Amiodarone and the risk of bradyarrhythmia requiring permanent pacemaker in elderly patients with atrial fibrillation and prior myocardial infarction

Objectives The aim of this study was to determine whether the use of amiodarone in patients with atrial fibrillation (AF) increases the risk of bradyarrhythmia requiring a permanent pacemaker. Background Reports of severe bradyarrhythmia during amiodarone therapy are infrequent and limited to studies assessing the therapy’s use in the management of patients with ventricular arrhythmias. Methods A study cohort of 8,770 patients age ≥65 years with a new diagnosis of AF was identified from a provincewide database of Quebec residents with a myocardial infarction (MI) between 1991 and 1999. Using a nested case-control design, 477 cases of bradyarrhythmia requiring a permanent pacemaker were matched (1:4) to 1,908 controls. Multivariable logistic regression was used to estimate the odds ratio (OR) of pacemaker insertion associated with amiodarone use, controlling for baseline risk factors and exposure to sotalol, Class I antiarrhythmic agents, beta-blockers, calcium channel blockers, and digoxin. Results Amiodarone use was associated with an increased risk of pacemaker insertion (OR: 2.14, 95% confidence interval [CI]: 1.30 to 3.54). This effect was modified by gender, with a greater risk in women versus men (OR: 3.86, 95% CI: 1.70 to 8.75 vs. OR: 1.52, 95% CI: 0.80 to 2.89). Digoxin was the only other medication associated with an increased risk of pacemaker insertion (OR: 1.78, 95% CI: 1.37 to 2.31). Conclusions This study suggests that the use of amiodarone in elderly patients with AF and a previous MI increases the risk of bradyarrhythmia requiring a permanent pacemaker. The finding of an augmented risk of pacemaker insertion in elderly women receiving amiodarone requires further investigation.