Prognostic implications of increased QRS duration in patients with moderate and severe left ventricular systolic dysfunction.

Survival analysis was performed on a cohort of 2,265 patients with left ventricular ejection fraction of </= 40% to investigate the effect of increased QRS duration on all-cause mortality. Presence of QRS prolongation independently predicted higher mortality in patients with left ventricular systolic dysfunction. This finding may have important prognostic and therapeutic implications in this patient population.