Predictors and outcomes of cardiac resynchronization therapy extended to the second generator

Abstract

A proportion of patients who receive cardiac resynchronization therapy with defibrillator (CRT-D) live to receive a second generator. Controversy exists on whether an implantable cardioverter-defibrillator (ICD) should be offered to patients who have normalized or near-normalized left ventricular ejection fraction (LVEF) at the time of generator replacement (GR). The purpose of this study was to evaluate incidence of appropriate ICD therapy after CRT-D GR. This series involved 1026 consecutive patients who underwent CRT-D implant between January 1, 2002 and December 31, 2012. Echocardiography was assessed before the initial device implant and before GR. ICDs were monitored at our device clinic in person or remotely, or both. Of the cohort, 227 patients (22.1%) underwent CRT-D GR at our institution. Approximately 48% of the patients who received new CRT-D generators were no longer meeting the guidelines indication for ICD use at the time of GR. These patients received subsequent appropriate ICD therapies at a significantly lower rate than those with LVEF <35% (12% vs 35%; P < .001). Of these patients, 47 (20.7%) had LVEF improvement to ≥50% at the time of GR. ICD therapy for ventricular arrhythmia in the ischemic group was 18.2%, while no patient in the nonischemic group received ICD therapy from the second generator after GR. Improvement in LVEF after CRT-D GR is associated with significantly reduced incidence of appropriate ICD therapy. Ventricular arrhythmia is less likely to develop with normalized LVEF in nonischemic cardiomyopathy.