Isolated calf muscular vein thrombosis is associated with pulmonary embolism and a high incidence of additional ipsilateral and contralateral deep venous thrombosis.

Objective: Little is known about the natural history of isolated gastrocnemial and soleal vein thrombosis (IGSVT), and recommendations for treatment and follow-up are therefore anecdotal. This study sought to determine the rates of venous thromboembolism (VTE) progression and resolution and the effect of antithrombotic therapy in patients with IGSVT.

Methods: A vascular laboratory database was queried from January 2002 to December 2006 to identify patients with duplex-diagnosed IGSVT and follow-up duplex scan studies. Duplex scan examinations were reviewed to determine rates of resolution and development of new ipsilateral and contralateral VTE. Records were reviewed for comorbid conditions, VTE risk factors, anticoagulation therapy, the effect of anticoagulation on resolution of IGSVT, and diagnosis of pulmonary embolism (PE) confirmed by computed tomographic angiography.

Results: Patients with at least one follow-up duplex scan study were included in our analysis. Sixty-five limbs with isolated IGSVT were identified in 57 patients with follow-up duplex scans (mean, 2.75 studies per patient; mean follow-up, 113 days). Twenty patients (35%) received therapeutic anticoagulation after the IGSVT diagnosis. There were seven PEs, two on the same day as initial IGSVT diagnosis, and two within 1 week of diagnosis. IGSVT resolution rates by Kaplan-Meier analysis at 1 and 3 months were 20% and 41%, respectively. Eleven patients (19%) developed additional ipsilateral deep venous thrombosis (DVT; three axial calf vein thromboses and five proximal DVT) or contralateral DVT (one axial calf vein thrombosis [CVT], one IGSVT, and one proximal DVT) during follow-up. Of the eight patients who developed additional ipsilateral DVT, five also developed concurrent contralateral DVT. Overall, 14% of patients developed contralateral DVT. Median time to development of additional DVT was 10 days. Therapeutic anticoagulation was associated with DVT resolution. However, VTE recurrence was not significantly affected by age, gender, anticoagulation, oral contraceptives, known hypercoagulable states, or comorbidities (smoking, cancer, trauma, postsurgical status, renal failure, hyperlipidemia, diabetes, or cardiopulmonary abnormalities; P > .05).

Conclusions: Isolated calf muscular vein thrombosis is associated with PE and a significant incidence of VTE progression. Therapeutic anticoagulation is associated with DVT resolution, but its effect on VTE recurrence was not demonstrated. Untreated patients with IGSVT should receive follow-up bilateral lower extremity venous duplex scans within 10 days of diagnosis.