Arrhythmic Risk Following Recovery of Left Ventricular Ejection Fraction in Patients with Primary Prevention ICD.

BACKGROUND: Left ventricular ejection fraction (LVEF) recovers during follow-up in a significant proportion of patients implanted with a cardioverter defibrillator (ICD) for primary prevention. Little is known about the midterm arrhythmic risk in this population, particularly in relation to the presence or absence of ischemic cardiomyopathy. METHODS AND RESULTS: We retrospectively analyzed 286 patients with an ICD implanted for primary prevention between 2002 and 2010. Patients were divided into two groups based on their last LVEF assessment: (1) Recovery, defined as an LVEF > 35%; and (2) No-Recovery, defined as an LVEF ≤ 35%. Kaplan-Meir curves and multivariate Cox regression analysis were performed separately for patients with ischemic (211 patients) and nonischemic (75 patients) cardiomyopathy. Forty-nine patients (17.1%) had LVEF recovery to >35% at last follow-up. Overall, 72 patients (25.2%) experienced ventricular arrhythmias requiring ICD therapy during a median follow-up of 4.4 years. With multivariate Cox regression, LVEF recovery was associated with a lower arrhythmic risk in the whole cohort (hazard ratio [HR]: 0.38 [0.13-0.85]; P = 0.02) and in the nonischemic cardiomyopathy cohort (HR: 0.10 [0.005-0.55]; P = 0.005), but not in the ischemic cardiomyopathy cohort (HR: 0.84 [0.25-2.10]; P = 0.74). CONCLUSION: In conclusion, patients with nonischemic cardiomyopathy who improved their LVEF to >35% after primary prevention ICD implantation were at very low absolute arrhythmic risk. Our study raises the possibility that the LVEF cutoff to safely withhold ICD replacement might be higher in patients with ischemic compared to nonischemic cardiomyopathy. This will need to be confirmed in prospective studies.