Antithrombotic treatment switching in elderly patients with atrial fibrillation and the risk of thromboembolism, bleeding, and cardiac death

Background Risks of antithrombotic switching is not investigated in elderly atrial fibrillation patients. Objectives To investigate the effectiveness and safety of antithrombotic treatment and switching of antithrombotic treatment in elderly patients (aged 75 years or older) with atrial fibrillation (AF). Methods We conducted a cohort study of 2943 patients with AF (Carrebean-elderly), hospitalized during 2010-2017. Cox models were used to estimate the association of antithrombotic treatment (warfarin, direct oral anticoagulants [DOAC] and non-guideline-recommended therapy [NG], i.e., aspirin and low-molecular-weight heparin) at discharge and antithrombotic treatment switching during follow-up with the risk of a composite and single end points of thromboembolism, bleeding, and cardiac death. Crude and adjusted risk estimates were expressed as hazard ratios (HRs) with 95% confidence intervals (CIs). All-cause death was evaluated, with competing risk regression and estimates expressed as subhazard ratios and 95% CIs. Results We observed an increased risk for the composite end point associated with NG as compared to warfarin at discharge (HR, 1.18; 95% CI, 1.01-1.38) with congruent competing risk regression results, while no significant risk difference was seen for DOACs compared to warfarin (HR, 1.12; 95% CI, 0.92-1.36). Switching from NG to warfarin/DOAC and from warfarin to DOAC occurred in 30.4% and 33.1% of respective antithrombotic treatment groups at discharge and was associated with a decreased risk for the composite end point with an adjusted HR of 0.45 (95% CI, 0.32-0.63) and a HR of 0.50 (95% CI, 0.38-0.65), respectively. Conclusions Antithrombotic treatment switching is common in the elderly AF population. Importantly, switching to guideline-recommended treatment has a favorable impact on both effectiveness and safety.