Prognostic impact of prolonged QRS duration or LBBB morphology on cardiovascular outcomes in chronic heart failure without ventricular pacing or cardiac resynchronization therapy: A systematic review and meta-analysis

BACKGROUND AND AIMS Prolonged QRS duration and left bundle branch block (LBBB) morphology are markers of ventricular dyssynchrony associated with adverse outcomes in chronic heart failure (CHF). Whether these findings independently predict prognosis across heart failure phenotypes without ventricular pacing or cardiac resynchronization therapy (CRT) is uncertain. Therefore, we conducted a systematic review and meta-analysis to address this question. METHODS We searched PubMed, Embase, and Cochrane Library for studies comparing prolonged versus narrow QRS (≥120 ms vs <120 ms) or LBBB versus non-LBBB in CHF without ventricular pacing or CRT. Hazard ratios were pooled using random-effects models. Outcomes included all-cause mortality, cardiovascular death, heart failure hospitalization, sudden cardiac death, and overall survival. RESULTS Eleven studies comprising 83,698 patients were included; 24,963 (30%) had prolonged QRS or LBBB. Prolonged QRS was associated with increased all-cause mortality (HR 1.20; 95% CI 1.13-1.28), cardiovascular death (HR 1.31; 95% CI 1.19-1.44), heart failure hospitalization (HR 1.42; 95% CI 1.33-1.51), and sudden cardiac death (HR 1.38; 95% CI 1.20-1.59). LBBB showed comparable associations across all endpoints, including worse overall survival (HR 1.32; 95% CI 1.28-1.37). Results were consistent across HFrEF; however, all-cause mortality did not reach significance in HFpEF, and LBBB was not associated with worse overall survival in HFmrEF. CONCLUSIONS In CHF patients without ventricular pacing or CRT, prolonged QRS duration and LBBB morphology are independent prognostic markers supporting their use as simple ECG tools for risk stratification across heart failure phenotypes, though associations were weaker in HFpEF and HFmrEF.