A new randomized clinical trial challenges the long-standing recommendation that people with atrial fibrillation (AFib) should avoid coffee. The DECAF trial found that daily coffee consumption was associated with fewer recurrent AFib episodes than complete caffeine abstinence.
Background and trial design
Coffee is the most popular beverage in the U.S., consumed daily by about two-thirds of adults. Conventional guidance has often urged people with AFib or at risk for it to cut back on coffee, but recommendations have been mixed. To investigate, researchers enrolled 200 patients with a history of AFib or atrial flutter shortly after successful cardioversion, a procedure that restores normal heart rhythm. The average participant was 69 years old; 71% were male and 80% identified as white. All were regular coffee drinkers, averaging about one cup per day.
Participants were randomly assigned to either continue drinking caffeinated coffee daily or to completely abstain from all caffeinated products, including decaffeinated coffee, for six months. Researchers tracked any recurrence of AFib or atrial flutter lasting at least 30 seconds. The trial results were published in JAMA.
Key findings
At six months, 47% of the coffee drinkers experienced a recurrent AFib episode versus 64% of those who abstained — a 40% lower risk of recurrence among the regular coffee group. Senior author Gregory Marcus, MD, noted this is, to their knowledge, the only long-term randomized trial of caffeinated coffee on a cardiovascular endpoint and suggested that caffeinated coffee may protect against AFib in people who tolerate it.
Expert reactions
Rod Passman, MD, who was not involved in the study, said the trial is important and calls into question lifestyle advice given without robust data. Alyssa Kwan, a clinical dietitian in cardiology, pointed out coffee’s antioxidant compounds, like chlorogenic acids and melanoidins, which might offer protective effects.
Possible explanations
The trial does not establish why coffee drinkers had fewer recurrences, but authors propose several hypotheses. Caffeine blocks adenosine receptors; adenosine can provoke AFib, so blocking it could have antiarrhythmic effects. Coffee also contains antioxidant compounds that might protect heart tissue. Lifestyle differences could contribute as well: a prior trial found people in a coffee group walked about 1,000 more steps per day than those who abstained.
Caveats and practical advice
The study’s findings apply only to coffee, not to other sources of caffeine such as energy drinks, pills, or supplements. Energy drinks can contain much higher caffeine doses and have been linked to AFib even in young, healthy people. Marcus cautioned against interpreting the results as evidence that more caffeine is better; existing observational evidence suggesting reduced AFib risk relates to moderate consumption of naturally occurring caffeine, such as that in coffee.
Patients should also watch what they add to coffee; beverages high in added sugars or saturated fat (like some lattes and mochas) may be undesirable. If a clinician has advised a patient with AFib to avoid coffee, that patient should consult their doctor before restarting regular consumption.
Bottom line
For people with AFib who enjoy and tolerate caffeinated coffee, moderate daily coffee appears unlikely to trigger episodes and may reduce the risk of recurrence. Further research is needed before recommending that people without coffee habits start drinking it specifically to prevent AFib.
