Importance: Conventional wisdom holds that caffeinated coffee is proarrhythmic. Coffee is the most commonly consumed caffeinated beverage in the US, and a randomized trial assessing caffeinated coffee consumption in patients with atrial fibrillation (AF) has not previously been performed.

Objective: To determine the effect of caffeinated coffee consumption compared with abstinence from coffee and caffeine on recurrent AF.

Design, setting, and participants: This was a prospective, open-label, randomized clinical trial enrolling 200 current or previous (within past 5 years) coffee-drinking adults with persistent AF, or atrial flutter with a history of AF, planned for electrical cardioversion from 5 hospitals in the US, Canada, and Australia between November 2021 and December 2024. The date of final follow-up was June 5, 2025.

Intervention: Patients were randomized in a 1:1 ratio to regular caffeinated coffee consumption vs coffee and caffeine abstinence for 6 months. Patients in the coffee consumption group were encouraged to drink at least 1 cup of caffeinated coffee daily. Patients in the abstinence group were encouraged to completely abstain from both caffeinated and decaffeinated coffee and other caffeine-containing products.

Main outcomes and measures: The primary end point was clinically detected recurrence of AF or atrial flutter over 6 months.

Results: Two hundred patients (mean [SD] age, 69 [11] years; 71% male) were randomized to caffeinated coffee consumption (n = 100) or coffee abstinence (n = 100). Baseline coffee intake was 7 cups (IQR, 7-18) per week in both groups. During follow-up, coffee intake in the consumption and abstinence groups was 7 (IQR, 6-11) and 0 (IQR, 0-2) cups per week, respectively, resulting in a between-group difference of 7 cups (95% CI, 7-7) per week. In the primary analysis, AF or atrial flutter recurrence was less in the coffee consumption (47%) than the coffee abstinence (64%) group, resulting in a 39% lower hazard of recurrence (hazard ratio, 0.61 [95% CI, 0.42-0.89]; P = .01). A comparable benefit of coffee consumption was observed with AF recurrence only. There was no significant difference in adverse events.

Conclusions and relevance: In this clinical trial of coffee drinkers after successful cardioversion, allocation to consumption of caffeinated coffee averaging 1 cup a day was associated with less recurrence of AF or atrial flutter compared with abstinence from coffee and caffeinated products.

Trial registration: ClinicalTrials.gov Identifier: NCT05121519.