PB0448 - Fibrin clot properties identify patients that benefit from catheter-directed thrombolysis: A post hoc analysis of the CAVA trial

Background: Catheter-directed thrombolysis (CDT) to improve patency after deep vein thrombosis (DVT) has not conclusively been shown to prevent the post-thrombotic syndrome in randomized-controlled trials. However, additional CDT might benefit selected patients that are unlikely to attain patency with standard treatment.

Aims: We assessed whether fibrin clot properties are associated with long-term patency in patients with iliofemoral DVT.

Methods: Patients included in the CAVA trial had blood samples taken at inclusion and at 12 months. Properties of fibrin clot formation and lysis in plasma were determined using turbidity assays, permeation, and confocal microscopy. Patency was defined as >90% iliofemoral vein compressibility on ultrasound assessment at 12 months. The medical ethics committee approved this study, and all patients gave written informed consent.

Results: Of 152 patients, 67 remained after excluding patients without blood samples (n=65), without ultrasound assessment (n=8) or with unmeasurable samples at inclusion (n=12), likely due to low-molecular-weight heparin treatment. Patients’ clinical characteristics did not differ between treatment groups. Patency was attained in 50.0% (14/28) of patients with CDT and 25.6% (10/39) of those with standard treatment (p=0.040). In patients on standard treatment not reaching patency, clot properties at inclusion showed shorter lag time, higher maximal clotting rate and higher maximal turbidity (Table 1), while clot properties were not associated with patency in patients with CDT. No differences were observed at 12 months (data not shown). Maximal turbidity most accurately predicted patency (Figure 1). In patients with high maximal turbidity, none attainted patency with standard treatment while 44.4% achieved patency with CDT (p=0.012). In contrast, patency did not differ between treatment groups in patients with low maximal turbidity.

Conclusion(s): Fibrin clot properties, especially maximal turbidity, could identify patients unlikely to attain patency with standard treatment. This predictor might be used to select patients that would benefit from CDT in a point-of-care setting.