Randomized trials suggest that avoiding coffee after cardioversion may not be effective and that moderate caffeine intake may indeed be associated with reduced recurrence of atrial fibrillation.
study: Consumption or abstinence from caffeinated coffee to reduce atrial fibrillation. Image credit: diignat/Shutterstock.com
Consuming moderate amounts of caffeinated coffee after defibrillation may reduce the risk of recurrent atrial fibrillation, as reported in a randomized clinical trial published in . Japan Automobile Manufacturers Association. For many patients with persistent atrial fibrillation, it may not be necessary to routinely avoid coffee after cardioversion.
Coffee has a long-standing reputation as a trigger for atrial fibrillation.
Atrial fibrillation is the most common heart rhythm disorder characterized by irregular and often fast heartbeats. This condition affects nearly one in three people during their lifetime. With increasing global prevalence, there is growing scientific interest in identifying modifiable risk factors to reduce the burden of AF.
Caffeinated coffee is traditionally thought to have the potential to cause arrhythmia, meaning it can cause changes in the heart’s rhythm. Existing evidence, covering both patient reports and physician recommendations, indicates that caffeinated coffee consumption has long been thought to cause atrial fibrillation episodes.
However, recent randomized controlled trials and observational studies investigating the proarrhythmic effects of caffeinated coffee have not reported consistent evidence of increased AF episodes.
Given that coffee is the most commonly consumed caffeinated beverage worldwide, understanding whether coffee intake has a beneficial, detrimental, or neutral effect on atrial fibrillation recurrence, especially after rhythm restoration procedures, may be of great importance to both patients and physicians.
The study, led by researchers at the University of California, San Francisco, aims to assess the risk of atrial fibrillation recurrence among individuals assigned to consume caffeinated coffee or abstain from coffee and caffeine for six months after successful electrical cardioversion.
Comparison of daily coffee intake and completely abstaining from caffeine
The study included a total of 200 coffee drinkers with current or previous persistent atrial fibrillation or atrial flutter, a history of atrial fibrillation, and who underwent electrical cardioversion. Participants were randomly assigned to the intervention or control group.
Participants in the intervention group were asked to drink at least one cup of caffeinated coffee per day without intentionally increasing or decreasing their usual coffee intake, resulting in a typical, albeit variable, real-world consumption level. In the control group, participants were encouraged to completely avoid caffeinated or decaffeinated coffee and to avoid other caffeine-containing products as well.
All participants were followed for 6 months to assess the risk of recurrence of clinically detected atrial fibrillation or atrial flutter. These recurrences were identified during routine clinical care rather than continuous rhythm monitoring.
Coffee drinkers are less likely to have atrial fibrillation recurrence
The study included 100 participants in the intervention group, who consumed approximately one cup of caffeinated coffee per day over the six-month study period. An equal number of participants were randomly assigned to a control group and instructed to abstain from coffee and caffeine, but compliance was incomplete.
At the end of the 6-month follow-up period, recurrence of atrial fibrillation or atrial flutter was clinically detected in 47% of participants in the intervention group and 64% in the control group. Time to recurrence was longer in the intervention group. These findings translated to a 39% lower risk of relapse among participants assigned to consume caffeinated coffee.
The number of participants who required hospitalization for atrial fibrillation or atrial flutter was numerically 15 to 10 higher in the control group than in the intervention group, but the study was not designed to detect statistically significant differences in hospitalization rates.
Coffee drinkers are less likely to have atrial fibrillation recurrence
This study suggests that caffeinated coffee consumption is associated with a reduced risk of recurrence of atrial fibrillation or atrial flutter in patients with persistent atrial fibrillation after cardioversion and does not represent a general protective effect across the atrial fibrillation population.
Coffee contains several active compounds, caffeine being the most well-known. Potential mechanisms proposed by the authors include the ability of caffeine to block adenosine receptors, thereby attenuating adenosine-induced shortening of atrial action potential duration and refractoriness. Although these mechanisms were not directly tested in this study, coffee’s anti-inflammatory and antihypertensive properties may also contribute.
Participants consumed more soda and were more likely to add sugar to their coffee. These habits can increase your risk of obesity, diabetes, and atrial fibrillation. Importantly, these observations are descriptive and not causal findings of the trial. Recent randomized trials have also associated coffee intake with increased physical activity, which may partially contribute to reduced recurrence of atrial fibrillation.
Overall, this study reports that in this specific post-cardioversion setting, consuming moderate amounts of naturally occurring caffeine (approximately 1 cup of coffee per day) is associated with lower rates of atrial fibrillation recurrence. The authors caution that these findings do not apply to patients with high-dose caffeine intake or paroxysmal atrial fibrillation, nor do they establish coffee consumption as a proven preventive strategy, emphasizing the need for further research.
This study was not blinded. This means that both the physician who diagnosed the atrial fibrillation recurrence and the participants were aware of the study design and caffeine exposure. These factors may have introduced bias in detection and reporting, particularly as recurrences were identified through routine clinical care rather than continuous monitoring.
Additionally, many participants believed that coffee worsened atrial fibrillation, reflecting the long-held conventional view that caffeinated coffee causes arrhythmias. Previous randomized trials have shown that people who believe that caffeine is an acute trigger for atrial fibrillation do not objectively demonstrate its effects, suggesting that such beliefs may stem from perception rather than evidence-based effects.
Only 69% of participants in the control group fully complied with the protocol of avoiding coffee during the study period. This suboptimal compliance may have led to an underestimation of the true differences between the groups. Future studies with improved adherence, more standardized exposure assessments, and objective rhythm monitoring may help provide more definitive interpretations.