Reduction in the QRS area after cardiac resynchronization therapy is associated with survival and echocardiographic response

Introduction Recent studies have shown that the baseline QRS area is associated with the clinical response after cardiac resynchronization therapy (CRT). In this study, we investigated the association of QRS area reduction (∆QRS area) after CRT with the outcome. We hypothesize that a larger ∆QRS area is associated with a better survival and echocardiographic response. Methods and Results Electrocardiograms (ECG) obtained before and 2–12 months after CRT from 1299 patients in a multi‐center CRT‐registry were analyzed. The QRS area was calculated from vectorcardiograms that were synthesized from 12‐lead ECGs. The primary endpoint was a combination of all‐cause mortality, heart transplantation, and left ventricular (LV) assist device implantation. The secondary endpoint was the echocardiographic response, defined as LV end‐systolic volume reduction ≥ of 15%. Patients with ∆QRS area above the optimal cut‐off value (62 µVs) had a lower risk of reaching the primary endpoint (hazard ratio: 0.43; confidence interval [CI] 0.33–0.56, p