Chronic alcohol use increases the risk of developing new-onset atrial fibrillation (AF), which is partially driven by alcohol-associated left atrial (LA) enlargement, according to research published in the Journal of the American Heart Association.

While a link between alcohol consumption and AF has been observed in epidemiological studies, the mechanism for this relationship remains unclear. Limited data from electrophysiologic studies have not revealed any electrical mechanisms. Additional studies have demonstrated that alcohol consumption may induce LA enlargement, but it is not known if LA enlargement leads to AF or if AF causes LA enlargement in alcohol users.

Gregory M. Marcus, MD, MAS, of the University of California, San Francisco, and colleagues examined the relationships between cumulative alcohol use, AF risk, and echocardiographic measurements of LA size in 5220 participants from the Offspring and Original Framingham Heart Study.


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For every additional 10 g of alcohol consumed per day (nearly 1 drink per day), LA dimension increased by 0.16 mm (95% confidence interval [CI]: 0.10–0.21 mm) and the risk of new-onset AF rose by 5% (hazard ratio: 1.05; 95% CI: 1.01–1.09).

Chronic alcohol use was not associated with changes in LA dimension over a median follow-up time of 6.0 years.

LA enlargement accounted for 24% (95% CI: 8%–75%) of the correlation between alcohol consumption and AF risk.

“The attenuation of the association between alcohol and incident AF after adjustment for [LA dimension] is consistent with the hypothesis that LA enlargement is a key intermediate phenotype along the causal pathway to AF,” the authors wrote.

“But we still don’t know the fundamental mechanisms responsible for the apparent effect of alcohol on LA enlargement,” Dr Marcus noted in an interview with Cardiology Advisor.

Understanding the mechanisms behind the association between alcohol use and AF has important clinical implications. Identifying patients who are at risk for AF based on parameters such as LA size may facilitate discussions regarding the risks and benefits of continued alcohol use. Clarifying the mechanisms for AF risk factors such as alcohol consumption may also identify new therapeutic targets for AF.

Further research is needed to determine the mechanisms underlying the link between alcohol consumption and AF. “There are a number of ways future studies might be pursued: animal studies, research at the cell level in basic science laboratories, or examination of autopsy or explanted heart specimens from humans,” Dr Marcus said.

Disclosures: Dr Marcus has received research funding from Medtronic, Pfizer, and Rhythm Diagnostic Systems, and is a consultant and equity holder of InCarda Therapeutics. Dr McManus is a consultant for Pfizer and Bristol Meyers Squibb, and has received research funding from Biotronik and Philips Healthcare. Dr McManus is also a consultant and equity holder of ATRIA, Inc. and MobileSense, Inc.

Reference

McManus D, Yin X, Gladstone R, et al. Alcohol consumption, left atrial diameter, and atrial fibrillation. J Am Heart Assoc. 2016. doi:10.1161/JAHA.116.004060.