Clinical Trial Reveals Effectiveness Of Common Treatments For Deep Vein Thrombosis

ORANGE, Calif. - Dec. 20, 2017 - PRLog -- Not all patients with blood clots in their legs – a condition known as deep vein thrombosis (DVT) – need to receive powerful clot-busting drugs, according to results of a large-scale, multicenter clinical trial.

The study showed that clearing the clot with drugs and specialized devices could reduce the likelihood of long-term complications of DVT in some but not all patients.

"What we know now is that we can spare many patients the need to undergo a risky and costly treatment," said Principal Investigator Suresh Vedantham, MD, a professor of radiology and of surgery at Washington University School of Medicine in St. Louis.

The findings were published Dec. 7 in The New England Journal of Medicine.

Between 300,000 and 600,000 people a year in the United States are diagnosed with a first episode of deep vein thrombosis and, despite standard treatment with blood thinners, roughly half will develop post-thrombotic syndrome, a condition leading to leg pain, pressure, swelling and difficulty walking. There is no treatment to prevent the potentially debilitating complication. However, small studies had suggested that a procedure that delivers clot-busting drugs directly into the clot may reduce the chance the syndrome will develop. The procedure is currently used as a second-line treatment to alleviate pain and swelling in people who do not improve on blood thinners.

The Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) study – a randomized controlled trial primarily funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH) – was designed to determine whether performing the procedure as part of initial treatment for patients when they are first diagnosed with deep vein thrombosis would reduce the number of people who later develop the syndrome. In 2008, then-Acting Surgeon General Steven K. Galson, MD, issued a national call to action on deep vein thrombosis and specifically called for research into the benefits and risks of removing clots.

"The clinical research in deep vein thrombosis and post-thrombotic syndrome is very important to the clinical community and of interest to the National Heart, Lung, and Blood Institute," said Andrei Kindzelski, MD, PhD, the NHLBI program officer for the ATTRACT trial. "This landmark study, conducted at 56 clinical sites, demonstrated in an unbiased manner no benefits of catheter-directed thrombolysis as a first-line deep vein thrombosis treatment, enabling patients to avoid an unnecessary medical procedure. At the same time, ATTRACT identified a potential future research need in more targeted use of catheter-directed thrombolysis in specific patient groups."

The study involved 692 patients, randomly assigned to receive blood thinners alone or blood thinners and the procedure. Each patient was followed for two years.

St. Joseph Hospital's Heart and Vascular Services program was one of the participating sites and a major contributor to the study. Site Principal Investigators were Interventional Radiologist Mahmood Razavi, MD, who also acted as a study steering committee member and James Pierog, MD, medical director of Emergency Services.

The clinical trial showed that routine use of the procedure did not reduce the chance of developing post-thrombotic syndrome in all patients, but did reduce the severity of post-thrombotic syndrome, easing patients' long-term symptoms. About 24 percent of people on blood thinners alone experienced moderate to severe pain and swelling, but only 18 percent of people who were treated with blood thinners and clot busters did so.

The procedure also alleviated pain and swelling in the early stages of the disease, when patients are often very uncomfortable.

However, the researchers noted an increase in the number of people who developed major bleeding after undergoing the procedure. While the numbers were small (0.3 percent versus 1.7 percent) and none of the bleeds were fatal, any increase in bleeding is a red flag.

"We are dealing with a very sharp double-edged sword here," said Vedantham, who also is an interventional radiologist at the university's Mallinckrodt Institute of Radiology. "None of us was surprised to find that this treatment is riskier than blood-thinning drugs alone. To justify that extra risk, we would have had to show a dramatic improvement in long-term outcomes, and the study didn't show that. We saw some improvement in disease severity but not enough to justify the risks for most patients."

While the study showed that most patients should not undergo the procedure, the data hint that the benefits may outweigh the risks in some patients, such as those with large clots.

The ATTRACT study was led by researchers at Washington University; McMaster University in Ontario, Canada; Massachusetts General Hospital in Boston; and St. Luke's Mid-America Heart Institute in Kansas City, Mo.