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Physicians Update

 
Spring 2012

New Clot-Removing Device Approved for Use at Advanced Stroke Centers

A newly approved device to remove blood clots from blocked arteries in the brains of stroke patients heralds a “game-changing” approach to acute stroke care.

A mesh-columned cage, SOLITAIRE is designed to expand and capture a clot at multiple grabbing points, pulling it our more cleanly.

The SOLITAIRE Flow Restoration Device far outperformed what has been the standard mechanical device for removing clots, the MERCI Retriever, in a UCLA-led multicenter clinical trial. SOLITAIRE opened blocked vessels without causing symptomatic bleeding in or around the brain in 61-percent of patients, vs. 24-percent for the MERCI device. Three months after the stroke, the mortality rate for patients treated with the new device was 17-percent, vs. 38-percent with the older one. The results were so dramatic that the trial was concluded nearly a year earlier than planned, with the U.S. Food and Drug Administration announcing in March that SOLITAIRE was approved for use at advanced stroke centers such as UCLA.

"This really is a game-changing result," says neurologist Jeffrey L. Saver, M.D., director of the UCLA Stroke Center and principal investigator of the SOLITAIRE trial. "We are going from our first generation of clot-removing procedures, which were only moderately good in reopening target arteries, to now having a highly effective tool."

The 61-percent success rate of SOLITAIRE is also significantly higher than the approximately 5-to- 40-percent recanalization rate of tissue plasminogen activator (tPA), the clot-busting drug approved for use in the first four-and-a half hours after onset of a stroke. Between the drug and the new device, Dr. Saver says, stroke physicians will be able to reliably open the arteries in 80-to-90 percent of their patients.

Four out of five strokes are ischemic - caused by blockage in a blood vessel supplying the brain. The only proven medical treatment for ischemic stroke is to administer tPA in the first hours after the stroke to dissolve the clot and restore blood flow. But the only moderate recanalization rate and limited time window have led researchers to develop devices that can mechanically remove the clot during or beyond the window. UCLA has been at the forefront of such efforts. Nearly a decade ago, the UCLA Stroke Center team invented the first mechanical thrombectomy device: the MERCI Retriever, approved in 2004, a helicalshaped coil designed to grab and pull the clots out of the blocked artery.

SOLITAIRE represents a new retrieval device design. A mesh-columned cage, it is shaped like a vessel stent but designed to expand and capture the clot at multiple grabbing points, pulling it out more cleanly.

For the trial, researchers randomly assigned 113 stroke patients at 18 hospitals to receive either SOLITAIRE or MERCI therapy within eight hours of stroke onset. The patients' average age was 67, and 68-percent were male. The time from the beginning of stroke symptoms to the start of the clot-retriever treatment averaged 5.1 hours. Forty percent of the patients had not improved with standard clot-busting medication prior to the study, while the remainder had not received it. In addition to finding that SOLITAIRE successfully opened blocked vessels far more often than MERCI, the study found:

  • 2-percent of SOLITAIRE-treated patients had symptoms of bleeding in the brain, compared with 11-percent of MERCI patients.
  • After 90 days, overall adverse-event rates, including bleeding in the brain, were similar for the two devices.
  • 58-percent of SOLITAIRE-treated patients had good or improved mental/motor functioning at 90 days, compared with 33-percent of MERCI patients.
  • The SOLITARE device also opened more vessels when used as the first treatment approach, necessitating fewer subsequent attempts with other devices or drugs.

While the FDA approved the device for use up to eight hours after the stroke's onset, timing, as in any stroke treatment, still remains critical. "The more time that has elapsed since the strokeoccurred before you reopen the blocked artery, the less brain there is to save," Dr. Saver says. "Time lost is brain lost in acute stroke."

Initial angiogram showing clockage at distal internal carotid artery (arrow).

SOLITAIRE device in (arrow-distal tip) with some reperfusion of distal artery (red arrows). Clot is still present (blue arrows).

After SOLITAIRE retrieval, complete reopening of vessels.


The "Five Suddens"

It is important for patients to be aware of the five sudden warning signs of acute stroke:

  • Sudden weakness on one side of the body
  • Sudden trouble speaking
  • Sudden change or loss of vision
  • Sudden severe dizziness or imbalance
  • Sudden severe headache

 





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