Study details safety and efficacy of new Merci Retriever treatment for stroke patients

Jul 6 2005

The recently released July issue of "Stroke," the official journal of the American Stroke Association, published new data on the safety and efficacy of the Merci Retriever System, the first medical device cleared by the FDA to remove blood clots from the brain in patients suffering an ischemic stroke. Manufactured by Concentric Medical, a private medical device company, the device - cleared for use in August of 2004 - is now available in more than 165 U.S. hospitals.

"The new study data serves to reinforce the overall success and safety of the Merci Retriever and the role of medical devices in stroke treatment," says Gary Duckwiler, Investigator for the MERCI Study at the University of California at Los Angeles and president of the American Society of Interventional and Therapeutic Neuroradiology (ASITN), the medical society representing the 275 interventional neuroradiologists and other neurointerventionists who utilize the Merci Retriever. "The fact that the enrolled study patients presented with serious strokes, but improved significantly, gives physicians and patients hope in the new treatment options for this devastating disease."

The study results were obtained from a multi-center trial including 141 patients treated at 25 U.S. hospitals. All patients were ineligible for a clot-dissolving drug called tPA. The treatment window in the trial was within eight hours of stroke onset. Forty-eight percent of the patients (68/141) were recanalized, or had their blood flow restored. The peer-reviewed study noted, "This rate is significantly higher than the established historical control of 18%." It also reported, "Good neurological outcomes ... . were more frequent at 90 days in patients with successful recanalization compared with patients with unsuccessful recanalization ... and mortality was less."

A national opinion leader in the field of interventional neuroradiology, Duckwiler said "This data reveals that the Merci Retriever showed success in patients with severe strokes who would have otherwise died or suffered severe disability and for whom, before this device was available, there was no approved alternative treatment. Also important to note is that there were very few complications, such as hemorrhages, which can create serious problems in cases where other treatments such as "clot busting" drugs are used. Ultimately, this new tool could very well revolutionize stroke treatment as we know it."

An ischemic stroke occurs when a blood vessel in the brain is blocked by a blood clot that can impair brain function and cause severe disability or death. Of the 700,000 annual U.S. strokes, approximately 88 percent - or 616,0000 - are ischemic.

Physicians participating in the study navigated the Merci Retriever into the brain using standard catheterization techniques. Under radiological guidance, a catheter is inserted into the groin and routed through the blood vessels leading to the brain. The Merci Retriever is then introduced through the catheter directly to the targeted area. Once positioned, the device is deployed to engage and ensnare the clot, pulling it back through the catheter and out of the body.

"Every 45 seconds someone in this country suffers a stroke and as the population ages, the incidence is likely to increase," said Gary Curtis, President and CEO of Concentric Medical. "Our goal is to not only provide treatment options for stroke patients but also to improve management of this disease by raising awareness of stroke symptoms and the importance of getting into stroke centers quickly."

Through multiple initiatives, ASITN works to inform the general public of signs and symptoms that could potentially indicate that a stroke is in progress. Anyone should be aware that sudden numbness or weakness of the face, arm or leg (especially on one side of the body), sudden trouble speaking, sudden trouble seeing in one or both eyes, sudden trouble walking, dizziness or loss of balance necessitates calling 911. A stroke should be considered a medical emergency.

According to the American Stroke Association, stroke killed 162,672 people in 2002 and is the leading cause of serious, long-term disability in the U.S. It is also the third largest cause of death, ranking behind heart disease and all forms of cancer.