease is commonly referred to as idiopathic VT and is often due to an automatic focus in a characteristic location, giving rise to typical electrocardiographic appearances. Polymorphic VT and VF occurring in the absence of structural heart disease are rare and may be due to a cardiac channelopathy (
      • Ackerman M.J.
      • Priori S.G.
      • Willems S.
      • et al.
      HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies: this document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA).
      ,
      • Nannenberg E.A.
      • Sijbrands E.J.
      • Dijksman L.M.
      • et al.
      Mortality of inherited arrhythmia syndromes: insight into their natural history.
      ), medication-induced long QT syndrome (
      • Nannenberg E.A.
      • Sijbrands E.J.
      • Dijksman L.M.
      • et al.
      Mortality of inherited arrhythmia syndromes: insight into their natural history.
      ), or they may be idiopathic (
      • Haïssaguerre M.
      • Shah D.C.
      • Jais P.
      • et al.
      Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation.
      ,
      • Haïssaguerre M.
      • Shoda M.
      • Jais P.
      • et al.
      Mapping and ablation of idiopathic ventricular fibrillation.
      ).

      2.2 Sudden Cardiac Death

      2.2.1 Incidence of SCD

      SCA and its most common consequence, SCD, constitute major public health problems, accounting for approximately 50% of all cardiovascular deaths (
      • Myerburg R.J.
      • Junttila M.J.
      Sudden cardiac death caused by coronary heart disease.
      ,
      • Goldberger J.J.
      • Buxton A.E.
      • Cain M.
      • et al.
      Risk stratification for arrhythmic sudden cardiac death: identifying the roadblocks.
      ), with at least 25% being first symptomatic cardiac events (
      • Myerburg R.J.
      • Junttila M.J.
      Sudden cardiac death caused by coronary heart disease.
      ,
      • Fishman G.I.
      • Chugh S.S.
      • DiMarco J.P.
      • et al.
      Sudden cardiac death prediction and prevention: report from a National Heart, Lung, and Blood Institute and Heart Rhythm Society Workshop.
      ,
      • Myerburg R.J.
      Sudden cardiac death: exploring the limits of our knowledge.
      ). In addition, analyses of the magnitude of SCD are limited, in part because of the broad range of estimates of the risk based on different epidemiological methods (
      • Kong M.H.
      • Fonarow G.C.
      • Peterson E.D.
      • et al.
      Systematic review of the incidence of sudden cardiac death in the United States.
      ). During the past 20 to 30 years, SCD accounted for approximately 230,000 to 350,000 deaths per year in the United States, with a range of <170,000 to >450,000, depending on epidemiological methods, data sources, and inclusion criteria (
      • Myerburg R.J.
      Sudden cardiac death: exploring the limits of our knowledge.
      ,
      • Mozaffarian D.
      • Benjamin E.J.
      • Go A.S.
      • et al.
      Heart disease and stroke statistics—2016 update: a report from the American Heart Association.
      ). The lowest of these extremes came from national extrapolation of data from specific local programs, while the highest rates included noncardiac causes of sudden death such as pulmonary embolism or intracranial bleeding. The mid-range numbers were largely based on death certificate studies that required a code inclusive of ischemic heart disease.
      The 2017 update of cardiovascular statistics from the AHA estimated the total annual burden of out-of-hospital cardiac arrest at 356,500 (
      • Benjamin E.J.
      • Blaha M.J.
      • Chiuve S.E.
      • et al.
      Heart disease and stroke statistics—2017 update: a report from the American Heart Association.
      ). An additional 209,000 in-hospital cardiac arrests occur annually (
      • Merchant R.M.
      • Yang L.
      • Becker L.B.
      • et al.
      Incidence of treated cardiac arrest in hospitalized patients in the United States.
      ). Among the out-of-hospital cardiac arrest group, approximately 357,000 events trigger emergency rescue response, with 97% occurring in adults >18 years of age.
      The survival statistics for out-of-hospital cardiac arrest remain disappointing, with an estimated 10% overall survival rate (
      • Benjamin E.J.
      • Blaha M.J.
      • Chiuve S.E.
      • et al.
      Heart disease and stroke statistics—2017 update: a report from the American Heart Association.
      ). Among the subgroup of 70% of out-of-hospital cardiac arrests that occur in the home, survival is 6%. The best reported outcomes are from locations with highly developed and publicly visible emergency rescue response, along with the combination of public location of cardiac arrest, bystander witnesses willing to provide CPR, first responders arriving quickly, shockable rhythm at initial contact, availability of automated external defibrillators (AEDs), and possibly a benefit from telecommunication-directed CPR (
      Institute of Medicine
      Committee on the Treatment of Cardiac Arrest: Current Status and Future Directions: Strategies to improve cardiac arrest survival: a time to act.
      ,
      • Jollis J.G.
      • Granger C.B.
      Improving care of out-of-hospital cardiac arrest: next steps.
      ). Survival to hospital discharge after in-hospital cardiac arrests is estimated to be 24% (

      Daya MR, Schmicker R, May SH, et al. Current burden of cardiac arrest in the United States: report from the Resuscitation Outcomes Consortium. Paper commissioned by the Committee on the Treatment of Cardiac Arrest: Current Status and Future Directions. 2015.

      ). In all settings, survival statistics appear to be better when rhythms recorded by responders are shockable (VF, pulseless VT), compared with pulseless electrical activity or asystole (
      • Myerburg R.J.
      • Halperin H.
      • Egan D.A.
      • et al.
      Pulseless electric activity: definition, causes, mechanisms, management, and research priorities for the next decade: report from a National Heart, Lung, and Blood Institute workshop.
      ). Although the apparent increase in the incidence of pulseless electrical activity or asystole could be due to the later arrival of medical care, the decrease in the incidence of shockable rhythm has also been attributed, in part, to improvements in diagnosis and treatment of structural heart disease (
      • Fishman G.I.
      • Chugh S.S.
      • DiMarco J.P.
      • et al.
      Sudden cardiac death prediction and prevention: report from a National Heart, Lung, and Blood Institute and Heart Rhythm Society Workshop.
      ).

      2.2.2 Population Subgroups and Risk Prediction

      Risk prediction for SCA and SCD is complex. Risk analysis is divided into 2 general categories: population risk prediction and individual risk prediction (
      • Myerburg R.J.
      Sudden cardiac death: exploring the limits of our knowledge.
      ,
      • Myerburg R.J.
      • Goldberger J.J.
      Sudden cardiac arrest risk assessment: population science and the individual risk mandate.
      ). Conventional epidemiological markers provide insight into probabilities for the development of ischemic heart disease within a general class of subjects, but adequately tested and validated profiles for SCA risk stratification of individuals in the general population do not presently exist. The challenge of defining SCA risk in individuals derives from a population model characterized by large numbers of events diluted into a very large denominator (Figure 1A, Figure 1B). The overall population can be subgrouped into categories based on integration of age, presence and extent of disease, and identification of small, high-risk subgroups within the large denominator general population.
      Figure thumbnail gr1a
      Figure 1ASCD Incidence and Total Events
      (
      • Myerburg R.J.
      • Junttila M.J.
      Sudden cardiac death caused by coronary heart disease.
      )
      . EF = ejection fraction; SCD = sudden cardiac death.
      Figure thumbnail gr1b
      Figure 1BSCD and Clinical Subsets
      (
      • Myerburg R.J.
      • Junttila M.J.
      Sudden cardiac death caused by coronary heart disease.
      )
      . SCD = sudden cardiac death.
      Increasing age is a strong predictor of risk for SCA, but it is not linear. Risk in the general population, over time, beginning at 35 years of age has been estimated at 1 per 1000 population per year, increasing from a risk <1000 at the younger end of that spectrum to a higher risk in the elderly (
      • Myerburg R.J.
      Sudden cardiac death: exploring the limits of our knowledge.
      ). However, an analysis of lifetime risk of SCD, derived from the Framingham data, suggested that the incidence of SCD decreases in later years, especially in people >75 years of age (
      • Bogle B.M.
      • Ning H.
      • Mehrotra S.
      • et al.
      Lifetime risk for sudden cardiac death in the community.