Abstract 9368: Association Between Concurrent Use of Amiodarone and DOACs and Bleeding Risk in Atrial Fibrillation Patients

Abstract

Introduction: Amiodarone is a commonly used pharmacotherapy in patients with atrial fibrillation (AF) with potential for drug-drug interactions (DDIs) with direct oral anticoagulants (DOACs). We aimed to assess the bleeding risk after co-prescription of amiodarone and DOACs among adults with AF. Methods: We conducted a population-based, nested case-control study in Ontario, Canada. The study population included all patients with AF > 66 years on a DOAC between April 1, 2011-March 31, 2018. Cases were patients admitted with major bleeding (index date). Controls were matched in a 2:1 ratio to cases. We categorized exposure to amiodarone before the index date as: a) current users (amiodarone within 60 days); b) past users (amiodarone within 61 to 140 days); and c) unexposed (no amiodarone prescription or amiodarone prescription >140 days before index date). Conditional logistic regression models were used to examine the association between bleeding and amiodarone co-prescription. Results: Among 86,679 AF patients on a DOAC, we identified 2,766 cases (3.2%) admitted with major bleeding. The median age of AF patients was 80 years (interquartile range 75-85); 48.3% were women. After multivariable adjustment, there was a significant association between major bleeding and current use of amiodarone (adjusted odds ratio (aOR) 1.53; 95% confidence interval (CI) 1.24-1.89, p<0.001) but no significant association between major bleeding and past use of amiodarone (aOR 1.13, 95% CI 0.76-1.68, p=0.545) as compared with the unexposed group. Conclusions: Among older patients with AF on a DOAC, there was 53% increased odds of current use of amiodarone in those with versus without major bleeding.