Administration of sulodexide after discontinuation of anticoagulant treatment in patients with unprovoked venous thromboembolism significantly reduced the incidence of recurrences, and did not increase the risk of bleeding events. These findings come from the SURVET study, a randomised controlled double-blind trial that assessed the safety and efficacy of this natural glycosaminoglycan in preventing the recurrence of venous thromboembolism once standard anticoagulation treatment has been discontinued.

The risk of recurrence is particularly high in patients with a first episode of unprovoked venous thromboembolism. Although extending anticoagulant therapy can reduce the risk of recurrence, it is also associated with increased bleeding, emphasizing the need to find alternative drugs. Sulodexide, which has antithrombotic and profibrinolytic activities, has been previously shown to be associated with very low risk of bleeding and is approved in some countries for the treatment of chronic venous diseases.

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The SURVET trial recruited patients with a first-ever episode of unprovoked proximal deep vein thrombosis or pulmonary embolism who had completed vitamin K antagonist (VKA) anticoagulant treatment. The researchers randomly assigned the patients to receive either sulodexide (500 lipasemic units twice daily) or placebo for two years, in addition to compression therapy. Venous thromboembolism—the primary efficacy outcome—recurred in 4.9% (n = 15) of patients receiving sulodexide and in 9.7% (n = 30) of patients receiving placebo (HR 0.49, 95% CI 0.27–0.92, P = 0.025). Major bleeding events did not occur in either group, but clinically relevant, nonmajor bleeding was observed in two patients in each group. The researchers acknowledge, however, that the study was not powered to detect events with very small frequency and, therefore, caution that the absence of serious bleeding could be a chance finding.

The results from this multicentre study are consistent with findings from the WARFASA and ASPIRE aspirin trials. In fact, sulodexide performed better in the SURVET trial, showing a lower hazard ratio for venous thromboembolism and for clinically relevant bleeding compared with aspirin. Giuseppe M. Andreozzi, lead author of this study, describes sulodexide as “an important treatment option when bleeding risk suggests discontinuation of extended anticoagulation”, and believes future studies are needed to “examine whether a similar effect can be obtained after treatment of the index event with non-VKA oral anticoagulants, and whether there is a summation of effects with aspirin.”