Abstract 4370764: Single Chamber (Right Atrial) Leadless Pacemaker to Prevent Ventricular Tachycardia

Introduction: Sudden changes in ventricular cycle lengths (or short-long-short [S-L-S] sequences) can initiate polymorphic ventricular tachycardia (VT). This pattern involves a premature ventricular beat (PVC), followed by a compensatory pause and subsequent premature beat. The compensatory pause leading to the long cycle is followed by a prolonged repolarization phase. Suppressing S-L-S sequences with anti-bradycardic pacing may prevent polymorphic VT in at-risk patients. Herein we describe a case of a patient being treated for fungal endocarditis who developed recurrent VT storm in whom anti-bradycardia pacing via a single-chamber right atrial pacemaker prevented further sustained VT episodes. Case: A 69-year-old patient with fungal bioprosthetic aortic valve endocarditis developed sustained VT, for which he was successfully resuscitated. He was prescribed a secondary prevention wearable defibrillator lifevest on discharge, but over a 2-week period the patient received 6 appropriate shocks by his wearable defibrillator for polymorphic and monomorphic VT episodes despite treatment with multiple anti-arrhythmic agents. In-patient telemetry identified S-L-S sequence preceding the VT episodes. Subsequently, a single chamber right atrial leadless pacemaker was placed and programmed to pace at eighty beats per minute. At 8 weeks post-implant, he experienced no further VT episodes (non-sustained or sustained). Discussion: Due to ongoing treatment for fungemia, placement of a transvenous pacing/defibrillator system was a relative contraindication, due to high risk for cardiac device infection. While a subcutaneous ICD could have been implanted with less infectious risk, it does not have pacing function, and would not have prevented further VT episodes. Conclusion: This case highlights a unique management strategy utilizing anti-bradycardia pacing via a single chamber right atrial leadless pacemaker to prevent ventricular arrhythmias triggered by S-L-S sequences when other treatment options were less plausible.