Drinking a cup of caffeinated coffee daily led to a significant drop in atrial fibrillation (AF) or flutter in patients with sustained AF compared with those who abstained from coffee and caffeine, according to results of the DECAF trial.

“These data demonstrate that atrial fibrillation patients who enjoy drinking caffeinated coffee should not be admonished to avoid doing so,” said Gregory M. Marcus, MD, professor of medicine at the University of California, San Francisco, and study coauthor.

The findings of the DECAF trial were presented at the American Heart Association (AHA) Scientific Sessions 2025 and published in JAMA.

Although caffeinated coffee is one of the most commonly consumed beverages in the US, remarkably little is known about its true health effects, Marcus told Medscape Medical News.

“While traditionally arrhythmia patients have been instructed to avoid caffeine, the available observational data has suggested that those who consume caffeinated coffee might actually be protected against atrial fibrillation,” Marcus said. “We therefore sought to conduct this randomized trial among persistent atrial fibrillation patients undergoing cardioversion.

Coffee’s Effect on Arrhythmias

The prospective, open-label, randomized clinical trial included 200 patients (mean age, 69 years; 71% men) with AF or atrial flutter with a history of AF from five hospitals in the US, Canada, and Australia. All were current coffee drinkers or had been regular coffee drinkers in the past 5 years and had planned an electrical cardioversion.

Clinically detected recurrence of AF or atrial flutter over 6 months served as the primary outcome measure.

The researchers randomly assigned patients 1:1 to caffeinated coffee consumption or coffee abstinence. Patients in both arms had a baseline coffee intake of seven cups per week.

During follow-up, coffee intake in the consumption arm was seven cups per week compared with none in the abstinence group.

Results indicated a decrease in AF or atrial flutter recurrence in the coffee-consumption group compared with the coffee-abstinence group (47% vs 64%; hazard ratio [HR], 0.61; 95% CI, 0.42-0.89). Researchers also observed a similar benefit of coffee consumption for AF recurrence only (HR, 0.62; 95% CI, 0.43-0.91), but not for flutter recurrence only, which occurred in just 6% of the study population (HR, 0.37; 95% CI, 0.10-1.41).

Adverse events did not differ between groups.

“While conventional wisdom had previously led physicians to recommend that patients with atrial fibrillation abstain from coffee, this is not supported by this randomized trial data,” Andrea M. Russo, MD, a professor of medicine at Cooper Medical School of Rowan University in Camden, New Jersey, told Medscape Medical News. “In fact, recommending caffeine abstention to prevent atrial fibrillation episodes was felt to be of ‘no benefit’ in the 2023 American College of Cardiology/American Heart Association/American College of Clinical Pharmacy/Heart Rhythm Society Guidelines for the Diagnosis and Management of Atrial Fibrillation.”

Russo, who served as a discussant for the DECAF trial, also noted that caffeinated coffee intake was not excessive in the trial and that the results should not be extrapolated to other caffeinated products, such as energy drinks, which were not examined in the study.

Important Considerations

The trial had several noteworthy limitations, according to Russo, including the potential for recall bias with self-reported caffeine intake and the varying strength of single cup of coffee. The amount or burden of AF was also not measured.

“Other lifestyle factors, such as exercise, weight loss, and alcohol intake, that are known to be important in AF management were not measured in the current study and could potentially impact results,” she said.

Marcus added that the study only included people who, at some point in the last 5 years, regularly consumed at least one cup of caffeinated coffee. “Therefore, it is possible that there are some people who really do have caffeine-induced atrial fibrillation that just always avoid caffeinated coffee and would have been excluded,” he said.

Although these data suggest caffeinated coffee may reduce the risk for AF, “additional studies to replicate these findings are likely needed before we proactively suggest caffeinated coffee as an atrial fibrillation remedy in any capacity,” Marcus concluded.

Marcus reported receiving personal fees and equity interest from InCarda Therapeutics and research funding from the National Institutes of Health, the Patient-Centered Outcomes Research Institute, the Bill and Melinda Gates Foundation, the California Department of Cannabis Control, and the California Tobacco-Related Disease Research Program during the conduct of the study. He also reported being an associate editor of JAMA but was not involved in any of the decisions regarding the review of the manuscript or its acceptance. Russo reported having no relevant financial relationships.

Brian Ellis is a freelance writer and editor who lives in Southwest Virginia.