Super-responders to cardiac resynchronization therapy remain at risk for ventricular arrhythmias and benefit from defibrillator treatment

Aims Mortality and ventricular arrhythmias are reduced in patients responding to cardiac resynchronization therapy (CRT). This response is accompanied by improvement in LVEF, and some patients even outgrow original eligibility criteria for implantable cardioverter‐defibrillator (ICD) implantation. It is however unclear if these patients still benefit from ICD treatment. The current study aimed to evaluate if the incidence of ICD therapy is related to the extent of CRT response. Methods and results All patients who underwent primary prevention CRT‐defibrillator implantation were included. They were divided into subgroups according to the reduction in LV end‐systolic volume (LVESV) 6 months after implantation. Pre‐defined subgroups were: negative responders (increased LVESV), non‐responders (decreased LVESV 0–14%), responders (decreased LVESV 15–29%), and super‐responders (decreased LVESV ≥30%). During a median follow‐up of 57 months (25th–75th percentile 39–84), 512 patients were studied [101 (20%) negative responders, 101 (20%) non‐responders, 149 (29%) responders, and 161 (31%) super‐responders]. In the first year of follow‐up super‐responders received significantly less appropriate ICD therapy (3% vs. 12%; P