Increased need for pacemaker insertion demonstrated among women treated with amiodarone for AF

Key Points

According to the results of a prospective cohort study of 1,005 patients with new-onset atrial fibrillation (AF), women who are treated with amiodarone are at greater risk for bradyarrhythmia requiring pacemaker insertion than men who are treated with the drug. This study of patients enrolled in the Fibrillation Registry Assessing Costs, Therapies, Adverse events, and Lifestyle (FRACTAL), which included patients from 17 medical centers in the United States and Canada, was published in the Archives of Internal Medicine.

Patients who had a pacemaker or pacemaker-defibrillator inserted before study initiation were excluded. A total of 973 patients (390 women and 583 men) were included in the final study group. Patients were assessed at 3, 6, 12, 18, 24, and 30 months after enrollment; mean follow-up was 2 years.

The primary outcome variable was the insertion of a new, permanent pacemaker for bradyarrhythmia. Researchers used multivariable Cox regression to assess the risk of pacemaker insertion associated with amiodarone use; a time-dependent covariate was used to account for variations in amiodarone exposure. The researchers also used separate regression models to determine the risk of pacemaker insertion associated with sotalol and with class 1 antiarrhythmic agents. The effects of amiodarone use were also evaluated using regression models that were adjusted for sex, with additional adjustments for weight, body mass index (BMI), amiodarone dose, weight-adjusted amiodarone dose, and exposure to other antiarrhythmic or rate control agents.

After adjustments for age, sex, atrial flutter, coronary artery disease, congestive heart failure, and hypertension, amiodarone use was associated with an increased risk of pacemaker insertion (HR=2.01; 95% CI, 1.08–3.76). This risk was demonstrated to be significantly higher for women (HR=4.69; 95% CI, 1.99–11.05; P<.001) than for men (HR=1.05; 95% CI, 0.42–2.58; P=.92). This increased risk existed independently of weight or BMI.

The use of sotalol or class 1 anti-arrhythmic drugs was not associated with an increased risk of pacemaker insertion.

SOURCE

Essebag V, Reynolds MR, Hadjis T, et al. Sex differences in the relationship between amiodarone use and the need for permanent pacing in patients with atrial fibrillation. Arch Intern Med. 2007;167:1648–1653.