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.