Published: 23-09-2015 08:00 | Updated: 23-09-2015 10:06

No link between atrial fibrillation and drinking coffee

There is no association between coffee consumption and an increased risk of atrial fibrillation, according to a new study by researchers from the Institute of Environmental Medicine at Karolinska Institutet. The study also includes a meta-analysis of four other research articles, making it the largest of its kind to investigate a possible link between a common irregular-heartbeat condition and drinking coffee

“Our study results shows that people who like coffee can safely continue to consume it, at least in moderation, without the risk of developing this condition”, says lead author Susanna Larsson, PhD, Associate professor at the Institute of Environmental Medicine.

Moderate coffee consumption has been associated with a reduced risk of coronary heart disease and stroke. Its association with atrial fibrillation (AF), a heart condition that causes an irregular and often abnormally fast heart rate substantially increasing the risk of stroke, heart failure and all-cause mortality, has been unclear. However, it has sometimes been speculated that high coffee consumption may increase the risk of developing this disorder.

The current study, which is being published in the online journal BMC Medicine, included 41,881 men and 34,594 women who, in 1997, reported how many cups of coffee they consumed and were followed up for 12 years. There were 4,311 and 2,730 incident AF cases in men and women, respectively, in the two cohorts. The median daily coffee consumption was three cups among both men and women.

Extreme levels of coffee consumption

In their analysis of the two cohorts, the research team found no evidence that high consumption of coffee increases the risk of atrial fibrillation, not even in more extreme levels of coffee consumption. This lack of association was then confirmed in a follow-up meta-analysis that included the present two cohorts and four other prospective studies, giving a total of 10,406 cases of AF diagnosed among 248,910 individuals.

“However, in sex-specific analyses of this larger follow-up material, coffee consumption was associated with a non-significant increased risk of AF in men, but a non-significant decreased risk of AF in women”, says Susanna Larsson. “Whether men may be more sensitive to a high coffee or caffeine intake warrants further study.”

Although available evidence does not indicate that coffee consumption increases the risk of developing AF specifically, coffee may still trigger other forms of irregular heartbeat. Data in the study suggests that some individuals with AF at the start of the study may have quit drinking coffee or lowered their consumption because of an arrhythmic-triggering effect.

While the authors adjusted for major AF risk factors, they warn of possible bias and confounding factors that may have influenced their results, and highlight the limits of self-reported data. All studies were conducted in either Sweden or the US, thus reducing the generalizability of the results.

The study was funded by the Swedish Research Council, and the Strategic Research Area in Epidemiology (SfoEpi) at Karolinska Institutet. This news article is an edited version of a press release from BioMed Central.