Catheter thrombolysis doesn't prevent thrombotic syndrome after DVT

By John Murphy, MDLinx
Published December 6, 2017

Key Takeaways

Catheter-directed thrombolysis plus anticoagulant therapy is no better than anticoagulation alone for preventing post-thrombotic syndrome (PTS) after deep vein thrombosis (DVT), researchers reported recently in the New England Journal of Medicine.

About half of patients with DVT develop PTS as a long-term complication. Pharmacomechanical catheter-directed thrombolysis (PCDT) macerates or aspirates the blood clot while also delivering an anticoagulant. Small studies have shown that this type of thrombolysis can reduce the risk of PTS, but no large studies have been conducted to confirm those results.

To that end, investigators from 56 centers undertook the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial. They randomly assigned 692 patients with acute proximal DVT to receive either catheter-directed thrombolysis plus an anticoagulant (recombinant tissue plasminogen activator [TPA]) or anticoagulant therapy alone.

Patients in both groups received initial and long-term anticoagulant therapy consistent with published guidelines and were also provided compression stockings.

Same risk for PTS

After 2 years of follow-up, results showed that the procedure didn’t result in a lower risk of PTS. The complication developed in about the same percentage of patients in either group—47% in the PCDT group and 48% in the anticoagulant-only group (risk ratio: 0.96, 95% confidence interval: 0.82-1.11, P=0.56).

“It seemed logical that rapidly eliminating the blood clot with the procedure would re-open the veins and prevent damage to the one-way valves. But in this study, the veins were successfully opened, but people still developed PTS,” said principal investigator Suresh Vedantham, MD, professor of radiology and surgery at Washington University School of Medicine, St. Louis, MO.

“What we know now is that we can spare most patients the need to undergo a risky and costly treatment,” he noted.

Comfort and safety

Although the procedure didn’t lower the risk of PTS, it did significantly reduce PTS severity in some patients. More patients in the PCDT group had decreased leg pain and reduced leg circumference than patients in the anticoagulant-only group.

However, a small but significant number of patients who had the procedure—6 (1.7%)—also developed major bleeding, compared with 1 patient (0.3%) in the anticoagulant-only group (P=0.049).

“Increased bleeding was entirely expected because the procedure used TPA, a powerful clot-busting drug,” Dr. Vedantham said. “But, from a patient's perspective, the additional bleeding risk certainly can't be discounted, and is part of why we could not recommend routine use of PCDT as first-line treatment for DVT without a large benefit in preventing PTS—which this study did not show.”

The upside of this study is that it will help many people avoid an unnecessary procedure, Dr. Vedantham added.

“The findings are also interesting because there is the suggestion that at least some patients may have benefited. Sorting that out is going to be very important,” he said. “The ATTRACT trial will provide crucial guidance in designing further targeted studies to determine who is most likely to benefit from this procedure as a first-line treatment.”

Sorting it out

So, why didn’t the procedure prevent PTS? Dr. Vedantham speculated that there might be differences in the biological pathways between the development of PTS and its progression to more severe forms.

“To date, physicians have assumed this is one continuous process influenced by the same main factors. But one of the potentially important elements of this study’s findings is that we may now need to challenge that assumption,” he explained. “In other words, it could be that once you develop a blood clot, genetics (or other factors we don’t understand yet) determine whether you develop PTS—but whether or not the vein stays blocked and functionally intact determines how bad it gets.”

But for now, PCDT should be reserved only for certain carefully selected DVT patients who develop severe limitations of leg function and are not responding to blood thinners, Dr. Vedantham added.

This research was supported by grants from the National Heart, Lung, and Blood Institute (NHLBI), as well as the Washington University Center for Translational Therapies in Thrombosis, the Washington University Institute of Clinical and Translational Sciences, Boston Scientific, Covidien (now Medtronic), Genentech, the Society of Interventional Radiology Foundation, the Canada Research Chairs Program, the CanVECTOR Network, the Heart and Stroke Foundation of Canada, and a Jack Hirsh Professorship in Thrombosis. BSN Medical donated the compression stockings.

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