Influence of left bundle branch block on long-term mortality in a population with heart failure.

BACKGROUND The purpose of this study was to assess the independent contribution of left bundle branch block (LBBB) on long-term mortality in a large cohort with symptomatic heart failure (HF) requiring hospitalization. METHODS AND RESULTS We studied a prospective cohort of 21 685 cases of symptomatic HF requiring hospitalization in the Register of Information and Knowledge about Swedish Heart Intensive care Admissions in 1995-2003. Long-term mortality was evaluated by Logistic regression analysis, adjusted for multiple covariates that could influence long-term prognosis. LBBB was present in 20% (4395 of 21 685) of HF admissions. Patients with LBBB had a higher prevalence of cardiac comorbid conditions than patients with no LBBB. 1-, 5-, and 10-year mortality was 31.5 vs. 28.4%, 69.3 vs. 61.3%, and 90.1 vs. 84.7% for HF patients with and without respectively LBBB. When adjusting for comorbidity, LBBB was associated with increased 5-year mortality (OR, 1.21; 95% CI, 1.10-1.35; P < 0.001). When left ventricular ejection fraction was included in the analysis LBBB had no longer any independent influence on 5-mortality (OR, 0.99; 95% CI, 0.62-1.56; P = 0.953). CONCLUSION LBBB occurs in 1/5 in HF patients requiring hospitalization and is associated with a very high mortality. However, the high long-term mortality appears to be caused by cardiac comorbidities and myocardial dysfunction rather than the LBBB per se.