Background: Amiodarone use was associated with an increased need for pacemaker insertion in a retrospective study of patients with atrial fibrillation (AF) and prior myocardial infarction. The aims of this study were to determine prospectively whether amiodarone increases the need for pacemakers in a general population of patients with AF and whether this effect is modified by sex.
Methods: The study included 1005 patients with new-onset AF who were enrolled in the Fibrillation Registry Assessing Costs, Therapies, Adverse events, and Lifestyle (FRACTAL). Multivariable Cox regression models, including time-dependent covariates accounting for medication exposure, were used to evaluate the risk of pacemaker insertion associated with amiodarone use.
Results: Amiodarone use was associated with an increased risk of pacemaker insertion (hazard ratio [HR], 2.01; 95% confidence interval [CI], 1.08-3.76) after adjustment for age, sex, atrial flutter, coronary artery disease, heart failure, and hypertension. The effect of amiodarone use was modified by sex, with a significant risk in women but not in men (HR, 4.69; 95% CI, 1.99-11.05 vs HR, 1.05; 95% CI, 0.42-2.58 [P = .02]). This interaction remained significant after adjustment for weight, body mass index, weight-adjusted amiodarone dose, and use of other antiarrhythmic or rate control drugs.
Conclusion: The risk of bradyarrhythmia requiring pacemaker insertion associated with amiodarone use for AF is significantly greater in women than in men, independent of weight or body mass index.