NEW ORLEANS – An investigational clot-retrieval device completely recanalized blocked cerebral arteries, improved neurologic outcomes, and significantly reduced mortality from acute ischemic stroke more often than did the widely used Merci device in a randomized, open-label trial.
The SWIFT (SOLITAIRE-FR With the Intention for Thrombectomy) study intended to randomize 200 patients with ischemic stroke to treatment with either of the devices, but after 18 months, the trial’s data safety monitoring board stopped the study with 144 patients treated, citing "an overwhelming benefit" of the Solitaire-Flow Restoration device over the Merci device, Dr. Jeffrey Saver said at the International Stroke Conference.
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Dr. Jeffrey L. Saver
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"With these results, we see for the first time a highly effective cerebral recanalization procedure for ischemic stroke," said Dr. Saver, director of the stroke unit at the University of California, Los Angeles, in an interview. "[Tissue plasminogen activator] opens the arteries partially 40% of the time and completely just 5% of the time. This device opens them completely 60% of the time. It’s a dramatic step forward and a device that will probably be a game-changer for our systems, once it becomes available."
Solitaire is a columnar metal cage which, when expanded, engages the clot at multiple points, facilitating extraction and decreasing the chance of symptomatic intracranial bleeding. The Merci device, a corkscrew-like coil, does release pressure on the atrial wall, "but has a tendency to uncoil and fail to engage the clot," he said.
The patients’ average age was 67 years; most (68%) were male. The median pre-stroke modified Rankin Scale score was 0.5. Time to first angiogram was 4-5 hours.
The primary end point – successful recanalization without symptomatic intracranial hemorrhage – occurred in 61% of the Solitaire group and 24% of the Merci group. This was a highly significant difference with a P value of .0001 in both noninferiority and superiority analyses.
The trial’s secondary end points also indicated the superiority and noninferiority of Solitaire in comparison with Merci:
• Use of rescue therapy (21% vs. 44%).
• Symptomatic intracranial hemorrhage (2% vs. 11%).
• All intracranial hemorrhage (17% vs. 38%).
• Good 90-day neurologic outcome (58% vs. 33%).
• 90-day mortality (17% vs. 38%).
The investigators defined a good neurologic outcome as a modified Rankin Scale score of 0-2 if a patient came in at that level, if the patient returned to their baseline score after coming in with a worse score, or for patients who achieved at least a 10-point increase in their National Institutes of Health Stroke Scale score also were assessed as having a good outcome.
The results demonstrate an excellent number-needed-to-treat analysis, Dr. Saver said.
"For every 2.7 patients treated, 1 additional patient had a successful recanalization with no brain bleed. For every five patients treated, one patient was saved from death. And for every four patients treated, there was one more with a good neurologic outcome."
Device fracture occurred in two instances with Solitaire but in no cases with Merci. There were two instances with each device in which the device could not be delivered appropriately. Air embolism occurred in one patient with each device. Vasospasms occurred in eight cases with Solitaire and six cases with Merci. Two patients undergoing interventions with the Merci device had vessel perforations, compared with none who were treated with the Solitaire device. Distal emboli occurred with Solitaire in two patients and with Merci in three patients.
A New Generation of Tools
This trial brings us into the third generation of new and potentially better devices to open blocked arteries in acute ischemic stroke. Solitaire showed pretty impressive recanalization rates, compared with Merci, and improved clinical and functional outcomes.
This device also looks at little easier to deploy than Merci, and it seems to be somewhat more practical and better-designed.
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Dr. Ralph L. Sacco
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I think the SWIFT trial will bring very important information to the FDA review, and hopefully we will have another device entering the market to help us treat acute stroke.
But even after interventionists get the Solitaire device, they must be well trained before they start using it. Additionally, devices like this are primarily used in comprehensive stroke centers. To increase the number of patients who might benefit from it, we need to increase the numbers of our comprehensive stroke centers.
Dr. Ralph L. Sacco is the immediate past president of the American Heart Association and chairman of neurology at the University of Miami. He had no relevant disclosures.
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