Washington: An experimental device for removing blood clots in stroke patients dramatically outperformed the standard mechanical treatment, according to research presented by UCLA (University of California, Los Angeles) Stroke Centre director Dr Jeffrey L Saver at the American Stroke Association’s 2012 international conference in New Orleans on February 3.
The Solitaire Flow Restoration Device is among an entirely new generation of devices designed to remove blood clots from blocked brain arteries in patients experiencing stroke. It has a self-expanding, stent-like design and, once inserted into a clot using a thin catheter tube, it compresses and traps the clot. The clot is then removed by withdrawing the device, thus reopening the blocked blood vessel.
In the first US clinical trial of ‘Solitaire’, the device opened blocked vessels without causing symptomatic bleeding in or around the brain in 61 per cent of patients. The standard Food and Drug Administration (FDA)–approved mechanical device — a corkscrew-type clot remover called the MERCI (Mechanical Embolus Retrieval in Cerebral Ischemia) Retriever — was effective in 24 per cent of cases.
The use of the new device also led to better survival three months after a stroke. There was a 17.2 per cent mortality rate with the new device, compared with a 38.2 per cent rate with the older one.
“This new device heralds a new era in acute stroke care,” says Dr Saver, the study’s lead author and a professor of neurology at the David Geffen School of Medicine at UCLA. “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. This really is a game-changing result.”
About 87 per cent of all strokes are caused by blood clots blocking a blood vessel supplying the brain. The stroke treatment that has received the most study is the FDA–approved clot-busting drug known as tissue plasminogen activator, but this drug must be given within four-and-a-half hours after the onset of stroke symptoms, and even more quickly in older patients.
When clot-busting drugs cannot be used or are ineffective, the clot can sometimes be mechanically removed during, or beyond, the four-and-a-half–hour window. The current study, however, did not compare mechanical clot removal to drug treatment.
For the trial, called Solitaire With the Intention for Thrombectomy (SWIFT), researchers randomly assigned 113 stroke patients at 18 hospitals to receive either Solitaire or MERCI therapy within eight hours of stroke onset, between January 2010 and February 2011. The patients’ average age was 67, and 68 per cent were male. The time from the beginning of stroke symptoms to the start of the clot-retriever treatment averaged 5.1 hours. Forty per cent of the patients had not improved with standard clot-busting medication prior to the study, while the remainder had not received it.
At the suggestion of a safety monitoring committee, the trial was ended nearly a year earlier than planned due to significantly better outcomes with the experimental device.
Other statistically significant findings included:
- 2 per cent of Solitaire-treated patients had symptoms of bleeding in the brain, compared with 11 per cent of MERCI patients.
- At the 90-day follow-up, overall adverse event rates, including bleeding in the brain, were similar for the two devices.
- 58 per cent of Solitaire-treated patients had good mental/motor functioning at 90 days, compared with 33 per cent of MERCI patients.
- The Solitaire device also opened more vessels when used as the first treatment approach, necessitating fewer subsequent attempts with other devices or drugs.
“Nearly a decade ago, our UCLA Stroke Centre team invented the first stroke retrieval device — the MERCI Retriever — and now we are pleased to have helped develop and successfully test a superior, next-generation clot removing device,” says Dr Reza Jahan, associate professor of radiology at UCLA and the study’s principal neuro-interventional investigator, who also led the pre-clinical studies. “It is exciting to have a highly effective new tool that can improve the outcomes for more stroke patients.”