Western observational studies show that moderate alcohol use is associated with lower cardiovascular disease (CVD) risk, but these associations may be confounded by the healthier attributes of moderate users in these settings. Mendelian randomization analysis may help to ascertain the causal effect of moderate alcohol use on specific factors related to CVD and thereby clarify the role of alcohol. We used Mendelian randomization analysis with the aldehyde dehydrogenase 2 gene (ALDH2) as an instrumental variable to examine the association of alcohol units (10 g of ethanol) per day with heart rate-corrected QT interval and heart rate assessed from electrocardiogram among 4,588 older southern Chinese men in the Guangzhou Biobank Cohort Study (2003-2008). The F statistic was 77 for ALDH2 on alcohol use, suggesting little weak-instrument bias. Instrumental variable analysis showed that alcohol units were not associated with the corrected QT interval, with β = 1.04 (95% confidence interval: -0.61, 2.70) milliseconds, but they were associated with increased heart rate, with β = 0.98 (95% confidence interval: 0.04, 1.92) beat per minute. This study suggests that moderate alcohol use in men is not beneficial for heart function via QT interval or heart rate but could be detrimental. Future studies using specific cardiovascular outcomes may elucidate how alcohol affects different aspects of the cardiovascular system and, hence, the overall effects of alcohol on CVD can be estimated.
Keywords: Chinese; Mendelian randomization; alcohol; electrocardiogram.
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