A randomized clinical trial called DECAF challenges the common advice that people with atrial fibrillation (AFib) should avoid coffee. The study found that patients who continued drinking caffeinated coffee daily had fewer recurrent AFib or atrial flutter episodes over six months than those who completely abstained from caffeine.
Trial design and participants
Researchers enrolled 200 patients with a history of AFib or atrial flutter shortly after successful cardioversion. The average participant was 69 years old; 71% were male and 80% identified as white. All participants were habitual coffee drinkers, averaging roughly one cup per day. They were randomized to either continue daily caffeinated coffee or to avoid all caffeinated products (including decaf) for six months. The primary outcome was any recurrence of AFib or atrial flutter lasting at least 30 seconds. Results were published in JAMA.
Main findings
At six months, 47% of the participants who kept drinking coffee had a recurrent episode, compared with 64% in the abstinence group. That difference corresponds to about a 40% lower risk of recurrence among the coffee group in this trial.
How it might work
The trial does not prove why coffee drinkers had fewer recurrences, but investigators and commentators suggest several possible mechanisms. Caffeine blocks adenosine receptors, and adenosine can trigger AFib in susceptible people, so caffeine’s receptor effects could be antiarrhythmic. Coffee also contains antioxidant compounds such as chlorogenic acids and melanoidins that might protect heart tissue. Lifestyle differences could also play a role: prior studies have observed that people randomized to continue drinking coffee sometimes had higher daily activity (about 1,000 more steps per day in one trial) than those who quit.
Expert perspective
Senior author Gregory Marcus, MD, noted that, to their knowledge, DECAF is the only long-term randomized trial of caffeinated coffee assessing a cardiovascular outcome and suggested caffeinated coffee may be protective in people who tolerate it. Independent cardiologists and dietitians responding to the study emphasized that it questions blanket lifestyle advice given without strong evidence and highlighted the potential role of coffee’s antioxidants.
Important caveats
The findings apply to caffeinated coffee specifically, not to other caffeine sources. Energy drinks, caffeine pills, and supplements can deliver much higher doses and have been linked to AFib even in young, healthy people. The trial does not support the idea that more caffeine is better; observational signals of lower AFib risk relate to moderate consumption of naturally occurring caffeine. Also, what you add to coffee matters—sugary or high–saturated-fat specialty drinks may have other health downsides. If a clinician has previously advised a patient with AFib to avoid coffee, that patient should consult their doctor before restarting.
Bottom line
For people with AFib who already enjoy and tolerate caffeinated coffee, moderate daily coffee appears unlikely to provoke episodes and may even reduce the risk of recurrence. More research is needed before recommending that non-coffee drinkers start drinking coffee specifically to prevent AFib.
