Abstract 14731: T-wave Oversensing Secondary to an Inappropriate ICD Shock Resulting in Subsequent Unnecessary Shocks

Abstract

Introduction: Inappropriate ICD shocks commonly result from persistent atrial arrhythmias or oversensing. We report a scenario where an ICD shock for a rapid, sustained atrial tachycardia (AT) resulted in T-wave oversensing (TWO), triggering further inappropriate shocks. Presentation: A 69-year-old woman with secondary prevention dual chamber ICD underwent pulmonary vein isolation for symptomatic paroxysmal atrial fibrillation (AF). The patient remained free of AT/AF off antiarrhythmics for 3 months after the procedure when she was admitted with four consecutive ICD shocks. Electrolytes were within normal limits. Device interrogation showed that the first shock was triggered by a rapid, sustained AT (cycle length: 270 msec) detected in the VF zone (single zone device; 280 msec cut-off) and failed ATP. Following the first shock, an irregular AT ensued, with cycle length ranging from 280-370 msec, but now with high amplitude T-waves in the RV channel, resulting in TWO and three subsequent inappropriate shocks (Figure). She received IV metoprolol and digoxin with subsequent resolution of AT and TWO. Beta-blocker dosing was increased and she has remained free of AT/AF at 6 month follow-up. Conclusions: ICD shocks can trigger marked repolarization changes in near-field intracardiac RV electrograms resulting in TWO and subsequent appropriate shocks. Further studies are warranted to understand the mechanism underlying this phenomenon and potential risk for these events.