For decades, conventional wisdom has held that coffee and caffeine act as triggers for heart rhythm disorders, particularly atrial fibrillation (AF). Patients with arrhythmias are routinely advised to avoid caffeinated beverages to reduce the risk of palpitations and AF episodes. This belief stems mainly from the known stimulant effects of caffeine and anecdotal patient reports. However, scientific evidence supporting this theory has been inconsistent. While caffeine can acutely raise heart rate, several large observational studies have actually suggested a neutral or even protective association between regular coffee consumption and the development of AF. Until recently, randomized clinical trial data to definitively settle this debate has been lacking.

The DECAF (Does Eliminating Coffee Avoid Fibrillation?) randomized clinical trial, published in JAMA in 2025, sought to address this gap. The study enrolled 200 adults who were regular coffee drinkers and had a history of persistent AF or atrial flutter. Following successful electrical cardioversion to restore normal sinus rhythm, participants were randomly assigned to either continue drinking caffeinated coffee (at least one cup daily) or to completely abstain from all coffee and caffeine products for six months. The primary outcome was the clinically detected recurrence of AF or atrial flutter. Surprisingly, the group randomized to coffee consumption experienced significantly fewer arrhythmia recurrences. Specifically, AF or atrial flutter recurred in 47% of the coffee consumption group compared to 64% of the abstinence group. This difference translated to a 39% lower hazard of recurrence for those who continued drinking coffee (Hazard Ratio 0.61; 95% CI, 0.42-0.89; P=.01). Adherence to the study protocols was good, with the coffee group consuming a median of 7 cups per week and the abstinence group reducing intake to near zero.

These findings directly contradict the long-standing assumption that coffee worsens AF. The authors suggest several potential mechanisms for this protective effect, including caffeine's blockade of adenosine receptors (adenosine can promote AF), coffee's anti-inflammatory properties, and potential diuretic effects. While the study had some limitations, such as its open-label design and modest sample size, it provides the strongest evidence to date that moderate caffeinated coffee consumption is safe and potentially beneficial for patients with atrial fibrillation. For patients who enjoy their daily cup, these results offer reassurance that coffee does not need to be on the restricted list.

• Caffeinated Coffee Consumption or Abstinence to Reduce Atrial Fibrillation: The DECAF Randomized Clinical Trial, JAMA (2025)
• Atrial fibrillation review