Prognostic values of bundle branch blocks for cardiovascular mortality in Japanese (24 year follow-up of NIPPON DATA80)

Aims: Left bundle branch block (LBBB) is generally considered to be associated with a poorer prognosis in comparison with normal controls. However, there are some studies that showed no difference in prognosis of LBBB in comparison with normal controls. Methods and Results: We studied prognostic values of BBBs on cardiovascular disease (CVD) and total mortality using the NIPPON DATA80 database with a 24-year follow-up. At the baseline in 1980, data were collected on study participants, ages 30 years and over, from randomly selected areas in Japan. We followed 9,090 participants (44% men, mean age 51). During the 24 year follow-up, there were 886 CVD, and 2,597 total mortality cases. Among participants, 0.2% of them were in LBBB, 1.3% in RBBB, 4.3% in other ventricular conduction defect (VCD) groups. The multivariate-adjusted hazard ratio (HR) using the Cox model including biochemical and other ECG variables revealed that LBBB was significantly positively associated with CVD (HR = 2.71, 95% confidence intervals [CI]: 1.35-5.45, P = 0.005), and total (HR = 2.07, 95%CI: 1.26-3.39, P = 0.004) mortality in men and women combined compared to participants without VCD. RBBB and other VCDs did not carry any significant risk for CVD or total mortality. Conclusions: We found significant positive associations of LBBB with CVD and total mortality independent of confounding factors including other ECG changes. (C) 2013 Elsevier Inc. All rights reserved.