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Are intracardiac defibrillator electrogram recordings of triggering ectopy the key to successful ablation of polymorphic ventricular tachycardia/ventricular fibrillation?

  • Dipen Shah
    Correspondence
    Address reprint requests and correspondence: Dr Dipen C. Shah, Cardiology Division, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205 Geneva, Switzerland.
    Affiliations
    Cardiology Division, Geneva University Hospitals, Geneva, Switzerland
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Published:November 25, 2021DOI:https://doi.org/10.1016/j.hrthm.2021.11.024
      Current guidelines recommend catheter ablation of reproducible stereotypic triggering ventricular ectopy for suppressing polymorphic ventricular tachycardia/ventricular fibrillation (PMVT/VF), both idiopathic, and in the setting of structural heart disease.
      • Cronin E.M.
      • Bogun F.M.
      • Maury P.
      • et al.
      2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias.
      Short coupled ventricular premature complexes (VPCs) with a coupling interval of 200–400 ms, typically with an “R on T” wave appearance, were first documented to reproducibly trigger PMVT either nonsustained or degenerating into VF in 1981.
      • Belhassen B.
      • Pelleg A.
      • Miller H.I.
      • Laniado S.
      Serial electrophysiological studies in a young patient with recurrent ventricular fibrillation.
      An idiopathic PMVT/VF cohort, with a dominantly characteristic triggering VPC was first described by Leenhardt et al in 1994.
      • Leenhardt A.
      • Glaser E.
      • Burguera M.
      • Nürnberg M.
      • Maison-Blanche P.
      • Coumel P.
      Short-coupled variant of torsade de pointes: a new electrocardiographic entity in the spectrum of idiopathic ventricular tachyarrhythmias.
      Haïssaguerre
      • Haïssaguerre M.
      • Shah D.C.
      • Jaïs P.
      • et al.
      Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation.
      provided the key pathophysiological insight by recognizing the predominantly Purkinje fiber origin of these short coupled VPCs. Triggered activity is thought to be the underlying mechanism, because of abnormalities in calcium handling or of ryanodine receptors. These patients most often present malignant arrhythmias in intermittent temporally widely separated bursts, typically preceded and followed by frequent VPCs, in couplets, triplets, or even nonsustained PMVT/VF. Mapping (and ablation) of these triggers is therefore most successful when performed in the immediate aftermath (within about 72 hours). Outside this temporal bracket around the index arrhythmic event, spontaneous ventricular ectopy tends to be scarce and even extensive provocative maneuvers are often unsuccessful in eliciting the target short coupled ectopy during the electrophysiology procedure. In this not uncommon situation, pace mapping is used to localize the VPC source on the basis of previously recorded 12-lead electrocardiograms (ECGs). In our experience, even with a properly recorded ECG (with correct reproducible precordial electrode placement), multiple closely spaced radiofrequency lesions in a 1–2 cm2 area around the best pace-map match are required. This is understandable given the underlying limitations of pace mapping, which include the unknowns of anodal vs cathodal capture, the amplitude and contact dependent variability of virtual electrode dimensions, as well as the imprecisions of surface ECG electrode positioning. In the absence of spontaneous and provoked short coupled ventricular ectopy, intracardiac electrograms (EGMs) from the implanted defibrillator are the last resort source of ectopy localizing electrical information. Intracardiac defibrillator (ICD)–sensed EGMs are routinely used for aiding discrimination of supraventricular from VT, for withholding inappropriate shocks due to oversensing, and for regulating cardiac resynchronization therapy device function but have also been shown to be capable of distinguishing the “clinical” VT from other induced “nonclinical” ones.
      • Almendral J.
      • Atienza F.
      • Everss E.
      • Castilla L.
      • et al.
      Implantable defibrillator electrograms and origin of left ventricular impulses: an analysis of regionalization ability and visual spatial resolution.
      The signal from the wide bipole between the right ventricular coil/tip and the ICD likely has a larger receptive field than does a near-field tip to ring bipole EGM and can be considered to have localizing information similar to a surface ECG—albeit limited to a single lead. Like the surface ECG, this wide bipole “far-field” EGM does require the high-pass filter setting to be close to flat to suppress baseline wander without eliminating low-frequency QRST distinguishing features (0.05–0.5 Hz).
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      References

        • Cronin E.M.
        • Bogun F.M.
        • Maury P.
        • et al.
        2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias.
        Europace. 2019; 21: 1143-1144
        • Belhassen B.
        • Pelleg A.
        • Miller H.I.
        • Laniado S.
        Serial electrophysiological studies in a young patient with recurrent ventricular fibrillation.
        Pacing Clin Electrophysiol. 1981; 4: 92-99
        • Leenhardt A.
        • Glaser E.
        • Burguera M.
        • Nürnberg M.
        • Maison-Blanche P.
        • Coumel P.
        Short-coupled variant of torsade de pointes: a new electrocardiographic entity in the spectrum of idiopathic ventricular tachyarrhythmias.
        Circulation. 1994; 89: 206-215
        • Haïssaguerre M.
        • Shah D.C.
        • Jaïs P.
        • et al.
        Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation.
        Lancet. 2002; 359: 677-678
        • Almendral J.
        • Atienza F.
        • Everss E.
        • Castilla L.
        • et al.
        Implantable defibrillator electrograms and origin of left ventricular impulses: an analysis of regionalization ability and visual spatial resolution.
        J Cardiovasc Electrophysiol. 2012; 23: 506-514
        • Salazar P.
        • Beaser A.
        • Upadhyay G.
        • et al.
        Empiric ablation of polymorphic ventricular tachycardia/fibrillation in the absence of a mappable trigger: prospective feasibility and efficacy of pace map matching to defibrillator electrograms.
        Heart Rhythm. 2021; (XX:XX–XX)
        • Lowery C.M.
        • Tzou W.S.
        • Aleong R.G.
        • et al.
        Use of stored implanted cardiac defibrillator electrograms in catheter ablation of ventricular fibrillation.
        Pacing Clin Electrophysiol. 2013; 36: 76-85
        • Shah D.
        Can an epicardially exiting VT be discerned from inside the heart?.
        J Cardiovasc Electrophysiol. 2019; 30: 1407-1409

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