Study finds devices no better than meds in recovery from clot-caused strokes

March 14, 2013

(Medical Xpress)—When someone has a stroke, time equals brain. The longer a stroke is left untreated, the more brain tissue is lost. Since the only proven treatment—a clot-busting drug—works in less than half of patients, stroke physicians had high hopes for a mechanical device that could travel through the blocked blood vessel to retrieve or break up the clot, restoring blood flow to the brain.

But in a recently completed multi-site trial in which UCLA served as the clinical coordinating center, researchers found there was no overall recovery benefit to treated with clot-removal (embolectomy) devices, compared with standard post- care, which includes monitoring blood pressure and ensuring the brain is receiving oxygen.

The study also found that using brain scans to identify which patients might be the best candidates for embolectomy did not lead to better outcomes for those patients.

The study was sponsored by the National Institutes of Health, and the results appeared in the March 7 edition of the New England Journal of Medicine.

Treating an is always a race against the clock, and the first step is to immediately determine, through the use of a CT or , whether the stroke is a , caused by a burst blood vessel, or the much more common ischemic stroke, caused by a clot blocking the flow of blood in a blood vessel.

With an ischemic stroke, the clot-dissolving drug called , or tPA, is approved for use within three hours of the onset of . But most don't arrive at the hospital within that time frame, and even then, tPA may simply not work. Patients who don't respond to tPA then receive standard post-, or they may be considered for an embolectomy.

The MR RESCUE (Mechanical Retrieval and REcanalization of Stroke Clots Using Embolectomy) trial sought to determine if imaging the brain to see how much has already occurred could identify which patients might be the best candidate for this procedure.

The trial, which began in 2004 and involved 22 sites in the U.S., included 118 patients (average age 65.5) who were treated within eight hours of experiencing an ischemic stroke. All the patients underwent a CT or MRI brain-imaging scan before treatment.

Drawing on information from the scans, the investigators divided the patients into two groups. Patients with a favorable treatment pattern had only a small area of infarct (dead tissue) and a large area of threatened but salvageable brain tissue (called penumbral tissue). Patients with an unfavorable pattern already had a large area of infarct or a small area of penumbral tissue.

Patients from both of these groups were randomly assigned either to receive the standard medical treatment or to have their clot removed by the MERCI Retriever (a tiny corkscrew-like device developed at UCLA that "grabs" clots) or the Penumbra System (a device that sucks clots out). Both devices work by inserting a catheter through the patient's groin to the blocked brain artery.

The hope was that by quickly removing the clot, blood would be restored to the penumbral tissue, thereby saving it. But the results showed that the level of disability 90 days after suffering a stroke was no different between those patients who underwent the clot-removal procedure and those who received standard care. Rates of death and bleeding in the brain were also the same. In addition, there was no difference between the group in which brain scans showed significant amounts of salvageable and those with only a small area of penumbral tissue.

"We found no data showing that imaging could help select patients for treatment, nor did we show an overall benefit of performing an intervention to physically remove the clot," said Dr. Reza Jahan, co-principal investigator for the trial, an associate professor of interventional neuroradiology and a member of the UCLA Stroke Center. "So that was disappointing. On the other hand, there are new devices that open up vessels better and faster, and with fewer complications, than the first-generation devices used in our trial."

Last March, the U.S. Food and Drug Administration approved the use of the next-generation mechanical device. Developed for , in part by Jahan, the SOLITAIRE Flow Restoration Device dramatically outperformed the Merci Receiver. SOLITARE has a self-expanding, stent-like design, and once inserted into a blocked artery using a thin catheter tube, it compresses and traps the clot. The clot is then removed by withdrawing the device, reopening the blocked blood vessel.

Results of the SOLITARE study showed that the device opened blocked vessels without causing symptomatic bleeding in or around the in 61 percent of patients. By comparison, the older MERCI Retriever was effective in 24 percent of cases.

Jahan believes, then, that it would be premature to dismiss the value of endovascular therapy.

"The new devices do work better," he said. "Whether that will translate into improvement in outcomes is not known, and the only way to test efficacy is by doing a controlled trial."

Explore further: Comparing mechanical clot removal and standard medical therapy for severe stroke

Related Stories

Comparing mechanical clot removal and standard medical therapy for severe stroke

February 8, 2013
Results of the first randomized controlled study to evaluate a procedure that removes blood clots in the brain from patients experiencing severe strokes will be presented at the International Stroke Conference in Honolulu, ...

New device to remove stroke-causing blood clots proves better than standard tool

August 26, 2012
Stroke is the fourth leading cause of death and a common cause of long-term disability in the United States, but doctors have very few proven treatment methods. Now a new device that mechanically removes stroke-causing clots ...

New device performs better than old for removing blood clots

February 3, 2012
An experimental blood clot-removing device outperformed the FDA-approved MERCI; retriever device, according to late-breaking science presented at the American Stroke Association's 2012 International Stroke Conference.

Imaging acute ischemic stroke patients' brains did not lead to improved outcomes

February 8, 2013
The use of advanced imaging shortly after the onset of acute stroke failed to identify a subgroup of patients who could benefit from a clot-removal procedure, a study has found.

The Medical Minute: Solitaire for stroke -- It's not a game

May 22, 2012
Stroke is the fourth leading cause of death in North America -- down from third. Despite this "improvement," stroke remains the leading cause of adult disability. Ischemic strokes, caused by blood vessel blockages, are by ...

Clot-busting drug safe for stroke patients taking blood thinner

May 10, 2012
Acute ischemic stroke patients taking the blood thinner warfarin can be treated safely with the clot-busting drug tissue plasminogen activator (tPA), according to research presented at the American Heart Association's Quality ...

Recommended for you

Five vascular diseases linked to one common genetic variant

July 27, 2017
Genome-wide association studies have implicated a common genetic variant in chromosome 6p24 in coronary artery disease, as well as four other vascular diseases: migraine headache, cervical artery dissection, fibromuscular ...

Could aggressive blood pressure treatments lead to kidney damage?

July 18, 2017
Aggressive combination treatments for high blood pressure that are intended to protect the kidneys may actually be damaging the organs, new research from the University of Virginia School of Medicine suggests.

Quantifying effectiveness of treatment for irregular heartbeat

July 17, 2017
In a small proof-of-concept study, researchers at Johns Hopkins report a complex mathematical method to measure electrical communications within the heart can successfully predict the effectiveness of catheter ablation, the ...

Concerns over side effects of statins stopping stroke survivors taking medication

July 17, 2017
Negative media coverage of the side effects associated with taking statins, and patients' own experiences of taking the drugs, are among the reasons cited by stroke survivors and their carers for stopping taking potentially ...

Study discovers anticoagulant drugs are being prescribed against safety advice

July 17, 2017
A study by researchers at the University of Birmingham has shown that GPs are prescribing anticoagulants to patients with an irregular heartbeat against official safety advice.

Protein may protect against heart attack

July 14, 2017
DDK3 could be used as a new therapy to stop the build-up of fatty material inside the arteries

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.