Impact of QRS complex duration and morphology on left ventricular reverse remodelling and left ventricular function improvement after cardiac resynchronization therapy

Aims To evaluate the impact of the interaction of QRS duration and morphology on left ventricular (LV) reverse remodelling and LV functional improvement in heart failure (HF) patients treated with cardiac resynchronization therapy (CRT). Methods and results From an ongoing registry of HF patients treated with CRT according to contemporary guidelines, demographic, clinical, electrocardiographic (ECG) and echocardiographic characteristics were analysed. Patients were divided according to QRS duration and morphology: < 150 ms vs. >= 150 ms and left bundle branch block (LBBB) vs. non-LBBB, respectively. Echocardiographic measurements were performed at baseline and at 6 months' follow-up. The effect of the interaction between QRS duration and morphology on LV reverse remodelling and LV ejection fraction (LVEF) was analysed using linear, mixed models. Of 1467 patients (mean age 65 +/- 10 years, 77% male), 884 (60%) had a QRS >= 150 ms and 814 (55%) showed LBBB. The group with QRS >= 150 ms demonstrated larger LV reverse remodelling (mean reduction in LV end-systolic volume 34.3mL vs. 14.8mL; P < 0.001) and improvement in LVEF (mean increase 6.8% vs. 5.2%; P < 0.001) compared with their counterparts. Similarly, patients with LBBB QRS morphology showed greater LV reverse remodelling (mean reduction in LV end-systolic volume 30.8 mL vs. 17.4mL; P < 0.001) and improvement in LVEF (mean increase 6.9% vs. 3.7%; P < 0.001) than those with non-LBBB QRS morphology. Conclusions Left ventricular reverse remodelling and LV functional improvement are greater among HF patients with LBBB morphology and increasing QRS duration who receive CRT.