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ATTRACT results

Most DVT patients should be treated with anticoagulant drugs alone

Pivotal study of minimally invasive therapy improves the care of patients with DVT

The results from the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) randomised, multi-centre clinical trial, has reported that most patients with DVT 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

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.

The outcomes, presented at the Society of Interventional Radiology’s (SIR) 2017 Annual Scientific Meeting, will serve as the basis for future, evidence-based guidance on how to treat various forms of DVT, said Dr Suresh Vedantham, professor of radiology and surgery at the Mallinckrodt Institute of Radiology at the Washington University School of Medicine, the study’s principal investigator.

Suresh Vedantham

“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 Vedantham. “Today’s health care environment is focused on delivering the right care for the right patient, and our results support this trend.”

The clinical trial of 692 patients with acute DVT was funded in part by a US$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), which 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, therefore, the prevention of PTS and moderate-to-severe PTS are important goals of DVT treatment.

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.