The following is a summary of “Six-week low-molecular-weight heparin versus 12-week warfarin for calf deep vein thrombosis: A randomized, prospective, open-label study,” published in the February 2024 issue of Hematology by Sartori et al. 

While guidelines recommend 3 months of anticoagulation for isolated distal deep vein thrombosis (IDDVT), shorter durations are often used in practice, prompting an investigation into their effectiveness.

Researchers performed a retrospective study to determine whether a 6-week intermediate-dose low-molecular-weight heparin (LMWH) regimen could offer comparable efficacy and safety to vitamin K antagonists (VKA) in patients with IDDVT through a non-inferiority trial.

They conducted a multicenter, open-label, randomized trial involving 260 outpatients diagnosed with symptomatic IDDVT. Participants were randomly assigned to receive either LMWH followed by VKA for 12 weeks or LMWH at a dose of 1 mg/kg subcutaneously twice a day for 2 weeks, followed by 1 mg/kg subcutaneously once a day for 4 weeks and the follow-up period lasted for 6 months, with the primary endpoint being the composite measure of recurrent venous thromboembolism (VTE), defined as the recurrence or extension of IDDVT, proximal DVT, and pulmonary embolism (PE). However, the study was prematurely halted due to slow recruiting rates.

The results showed that the primary efficacy outcome occurred in 14 patients receiving LMWH (10.8%) and in five patients receiving VKA (3.8%), with a risk difference of 0.069 (95% CI: 0.006–0.132) and a hazard ratio of 2.8 (95% CI: 1.04–7.55). One PE was in the VKA group, and one proximal DVT was in the LMWH group. IDDVT recurrence was 10.0% in the LMWH group versus 3.1% in the VKA group (P=.024). Two patients experienced clinically relevant bleedings (1.6%) in the LMWH group versus one (0.8%) in the VKA group (P=.56).

Investigators concluded that 12-week VKA treatment outperformed 6-week LMWH in preventing VTE recurrence among outpatients with IDDVT.

Source: onlinelibrary.wiley.com/doi/abs/10.1002/ajh.27255