Daily Bulletin 2015

Catheter-directed Thrombolysis Helps Patients with Deep Vein Thrombosis

Tuesday, Dec. 01, 2015

Ole Grotta, M.D.

Ole Grotta, M.D.

Additional treatment with catheter-directed thrombolysis (CDT) is effective in certain patients with deep vein thrombosis (DVT), according to results of a study presented Monday.

In DVT, a clot, or thrombus, forms in the deep veins, typically in the legs. About one in four DVT patients develop post-thrombotic syndrome (PTS), in which the clots cause inflammation, block blood flow and damage the tiny vein valves that allow blood to flow against gravity from the legs back to the heart. When valves are damaged and fail to close properly, the flow reverses—a phenomenon known as venous reflux. As PTS worsens, poor blood flow in the leg can cause leg ulcers, which can be difficult to treat.

The current standard of care for post-thrombotic syndrome includes anticoagulation drugs, compression stockings and surgical treatment of superficial insufficient veins. Severe PTS with ulcers and/or pain caused by too little blood flow may require more invasive procedures, such as venous bypass, placement of stents to keep the vessels open and the creation of new valves, or neo-valves, from the vein's inner wall.

These treatments have significant shortcomings, according to study co-author Ole Grotta, M.D., from the University of Oslo in Norway. Stockings and surgical treatment of superficial veins may not provide sufficient relief of symptoms, and in treatments for severe PTS, stents can become blocked and neo-valves may prove insufficient.

Another treatment option is CDT, where a catheter is used to deliver clot-busting drugs to the site of the thrombus.

For the study, researchers examined whether the addition of CDT to conventional therapy had a persistent benefit in reducing PTS, and if CDT increased the unobstructed area of the vessel and reduced reflux five years following DVT. The 209 patients were drawn from the Norway-based CaVenT Study, the first randomized controlled trial to evaluate the effect of additional CDT.

Patients with DVT were randomized to receive conventional therapy alone or additional CDT. PTS was assessed and the venous system was examined by duplex ultrasound and air plethysmography, a technique that measures circulatory capacity, to analyze blood flow and look for evidence of reflux.

The results revealed significant benefits for patients who received CDT, and the effect was sustained and increased from two to five years post-treatment.

"In the intervention group who received additional CDT, the percentage of patients with PTS at five years was 42.5 percent, compared to 70.8 percent in the control group," Dr. Grotta said. "We suggest CDT be considered in patients with extensive DVT and a low risk of bleeding."

The findings support the open vein hypothesis, a theory that rapid thrombus elimination and restoration of unobstructed deep venous flow may prevent reflux, venous obstruction, and PTS, according to Dr. Grotta.

Dr. Grotta noted that two ongoing studies will provide more knowledge about the effect of CDT in patients with DVT. The U.S.-based Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial is looking at CDT's effectiveness in reducing the occurrence of PTS over a 24-month follow-up period. The Catheter Versus Anticoagulation (CAVA) Trial is a Dutch multicenter trial comparing ultrasound-accelerated CDT and standard anticoagulant therapy with standard anticoagulant therapy alone in acute DVT.

Question of the Day:

I want to change the MR imaging parameters for a new protocol based on a research paper I read, but the console says the SAR is too high. What is SAR?

Tip of the day:

Patients who have many follow-up head CTs should be assessed for dose to the eyes as they swiftly become at risk for cataracts.

The RSNA 2015 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Oak Brook, IL 60523.