Iliac vein thrombosis: Feasibility assessment of randomized controlled trials of endovascular pharmacomechanical thrombolysis

Background: Optimal treatment for iliac vein thrombosis has not been established by randomized clinical trials largely owing to difficulty in patient recruitment. To assess the feasibility of a prospective randomized trial of thrombolysis and stenting, we determined the incidence of iliac vein thrombosis and randomization eligibility based on criteria for two ongoing trials. Methods: All patients with incident leg deep vein thrombosis during the calendar year 2005 seen at the Mayo Clinic were identified to determine the frequency of iliac vein involvement and the number undergoing endovascular therapies. Each patient was assessed for eligibility for potential randomization into a theoretic trial of thrombolytic therapy. Results: Ninety-five (of 394) patients had iliac vein involvement. Of these, only nine patients would have been suitable for randomization. Of the remaining 86 patients, prolonged symptom duration (n = 28), active cancer (n = 24) and advanced age (n = 19) were the most common exclusion criteria. Of 31 patients who had intervention, 75% had at least one contraindication for randomization. Conclusions: Despite a philosophy of aggressive treatment for iliac vein thrombosis at this institution, the number of cases that could potentially be randomized into a clinical trial is relatively small. Trial design may require either multicenter cooperation or exclusion criteria revision for adequate recruitment.