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by Crystal Phend, Senior Associate Editor, MedPage Today
Thrombolytics delivered to acute proximal deep-vein thrombus (DVT) with clot removal did not reduce the risk of post-thrombotic syndrome but did raise major bleeding risk over anticoagulant treatment alone in the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) clinical trial.
The proportion of patients with post-thrombotic syndrome at 6 to 24 months was 47% in patients randomized to acute pharmacomechanical-thrombolysis atop standard anticoagulation and 48% with the standard approach alone (RR 0.96, 95% CI 0.82-1.11).
The intervention, though, increased major bleeding events within 10 days (1.7% versus 0.3%, P=0.049), Suresh Vedantham, MD, of Washington University in St. Louis, Missouri, and colleagues reported in the New England Journal of Medicine.
The phase III, open-label, assessor-blinded trial included 692 patients with acute, symptomatic proximal DVT involving the femoral, common femoral, or iliac vein who were ages 16 to 75 and not pregnant, at high bleeding risk, and did not have active cancer or established post-thrombotic syndrome, or recent ipsilateral DVT.
The intervention involved alteplase (Activase) delivered into the thrombus, followed by thrombus aspiration or maceration that removed an average 76% of the clot. Both groups received guideline-directed anticoagulation and used compression stockings.
Recurrence of venous thromboembolism over 24 months of follow-up were statistically similar between the groups, albeit with a trend for anticoagulation alone to be safer (12% with intervention and 8% among controls, P=0.09). Nor did improvement in quality of life from baseline to 24 months differ between groups.
But the severity scores for post-thrombotic syndrome that developed gave the upper hand to the intervention (P<0.01 for Villalta scores at 6, 12, 18, and 24 months). Moderate-to-severe post-thrombotic syndrome occurred in 18% versus 24% of controls (RR 0.73, P=0.04).
While the findings differed from those in the smaller CAVENT trial of catheter-directed thrombolysis, the researchers suggested that the conclusions of ATTRACT were solid:
Inadequate thrombus removal is unlikely to explain the failure of pharmacomechanical thrombolysis to prevent the post-thrombotic syndrome in our trial, since venography showed effective thrombus removal," the team wrote. "Standard care for deep-vein thrombosis did not substantially differ between the two treatment groups and would not explain the observed lack of a beneficial effect of pharmacomechanical thrombolysis in preventing the post-thrombotic syndrome."
The study was supported by grants from the National Heart, Lung, and Blood Institute, the Washington University Center for Translational Therapies in Thrombosis and Institute of Clinical and Translational Sciences, Boston Scientific, Covidien (now Medtronic), Genentech, the Society of Interventional Radiology Foundation, the Canada Research Chairs Program, the CanVECTOR Network (funded by the Canadian Institutes of Health Research), the Heart and Stroke Foundation of Canada, and a Jack Hirsh Professorship in Thrombosis. BSN Medical donated the compression stockings. Vedantham reported receiving grant support from Cook Medical and Volcano.
--From MedPage Today