ROME — Many physicians outside of interventional radiology are inappropriately complacent regarding the long-term sequelae of deep vein thrombosis in the lower extremities, speakers said at the annual meeting of the Cardiovascular and Radiological Interventional Society of Europe.

Deep vein thrombosis (DVT) occurs in more than 250,000 U.S. patients per year. Standard medical management—that is, anticoagulation, compression stockings, and leg elevation—is all about preventing pulmonary embolism, a dreaded acute complication with roughly a 13% in-hospital mortality.

But often, anticoagulation only partially clears the thrombus, and it doesn't fix the delicate venous valves threatened by low or absent blood flow. As a result, many patients develop chronic post-thrombotic syndrome (PTS), or “heavy leg,” marked by ruptured valves, lifelong chronic deep venous insufficiency, painful leg swelling, and stasis ulceration, according to Dr. Kenneth R. Thomson of the Alfred Hospital, Melbourne.

“No patient I've ever met who's had heavy leg syndrome or PTS after DVT thinks it's any good at all,” Dr. Thomson said. “We need to educate clinicians to think of [deep venous] thrombus as a valve attack, like a brain attack or a heart attack, and have a more rapid and aggressive treatment.”

That will require more accurate diagnosis. Even in premier medical centers, the radiologist continued, it's surprising how often patients who present to the emergency department with a swollen leg get an ultrasound exam that stops at the groin and doesn't include the iliac veins or inferior vena cava.

Dr. Stephen T. Kee stressed that PTS can be as disabling as severe peripheral arterial disease. The direct medical costs of PTS in the United States are estimated at &dollar;300 million annually.

“When venous disease is extensive, it is essentially beyond medicine's ability to treat. Anticoagulation alone is not enough. They need our help. Lysis in correct doses is very safe, although in most cases it must be combined with other endovascular techniques with which we are very familiar,” said Dr. Kee, chief of interventional radiology at the University of California, Los Angeles, Medical Center.

Interventional radiologists perform catheter-delivered thrombolysis (CDT) for DVT. It provides more complete clot lysis than the systemic infusion used in acute MI, and with much lower risk of bleeding complications. In roughly 90% of cases, there is an underlying anatomic defect that requires adjunctive angioplasty in order to maintain patency, along with stenting in the case of suprainguinal disease, he explained.

These procedures are most effective in acute DVT. Ideally, Dr. Thomson said, CDT ought to be done in the emergency department. The reality is most patients aren't referred for this more aggressive therapy until at least several months of anticoagulant therapy have gone by and the leg remains swollen. By then the thrombus is hardened and desiccated, crosslinked to fibrin, tightly adherent to the vein wall—and the valves are destroyed.

Dr. Thomson is a coinvestigator in a Cook Inc. project aimed at developing percutaneous bioprosthetic venous valves for use in DVT patients who have experienced “valve attack.” The 1-year clinical outcomes reported at the meeting are promising, but better biomaterials are needed to improve valve longevity.

CDT for DVT is an off-label use of lytics. Nonetheless, the Society for Interventional Radiology (SIR) this year issued a position statement declaring CDT as an adjunct to anticoagulation an acceptable initial treatment strategy for carefully selected patients with acute DVT of less than 14 days' duration.

The SIR statement cited registry data suggesting CDT has better outcomes than those obtained with anticoagulation alone, which results in PTS in up to 50% of patients if compression stockings aren't used and 25% if they are.

A SIR research consensus panel concluded that if more aggressive treatment of DVT is to become a multidisciplinary national priority, there is a pressing need for persuasive A-level supporting data.

Toward that end, the society has submitted to the National Institutes of Health a detailed protocol for a large randomized trial to be called Acute Venous Thrombosis Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT). The trial will compare anticoagulation alone to thrombolysis with or without angioplasty and stenting. The primary end point will be the cumulative 12-month PTS incidence.

“The trial will by protocol get interventional radiologists doing the same thing. One of the big problems with DVT is that each of the 250 of us in this room now do things in our own tweaky way. It makes it hard to get the point across to the physician who's referring patients that there's a standard method of treatment for this disease. I think if we can somehow or another get a consensus on the right way for interventionalists to treat DVT, it will help us to get data that's reproducible,” Dr. Kee said.

If approved by NIH, ATTRACT will start in April 2007 and be led by Dr. Suresh Vedantham of Washington University, St. Louis.

DVT Requires Aggressive Tx To Avoid Chronic Syndrome