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 (<120 ms). The proportion of echocardiographic responders was higher in LBBB (QRSd ≥150 ms) [74% vs. 51% vs. 38% vs. 52% vs. 50%, LBBB (QRSd ≥150 ms) vs. LBBB (QRSd 120-149 ms) vs. NLBBB (QRSd ≥150 ms) vs. NLBBB (QRSd 120-149 ms) vs. narrow, respectively, P<0.001]. During follow-up (3.2±1.5 years), the incidence of the primary endpoint was lowest in the LBBB group (QRSd ≥150) (28.6% vs. 42.3% vs. 45.9% vs. 55.6% vs. 55.3%, respectively, P<0.001). This difference was still significant after adjusting for other baseline characteristics.

CONCLUSIONS

In this Japanese patient population, LBBB intrinsic QRS morphology and prolonged QRSd (≥150 ms) exhibited the best response to CRT.