Comparative thromboembolic risk in atrial fibrillation with and without a secondary precipitant—Danish nationwide cohort study

OBJECTIVES: We compared long-term outcomes in patients with atrial fibrillation (AF) with and without a secondary precipitant. DESIGN AND SETTING: Retrospective cohort study based on Danish nationwide registries. PARTICIPANTS: Patients with AF with and without secondary precipitants (1996–2015) were matched 1:1 according to age, sex, calendar year, CHA(2)DS(2)-VASc score and oral anticoagulation therapy (OAC), resulting in a cohort of 39 723 patients with AF with a secondary precipitant and the same number of patients with AF without a secondary precipitant. Secondary precipitants included alcohol intoxication, thyrotoxicosis, myocardial infarction, surgery and infection in conjunction with AF. PRIMARY AND SECONDARY OUTCOMES: The primary outcome in this study was thromboembolic events. Secondary outcomes included AF rehospitalisation and death. Long-term risks of outcomes were examined by multivariable Cox regression analysis. RESULTS: The most common precipitants were infection (55.0%), surgery (13.2%) and myocardial infarction (12.0%). The 5-year absolute risk of thromboembolic events (taking death into account as a competing risk) in patients with AF grouped according to secondary precipitants were 8.3% (alcohol intoxication), 8.5% (thyrotoxicosis), 12.1% (myocardial infarction), 11.6% (surgery), 12.2% (infection), 10.1% (>1 precipitant) and 12.3% (no secondary precipitant). In the multivariable analyses, AF with a secondary precipitant was associated with the same or an even higher thromboembolic risk than AF without a secondary precipitant. One exception was patients with AF and thyrotoxicosis: those not initiated on OAC therapy carried a lower thromboembolic risk the first year of follow-up than matched patients with AF without a secondary precipitant and no OAC therapy. CONCLUSIONS: In general, AF with a secondary precipitant was associated with the same thromboembolic risk as AF without a secondary precipitant. Consequently, this study highlights the need for more research regarding the long-term management of patients with AF associated with a secondary precipitant.