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.