Pivotal study of minimally invasive therapy improves the care of patients with deep vein thrombosis

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WASHINGTON — The results of a prominent, National Institutes of Health (NIH)-sponsored study into the treatment of deep vein thrombosis (DVT) provide important guidance for physicians on how best to treat their DVT patients, according to new research presented today at the Society of Interventional Radiology’s (SIR) 2017 Annual Scientific Meeting.

The study, known as Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis or ATTRACT, compared two treatment strategies for DVT in a randomized, multicenter trial and will serve as the basis for future, evidence-based guidance on how to treat various forms of DVT.

This is the first public presentation of the long-awaited results of the ATTRACT Trial, which received its primary support from NIH, with additional support from the SIR Foundation and four companies—Boston Scientific, BSN Medical, Covidien (now Medtronic), and Genentech. The companies played no role in the study design, execution, or data analysis.

The trial found that most patients with DVT, a dangerous blood clot that forms in a deep leg vein, should continue to be treated with anticoagulant drugs alone, without undergoing a procedure-based intervention. However, the study also showed that a minimally invasive catheter-directed therapy, known as pharmacomechanical catheter-directed thrombolysis (PCDT), provides greater relief of initial leg pain and swelling and is likely to prevent disability in certain DVT patients. PCDT is a minimally invasive treatment that removes clots through a tiny incision—2–3 mm long—using a clot-busting drug along with catheter-driven devices that mechanically break up clots.

The study suggests that some patients who received PCDT were less likely to develop moderate-to-severe post-thrombotic syndrome (PTS). Because patients with the largest blood clots, known as iliofemoral DVT, are more likely to develop PTS, they appear to be the most likely to benefit from PCDT.

“These findings allow health care professionals to make better decisions as to who may benefit from PCDT, ensuring that patient care teams deliver the best care, while reducing harm from unnecessary treatments,” said Suresh Vedantham, M.D., FSIR, professor of radiology and surgery at the Mallinckrodt Institute of Radiology at the Washington University School of Medicine, the study’s principal investigator. “Today’s health care environment is focused on delivering the right care for the right patient, and our results support this trend.”

Every year, about 600,000 Americans experience a deep vein thrombosis, the formation of clots in several different veins that move blood from various parts of the body back to the heart and lungs. DVT is caused by a combination of factors: change in blood flow, injury to a vein, or other conditions.

The clinical trial of 692 patients with acute DVT was funded in part by a $10 million grant from the National Heart, Lung, and Blood Institute, and convened by SIR Foundation. Led by an interventional radiologist and involving 55 other hospitals and leading DVT researchers from multiple subspecialties, the trial included patients whose acute DVT occurred in the femoral, common femoral, and/or iliac veins.

Patients were randomly assigned to one of two treatment groups—the active treatment group which received blood-thinning drugs along with PCDT, and a control group that received blood-thinning drugs alone. The study found that PTS occurred with equal frequency in both groups.

Researchers also found that DVT patients who received both blood-thinning drugs and PCDT were 25 percent less likely (18 percent with PCDT vs. 24 percent without) to develop moderate-to-severe PTS.

Vedantham said that in the overall study population, researchers also found that the combination of PCDT and blood-thinners provided greater relief of leg pain and swelling during the first 30 days of treatment, compared to those who only received blood-thinners.

About 40 percent of DVT patients develop post-thrombotic syndrome (PTS), a long-term complication that occurs when blood flow is blocked or flows backwards due to damaged blood vessels, causing chronic pain, swelling, and fatigue of the affected limb. PTS can cause major disability that can prevent people from walking even short distances, working, or conducting normal daily activities. Many patients with PTS also develop venous leg ulcers, which are open sores that are difficult to heal. Therefore, the prevention of PTS and moderate-to-severe PTS are important goals of DVT treatment.

During March, which is DVT Awareness Month, the Society of Interventional Radiology is raising awareness of the dangers of DVT and updating health care professionals, patients, and family members about exciting new research defining how best to treat DVT. To learn more about PCDT and other minimally invasive treatments, visit www.sirweb.org.

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