A first-of-its-kind study has shown patients with atrial fibrillation who drink a cup of coffee a day are 39% less likely to have a recurrence of AF compared with those who abstained from caffeine.

While clinicians have traditionally often advised AF patients against caffeine consumption, the data suggests it’s reasonable to advise patients they can continue to enjoy coffee and other caffeinated beverages after diagnosis.

The DECAF trial, which was led by researchers at the University of Adelaide and University of California San Francisco, has been published in JAMA and was presented at the American Heart Association 2025 Scientific Sessions.

It randomised 200 patients with persistent AF who were about to commence cardioversion therapy to drink either at least one cup of coffee daily or completely abstain from caffeinated and decaffeinated coffee for a six month period.

At follow-up, AF or atrial flutter recurrence was significantly less in the coffee consumption group, at 47%, than in the abstinence group, which had a recurrence rate of 64%. This represented a 39% lower hazard of recurrence [link here].

A similar benefit was also seen when only instances of AFib, excluding atrial flutter episodes, were considered.

“The current results contrast with the traditional assumption that coffee promotes atrial arrhythmogenesis, but fit with some observational data on the subject,” the authors wrote in JAMA.

University of Adelaide Professor Christopher Wong was a co-author who presented on the DECAF trial at the AHA 2025 meeting.

Conventional wisdom has been that coffee is proarrhythmic, but observational studies have instead suggested a neutral or beneficial relationship between caffeine and AF, they noted.

“Our study results suggest that caffeinated coffee may not be responsible for raising the risk of AFib and may even reduce it,” senior study author and professor of medicine at University of California, Gregory Marcus, said.

The investigators said caffeine in concentrations from typical coffee consumption resulted in blockade of A1and A2a adenosine receptors, which was notable because adenosine facilitates AF induction.

“Coffee also appears to have anti-inflammatory properties,” the authors said.

“As systemic inflammation is an AF risk factor, coffee might reduce AF risk by decreasing inflammation.”

Could coffee be a protective strategy?

“It is reasonable for health care professionals to let their AFib patients consider experimenting with naturally caffeinated substances that they may enjoy, such as caffeinated tea and coffee. However, some people may still find that caffeine or caffeinated coffee triggers or worsens their AFib,” Professor Marcus said ahead of the data being presented at AHA 2025.

The research had several limitations, including that there was no mandated approach to detecting recurrent AF among the participants.

The sample size was also modest at just 200 participants.

The study only considered caffeine in around one cup of coffee per day, meaning the results could not be extrapolated to those consuming high-dose caffeine or products like energy drinks.

Despite this, the study presented the first randomised data on a head-to-head comparison of caffeine consumption versus abstinence in this patient group.

The findings appeared reassuring for AF patients who did not want to give up their morning coffee.

“Based on these results, coffee-drinking patients with AF can safely continue to enjoy their coffee. Furthermore, it may be worth investigating whether AF patients who don’t drink coffee should actually consider starting,” said co-author and University of Adelaide professor of medicine, Christopher Wong.