Improvements in pharmacological treatments and cardiac resynchronization therapy (CRT) raise questions about the benefit of implantable cardioverter defibrillators (ICDs) in non-ischaemic dilated cardiomyopathy (NI-DCM). In this context, the long-term incidence of ventricular arrhythmia events (VAEs) by response to CRT remains under-reported.

To assess the long-term risk of VAE by response to CRT in patients with NI-DCM.

Patients who underwent CRT-defibrillator (CRT-D) implantation for primary prevention of NI-DCM (left ventricular ejection fraction [LVEF]≤35%, bundle branch block>130ms) from February 2002 to January 2020 were retrospectively included. CRT response was defined as an increase in LVEF≥10%, with LVEF≥35% at first transthoracic echocardiography (TTE) evaluation. VAE was defined as a sudden arrhythmic death, sustained ventricular arrhythmia or device-treated ventricular arrhythmia, occurring after the first TTE evaluation.

A total of 192 patients (mean age 61years, 68% female, mean LVEF 25%) were included and followed for a median of 91months. Median time to first TTE evaluation after CRT-D implantation was 14months. The overall incidence of VAE was 18.8% (annual rate of 2.9%). CRT response was associated with a reduced risk of VAE (hazard ratio [HR]: 0.27, 95% CI: 0.14–0.55; P<0.001). Super responders to CRT had a lower risk of VAE compared to partial responders (HR: 0.06, 95% CI: 0.02–0.17; P<0.001). Among responders who were VAE free before generator replacement, super responders exhibited a lower incidence of VAE compared to partial responders (HR: 0.13, 95% CI: 0.02–0.82; P=0.04) after generator replacement.

In patients with NI-DCM undergoing CRT-D implantation for primary prevention, the CRT response was associated with a 73% decrease in the risk of VAE. Partial responders present a higher rate of VAE compared to super responders, persisting after generator replacement.