Effects of smoking habit on the prevalence of atrial fibrillation in Japanese patients with special reference to sex differences.

Background: Tobacco smoking is a well-known risk factor for cardiovascular disease, but controversial results have been reported regarding its relationship with atrial fibrillation (AF). Moreover, no study on the relationship between smoking and AF has yet been undertaken in a Japanese context.
Methods and Results: We used data from the Shinken Database 2004-2011 (men/women, n=10,714/6,803, respectively), which included all new patients attending the Cardiovascular Institute between June 2004 and March 2012. AF was diagnosed in 1,698 and 598 men and women, respectively. In men, smokers were more prevalent in the AF than in the non-AF group (54.5% vs. 44.7%), whereas in women the prevalence of smokers was similar between AF and non-AF groups (14.4% vs. 15.4%). This discrepancy between the sexes seems to derive from a characteristic distribution pattern of smoking habit in women. After adjustment for various cofactors, smoking was independently associated with AF (odds ratio 1.54; 95% confidence interval 1.35-1.75; P<0.001) without a significant interaction between sex categories (P=0.195).
Conclusions: Smoking was independently associated with AF without a significant interaction between sex categories among Japanese patients visiting a cardiovascular hospital. Further studies using a prospective cohort design are required to confirm a causal link between smoking and AF in Japanese patients.