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Blood clot removal device shows potential for patients with ischemic stroke
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A novel, self-expanding stent retriever outperformed the standard treatment in angiographic, safety and clinical outcomes, according to study results.
The Solitaire Flow Restoration Device (Covidien/ev3) is designed to restore blood flow from blocked brain arteries in patients who experience ischemic stroke. Once inserted into a blocked artery, the stent-like thin catheter tube traps the clot. The clot is removed as the device is extracted, reopening the blocked blood vessel.
The Merci Retriever (Stryker) was the first mechanical thrombectomy device cleared by the FDA for ischemic stroke in 2004.
The Merci Retriever is a corkscrew-shaped device that consists of nitinol wires with coil loops. Once inside the blocked vessel, the device assumes its coiled shape and extracts the clot, according to background information in the study.
In the randomized, parallel-group, noninferiority SWIFT study, researchers compared the efficacy and safety of Solitaire and Merci Retrieval devices by evaluating their performance in 113 stroke patients (mean age, 67.1 years) at 18 hospitals between February 2010 and February 2011.
Jeffery L. Saver, MD, director of stroke neurology for the UCLA Stroke Center, and colleagues randomly assigned the Solitaire (n=58) or Merci (n=55) devices within 8 hours of stroke symptom onset.
Results favored the Solitaire device in a number of key study areas.
The Solitaire device successfully recanalized without symptomatic intracranial hemorrhage in 34 of 56 patients (61%) compared with 13 of 54 patients (24%) in the Merci group (OR=4.87, 95% CI, 2.14-11.1).
The clinical efficacy endpoints at 90 days also indicated that the Solitaire device led to better survival compared with Merci.
More patients achieved good neurological outcomes with the Solitaire device (58%) compared with the Merci device (33%; OR=2.78; 95% CI, 1.25-6.22).
Ten of 58 patients (17%) in the Solitaire group died from any cause by 90 days of the procedure compared with 21 of 55 patients (38%) in the Merci group (OR=0.34; 95% CI, 0.14-0.81).
“Our study suggests that, compared with the Merci Retriever, neurothrombectomy with the Solitaire Flow Restoration device is associated with increased achievement of successful cerebral recanalization without symptomatic intracranial hemorrhage, improved final disability outcomes and reduced mortality,” the researchers wrote.
In September 2011, the Data and Safety Monitoring Board recommended ending the trial nearly a year earlier than planned due to a prespecified efficacy stopping rule.
Saver and colleagues said the halt of the study resulted in a smaller number of participants, which had the potential to limit the accuracy of treatment effect estimates.
Disclosure: Saver reports serving as a scientific consultant and unpaid site investigator in multicenter trials run by BrainsGate, CoAxia, Covidien/ev3, Genervon, Lundbeck and Mitsubishi. Other researchers involved with the study served as consultants for Abbot Vascular, Chestnut Medical, Codman, Concentric Medical, MicroVention, Shurtleff Inc. and Stryker.
Perspective
Back to TopCharles S. Abrams, MD
It is an interesting study that unfortunately suffers a bit from its small sample size. The original plan was to enroll more patients, but the trial was stopped by their data safety monitoring board because it felt there was a significant benefit to the Solitaire device. To my knowledge, there is not much compelling information on the Solitaire beyond what is shown in this study. It does appear to be superior to the Merci apparatus. What will be informative will be to see how it compares head to head against tissue plasminogen activator ( tPA). In theory, the Solitaire would be preferable to tPA in patients who are at high risk for anticoagulation. It also might be worth mentioning that big clots often do not lyse well with tPA, so this device might be beneficial in those patients, as well. However, until a direct comparison is done, tPA is still my first choice.
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