Cardiac resynchronization therapy (CRT) and implantable cardioverter-defibrillators (ICD) are effective therapies for heart failure (HF) patients with cardiac dyssynchrony. Patients receiving primary prevention CRT-D that positively remodel may no longer qualify for ICD indication due to CRT induced left ventricular ejection fraction (LVEF) improvement.

We aimed to evaluate the outcome of CRT-D patients at the time of device replacement (DR). Methods: Patients undergoing primary prevention CRT-D DR were prospectively included from November 2007 to March 2011 in two centers. CRT response was as a ≥1 NYHA class improvement and an increase in LVEF ≥10%. Six months before DR, all patients underwent echocardiography and device interrogation. Patients without theoretical ongoing ICD indication (TOII) at DR were defined as those with LVEF ≥40% without appropriate ICD therapy (AT) during the first ICD service-life.

A total of 107 consecutive patients were enrolled. Sixty-one patients (57%) were considered CRT responders after the index procedure. At the time of DR (56.4±14.4 months from initial implant), 87% of CRT responders were free of AT, compared with 70% of non CRT-responders (p=0.02). Thirty-nine patients (36%) did not meet the criteria for TOII. During follow-up (mean 26.4±14.4 months after DR) 37 patients (95%) without TOII were free of AT versus 49 of 68 patients (72%) with ongoing TOII (p=0.007). By multivariable analysis the only independent predictor of AT after DR was TOII (hazard ratio=6.43;p=0.01).

Absence of theoretical ICD indication occurs in more than one third of CRT-D patients undergoing DR. In addition AT rate is relatively low (2.2%/year) in this subgroup of patients.