Machines Are No Better Than Meds

Stroke treatment with mechanical devices may not improve upon therapy with medication

(RxWiki News) Strokes caused by clots in blood vessels leading to the brain are typically treated with medications. Medical devices can also be used on clots, but they may offer no advantage over medication.

Typically, a blockage-caused (ischemic) stroke is treated with a medication, which must be given within three to four and half hours after symptoms begin.

“The hope was, and to some degree still is, that if you pull out the clot within a certain period of time and there is salvageable brain tissue, there will be better outcomes,” the lead researcher said.

"If experiencing stroke symptoms, get treatment immediately.  "

Chelsea Kidwell, MD, professor of neurology and director of the Stroke Center at Georgetown University in Washington, DC, led the research.

Tissue plasminogen activator (tPA) is a medication that dissolves blood clots. It is given intravenously into a vein or sometimes directly into an artery. For it to be effective, the drug (brand name Activase) has to be given within hours of stroke symptoms occurring. According to National Stroke Association, tPA is an enzyme found naturally in the body that converts, or activates, plasminogen into another enzyme to dissolve blood clots.

The Merci Retriever (a tiny corkscrew device) and the Penumbra System (an aspiration device) are also used to remove clots from arteries and restore blood flow to the brain. In 2004, the FDA cleared the Merci Retriever for patients who arrive beyond the timeframe for tPA or whose obstructions don’t respond to tPA.

The Merci system is a tiny corkscrew shaped device that works by wrapping around the clot and trapping it. The clot is then retrieved and removed from the body.

In 2008, the Penumbra System became available for stroke treatment. It helps restore brain blood flow by using suction to grab blood clots in the brain. The device is effective if used within eight hours of symptom onset, according to the National Stroke Association.

This 22 center trial included 118 patients, average age 65 1/2 years old, who were treated within eight hours after experiencing an ischemic stroke in one of the large blood vessels carrying blood to the front of the brain.

Researchers divided patients into two groups: those showing a large area of at-risk but salvageable brain tissue near the clot and those without. They then randomly assigned patients in both groups to receive either tPA medication or to have the clot removed by the Merci Retriever or the Penumbra System.

When comparing patients who received medication to those who had treatment with the devices, there was no difference in disability 90 days after the stroke and there was no difference in death rates.

“Further studies are needed because there are new devices that open up vessels better and faster, and with fewer complications, than the first generation devices used in our trial,” said Reza Jahan, MD, co-principal investigator for the trial and associate professor of interventional neuroradiology at the University of California in Los Angeles.

Investigators also noted that imaging techniques (CT scans and MRI) used to measure the amount of salvageable brain tissue didn’t help predict which patients might benefit from mechanical clot removal.

“If you experience signs of stroke, the important thing is to get to a stroke center in time to qualify for the only proven treatment—tPA,” said Dr. Kidwell.

The study was presented in February at the American Stroke Association’s International Stroke Conference 2013. All findings are considered preliminary until published in a peer-reviewed journal.

The National Institutes of Health, National Institute of Neurological Disorders and Stroke funded the study.

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Review Date: 
February 14, 2013