Coffee and AFib recurrence: what the DECAF trial found

In the DECAF randomised trial, adults with persistent atrial fibrillation (AF) who were assigned to caffeinated coffee had less AF or flutter recurrence after cardioversion than those assigned to abstain: 47% versus 64% over six months. The result runs against the long-held assumption that coffee is proarrhythmic. It comes from a single open-label trial of 200 people who already drank coffee.

What did the DECAF trial compare?

DECAF randomised 200 current or previous coffee-drinking adults (mean age 69, 71% male) at five hospitals. All had persistent AF, or atrial flutter with a history of AF, and were planned for electrical cardioversion, a procedure that resets the heart rhythm. According to Wong et al., JAMA 2026, 100 were assigned to regular caffeinated coffee, averaging about one cup a day, and 100 to abstinence from coffee and caffeine for six months.

The primary endpoint was clinically detected recurrence of AF or atrial flutter. It occurred in 47% of the coffee group and 64% of the abstinence group (hazard ratio 0.61, 95% CI 0.42 to 0.89). Adverse events did not differ significantly: the ACC trial summary lists 13 emergency visits and 23 hospitalisations with coffee, 16 and 21 with abstinence, and no deaths in either group.

What does the DECAF trial not show?

Several limits apply. The trial was open-label, so participants knew which arm they were in. Everyone enrolled was already a coffee drinker, at roughly seven cups a week at baseline, so the result says little about non-drinkers, higher intakes, or other caffeinated drinks such as energy drinks, according to the ACC’s report from AHA 2025.

It also tested recurrence after cardioversion over six months. It did not test whether coffee changes who develops AF in the first place, and a single trial of 200 people is a starting point that replication would strengthen.

How rhythm problems are detected shapes what any study can count, and the EQUAL smartwatch trial looked at that side of the question.

The bottom line

• In 200 adults with persistent AF or flutter, recurrence over six months was 47% with regular caffeinated coffee versus 64% with abstinence (hazard ratio 0.61).
• Reported adverse events did not differ significantly between groups, and there were no deaths in either.
• The trial was open-label, enrolled existing coffee drinkers averaging about one cup a day, and cannot speak to other intakes or to who first develops AF.