March 6, 2012 — The US Food and Drug Administration (FDA) has granted approval for a new clot retrieval system, the Solitaire Flow Restoration (FR) device (Covidien), the company has announced.
The 510(k) application for the new device was based on results of the Solitaire With the Intention for Thrombectomy (SWIFT) trial, which compared the investigational Solitaire FR device against Concentric Medical's Merci Retriever device, already approved by the FDA.
Although SWIFT was a noninferiority trial, the results demonstrated superiority with the new retriever on several outcomes, said principal investigator Jeffrey L. Saver, MD, professor of medicine and director of the Stroke Center at the Geffen School of Medicine at the University of California, Los Angeles.
"With these results we have, for the first time, a highly effective cerebral recanalization procedure for ischemic stroke," Dr. Saver told a press briefing at the International Stroke Conference in New Orleans, where the SWIFT results were first presented. The results were reported by Medscape Medical News at that time.
Recanalization with tissue plasminogen activator occurs in about 40% of cases, with complete recanalization in about 5%, he noted. "The device opens arteries 60% of the time," Dr. Saver said. "It's a dramatic change and once this becomes available, I think it will be a game changer."
Solitaire FR is a self-expanding stent retriever designed to yield rapid flow restoration in acute cerebral ischemia. The device has shown high rates of recanalization in preclinical models and open clinical series, Dr. Saver said.
The Merci device is more of a "corkscrew" guided by a balloon-tipped wire to snare and remove the clot.
Describing the differences between the devices, Dr. Saver noted that although the helical shape of the Merci device helps to reduce the pressure on the arterial wall, it "has a tendency to uncoil and to fail to engage the clot" when it is withdrawn. "The Solitaire, in contrast, is a kind of columnar metal cage and when expanded, it engages the clot at multiple strut points, which may be why it is more often effective in pulling the clot out."
The multicenter SWIFT trial was the first US trial comparing the 2 devices. A total of 113 stroke patients at 18 hospitals were randomly assigned to undergo clot retrieval with the Solitaire FR or the Merci Retriever within 8 hours of symptom onset.
The primary efficacy endpoint was Thrombolysis in Myocardial Infarction (TIMI) 2 or 3 flow, by blinded core laboratory assessment, in all treatable vessels, without symptomatic intracranial hemorrhage, after up to 3 passes of the assigned device. Rescue therapy with intra-arterial lysis or other approved devices was permitted after reperfusion ascertainment, the primary endpoint.
SWIFT was stopped early because of robust results, Dr. Saver noted. A prespecified efficacy stopping rule triggered an early halt to the trial almost a year earlier than planned because of significantly better outcomes with the new device, Dr. Saver reported.
The primary efficacy outcome was achieved more often in the group treated with Solitaire than with Merci, Dr. Saver reported.
This endpoint was met by 60.7% of the Solitaire group vs 24.1% of the Merci group (P < .0001 for noninferiority), according to the blinded core laboratory results. On the basis of investigator determination, the recanalization rates were 83.3% and 48.1%, respectively (P < .0001).
"When we observed the statistical significance for noninferiority, we did a nested superiority hypothesis test and found the P value for that was also highly statistically significant (P = .0001), indicating a highly significant advantage for Solitaire over Merci in reopening arteries without causing symptomatic intracranial bleeding," he said.
SWIFT had an active comparator that has been established as a means of improving clinical outcomes compared with best supportive care, he added. "This suggests that the SWIFT treatment arm differences reflect an additional benefit for Solitaire above that already conveyed by the Merci Retriever," he added.
At 90 days, overall adverse events, including intracranial bleeding, were similar.
Solitaire also led to better outcomes by other measures:
Lower mortality at 3 months: 17.2% vs 38.2% (P = .02 for superiority);
Symptomatic intracranial bleeding in 1.7% vs 10.9% (P < .0001 for noninferiority); and
Good mental/motor functioning at 90 days in 58.2% vs 33.3% (P = .0001 for noninferiority).
The new device was also more likely to recanalize blood vessels on the first attempt and required less use of rescue therapy.
"Initial treatment with Solitaire rather than Merci is associated with more frequent reperfusion, less symptomatic intracranial hemorrhage, reduced mortality, and increased good final neurologic outcomes 3 months after stroke," Dr. Saver concluded.
The Solitaire FR device has already received CE Mark approval in Europe, the company release notes. Covidien anticipates that the Solitaire FR device will be available in the United States next month.
Covidien sponsored the SWIFT trial. Dr. Saver has received research grants from, and served as a consultant to, Covidien.
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Cite this: Solitaire Device for Stroke Gets FDA Nod - Medscape - Mar 06, 2012.