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13-09-2010 | Arrhythmia | Article

Caffeine link to AF risk dismissed


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MedWire News: Women who consume large amounts of caffeine are unlikely to increase their risk for developing atrial fibrillation (AF), say US researchers.

"Many patients with paroxysmal AF indicated coffee intake as a triggering factor for arrhythmia, and there is a fairly widespread belief that caffeine intake is related to the development of AF," say David Conen and colleagues from Harvard Medical School in Boston, Massachusetts.

The current findings, from the Women's Health Study (WHS), refute this notion. Indeed, they suggest that consuming moderate amounts of caffeine could even have a protective effect against AF.

But Conen et al caution that residual confounding could also explain this result, and stress that it requires confirmation in other large prospective studies.

During a median follow-up of 14.4 years, 945 of the 33,638 participants in the WHS developed AF.

The age-adjusted rates of AF were 2.15, 1.89, 2.01, 2.24, and 2.04 per 1000 person-years across increasing quintiles of caffeine intake: 22, 135, 285, 402, and 656 mg/day, respectively.

After accounting for confounders including age and vascular risk factors, women in the third quintile of caffeine intake were 22% less likely to develop AF than those in the first quintile. AF risk among women in other quintiles was no different to that of women in the first quintile.

However, the researchers did find a 36% increased risk for AF among women in the fourth quintile of caffeinated coffee intake (2-3 cups/day), relative to those in the first quintile (0 cups/day). But this risk was absent in women in the top quintile (≥4 cups/day) and was not seen for decaffeinated coffee or caffeine intake overall, so the team considers this a probable chance finding.

"Our data, in combination with prior prospective studies, suggest that elevated consumption of caffeine does not contribute to the increasing burden of AF in the general population," conclude Conen and team in the American Journal of Clinical Nutrition.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Eleanor McDermid

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