Every 40 seconds, someone in the United States has a stroke, usually caused when a clot blocks an artery that supplies blood to the brain. Now the results of two multicenter studies published online in The Lancet on August 26 are giving physicians new innovative tools proven to better remove these clots that block blood flow.

The TREVO 2 clinical trial, (Thrombectomy Revascularization of Large Vessel Occlusions in Acute Ischemic Stroke) showed that the Trevo Retriever, a clot-removal device, performed significantly better at restoring blood supply to the brain than the FDA approved predecessor Merci Retriever. The study, conducted at 16 U.S. sites and one in Spain, was led by neurointerventionalist Raul Nogueira, MD, professor of neurology at Emory University School of Medicine.

Nogueira also served as a member of the steering committee for the SWIFT (Solitaire With the Intention For Thrombectomy) clinical trial, which tested the efficacy of the flow restoration device Solitaire compared to the Merci Retriever at 18 U.S. sites and one in France.  

"The results of our studies show these next-generation devices (e.g. stent-retrievers) are superior at achieving restoration of blood flow to blocked arteries and were associated with better neurological outcomes as compared to the previously available technology," says Nogueira, who serves as director of the Neuroendovascular Division at the Marcus Stroke & Neuroscience Center at Grady Memorial Hospital.

"These devices truly refine treatment and represent another great stride in the evolution of stroke care. I'm excited about their potential and the opportunity to offer this cutting edge treatment option to patients at Grady and Emory."

Nogueira enrolled patients at the Marcus Stroke & Neuroscience Center at Grady Memorial Hospital in Atlanta. Located in the region known as the nation's stroke belt, Grady recruited the TREVO 2 study's largest number of patients, enrolling 31 participants. Rishi Gupta, MD, Emory associate professor of neurology, served as the primary investigator at Grady.

Nationwide, researchers randomly assigned 88 patients to the Trevo Retriever group. The remaining 90 patients received the procedure with the Merci Retriever, a predecessor to the Trevo Retriever. Patients treated with the Trevo Retriever scored better on the National Institutes of Health Stroke Scale, experienced shorter hospital stays and had significantly higher rates of functional independence 90 days post-stroke.

In the double-blind, randomized SWIFT trial researchers compared the performance of the Solitaire flow restoration device to the MERCI retriever in a total of 112 patients. Researchers found the blood clot was removed much more commonly with the Solitaire - a self-expanding stent retriever as compared to the Merci retriever. Additionally, more patients had a favorable neurological response with Solitaire than Merci.

The standard of treatment for acute ischemic stroke is an intravenous injection of the clot buster drug tissue plasminogen activator – tPA which dissolves the blood clot. However, Nogueira notes limitations such as a short treatment window, risk of bleeding, and failure to dissolve the larger blood clots that often cause the more disabling strokes.

"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 device," says Nogueira.

"We have traditionally seen poor outcomes for patients with large vessel occlusion strokes. This new generation of mechanical thrombectomy devices provides us with a highly effective tool for revascularising large vessel strokes and improving overall quality of care in patients with severe and potentially debilitating strokes if they can get to a comprehensive stroke center quickly for treatment."

The Trevo System was developed by Concentric Medical, Inc. and acquired by Stryker. Covidien is the manufacturer of Solitaire. Both devices are now approved in the U.S. and Europe.