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.

Funding: South-Eastern Norway Regional Health Authority; Research Council of Norway; University of Oslo; Oslo University Hospital.