Use of Prophylactic or Therapeutic Anticoagulation in Critically Ill Patients With Pre-existing Atrial Fibrillation

<b>Purpose:</b> The optimal anticoagulation regimen for atrial fibrillation (AF) in critically ill patients is challenging as these patients may be at an increased risk for bleeding and clotting despite an absence or presence of anticoagulation. The purpose of this study was to compare bleeding and thrombotic rates in critically-ill adults with pre-existing AF receiving therapeutic anticoagulation versus chemical or mechanical venous thromboembolism prophylaxis. <b>Methods:</b> A retrospective, observational study was conducted. The primary outcome identified rate of International Society of Thrombosis and Hemostasis bleeding, and secondarily assessed all venous or arterial thromboembolic events. To determine risk-factors associated with bleeding and to account for differences in baseline characteristics, a multivariable logistic regression model was used. <b>Results:</b> A total of 199 patients were included, 100 receiving therapeutic anticoagulation and 99 receiving venous thromboembolism prophylaxis. Patients receiving therapeutic anticoagulation compared to chemical or mechanical prophylaxis had a median (IQR) CHA₂DS₂VASc score of 4 (3-5) versus 4 (2-5) (<i>P</i> = .5499) and HAS-BLED score of 3 (3-4) versus 3 (2-4) (<i>P</i> = .0013); respectively. There was almost a threefold adjusted increased risk of bleeding in patients receiving therapeutic anticoagulation compared to venous thromboembolism prophylaxis (adjusted odds ratio [aOR] 2.7 [95% CI 1.1-9.9]; <i>P</i> = .0349). One stroke occurred in a patient receiving therapeutic anticoagulation, and none occurred in patients in the prophylaxis group (<i>P</i> = 1.000). <b>Conclusion:</b> Use of therapeutic anticoagulation in critically ill patients with pre-existing AF may increase bleed rates without protecting against stroke development.