Context: Population study data about relations of coffee drinking to arrhythmia are sparse.
Objective: To study relations of coffee drinking to risk of cardiac arrhythmia in 130,054 persons with previous data about coffee habits.Design and Outcome Measure: We used Cox proportional hazards models with 8 covariates to study coffee-related risk in 3137 persons hospitalized for cardiac arrhythmia. We conducted a similar analysis of total caffeine-related risk in a subgroup with data about other caffeine intake (11,679 study participants; 198 hospitalized).
Results: With non-coffee-drinkers as the referent, the adjusted hazard ratio (HR) for any arrhythmia at the level of <1 cup of coffee per day was 1.0 (95% confidence interval [CI] = 0.9-1.1; p = 0.7); for 1-3 cups/day, it was 0.9 (CI, 0.8-1.0; p = 0.2), and for ≥4 cups/day, it was 0.8 (CI, 0.7-0.9; p = 0.002). With coffee intake as a continuous variable, the HR per cup per day was 0.97 (CI, 0.95-0.99; p = 0.001). RESULTS were similar for several strata, including persons with history or symptoms of possible cardiore-spiratory disease and those without such history or symptoms. Coffee had similar relations to atrial fibrillation (48% of participants with arrhythmia) and most other specific arrhythmia diagnoses. Controlled for number of cups of coffee per day, total caffeine intake was inversely related to risk (HR highest quartile vs lowest = 0.6; p = 0.03).
Conclusion: The inverse relations of coffee and caffeine intake to hospitalization for arrhythmias make it unlikely that moderate caffeine intake increases arrhythmia risk.