Introduction
Atrial fibrillation (AF) is associated with an increased risk of stroke, systemic thromboembolic events, and mortality.1Long-term anticoagulation therapy, particularly with direct oral anticoagulants (DOACs), significantly reduces the risk of stroke and mortality.2 In terms of venous thromboembolism (VTE), including deep venous thrombosis (DVT) and pulmonary embolism(PE), the duration of anticoagulation therapy to prevent recurrences takes into consideration the risk of recurrent VTE and the risk of bleeding.3
AF and VTE have many pathophysiological and clinical risk factors in common. For example, the pathogenesis of thromboembolism in AF has been associated with a prothrombotic state by fulfilling Virchow’s triad for thrombogenesis, with abnormal blood flow (stasis), vessel wall abnormalities (structural heart disease) and abnormal blood constituents (coagulation factors).4 The pathogenesis of VTE also has similar predisposing factors.3,5 Patients with AF and/or VTE have many cardiovascular risk factors, such as hypertension, smoking, hyperlipidemia, diabetes, and obesity 6-8 and malignancy.9 VTE has also been reported to be associated with several cardiovascular diseases, including peripheral artery disease and myocardial infarction (MI)10,11 as well as non-cardiovascular factors, such as malignancy.12,13 Indeed, one community registry study reported that AF and VTE independently contributed to each other.14Thus, venous and arterial thrombosis may be different sides of the same coin.15
Of note, the duration of prescribing anticoagulation is quite different between AF and VTE in current practice. Long-term anticoagulation should be prescribed for AF patients 2,16 whereas more limited-duration of anticoagulation is sometimes prescribed for VTE patients unless there are high risk features for recurrence.3,17
We hypothesized that AF and VTE, despite sharing many pathophysiological and clinical risk factors, would have differential contribution to arterial thromboembolic events and mortality in the same population. Accordingly, we tested this hypothesis in a nationwide cohort study of VTE and AF patients from the Taiwan National Health Insurance Database.