Effect of QRS Morphology and Duration on Clinical Outcomes After Cardiac Resynchronization Therapy　― Analysis of Japanese Multicenter Registry

Background:QRS duration (QRSd) and morphology are established response predictors of cardiac resynchronization therapy (CRT). However, evidence in Japanese populations is lacking.Methods and Results:We retrospectively analyzed the Japanese multicenter CRT database. We divided patients according to their intrinsic QRSd and morphology, and assessed echocardiographic responses and clinical outcomes. The primary endpoint was a composite of all-cause death or hospitalization because of heart failure. A total of 510 patients were enrolled: 200 (39%) had left bundle branch block (LBBB) and QRSd ≥150 ms; 80 (16%) had LBBB (QRSd: 120–149 ms); 61 (12%) had non-LBBB (NLBBB) (QRSd: ≥150 ms); 54 (11%) had NLBBB (QRSd: 120–149 ms); 115 (23%), narrow (