Intraventricular conduction defects in patients with congestive heart failure: left but not right bundle branch block is an independent predictor of prognosis. A report from the Italian Network on Congestive Heart Failure (IN-CHF database).

Background: In industrialized countries the prevalence of congestive heart failure (CHF) is increasing. Many clinical factors have been shown to influence the prognosis of CHF. The effect of a wide QRS on mortality is debated; while left bundle branch block (LBBB) has been already identified as a negative prognostic factor, the effect of right bundle branch block (RBBB) is still unknown. The aim of this study was to compare the association of these two intraventricular conduction defects on the prognosis of CHF.

Methods: Data were derived from the Italian Registry of CHF. Entry in the Registry required that patients had a diagnosis of CHF based on the European Society of Cardiology guidelines. We analyzed the 1-year follow-up data of 5517 outpatients with CHF of different etiologies. The presence of a wide QRS was defined if the duration was > 120 ms.

Results: A wide QRS was present in 2066 patients (37.5%), 25.2% with LBBB, 6.1% with RBBB, 6.2% with other intraventricular defects. At univariate analysis patients with complete LBBB had a significantly higher 1-year mortality than those without (16.1 vs 11.9%) but this was not true for complete RBBB (11.9 vs 11.9%). Even after multivariate adjustment, complete LBBB still remained an independent predictor of death (relative risk 1.36, 95% confidence interval 1.15-1.61).

Conclusions: LBBB but not RBBB is an independent predictor of death in CHF.