Vedantham et al. performed the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial, in which 692 patients with acute proximal deep-vein thrombosis were randomized to receive either anticoagulation alone (control group) or anticoagulation plus pharmacomechanical thrombolysis (catheter-mediated or device-mediated intrathrombus delivery of recombinant tissue plasminogen activator and thrombus aspiration or maceration, with or without stenting). The primary outcome was development of the post-thrombotic syndrome between 6 and 24 months of follow-up. Read the latest Case of the Massachussetts General Hospital.
Q: How common is the post-thrombotic syndrome among patients with prior deep-vein thrombosis?
A: Despite the use of anticoagulant therapy, the post-thrombotic syndrome develops within 2 years in approximately half of patients with proximal deep-vein thrombosis. The post-thrombotic syndrome commonly causes chronic limb pain and swelling and can progress to cause major disability, leg ulcers, and impaired quality of life.
Q: How is pharmacomechanical catheter-directed thrombolysis performed?
A: In the trial by Vedantham et al., after the initial delivery of recombinant tissue plasminogen activator, physicians could use balloon maceration, catheter aspiration, thrombectomy with the use of the AngioJet or Trellis system, percutaneous transluminal balloon venoplasty, stent placement (iliac or common femoral vein), or a combination of procedures to clear residual thrombus and treat obstructive lesions. Stenting was encouraged for lesions that were causing 50% or greater narrowing of the diameter of the vein, robust collateral filling, or a mean pressure gradient of more than 2 mm Hg. Treatment was discontinued when there was at least 90% thrombus removal with restoration of flow or when there was a serious complication.
Q: Does pharmacomechanical thrombolysis reduce the risk of the post-thrombotic syndrome in patients with proximal deep-vein thrombosis?
A: In the primary analysis of the ATTRACT trial, the post-thrombotic syndrome developed over the 24-month period in 157 of 336 patients (47%) assigned to the pharmacomechanical-thrombolysis group and in 171 of 355 patients (48%) assigned to the control group (risk ratio, 0.96; 95% CI, 0.82 to 1.11; P=0.56). The pharmacomechanical-thrombolysis group did not have a significantly lower proportion of patients with major non–post-thrombotic syndrome treatment failure or overall treatment failure than the control group. Over the 24-month period, there was no significant between-group difference in the change in venous disease–specific quality of life (P=0.08) or general quality of life (P=0.37). Major bleeding within 10 days occurred in 6 patients (1.7%) assigned to the pharmacomechanical-thrombolysis group, as compared with 1 patient (0.3%) assigned to the control group (P=0.049).
Q: What was a limitation of the ATTRACT trial?
A: The authors of the ATTRACT trial note that there was a substantial number of missing assessments of the post-thrombotic syndrome. As expected, there were occasional missed visits among patients who returned for follow-up, which were balanced between the treatment groups. However, among the 80 patients with no post-thrombotic syndrome assessments, two thirds were in the control group, which is likely to have resulted in an underestimate of the treatment effect. Although the sensitivity analysis conducted with the use of methods to impute assessments of the post-thrombotic syndrome in these patients yielded findings similar to those in the primary analysis, the extent of incomplete follow-up is still a limitation of the trial.
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