Catheter-directed thrombolysis reasonable in some DVT cases

William Kuo

HOLLYWOOD, Fla. — Post-thrombotic syndrome remains a significant issue in patients with acute deep vein thrombosis treated with anticoagulation alone, leading one speaker at the International Symposium on Endovascular Therapy (ISET) to highlight contemporary approaches to catheter-directed thrombolysis in this patient population.

Post-thrombotic syndrome (PTS) is estimated to develop within 2 years in about 40% to 50% of patients with proximal DVT, despite the use of anticoagulation, with even higher risk for those with iliofemoral DVT. In addition to iliofemoral DVT, other risk factors for PTS include poor-quality initial anticoagulant therapy, recurrent ipsilateral DVT, older age, female sex, elevated BMI and anticoagulant-refractory DVT. The challenge of how to prevent PTS remains in patients with proximal DVT.

“Although major guidelines offer little to advocate lysis above anticoagulation alone for DVT, experts agree that some patients may benefit from catheter-directed thrombolysis, especially iliofemoral DVT, and perhaps as salvage therapy for DVT patients who fail anticoagulation,” William Kuo, MD, FSIR, FCCP, FSVM, FCIRSE, professor of vascular and interventional radiology at Stanford University School of Medicine, said during a presentation.

Previous randomized trials and a recent Cochrane metaanalysis suggested that the removal of acute thrombus may preserve venous function and prevent PTS. The 2016 Cochrane analysis of 17 randomized controlled trials with more than 1,100 participants with proximal DVT evaluated mainly systemic thrombolysis and a small number of patients treated with loco-regional or catheter-directed thrombolysis. The analysis highlighted a one-third reduction in PTS up to 5 years after thrombolysis, but showed an increased risk for bleeding in the thrombolysis groups. In spite of this, the evidence did not lead to a change in the American College of Chest Physicians 2016 guidelines on antithrombotic therapy for venous thromboembolism with regards to the use of catheter-directed thrombolysis in patients with DVT, Kuo said, and the ACCP wrote: “the overall (data) quality is still low because of very serious imprecision.”

Then came the ATTRACT trial of 692 patients with proximal DVT who were randomly assigned to anticoagulation alone or anticoagulation plus pharmacomechanical catheter-directed thrombolysis. As previously reported by Cardiology Today’s Intervention, the addition of pharmacomechanical thrombolysis did not lower risk for PTS, although there was reduction in the progression to moderate to severe PTS driven mainly by patients with iliofemoral DVT. There was an increased risk for bleeding with CDT but this occurred in only 1.7% (much lower than in prior studies showing 5-12% major bleeding using older protocols) and there were no fatal or intracranial bleeding complications.

The current guidelines recommend anticoagulation over catheter-directed thrombolysis in patients with acute proximal DVT, but notes that patients who are most likely to benefit from catheter-directed thrombolysis are likely to choose CDT over anticoagulation alone. According to the ACCP, patients most likely to benefit from catheter-directed thrombolysis include those with iliofemoral DVT, symptoms for less than 14 days, good functional status, a life expectancy of at least 1 year and low risk for bleeding.

For these patients undergoing CDT, Kuo also recommended several strategies to reduce risk for major bleeding with catheter-directed thrombolysis. “Careful patient selection is key,” he said. Based on results of the ATTRACT trial, avoiding patients with an older age, intracranial lesions, hypertension and active bleeding appears to be a good strategy, he said. Use of a modern thrombolysis protocol that focuses on low-dose lytic exposure and adjustment of anticoagulation dose during thrombolysis is important to reduce bleeding risk. Furthermore, a tailored protocol may be used for higher-risk patients, using low or even no thrombolytic in combination with aspiration/mechanical thrombectomy, to further reduce the risk of major bleeding,” Kuo said.

The modern lysis protocol is as follows:

For overnight lysis regimen, minimize tissue plasminogen activator (tPA) dose 0.01 mg/kg/hour; do not exceed 1 mg/kg/hour.
Adjust anticoagulation protocol during lysis: if IV heparin is given, then subtherapeutic dosing is suggested to reduce bleeding risk.

The tailored lysis protocol is as follows:

If there is increased risk for bleeding, use less or no tPA and more aspiration or mechanical thrombectomy.

Additionally, there are a growing number of devices aimed at decreasing or eliminating lytic requirements. Kuo highlighted the AngioJet (Boston Scientific), Indigo system (Penumbra), JETi (WalkVascular), Argon Cleaner (Argon Medical Devices), Aspirex (Straub Medical AG) and ClotTriever (Inari Medical) devices as examples. Following removal of acute clot, Kuo stated it is important to remember that the underlying venous outflow obstruction should also be addressed with angioplasty/stent placement to prevent rethrombosis. “If treatment of iliofemoral DVT/obstruction is a priority, we need to distinguish between acute and chronic DVT, with the goal of restoring both good inflow and outflow to optimize patency,” he said.

References:

Kuo WT. Deep Dive Session 1: Clot Management: Venous, Pulmonary and Arterial. Presented at: the International Symposium on Endovascular Therapy (ISET); Feb. 3-7, 2018; Hollywood, Fla.

Watson L, Broderick C, Armon MP. Thrombolysis for acute deep vein thrombosis (Review). Cochrane Database of Systematic Reviews 2016; Nov 10; 11: CD002783.

Kearon C, et al. Chest. 2016;doi:10.1016/j.chest.2015.11.026.

Vedantham S, et al. N Engl J Med. 2017;doi:10.1056/NEJMoa1615066.

Disclosure: Kuo reports he is a consultant for WalkVascular.