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WASHINGTON -- Anticoagulants alone remained the best course of therapy for deep vein thrombosis (DVT) -- though patients with iliofemoral disease showed a signal of benefit from pharmacomechanical catheter-directed thrombolysis (PCDT), according to the ATTRACT randomized trial.

By the Villalta Scale there was no difference in rates of post-thrombotic syndrome, a complication associated with DVT that has no effective treatment. At 24 months, post-thrombotic syndrome rates were 46.7% for PCDT and 48.2% for non-PCDT (P=0.56), , of Washington University School of Medicine in St. Louis, reported at the Society of Interventional Radiology meeting here.

However, there were two caveats: Moderate-to-severe post-thrombotic syndrome was numerically less likely with PCDT (17.9% versus 23.7%, P=0.035). And the population that had iliofemoral DVT showed numerically lower risk of moderate-to-severe post-thrombotic syndrome with PCDT (18.4% versus 28.2%), although statistical significance was not calculated.

"Most DVT patients can avoid this unhelpful procedure," Vedantham concluded, while suggesting that clinicians target patients with iliofemoral disease who have a high risk of post-thrombotic syndrome.

The most recent made a weak recommendation against using PCDT, but suggested that some patients may benefit from it.

Session panelist , of McMaster University in Hamilton, Ontario -- who helped create those guidelines -- told the audience that the ATTRACT data tip the scales "even more negatively than before."

"I think overall the results are disappointing," he said, adding that it's hard to say what position the guideline committee will take. "In our own clinical setting we are very conservative about using catheter-based interventions to treat DVT. We would be more comfortable in the future not using [them]."

Nonetheless, Kearon conceded that "there is a segment of the population that should receive this treatment."

The Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis () multicenter trial randomized 692 DVT patients to anticoagulants with or without PCDT (62% men, median age 53 years).

A quarter of the ATTRACT population had prior venous thromboembolism. There were no differences in baseline characteristics between groups, the presenter noted.

Within the PCDT group, operators took a single-session approach if there was good popliteal inflow (using the Angiojet or Trellis devices). In three out of five cases, however, patients didn't and required an infusion-first strategy with a multiple sidehole catheter.

Almost all of the PCDT cohort (94%) had more than half of their thrombus removed. More than half of participants got the adjunctive procedures of balloon maceration (56%), balloon angioplasty (56%), and AngioJet use (55%).

Major bleeding at 10 days was more likely with PCDT (1.7% versus 0.3%, P=0.049), as was any bleeding (4.5% versus 1.7%, P=0.034). But the treatment reduced symptoms in the leg better than anticoagulants alone:

• Pain at 10 days (-1.62 versus -1.29 on a seven-point Likert scale, P=0.019)
• Pain at 30 days (-2.17 versus -1.83, P=0.026)
• Swelling at 10 days (-0.26 versus +0.27 cm calf circumference, P=0.024)
• Swelling at 30 days (-0.74 versus -0.28 cm, P=0.051)

"I think this study does give us confidence to not offer this treatment modality to most of our patients with DVT. Some patients still might benefit and this gives us confidence in that case, since bleeding risk was encouragingly low in those patients," concluded panelist , of Jewish General Hospital in Montreal.

"I think that because of the high frequency of post-thrombotic syndrome in the study," she commented, "it's clear we need more research directed at preventing post-thrombotic syndrome and treating existing post-thrombotic syndrome."

Vedantham acknowledged ATTRACT's limitations, notably, "substantial patient loss" to 2-year follow-up and the trial being a medium-sized study that was underpowered for some secondary and subgroup analyses.

"We did, during the study, talk about extending the follow-up further but I think that opportunity didn't materialize. It's not likely that we'll get enough patients to be confident that patient loss to follow-up didn't change the results," the author said.

"I'm surprised to hear, Suresh, this data will never be seen again. I'm sure the money will be forthcoming," joked , of Alpert Medical School at Brown University in Providence, R.I. "How many think Suresh should lead that project?"

The audience responded in mass cheers.

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