Mechanically assisted thrombolysis boosts thrombosis therapy

Combining catheter-directed thrombolysis with a mechanical thrombectomy device could be more cost-effective than performing thrombolysis alone in patients with acute iliofemoral deep vein thrombosis, according to Johns Hopkins University researchers reporting on the first study of its kind.

Thrombolysis for the treatment of venous thrombi of the lower extremities has proved effective over the course of more than two decades. Clinical data validate lytic therapy, particularly in regard to the management and prevention of related complications such as chronic venous insufficiency, valvular dysfunction, and pulmonary embolism.

Albeit effective, catheter-directed thrombolysis may be riskier and more expensive than conventional anticoagulation therapy with warfarin or heparin. Several studies have shown that combining mechanical thrombectomy with catheter-directed thrombolysis for iliofemoral DVT may allow shorter treatment and thus lower lytic doses and risks. The team of researchers led by Dr. Hyun S. Kim, a JHU radiologist, set out to perform the first study comparing catheter-directed thrombolysis with and without percutaneous mechanical thrombectomy.

Kim and colleagues retrospectively reviewed from their clinical database 26 limbs in 23 consecutive patients (nine men and 14 women with a mean age of 42.9) who had undergone catheter-directed thrombolysis with urokinase between 1997 and 2003. They also retrospectively reviewed 19 limbs in 14 patients (seven men, seven women, mean age 53) who underwent percutaneous mechanical thrombectomy with the AngioJet system (Possis Medical, Minneapolis). Study cohorts included patients who received urokinase before it was temporarily recalled by the FDA in 1999 and after the drug's redistribution in 2002 under identical treatment protocols.

The investigators found that percutaneous catheter-directed thrombolysis with rheolytic percutaneous mechanical thrombectomy was as effective as thrombolysis alone. However, the combined approach was significantly faster, required lower lytic agent doses, and resulted in lower costs (J Vasc Interv Radiol 2006;17:1099-1104).

Catheter-directed thrombolysis alone lasted about 57 hours, almost twice as long as thrombolysis plus mechanical thrombectomy (30.3 hours). The mean urokinase dose for catheter-directed thrombolysis was 6.70 million units (U) compared with 2.95 U for thrombolysis/thrombectomy. Urokinase achieved complete clot lysis in 80.7% and 84.2% of limbs treated with thrombolysis alone and thrombolysis plus thrombectomy, respectively.

The hemorrhage and pulmonary embolism rates were better for combined thrombolysis/thrombectomy than thrombolysis alone (5.3% versus 7.7%), though the difference was not statistically significant. The mean cost for catheter-directed thrombolysis alone, however, was $10,127 compared with $5128 for combined thrombolysis/thrombectomy.

The study had several limitations, including its retrospective nonrandomized design and potential demographic, operator skill, and material biases (exclusive use of urokinase and one mechanical thrombectomy device). Future prospective randomized trials, however, should confirm the promise of combined catheter-directed thrombolysis and percutaneous mechanical thrombectomy for patients with acute DVT, the researchers said.

For more information from the Diagnostic Imaging archives:

Intravascular 'sonic lysis' busts peripheral thrombi

Minimally invasive therapies break through in DVT

Revolution storms along in thrombolytic agents

Ultrasound shows promise for treatment of thrombosis