ESC: Neuro clot removal device bests older model for large vessel occlusions
The study was simultaneously published online in the Lancet.
While rt-PA is the standard of care for treatment of acute ischemic stroke, it has “limitations,” according to the study authors, including a short therapeutic window that restricts more widespread adoption and poor reperfusion rates in the setting of extensive clot burden. As the only alternative to medical therapy, current mechanical devices are unable to achieve recanalization in up to 20 to 40 percent of large vessel occlusion strokes.
In this open-label, randomized controlled trial, Raul G. Nogueira, MD, professor of neurology and neurointerventionalist at Emory University School of Medicine in Atlanta, and colleagues compared the efficacy and safety of the Trevo Retriever (Stryker Neurovascular), a stent-like device, with its FDA-cleared predecessor, the Merci Retriever (Stryker Neurovascular) by recruiting patients at 26 sites in the U.S. and one in Spain.
The TREVO 2 (Thrombectomy Revascularization of Large Vessel Occlusions in Acute Ischemic Stroke) trial included adults age 18 to 85 years with angiographically confirmed large vessel occlusion strokes and National Institutes of Health Stroke Scale (NIHSS) scores of eight to 29 within eight hours of symptom onset. The researchers randomly assigned patients (1:1) with sequentially numbered sealed envelopes to thrombectomy with Trevo or Merci devices. They stratified randomization by age (at least 68 years vs. 69 to 85 years) and NIHSS scores (at least 18 vs. 19 to 29) with alternating blocks of various sizes.
The primary efficacy endpoint, assessed by an unmasked core laboratory, was thrombolysis in cerebral infarction (TICI) scores of 2 or greater reperfusion with the assigned device alone. The primary safety endpoint was a composite of procedure-related adverse events. The researchers conducted the analysis through intention to treat.
Between Feb. 3, 2011, and Dec. 1, 2011, Nogueira et al randomly assigned 88 patients to the Trevo Retriever group and 90 patients to Merci Retriever group.
In the study, 86 percent of patients in the Trevo group and 60 percent in the Merci group met the primary endpoint after the assigned device was used. Also, incidence of the primary safety endpoint did not differ between groups (15 percent of patients in the Trevo group vs. 23 percent in the Merci group).
While the safety profiles were similar with both devices, vessel perforations were almost 10 times more common with the Merci retriever (10 percent) than they were with the Trevo retriever (1 percent). The researchers attributed this perforation rate to a less effective recanalization of the artery, and Trevo is usually deployed by unsheathing the microcatheter compared with the active pushing required with Merci.
"In this patient population, rapidly restoring blood flow to the brain is critical. Patients who have had large vessel blockage strokes but are ineligible for or fail to respond to intravenous t-PA should be treated with the Trevo or Solitaire [Flow] device," Nogueira, who also serves as director of the neuroendovascular division at the Marcus Stroke & Neuroscience Center at Grady Memorial Hospital in Atlanta, said in a release.
Promising results from the SWIFT trial presented at ESC.12 showed the Solitaire Flow device’s (Covidien) superiority over the Merci Retreiver. Nogueira served as a member of the steering committee for SWIFT.
The study authors concluded that their trial showed that the Trevo Retriever “was superior to the Merci Retriever for arterial revascularization in terms of reperfusion to TICI 2 or greater in the setting of acute ischemic stroke. Notably, increased frequency and extent of reperfusion was associated with improved clinical outcomes at 24 hours, shorter hospital stays and improved independence.”
Among the study’s limitations is the fact that the study’s interventionalists and the angiographic core laboratory were not masked to device assignment.
“Mechanical thrombectomy trials have historically been single-group studies that aim to show safety of recanalization of intracranial thromboembolic occlusions for device regulatory approval purposes,” wrote Nogueira and colleagues. “TREVO 2 is the second published randomized trial of intra-arterial treatment to show superiority of one treatment over another in terms of long-term independent functional outcomes. Our data suggest superiority of the novel Trevo technology over its predecessor, the Merci Retriever, with achievement of better reperfusion and higher rates of long-term functional independence.”
They added that this study supports the use of the Trevo Retriever in a prospective randomized trial of endovascular therapy against medical treatment alone.
Stryker Neurovascular of Mountain View, Calif., funded the study.