Coffee not linked to increased risk of irregular heartbeat

Coffee consumption does not raise the risk of atrial fibrillation, a common type of irregular heartbeat that is linked to increased odds of suffering stroke and heart failure, the largest study of its kind has found.
The research included a meta-analysis of four other studies involving nearly 250,000 individuals over the course of 12 years.
Atrial fibrillation (AF) is the most frequent form of irregular heartbeat, causing a substantially increased risk of stroke, heart failure and all-cause mortality.
It has previously been speculated that high coffee consumption may increase the risk of developing atrial fibrillation.
"This is the largest prospective study to date on the association between coffee consumption and risk of atrial fibrillation," said lead author Susanna Larsson, from Karolinska Institutet in Sweden.

"We find no evidence that high consumption of coffee increases the risk of atrial fibrillation," said Larsson.

"This is important because it shows that people who like coffee can safely continue to consume it, at least in moderation, without the risk of developing this condition," she said.
The study population comprised 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. All studies were conducted in either Sweden or the US.
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.

In their analysis, the researchers found that coffee consumption was not associated with AF incidence in these cohort studies, even in more extreme levels of coffee consumption.
This lack of association was 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.
As the number of studies of coffee consumption and AF risk is quite limited, the researchers said that more large prospective studies investigating this relationship are needed.
In sex-specific analyses, coffee consumption was associated with a non-significant increased risk of AF in men, but a non-significant decreased risk of AF in women.

Whether men may be more sensitive to a high coffee or caffeine intake warrants further study, the researchers said.
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, researchers said.
The study was published in the journal BMC Medicine.