Quantity of residual thrombus after successful catheter-directed thrombolysis for Iliofemoral deep venous thrombosis correlates with recurrence

Objectives: Iliofemoral deep venous thrombosis (IFDVT) is an independent risk factor for recurrent DVT. It has been observed that recurrent DVT correlates with residual thrombus. This study evaluates whether risk of recurrence is related to the amount of residual thrombus following catheter-directed thrombolysis (CDT) for IFDVT. Methods: Patients who underwent CDT for IFDVT had their degree of lysis quantified by a reader blind to the patients' long-term clinical outcome. Patients were classified into two groups, ≥50% and <50% residual thrombus. Recurrence was defined as a symptomatic presentation with image verification of new or additional thrombus. Results: A total of 75 patients underwent CDT for IFDVT. Median follow-up was 35.9 months. Sixty-eight patients (91%) had no evidence of recurrence and seven (9%) developed recurrence. Of the patients who had ≥50% (mean 80%) residual thrombus, 50% (4/8) experienced recurrence, but in those with <50% (mean 35%) residual thrombus, only 5% (3/67) had recurrent DVT (P = 0.0014). Conclusion: The burden of residual thrombus at completion of CDT correlates with the risk of DVT recurrence. Patients having CDT for IFDVT had a lower risk of recurrence than expected. Successful clearing of acute clot in IFDVT patients significantly reduces the recurrence risk compared to patients with a large residual thrombus burden.