Long-term outcome after additional catheter-directed thrombolysis versus standard treatment for acute iliofemoral deep vein thrombosis (the CaVenT study): a randomised controlled trial

Background Conventional anticoagulant treatment for acute deep vein thrombosis (DVT) effectively prevents thrombus extension and recurrence, but does not dissolve the clot, and many patients develop post-thrombotic syndrome (PTS). We aimed to examine whether additional treatment with catheter-directed thrombolysis (CDT) using alteplase reduced development of PTS. Methods Participants in this open-label, randomised controlled trial were recruited from 20 hospitals in the Norwegian southeastern health region. Patients aged 18-75 years with a first-time iliofemoral DVT were included within 21 days from symptom onset. Patients were randomly assigned (1:1) by picking lowest number of sealed envelopes to conventional treatment alone or additional CDT. Randomisation was stratified for involvement of the pelvic veins with blocks of six. We assessed two co-primary outcomes: frequency of PTS as assessed by Villalta score at 24 months, and iliofemoral patency after 6 months. Analyses were by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00251771. Findings 209 patients were randomly assigned to treatment groups (108 control, 101 CDT). At completion of 24 months' follow-up, data for clinical status were available for 189 patients (90%; 99 control, 90 CDT). At 24 months, 37 (41.1%, 95% CI 31.5-51.4) patients allocated additional CDT presented with PTS compared with 55 (55.6%, 95% CI 45.7-65.0) in the control group (p=0.047). The difference in PTS corresponds to an absolute risk reduction of 14.4% (95% CI 0.2-27.9), and the number needed to treat was 7 (95% CI 4-502). Iliofemoral patency after 6 months was reported in 58 patients (65.9%, 95% CI 55.5-75.0) on CDT versus 45 (47.4%, 37.6-57.3) on control (p=0.012). 20 bleeding complications related to CDT included three major and five clinically relevant bleeds. Interpretation Additional CDT should be considered in patients with a high proximal DVT and low risk of bleeding.