Etiology and management of venous thromboembolism recurrence in patients anticoagulated for venous thromboembolism: a single-center study

BACKGROUND Venous thromboembolic (VTE) recurrence on anticoagulation (ROA) and anticoagulant failure (ACF) are frequently described, but poorly defined. AIMS To determine the incidence and causes of ROA and ACF in patients with venous thromboembolism (VTE). Secondary aims are to describe management of these cases including anticoagulation selection and dosing strategies. METHODS Patients with acute VTE enrolled in the Mayo Clinic Venous Thromboembolism Registry from 2013 to 2022 were included. Charts of patients with VTE recurrence despite anticoagulation were reviewed. ROA was defined as any new thrombotic event in patients prescribed and recently taking anticoagulation. Anticoagulant failure (ACF) was defined as ROA in the absence of modifiable risk factors. RESULTS Of the 4,980 patients included 150 (3.0%) ROA events occurred in 130 patients. Altered absorption (40, 26.7%), medication dosing (35, 23.3%), and recent interruption of therapy (37, 24.7%) were frequently documented reasons. Malignancy was present in 107 (71.3%) with 47 (43.9%) having metastatic malignancy. ROA was attributed to a modifiable cause in 75 (50.0%). In 26 (17.3%) patients, there were no identifiable reasons for failure, and these were labelled as ACF. After recurrent VTE event, 92 (61.3%) were transitioned to an alternative anticoagulant with the most frequent being enoxaparin. However, 27 (18.0%) remained on the same medication at an increased dose and 27 (18.0%) did not have any change in therapy. There were 4 (2.7%) with unclear management strategies. CONCLUSION ROA can affect 3% of patients with VTE. In review, nearly half of ROA events are preventable with a careful review of medication and patient characteristics. When not modifiable, the most utilized strategy for managing patients with ACF is to transition to another anticoagulant, usually enoxaparin. Our practice strategy for evaluation and management of ROA is outlined.