Abstract
OBJECTIVE: Thrombi in the axial calf veins have quite different anatomical and physiological characteristics from that in the muscular calf veins, but their treatment was usually addressed in the same manner. We performed a meta-analysis of randomized and cohort studies to compare clinical outcomes among patients with isolated axial vs muscular calf deep vein thrombosis (DVT). METHODS: Recurrent venous thromboembolism (VTE) was selected as the primary outcome. Resolution, proximal propagation of calf DVT, pulmonary embolism (PE), major bleeds, and clinically relevant non-major bleeds were separately analyzed as secondary outcomes. Data were pooled and compared with risk ratio (RR) and 95% confidence interval (CI). RESULTS: Thirteen studies, consisting of 4889 patients, met the inclusion criteria and were included for analysis. A greater rate of recurrent VTE (FE model: RR, 1.23; 95% CI, 1.00-1.53; I(2) = 29%), resolution (FE model: RR, 1.32; 95% CI, 1.01-1.72; I(2) = 31%), proximal propagation (FE model: RR, 1.63; 95% CI, 1.10-2.41; I(2) = 40%), and PE (FE model: RR, 2.79; 95% CI, 1.31-5.95; I(2) = 0%) in the axial group compared with the muscular group. There was no difference in the pooled estimates for major bleeds (FE model: RR, 1.09; 95% CI, 0.61-1.95; I(2) = 0%), and clinically relevant non-major bleeds (FE model: RR, 1.80; 95% CI, 0.93-3.48) in the axial and muscular arms. CONCLUSIONS: Patients with calf DVT limited to muscular veins might have a lower rate of recurrent VTE, resolution, proximal propagation, and PE vs those with axial calf vein involvement and exhibited similar safety outcomes.