A randomized trial suggests that avoiding coffee after cardioversion may not help, and that modest caffeine intake may actually be associated with fewer atrial fibrillation recurrences.
Study: Caffeinated Coffee Consumption or Abstinence to Reduce Atrial Fibrillation. Image credit: diignat/Shutterstock.com
Consuming modest amounts of caffeinated coffee after cardioversion may be linked to a lower risk of recurrent atrial fibrillation, as reported by a randomized clinical trial published in JAMA. For many patients with persistent atrial fibrillation, routinely avoiding coffee after cardioversion may not be necessary.
Coffee’s long-standing reputation as an atrial fibrillation trigger
Atrial fibrillation is the most common heart rhythm disorder characterized by irregular and often rapid heartbeats. The condition affects nearly one in three people over their lifetime. With increasing global prevalence, scientific interest in identifying modifiable risk factors to reduce the burden of atrial fibrillation is growing.
Caffeinated coffee is traditionally considered potentially proarrhythmic, meaning it can cause changes in heart rhythm. Existing evidence covering both patients’ reports and physicians’ recommendations indicates that intake of caffeinated coffee has long been thought to trigger atrial fibrillation episodes.
However, recent randomized controlled trials and observational studies have examined the proarrhythmic effects of caffeinated coffee and have reported no consistent evidence of increased atrial fibrillation episodes.
Given that coffee is the most commonly consumed caffeinated beverage worldwide, it would be of great importance for both patients and physicians to understand whether coffee intake has a beneficial, detrimental, or neutral effect on atrial fibrillation recurrence, particularly after rhythm-restoring procedures.
The current study, led by University of California, San Francisco researchers, aimed to evaluate the risk of recurrent atrial fibrillation among individuals assigned to consume caffeinated coffee or abstain from coffee and caffeine for 6 months following successful electrical cardioversion.
Comparing daily coffee intake with complete caffeine abstinence
The study included a total of 200 current or prior coffee drinkers with persistent atrial fibrillation or atrial flutter with a history of atrial fibrillation who had undergone 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 variable but typical real-world consumption levels. In the control group, participants were encouraged to completely avoid drinking caffeinated or decaffeinated coffee and to avoid other caffeine-containing products.
All participants were followed up for six months to evaluate the risk of clinically detected recurrence of atrial fibrillation or atrial flutter, identified during routine clinical care rather than through continuous rhythm monitoring.
Coffee drinkers experienced fewer atrial fibrillation recurrences
The study included 100 participants in the intervention group, who consumed approximately one cup of caffeinated coffee per day over the 6-month study period. The same number of participants were randomized into the control group, who were instructed to abstain from coffee and caffeine, although adherence was incomplete.
At the end of the six-month follow-up period, atrial fibrillation or atrial flutter recurrence was clinically detected in 47 % of participants in the intervention group and 64 % in the control group. The time to recurrence was longer in the intervention group. These findings corresponded to a 39 % lower hazard of recurrence among participants assigned to consume caffeinated coffee.
The number of participants who required hospitalization for atrial fibrillation or atrial flutter was numerically higher in the control group, 15 vs 10 events, than in the intervention group, although the study was not designed to detect statistically significant differences in hospitalization rates.
Coffee drinkers experienced fewer atrial fibrillation recurrences
The study suggests that consuming caffeinated coffee is associated with a lower risk of atrial fibrillation or atrial flutter recurrence in patients with persistent atrial fibrillation after electrical cardioversion, rather than indicating a general preventive effect across all atrial fibrillation populations.
Coffee contains several active compounds, with caffeine being the most recognized. Potential mechanisms proposed by the authors include caffeine’s ability to block adenosine receptors, thereby mitigating adenosine-induced shortening of atrial action potential duration and refractoriness. Anti-inflammatory and blood pressure–lowering properties of coffee may also contribute, although these mechanisms were not directly tested in this trial.
Participants showed higher soda intake and a greater tendency to add sugar to coffee. These habits can potentially increase the risk of obesity, diabetes, and atrial fibrillation. Importantly, these observations were descriptive and not causal findings of the trial. Recent randomized trials have also linked coffee intake to increased physical activity, which could partially contribute to reduced recurrence of atrial fibrillation.
Overall, the study reports that consuming a modest amount of naturally occurring caffeine, about one cup of coffee per day, was associated with a lower rate of atrial fibrillation recurrence in this specific post-cardioversion setting. The authors caution that these findings do not apply to high-dose caffeine intake or to patients with paroxysmal atrial fibrillation, nor do they establish coffee consumption as a proven preventive strategy, and they emphasize the need for further research.
The study was not blinded, meaning that both the physicians who diagnosed atrial fibrillation recurrence and the participants were aware of the study design and caffeine exposure. These factors may have introduced detection and reporting bias, particularly because recurrence was identified through routine clinical care rather than continuous monitoring.
Furthermore, many participants believed that coffee worsened atrial fibrillation, reflecting a long-held conventional view that caffeinated coffee is proarrhythmic. Previous randomized trials have shown that people who believe caffeine to be an acute trigger for atrial fibrillation do not demonstrate this effect objectively, suggesting that such beliefs may arise from perception rather than evidence-based effects.
Only 69 % of participants in the control group fully adhered to the protocol of avoiding coffee during the study period. This suboptimal adherence may have led to an underestimation of the true difference between the groups. Future studies with improved adherence, more standardized exposure assessment, and objective rhythm monitoring may help provide a more definitive interpretation.
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