PO-707-07 SUDDEN CARDIAC DEATH AND APPROPRIATE DEFIBRILLATOR THERAPIES IN PATIENTS WITH IMPROVED EJECTION FRACTION >35%

Implantable cardioverter-defibrillators (ICDs) and CRT-defibrillator (CRT-D) improve survival in indicated patients with left ventricular ejection fraction (LVEF) less than 35%. Approximately 75% of patients with ICD implantation for primary prevention do not experience an appropriate ICD Tachyarrhythmia Therapy (ITT) in the initial generator lifespan. The role of continued arrhythmia monitoring and therapies(and need for generator change) in those with improved left ventricular ejection fraction(LVEF) is not well studied. Evaluation of rates of ITT and incidence of sudden cardiac death(SCD) among patients with improved LVEF>35% after defibrillator placement. A retrospective study of patients who underwent CRT-D and ICD implantation for primary prevention was done. Patients >18 years of age with ischemic(ICM) or non-ischemic cardiomyopathy(NICM) with an initial EF<35%, and who had an improvement in LVEF post-implantation were included. Patients whose LVEF remained <35% after implantation were excluded. We stratified the patients based on their improved EF, as 36-45%, 46-55%, and >55%, respectively. Of 337 patients evaluated, LVEF improved >35% in 79 patients. The mean age for the study population was 59 ± 15 years; NICM was the etiology for heart failure in 65.8% of patients. Over a median follow-up of 73 months, LVEF improved to 36-45% in 44 patients, 46-55% in 25 patients, and > 55% in 10 patients. Eight patients died during the follow-up; none from sudden cardiac death. Overall, patients with NICM received more appropriate therapies than ICM patients. Of 41 ITT events in NICM, 85% occurred in patients before EF improvement >35% (OR 8.0,95% CI: 1.12-56.79). 60% of the ITT events in ICM group were observed before EF improved >35%. Patients with NICM whose EF improved to >45 % were more likely to receive inappropriate than appropriate therapies. No events were reported in either NICM or ICM groups after LVEF improvement beyond 55%(Table 1). Among patients who receive an ICD for primary prevention, most events occurred before EF improvement. Among patients with NICM, patients experienced only inappropriate therapies once their EF improved >45%. Larger prospective studies are needed to evaluate the necessity of ICD generator change in this subgroup.