Most have heard the adage that drinking in moderation may be protective for your heart. Moderate drinking is defined as 2 or fewer drinks/day for men and 1 or fewer drinks/day for women. However, we are beginning to learn more about the effects of alcohol on other aspects of the heart, such as its rhythm. Atrial fibrillation (AF) is the most common type of abnormal heart rhythm, estimated to impact over 12 million people in the United States and result in over 450,000 hospitalizations each year. The number of cases of AF generally increases with age and carries a significant risk of stroke. Multiple risk factors such as smoking tobacco, hypertension, and diabetes are associated with the development of AF; however, a lesser discussed significant risk factor for AF is alcohol use. Alcohol use is widespread in western countries, and over 50% of Americans regularly consume alcohol. Binge drinking is a well-established cause of AF. Indeed, the term “Holiday Heart Syndrome” has been used to describe AF following a weekend binge that is usually temporary. However, large meta-analyses have demonstrated that even light to moderate consumption of alcohol can increase the risk of AF.
One such meta-analysis followed over 79,000 patients who did not have AF at baseline. Participants were asked to complete a questionnaire covering alcohol use, and cases of AF were determined through a Swedish Registry. A dose-response relationship was ascertained, demonstrating a relative risk of 1.07 for those who drink 7 to 14 drinks/week, 1.14 for 15 to 21 drinks/week, and 1.39 for those drinking more than 21 drinks/week. No significant difference existed between men and women, and results were comparable even after excluding binge drinkers. A stronger association with wine and liquor rather than with beer was noted. This was deemed to be most likely due to different patterns in drinking behavior and the higher alcohol content in these spirits.
Certain limitations exist when reviewing this data. For example, the quantity of alcohol was determined by self-reporting, increasing the risk of bias. In addition, AF can be asymptomatic. This suggests that AF risk may have been under-estimated in those who regularly use alcohol even at low to moderate levels. Drinking in moderation may be cardioprotective in certain respects; however, these benefits may not apply to AF.