A randomized trial challenges decades of caution about caffeine, finding that modest daily coffee intake did not worsen atrial fibrillation and was associated with fewer clinically detected recurrences.
The DECAF trial: coffee, caffeine, and atrial fibrillation. Image Credit: vagabondatheart / Shutterstock
In a recent article published in the journal Cardiovascular Research, authors Christopher Wong and Gregory Marcus discussed findings from the DECAF randomized clinical trial, which evaluated whether daily consumption of caffeinated coffee, compared with abstinence from coffee and caffeine, affects the risk of recurrent atrial fibrillation (AF) or atrial flutter in patients with AF.
Background
Traditionally, coffee and caffeine have been thought of as possible triggers of AF or factors that could worsen arrhythmias, thus prompting doctors to advise their patients to eliminate or limit caffeinated drinks from their diet. Nevertheless, most observational studies have not identified an increased risk of developing AF among coffee drinkers, and some studies have implied that those who drink more coffee might even have a lower risk of developing AF, although residual or unmeasured confounding remains possible.
Randomized evidence has also been reassuring: Individualized Studies of Triggers of Paroxysmal Atrial Fibrillation (I-STOP-AFib) found no significant increase in AF with caffeine exposure, while Coffee and Real-time Atrial and Ventricular Ectopy (CRAVE) found no significant increase in premature atrial contractions with caffeinated coffee.
Because no randomized trial had directly examined coffee consumption in people with AF, the Does Eliminating Coffee Avoid Fibrillation (DECAF) trial was designed to determine whether caffeinated coffee affects AF recurrence.
Study overview
The DECAF trial was an investigator-initiated, international, multicenter, randomized clinical trial evaluating whether caffeinated coffee consumption affects recurrence of AF or atrial flutter. The study included 200 patients with persistent AF, or atrial flutter with a history of AF, who were scheduled for electrical cardioversion.
Eligible patients had to have consumed at least one cup of caffeinated coffee per day at some point in the last five years. Eligibility also included people who were no longer consuming caffeinated coffee because of personal beliefs or physician advice regarding AF.
Following successful cardioversion, participants were randomized 1:1 to either consume at least one cup of caffeinated coffee daily or abstain from all coffee, including decaffeinated coffee, and caffeinated products. Follow-up lasted for 6 months or until an occurrence of AF or flutter. Median coffee intake in the coffee group was 7 cups per week, whereas median intake in the abstinence group was 0 cups per week.
Key findings
According to the primary analysis based on the intention-to-treat principle, participants allocated to caffeinated coffee had a 39% lower hazard of recurrent clinically diagnosed AF or atrial flutter compared with those assigned to abstain from coffee and caffeine during the study period. The hazard ratio was equal to 0.61 (95% confidence interval, 0.42-0.89; P=0.01). No differences in adverse events were found between groups.
The authors emphasize that the findings challenge the longstanding belief that caffeinated coffee can precipitate or worsen AF. At minimum, the results suggest that modest caffeinated coffee consumption, approximately one cup daily, is unlikely to worsen AF in most individuals, and whether coffee provides a direct protective benefit requires further investigation.
Possible mechanisms
The biological mechanisms underlying the findings remain uncertain because coffee contains numerous biologically active compounds. Caffeine blocks A1 and A2a adenosine receptors, potentially counteracting adenosine-mediated effects that can facilitate AF induction. Some observational data also suggest that caffeinated, but not decaffeinated, coffee is associated with a lower risk of AF.
Other hypothesized potentially beneficial mechanisms include the antivagal, anti-inflammatory, antioxidant, and antifibrotic properties of coffee constituents. Coffee may also influence cardiometabolic factors associated with AF, including blood pressure, physical activity, adiposity, and heart failure. However, the article also recognizes potentially pro-arrhythmic mechanisms, including caffeine-related calcium release, increased blood pressure, and behavioral factors such as added sugar or smoking.
Limitations and implications
The trial had limitations, including the difficulty of conducting randomized trials involving everyday lifestyle behaviors. The planned follow-up was initially 12 months but was reduced to 6 months because prolonged caffeine abstinence was expected to hinder recruitment.
Nearly 2,000 patients had to be screened to enroll 200 participants. The authors therefore emphasize the importance of additional randomized trials to complement observational and mechanistic evidence and to provide greater confidence in changes to clinical practice.
Conclusion
The DECAF trial challenges the longstanding practice of routinely restricting caffeinated coffee in people with atrial fibrillation. Among patients with AF or flutter undergoing cardioversion, consuming at least one cup of caffeinated coffee daily was associated with a 39% lower hazard of clinically detected recurrent AF or flutter over six months compared with abstaining from coffee and caffeine, with no differences in adverse events.
The findings suggest that modest consumption of caffeinated coffee is unlikely to precipitate or worsen AF in most patients. However, further research is needed to understand the mechanisms and determine whether caffeinated coffee provides a genuine protective benefit.
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