Prognostic values of bundle branch blocks for cardiovascular mortality in Japanese (24 year follow-up of NIPPON DATA80) ☆ Yasuyuki Nakamura, MD, a,b, ⁎ Tomonori Okamura, MD, c Taku Inohara, MD, d Shun Kohsaka, MD, d Makoto Watanabe, MD, e Aya Higashiyama, MD, f Aya Kadota, MD, g Nagako Okuda, MD, h Takayoshi Ohkubo, MD, b Shin-ya Nagasawa, MD, i Katsuyuki Miura, MD, b Akira Okayama, MD, j Hirotsugu Ueshima, MD b,k for the NIPPON DATA 80 Research Group a Cardiovascular Epidemiology, Kyoto Women's University, Kyoto, Japan b Department of Health Science, Shiga University of Medical Science, Otsu, Japan c Department of Preventive Medicine and Public Health, Keio University, Tokyo, Japan d Department of Cardiology, Keio University, Tokyo, Japan e Department of Preventive Cardiology, National Cardiovascular Center, Suita, Japan f Department of Environmental Medicine, Hyogo Medical School, Nishinomiya, Japan g Department of School Nursing and Health Education, Osaka Kyoiku University, Kashiwara, Japan h Department of Nutritional Epidemiology, National Institute of Health and Nutrition, Tokyo, Japan i Department of Epidemiology and Public Health, Kanazawa Medical University, Ishikawa, Japan j First Institute for Health Promotion and Health Care, Tokyo, Japan k Department of Lifestyle Related Disease Prevention Center, Shiga University of Medical Science, Otsu, Japan Abstract 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. © 2013 Elsevier Inc. All rights reserved. Keywords: Electrocardiography; Bundle branch blocks; Total mortality; Cardiovascular mortality Introduction Among ventricular conduction defects (VCD), complete left (LBBB) and right bundle branch (RBBB) are distinct findings of ECG. 1 RBBB is generally considered to be benign in the absence of any underlying cardiac abnormality such as congenital heart disease. 2–5 LBBB, on the other hand, is generally considered to be associated with a poorer Available online at www.sciencedirect.com Journal of Electrocardiology 46 (2013) 360 – 365 www.jecgonline.com ☆ Disclosures: None. ⁎ Corresponding author. Cardiovascular Epidemiology, Kyoto Women's University, 35 Imakumano Kitahiyoshi-cho, Higashiyama-ku, Kyoto 605–8501, Japan. E-mail address: nakamury@kyoto-wu.ac.jp 0022-0736/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jelectrocard.2013.03.009