(VP120) TREATMENT OF ISOLATED CALF MUSCLE VEIN THROMBOSIS: A RETROSPECTIVE ANALYSIS AT A TERTIARY HOSPITAL

Background: Isolated calf muscle vein thrombosis (ICMVT), defined as thrombosis of the soleal or gastrocnemius vein, without concomitant pulmonary embolism (PE) or deep vein thrombosis (DVT) (either proximal or axial distal), represents around 10-15% of all diagnosed DVT of the leg. Unlike treatment of acute proximal DVT, management of acute distal DVT is more ambiguous within international guidelines, and even more so in cases of ICMVT. Hence, we aim to describe local practices at our tertiary academic institution regarding ICMVT management (risk factor for treatment, anticoagulation treatment and length).

METHODS AND RESULTS: A retrospective study was conducted from 2005-2019 at the Centre Hospitalier de l’Université de Sherbrooke. All patients 18 years and older diagnosed with ICMVT were included. Patients already under long term anticoagulation treatment at time of diagnosis were excluded.

A total of 186 patients were included in this study. Among them, 93 received anticoagulation; 73 at therapeutic dose and 20 at prophylactic dose. Direct oral anticoagulants were the preferred agent for anticoagulation (54/93; 58,0%). Patients on therapeutic dose anticoagulation were, compared to patients on prophylactic dose, treated for a longer period of time. Factors such as clot length (>5cm), cast immobilization, surgery within 3 months, recent hospitalization, and having an internal medicine subspeciality consultation were all associated with a higher rate of anticoagulation. However, inpatient status at time of diagnosis, active cancer and a past history of VTE didn’t impact the use of anticoagulation.

Nine patients had a thromboembolic progression within 6 months of ICMVT diagnosis, of which 6 patients had received anticoagulation. Only 54,8% of cases (102/186) of ICMVT had an internal medicine subspeciality consultation. Among patients not anticoagulated after internal medicine subspecialty consultation, 10.3% (3/29) had a thromboembolic progression, compared to none (0/61) of the patients who did not see an internal medicine subspecialist and were not anticoagulated. Finally, only 23,8% of patients without anticoagulation therapy had a follow up doppler ultrasound to evaluate for thromboembolic progression.

Conclusion: The uncertainty around treatment of ICMVT is well demonstrated in our tertiary hospital, with half of patients receiving anticoagulation, and half not. We need to increase physician awareness on known risk factors of VTE progression, such as past history of VTE and active cancer, and on the necessity of doing a follow up doppler at one week for ICMVT not treated with anticoagulation, as recommended by the CHEST guidelines.