Moderate alcohol consumption increases the risk of atrial fibrillation in older people with heart disease or advanced diabetes, found a study in CMAJ (Canadian Medical Association Journal).
"Moderate to high alcohol intake was associated with an increased incidence of atrial fibrillation among people aged 55 or older with cardiovascular disease or diabetes," writes Dr. Koon Teo, McMaster University, Hamilton, Ontario, with coauthors. "Among moderate drinkers, the effect of binge drinking on the risk of atrial fibrillation was similar to that of habitual heavy drinking."
The findings come from a large study involving more than 30 000 individuals aged 55 years or older from 40 countries who had a history of cardiovascular disease or advanced diabetes with organ damage. Data came from the ONTARGET or TRANSCEND trials, which enrolled people between November 2001 and May 2004 with a follow up period of 56 months. The mean age of participants was 66.4 years and 29.8% (9064) were women. Of the participants, 61.7% were classified as having low alcohol consumption (up to 1 drink per week), 36.6% moderate and 1.7% high (more than 2 drinks a day for women and more than 3 for men).
Moderate alcohol consumption was defined using the World Health Organization's (WHO) recommended consumption levels of up to 2 drinks a day — or 1 to 14 drinks a week for women — and up to 3 drinks a day — or 1 to 21 drinks a week — for men. Binge drinking was classified as 5 or more drinks a day, regardless of whether someone was usually a low-, moderate- or high-level alcohol consumer.
Almost 79% of binge drinkers in the study (948 of 1204) fell into the moderate-consumption group.
There were 2093 new cases of atrial fibrillation during the follow-up period. The age- and sex-standardized incidence rate per 1000 person-years was 14.5 in the low-intake group, 17.3 in the moderate-intake group and 20.8 in the high-intake group. The increase in atrial fibrillation cases linked to higher alcohol consumption was found in each age group.
"Because drinking moderate quantities of alcohol was common in our study (36.6% of the participants), our findings suggest that the effect of increased alcohol consumption, even in moderate amounts, on the risk of atrial fibrillation among patients with existing cardiovascular disease may be considerable," state the authors.
Limited data from other studies indicates that binge drinking in healthy people may increase the risk of atrial fibrillation, although moderate drinking in healthy individuals does not appear to be linked to increased risk.
"Recommendations about the protective effects of moderate alcohol intake in patients at high risk of cardiovascular disease may need to be tempered with these findings," the authors conclude.