Who still remains at risk of arrhythmic death at time of implantable cardioverter‐defibrillator generator replacement?

Background Implantable cardioverter‐defibrillator (ICD) is associated with reduction in arrhythmic mortality. However, at the time of generator replacement (GR) some patients had not experienced therapies and had a different clinical profile. Therefore, the risk‐benefit ratio of ICD may have changed. Our aim was to determine the proportion of patients with ICD implanted in primary prevention that maintain guideline‐derived indications at the time of GR and assess predictors of therapies in the postreplacement period. We evaluate the long‐term benefit of ICD after GR in nonischemic cardiomyopathy (NICM) versus ischemic cardiomyopathy (ICM). Methods We included 141 patients undergoing GR from 11/2009 to 7/2015. Patients were divided into: G1 – guideline congruent indication for ICD at the time of GR (left ventricular ejection fraction [LVEF] ≤ 35% or appropriate therapies) and G2 – guideline incongruent indication (patients without appropriate therapies and LVEF >35%). We also compared ICD benefit between ICM and NICM patients. Results Maintenance of guideline‐driven indications for ICD (G1) was present in 68% of patients and 32% had recovery of LVEF and no ICD therapies at the time of GR (G2). After GR, G2 patients showed a lower rate of appropriate therapies (3% vs 33%, P < 0.01). LVEF ≤ 35% was the only independent predictor of appropriate therapies (OR 12.0, P < 0.01). In multivariate analysis, etiology of heart failure did not predict the arrhythmic risk. Conclusion At the time of GR, a significant proportion of patients no longer met guideline indications for ICD and their need for therapies is reduced. The etiology of heart failure did not predict freedom from therapies.