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B-PO05-210 PREMATURE ATRIAL DEPOLARIZATION WITH ABERRANT CONDUCTION TRIGGERING VENTRICULAR FIBRILLATION

      Background

      Premature atrial contractions are common and usually benign. However, they are rarely documented to trigger ventricular fibrillation (VF).

      Objective

      1. Describe a case of a patient with recurrent VF triggered by premature atrial contractions (PACs). 2. Describe our management approach.

      Methods

      N/A

      Results

      We present a 77 year old male with history of inferior myocardial infarction, coronary artery bypass grafting, and dual chamber implantable cardiac defibrillator (ICD) who presented with an episode of presyncope. Vital statistics and basic labs were normal in the emergency department. ECG showed an atrial-paced rhythm, inferior Q waves but otherwise normal QRS duration and normal QTc. Frequent PACs were noted, each with left bundle branch block aberrancy (LBBA). ICD interrogation revealed multiple episodes of defibrillation-terminated VF, each beginning with a PAC. Clinical PACs had the same ventricular aberrancy ICD EGM morphology as those triggering VF. His home Coreg dose was increased without improvement in PAC frequency. After discussion with the patient, we decided to proceed with EP study and ablation. In the EP lab, sedated, paced PACs from different locations demonstrated LBBA but did not trigger VF. PACs mapped to the anterior right atrium. Ablation in and around this region successfully eliminated the PACs. (figure 1A, B, C and D). No further PACs were observed during his hospitalization and no further VF episodes have occurred since discharge.

      Conclusion

      We hypothesize that in our case, VF was triggered by aberrantly conducted PAC which induced bundle branch reentry and degenerated into VF, in the presence of arrhythmogenic substrate.
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