Temple University Hospital Using Novel Stent Technology to Remove Brain Clots

Temple University Hospital is the only hospital in Philadelphia participating in an international clinical trial to evaluate the effectiveness of a device called a "stentriever" to remove brain-damaging clots that are causing a stroke. Patients began enrolling in the study at Temple on August 1.

Guillermo Linares, MD, Temple's Director of Neuro-Interventional Services, and Kadir Erkmen, MD, FAANS, Temple's Director of Cerebrovascular Neurosurgery, serve as clinical investigators for the study, which will compare standard-of-care medical treatment (i.e., administering a clot-busting drug to the blockage) against the stentriever, which grabs and removes the clot in the brain after being guided to the site via a catheter inserted into the femoral artery. With the clot gone, blood flow is restored to the brain, sparing further damage to critical brain tissue.

"The goal is to open up the artery very quickly," said Dr. Linares, a neuro-interventionist who is Assistant Professor of Neurology, Neurosurgery and Radiology at Temple University School of Medicine. "Time is brain. As soon as the clot is out, neurons stop dying."

Until now, doctors treating patients with stroke caused by a clot in a brain artery have been limited by time constraints on the use of the clot-busting drug tPA (tissue plasminogen activator). Generally, the drug must be administered within three hours of the onset of stroke symptoms, although in some cases it can be given up to 4.5 hours after symptom onset. In addition to limitations caused by that narrow time window, many patients are not appropriate candidates for the drug, in which case simple aspirin is the only stroke treatment doctors can offer.

According to Dr. Linares, while time is of the essence when brain cells are dying, the idea that stroke patients have such limited options so quickly is perhaps an outdated one.

"The notion that treatment options end at three to four-and-a-half hours, doesn't make sense," he said. "New ways of thinking must be tested – and that is what we are doing as part of this new clinical trial."

The new study, known as ESCAPE, is based at the University of Calgary in Canada and funded by the Canadian Institute for Health. A total of 420 patients will be enrolled at Temple and 10 other sites in the U.S., Canada and Europe. Dr. Linares said that earlier testing of various models of stentreivers showed enough promise that the devices will now be tested more rigorously in the clinical trial to compare their effectiveness to "gold standard" medical treatment.

Dr. Linares has already performed about 250 of the procedures in his own practice of interventional neurology and has found stentrievers to be safe and effective in retrieving clots from blocked brain arteries. Complication rates are relatively low, in the 1 percent to 3 percent range, and successful opening of a blocked artery can be achieved in about 90 percent of cases, he said. The approach works best when the clot is small and located in a large blood vessel in an easy-to-access area of the brain.

Since the artery must be opened before the brain suffers from irreversible injury, the procedure still needs to be done as quickly as possible, although it can be performed up to 12 hours after stroke symptoms begin. That longer treatment window could be beneficial for some patients, including those who have awakened from sleep with stroke symptoms, as long as the underlying area of injury is still small.

"We think this treatment option will increase the number of stroke patients who can be helped," Dr. Linares said.

In the ESCAPE trial, patients who are experiencing symptoms from a stroke and meet certain clinical and imaging criteria will be randomly assigned to either receive standard medical care or undergo a clot-removal procedure using a stentreiver.

Dr. Linares said the working hypothesis is that the device will lead to better outcomes for eligible patients than standard medical treatment.
"We think that it will lower mortality, improve quality of life for patients and lower their degree of disability," he said.

Stroke is the fourth leading cause of death in the U.S, and a major cause of disability in adults. About 800,000 people in the U.S. suffer a stroke each year.

Despite the prevalence of stroke, patients often fail to recognize its symptoms, which include numbness or weakness in the face, arm or leg, especially on one side of the body; mental confusion; and trouble speaking or seeing. In some cases, patients will ignore their symptoms or wait to see if they pass. The end result is that many stroke patients get to the hospital too late to be treated with clot-busting tPA.

"This disease is very serious and can cause a lifetime of disability," Dr. Linares said.

He predicts that the day is near when doctors can decide what stroke treatment to give a patient based less on conventional time constraints and more on factors specific to the individual patient's case.

"The brain responds to injury in different ways in different people and we have to recognize that," Dr. Linares said.

Physicians at Temple University Hospital and Temple University School of Medicine are leaders in the treatment of stroke. They also direct and participate in a wide range of stroke research, from basic science to the evaluation of new therapies. Referring physicians and emergency room physicians interested in learning more about the clinical trial to evaluate the stentriever technology can contact Dr. Linares at 215-707-3040.

Editor's Note: Neither Dr. Linares, Dr. Erkmen nor any member of their immediate families has financial interest in Stryker® or Covidien – eV3, companies that manufacture stentriever devices.