Lead: A four-year randomized clinical trial led by Dr. Gregory Marcus and presented at the American Heart Association meeting in New Orleans found that continuing to drink caffeinated coffee appears safe for people with a history of atrial fibrillation (A-fib) and was associated with fewer recurrences over six months. The DECAF trial enrolled 200 older adults across Australia, Canada and the United States and compared daily coffee consumption with caffeine avoidance. Results, published in JAMA, showed a lower proportion of recurrent irregular-heartbeat events in the coffee group versus the no-coffee group. The finding challenges routine advice to avoid caffeinated coffee for people with prior A-fib.
Key Takeaways
- The DECAF randomized trial enrolled 200 participants (average age 70; one-third women) who were regular coffee drinkers within the prior five years.
- Participants were randomized for six months to either eliminate caffeine or to consume at least one cup of caffeinated coffee daily.
- Monitoring combined office ECGs, wearable heart monitors and implantable cardiac devices to detect atrial fibrillation or atrial flutter recurrences.
- Overall, 111 participants (56%) experienced a recurrent episode during the study period.
- Recurrence rates differed: 47% in the coffee group versus 64% in the no-coffee group, and the coffee group had a longer time to first recurrence.
- The study was presented at the 2024 AHA annual meeting in New Orleans and the report appears in JAMA; Marcus is an associate editor at JAMA.
Background
Atrial fibrillation affects more than 10 million Americans and is the most common sustained cardiac arrhythmia, increasing risks for heart failure, thromboembolic events and stroke. Clinicians and patients have debated whether caffeine provokes A-fib episodes because it transiently raises heart rate and blood pressure. Many patients stop caffeinated beverages on medical advice despite limited randomized evidence. Observational studies previously suggested a neutral or even protective association between coffee and several cardiovascular outcomes, but confounding and reverse causation left uncertainty about cause and effect.
The DECAF trial (Does Eliminating Coffee Avoid Fibrillation?) was designed to test whether abstaining from caffeinated coffee reduces recurrence in people with prior, treated or resolved irregular rhythms. Investigators recruited older adults who had been regular coffee consumers at some point in the prior five years to maximize relevance to patients who already drink coffee. The trial focused on people not actively in an A-fib episode at enrollment, a distinction that affects how broadly results can be applied.
Main Event
Researchers randomized 200 participants across three countries to either avoid caffeine completely or to drink at least one cup of caffeinated coffee daily for six months. Self-reported intake was collected by telehealth or video check-ins at one, three and six months; monitoring for recurrence relied on a combination of clinic ECGs, wearable monitors and implantable cardiac devices. The protocol also included atrial flutter events, which are closely related to A-fib and produce similar clinical concerns.
At baseline, 60% of the coffee-assigned group and 65% of the no-coffee group said coffee had never triggered an A-fib episode for them. During follow-up, 111 participants (56%) experienced a recurrent atrial arrhythmia. The coffee group had a 47% recurrence rate compared with 64% in the no-coffee group, and time-to-first-recurrence favored the coffee arm. Investigators noted some crossover: about one-third of those instructed to avoid coffee admitted to drinking at least a cup during the trial.
Investigators and presenters emphasized safety outcomes in addition to recurrence counts. The trial did not find evidence that a single daily cup produced more recurrences or acute harm in this study population. However, the protocol did not test people who were actively experiencing A-fib at enrollment, so immediate symptomatic effects during an active episode were not assessed.
Analysis & Implications
The trial strengthens evidence that habitual, moderate coffee intake is not necessarily a trigger for recurrent atrial arrhythmias and may even be protective in people with prior, controlled A-fib. Randomization and objective rhythm monitoring support a causal interpretation, reducing some confounding present in observational work. Still, the protective mechanism is unclear: investigators proposed either a coffee-derived anti-inflammatory effect or, paradoxically, a role for modest sympathetic stimulation from caffeine that could stabilize certain autonomic triggers.
Limitations temper immediate clinical practice shifts. Self-reported adherence and crossover (one-third of the no-coffee group drank coffee) muddy the difference between groups and could bias results toward the null or complicate effect-size estimates. The trial also did not quantify other caffeinated beverages in detail, did not track diet or exercise changes systematically, and enrolled primarily older adults with treated or resolved arrhythmias, so applicability to younger patients or those in active, uncontrolled A-fib is uncertain.
Clinicians should weigh these findings against individual patient symptoms and comorbidities. For patients who already tolerate coffee without symptom provocation, a daily cup appears safe and might reduce recurrence risk. For patients reporting palpitations temporally linked to caffeine or consuming large amounts from multiple sources (energy drinks, supplements), personalized counseling remains appropriate.
Comparison & Data
| Group | Participants (n) | Recurrent Events (%) |
|---|---|---|
| Caffeinated coffee (≥1 cup/day) | ~100 | 47% |
| No-coffee (caffeine avoidance) | ~100 | 64% |
| Overall | 200 | 56% (111/200) |
The table summarizes primary recurrence outcomes reported over the six-month randomized period. Absolute and relative risk reductions depend on exact group sizes after accounting for crossover; investigators reported the 47% vs 64% figures as primary comparative outcomes. These data contrast with prior observational studies that suggested neutral or modestly protective associations but could not exclude behavioral confounders.
Reactions & Quotes
Study leaders and outside experts highlighted the practical message for patients who enjoy coffee while noting caution about overgeneralizing.
“There is no standard advice for atrial fibrillation and caffeine,”
Dr. Gregory Marcus, UCSF (DECAF principal investigator)
Marcus framed the trial as testing a common clinical recommendation and said he was surprised by the degree of apparent protection shown in the randomized setting.
“A cup of coffee a day seems to be perfectly safe for people with A-fib,”
Dr. Johanna Contreras, Mount Sinai (cardiologist, not involved in the trial)
Contreras emphasized individual variability in caffeine sensitivity and warned that high cumulative caffeine intake from multiple sources remains a separate concern.
Unconfirmed
- Whether the protective signal is due to caffeine itself or other bioactive compounds in coffee (such as anti-inflammatory agents) remains unresolved.
- It is unclear if consuming more than one cup daily would increase, decrease or have no additional effect on recurrence risk.
- The trial did not establish safety or effects for people who are actively in A-fib at the time of drinking coffee.
Bottom Line
The DECAF randomized trial provides higher-quality evidence that a single daily cup of caffeinated coffee is unlikely to provoke recurrence of atrial fibrillation in older adults with previously treated or resolved arrhythmias, and it was associated with fewer recurrences over six months. Clinicians should consider these results when advising patients who already drink coffee, balancing the trial’s strengths against crossover, limited beverage granularity and the study population’s characteristics.
For patients who experience palpitations temporally linked to caffeine or who consume large amounts from multiple sources, individualized counseling remains appropriate. Future research should clarify mechanisms, test higher or varying doses and assess effects in people with active, uncontrolled A-fib.
Sources
- NBC News — Kaitlin Sullivan report (media coverage of the DECAF trial)
- JAMA — Journal of the American Medical Association (peer-reviewed journal; published DECAF trial report)
- American Heart Association (professional society; AHA annual meeting where results were presented)