Residual rates of reflux and obstruction and their correlation to post-thrombotic syndrome in a randomized study on catheter-directed thrombolysis for deep vein thrombosis

Background: Deep vein thrombosis (DVT) often results in venous valvular incompetence and incomplete recanalization, followed by post-thrombotic syndrome (PTS). Treatment with additional catheter-directed thrombolysis (CDT) in patients with an iliofemoral DVT has been shown to reduce the frequency of PTS. The objective of this study was to assess the effect of CDT on venous reflux and patency and to identify possible predictors for the development of PTS. Methods: Open, multicenter, randomized, controlled clinical trial. Patients (18-75 years) with a first-time iliofemoral DVT were randomized to receive conventional treatment with anticoagulation and compression stockings or CDT in addition to conventional treatment. Follow-up after 6 and 24 months included ultrasound and air plethysmography for evaluation of venous reflux and patency. PTS was assessed with the Villalta score. Possible predictors of PTS were analyzed in multivariate logistic regression models. Results: Following additional CDT, deep venous reflux was detected in 65.2% (95% confidence interval [CI], 54.8-74.2) of patients at 6 months and 66.7% (95% CI, 56.4-75.6) at 24 months. The absolute risk reduction of deep venous reflux was 11.9% (95% CI, 1.1-24.9) after 6 months and 16.5% (95% CI, 4.2-28.8) after 24 months in the CDT arm compared with controls. Correspondingly, venous patency was regained in 65.9% (95% CI, 55.5-75.0) of patients at 6 months and 74.7% (95% CI, 64.9-82.6) after 24 months. Patency was regained in 18.5% (95% CI, 4.4-32.6) more patients after 6 months and 15.1% (95% CI, 1.8-28.5) more patients after 24 months compared with controls. Independent of treatment allocation, patients with fully recanalized and competent deep veins at 6-month follow-up had a 40.5% (95% CI, 26.4-54.7) absolute risk reduction of developing PTS compared with patients with abnormal vein assessment. Reflux and lack of patency at 6 months were found to be independent predictors of PTS development in patients treated with CDT (odds ratio, 8.3; 95% CI, 2.6-26.8 for patients with reflux, and odds ratio, 0.17; 95% CI, 0.06-0.49 for patients with patency). Conclusions: Additional CDT improved patency and reduced reflux. Both parameters were found to be strong predictors of PTS in patients treated with CDT. Noninvasive vein assessments of patency and reflux may be helpful to identify and monitor patients at high risk of PTS. Our findings provide evidence for the importance of early recanalization with CDT for acute iliofemoral DVT.