Novel Clot Retrieval System Superior to Older Device in Acute Stroke Patients

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A novel thrombectomy, or ‘stent on a wire,’ device for use in acute stroke patients improves outcomes out to 3 months compared with a previously approved system, cutting mortality in half, according to trial results presented February 3, 2012, at the American Stroke Association’s annual International Stroke Conference in New Orleans, LA.

The Solitaire device (ev3, Plymouth, MN) features a wire attached to an expandable stent that captures clot and removes it as the device is retrieved from the vessel. For the multicenter SWIFT (Solitaire With the Intention for Thrombectomy) trial, researchers led by Jeffrey L. Saver, MD, of the University of California, Los Angeles, Geffen School of Medicine (Los Angeles, CA), randomized 113 stroke patients who either failed or were not candidates for tPA to treatment with the Solitaire system (n = 58) or the Merci thrombectomy device (n = 55; Concentric Medical, Mountain View, CA), which was approved by the US Food and Drug Administration in 2004.

After an interim analysis, the trial was halted a year early due to the positive results encountered with the Solitaire device. The primary endpoint, successful recanalization with no symptomatic intracranial hemorrhage or rescue therapy, was significantly improved with the Solitaire device compared with the Merci retriever system. Other endpoints, such as corelab-adjudicated recanalization, use of rescue therapy, symptomatic intracranial hemorrhage, good neurologic outcome, and mortality, were also better with Solitaire (table 1).

Table 1. Primary, Secondary Outcomes

^a P values for superiority, noninferiority also met for all endpoints.

Procedure-related adverse events were similar in the 2 treatment groups.

“The Solitaire flow restoration device is superior to the Merci retriever in achieving successful recanalization free of symptomatic hemorrhagic transformation,” the researchers conclude.

A SWIFT Decision by FDA?

“For every five patients treated with Solitaire, [there is] one more averted death because of this new, more effective way of opening blocked arteries,” Dr. Saver said in a video interview after his presentation. “This new-generation device is already available in Europe, and the data from the SWIFT trial are being presented to FDA in the hopes that it will lead to approval of the device for release in the [United States] so it can become a part of standard practice [here].”

In a telephone interview with TCTMD, Philip M. Meyers, MD, of Columbia University Medical Center (New York, NY), greeted the findings with “cautious enthusiasm,” noting that “these results are much more encouraging with Solitaire, but what they’re comparing it to is the worst thing out there.”

He added that the Merci device has largely been supplanted in US practice by a different thrombectomy system called Penumbra (Penumbra, Alameda, CA). He praised Solitaire as representing the first to market out of a new class of stent retrievers, calling the device basically “a stent on a stick. You put the stent in and try to catch the clot, and then you yank out the clot with the stent.”

‘Gateway to the Future’

L. Nelson Hopkins, MD, of University at Buffalo Neurosurgery (Buffalo, NY), was also encouraged by the study. “SWIFT, I think, is a gateway to the future in terms of what might end up becoming the definitive treatment for acute stroke,” he told TCTMD in a telephone interview. “It’s a nice advance. The device tracks extremely well, [and] it’s easy to manage and deploy and to retrieve. And it works a lot of the time.”

He pointed out that the only potential downside of note is if there was a need to redeploy the device more than once or twice. “Each time you do that you’re going to have an increased risk of doing some damage to the artery,” Dr. Nelson said.

He indicated that most clinicians who treat acute stroke are familiar with the various thrombectomy devices on the market, and that they are mainly used in patients treated outside the tPA window of effectiveness and/or in those who suffer major strokes.

Dr. Meyers estimated that about 10,000 to 20,000 such procedures are performed a year. “So it’s still rare to have the right patient to do a stroke intervention on,” he said, adding that, “it always comes down to patient selection. If doctors are smart about who they do stroke treatment on, then they’re likely to have better outcomes.”

MI Analogy for Acute Stroke Debated

Currently, neurointerventionalists are the physicians who perform these procedures, but that may be changing, Dr. Hopkins said. “More and more cardiologists are learning how to treat stroke,” he said. “It’s important to think about acute stroke in the same way we think about MI. The etiology is different, but it’s an obstructive lesion in a major coronary or a major cranial artery, and what we have to do as quickly as possible is get that artery open to reperfuse the brain [in the case of acute stroke], assuming that the brain is still viable.”

Dr. Meyers, though, was not so sure. “I think trying to figure out who are the right patients is a lot harder with acute stroke than MI,” he said. “The problem is that it’s more than just opening a vessel. With MI, if you open the vessel, the patient tends to do well. With acute stroke, you can reopen the vessel and they still don’t do well, they require all this intensive care. The least of the challenges really is reopening the vessel.”

Regardless, both agreed that the SWIFT trial represents an important step forward for acute stroke treatment. “It’s a better device,” Dr. Hopkins said, calling the data, specifically with regard to the mortality reduction, “the best I’ve seen, and I hope it’s reproducible.”

Dr. Meyers concurred, noting that several trials, both large and small, are underway testing Solitaire as well as other devices for acute stroke treatment.

Study Details

Patients were randomized to the Solitaire and Merci groups within 8 hours of stroke onset and were similar in age (67.1 vs. 67.1 years), pretreatment National Institutes of Health Stroke Score (17.3 vs. 17.5), onset to treatment time (294 vs. 320 min; P = 0.14), and other baseline characteristics. Solitaire patients, though, showed a lower level of previous atrial fibrillation (45% vs. 67%; P = 0.022).

 

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Source:
Saver JL. Primary results of the SOLITAIRE with the intention for thrombectomy (SWIFT) multicenter, randomized clinical trial. Presented at: American Stroke Association 2012 International Stroke Conference; February 3, 2012; New Orleans, LA.

 

Disclosures:

• Dr. Saver reports receiving research support from and serving as a consultant/advisory board member for ev3.
• Dr. Meyer reports no relevant conflicts of interest.
• Dr. Hopkins reports serving as a consultant to ev3, Concentric Medical, and other companies involved in clot retrieval devices for acute stroke.

 

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