Michael J. Quon, Hassan Behlouli, Louise Pilote

The purpose of this study was to determine if anticoagulation of patients with new onset secondary atrial fibrillation (AF) occurring with acute coronary syndromes (ACS), acute pulmonary disease, or sepsis is associated with a reduction in ischemic stroke or an increase in bleeding risk. Studies evaluating the benefits and risks of anticoagulation in secondary AF are infrequent, and the optimal management of these patients is not well understood. A retrospective study cohort was identified of 2,304 patients age 65 years or older, hospitalized with a primary diagnosis of ACS, acute pulmonary disease (chronic obstructive pulmonary disease, pneumonia/influenza, pulmonary embolism, or pleural effusion) or sepsis, and a complication of new-onset AF during admission from 1999 to 2015. Over a follow-up of ∼3 years, we did not identify any association between anticoagulation and a lower incidence of ischemic stroke in patients with new-onset AF occurring with ACS, acute pulmonary disease, or sepsis (odds ratio [OR]: 1.22 [95% confidence interval (CI): 0.65 to 2.27], OR: 0.97 [95% CI: 0.53 to 1.77], and OR: 1.98 [95% CI: 0.29 to 13.47]), after adjusting for confounders. However, anticoagulation was associated with a higher risk of bleeding in patients with AF associated with acute pulmonary disease (OR: 1.72 [95% CI: 1.23 to 2.39]), but not in ACS or sepsis (OR: 1.42 [95% CI: 0.94 to 2.14], OR: 0.96 [95% CI: 0.29 to 3.21]). Our study demonstrates that the benefit of anticoagulation in secondary AF is not strong and can be associated with a higher risk of bleeding. Careful individual assessment regarding decisions on anticoagulation is warranted in these patients.