Patients with atrial fibrillation who kept drinking a cup of caffeinated coffee every day were significantly less likely to see the abnormal rhythm return than patients told to give up coffee entirely. The finding, from the DECAF randomized clinical trial published in JAMA on November 9, 2025, cuts against advice cardiologists have offered for decades.
Researchers followed 200 adults with persistent atrial fibrillation or atrial flutter for six months after a procedure to restore normal rhythm. Recurrence hit 47 percent of the coffee drinkers, compared with 64 percent of those who abstained. That works out to a 39 percent lower hazard of recurrence in the coffee group (hazard ratio 0.61, 95 percent CI 0.42 to 0.89).
Atrial fibrillation, or AFib, is a common heart rhythm disorder in which the upper chambers of the heart quiver instead of beating in a steady pattern. It raises the risk of stroke and heart failure, and it is one of the reasons doctors have historically warned patients to steer clear of stimulants.
Why the result was a surprise
Coffee has long been treated as suspect in AFib care. Christopher X. Wong, MBBS, MPH, PhD, formerly of the University of California, San Francisco and now professor of cardiology at the University of Adelaide, and senior author Gregory M. Marcus, MD, MAS, professor of medicine in the UCSF Division of Cardiology, ran the trial precisely because that advice had never been tested in a proper randomized study.
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Marcus told Healio the enrollment struggle underscored the point. He said many potential participants "didn't want to give up their coffee," which limited recruitment to about 200 of roughly 2,000 patients screened.
The trial was conducted at five hospitals in the United States, Canada and Australia between November 2021 and December 2024, according to the JAMA abstract. Participants had a mean age of 69, and 71 percent were male. All were regular coffee drinkers before enrollment.
What might explain the effect
Marcus has pointed to several biological pathways that could be at work, as reported by tctMD: caffeine prolongs electrical recovery in atrial cells, blocks certain adenosine receptors, and may modestly lower blood pressure while carrying anti-inflammatory effects. Coffee drinkers in the trial also logged around 1,000 more daily steps than abstainers, Medical News Today reported, suggesting the caffeine boost may translate into more movement.
Independent electrophysiologist José Joglar, MD, of UT Southwestern Medical Center in Dallas, told tctMD the coffee warning had become entrenched partly through repetition. He added a caveat: "This does not apply to excess coffee consumption or energy drinks for that matter."
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The limits of the finding
The result applies to a specific group. All participants had already been diagnosed with persistent AFib or atrial flutter and had undergone electrical cardioversion, a procedure that resets the heart's rhythm. The trial does not tell healthy people whether coffee prevents AFib in the first place, and it does not clear high doses of caffeine or energy drinks.
The trial was also open-label, meaning participants knew which group they were in. Coffee intake was self-reported, and compliance was imperfect. Only 69 percent of participants assigned to abstinence actually stopped drinking coffee, Wong acknowledged in his late-breaking presentation reported by Healio, which if anything would tend to blur the difference between groups rather than exaggerate it.
Andrea M. Russo, MD, of Cooper Medical School, said the results should give clinicians "comfort" that coffee is safe for most patients with AFib, according to Medical News Today. She also called for larger studies to confirm the effect.
People with AFib should still talk with their cardiologist before changing what they drink, especially if they take rhythm-control drugs or blood thinners. The DECAF authors concluded that coffee and other caffeinated products may be reasonably considered in patients with AFib, not that anyone should start drinking coffee for cardiac benefit.
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