More can benefit from stroke treatment

A trial led by Stanford shows dramatically better outcomes for patients

Greg Albers, MD, helped develop brain-imaging software that allows physicians to learn which patients will benefit from surgery to remove blood clots up to 16 hours after a stroke.

Last April, Cindi Dodd, a 46-year-old graphic designer who lives in Salinas, went to bed around 10:30 p.m., anticipating a 5 a.m. wake-up from her husband because she was scheduled for outpatient surgery at Stanford.

Though she arrived at Stanford Hospitalthe next morning, she didn't walk through the doors as an outpatient; she came via helicopter as the victim of a massive ischemic stroke.

"My husband woke me up at 5 o'clock as planned, and when I started to speak to him, I knew what I was trying to say in my mind, but it had nothing to do with the sounds that were coming out of my mouth," Dodd said. Her left side was paralyzed.    

Her husband called 911. An ambulance arrived shortly afterward and rushed Dodd to Salinas Valley Memorial Hospital. But because she'd had the stroke while asleep, no one knew when it occurred. In such cases, physicians refer to the last time the patient was well, which for Dodd was 10:30 p.m. The attending physician explained that it was too late to administer clot-busting medication or for her to undergo a thrombectomy, a blood clot removal procedure.

But an emergency room physician told her husband about a clinical trial led by researchers at Stanford and, with his permission, called Stanford. Within 30 to 45 minutes, a helicopter was on the scene to whisk Dodd to Stanford Hospital.

Clinical trial spurs stroke treatment changes

Dodd's treatment at Stanford was part of a trial looking at whether more people can benefit from thrombectomy. Until recently, the procedure was recommended only for patients who reach a treatment center within six hours of a stroke. The trial, sponsored by the National Institutes of Health and conducted at 38 health centers, confirmed that people whose stroke occurred more than six hours earlier can benefit.

Ischemic strokes account for about 85 percent of the roughly 750,000 strokes suffered annually in the United States. They occur when blood supply to part of the brain is cut off by a clot in a cerebral blood vessel. The resulting lack of oxygen and glucose quickly kills brain tissue in the immediate vicinity, and the affected area continues to expand until blood supply is restored.

Thrombectomy involves guiding a cagelike stent through the circulatory system to the site of an acute-stroke patient's brain clot, where the stent then encases the clot and physically extracts it. As many as 35 to 40 percent of all strokes occur during sleep, so the short window of time severely limits the number of stroke patients receiving this procedure.

Brain-imaging software developed at Stanford helped identify stroke patients for the trial who could benefit from thrombectomy. Gregory Albers, MD, the director of the Stanford Stroke Center, developed the software about a decade ago with Roland Bammer, PhD, then an associate professor of radiology at Stanford and now a professor at the University of Melbourne in Australia, and software engineer Matus Straka, PhD, who was then a senior scientist at Stanford.

Different individuals' strokes spread through brain tissue at different rates, Albers explained. It's not so much the amount of time elapsed since a stroke began as the amount of salvageable brain tissue that determines who will benefit from stroke therapy, he said.

In the trial, patients were evaluated at treatment centers between six and 16 hours after incurring strokes originating in either of two large arteries in the brain: the middle cerebral artery or the internal carotid artery. Patients age 90 or younger whose brains showed evidence of substantial amounts of salvageable tissue were randomized into two groups: One set of patients, the intervention group, received thrombectomies. The others, the control group, received standard medical therapy.

'Astounding results'

Among the patients in the study, those who received a thrombectomy had far superior outcomes compared with those who didn't. Some patients showed dramatic improvement even when their brain clots were removed as long as 10 hours after the end of this six-hour window.

"Nearly half of all patients treated between six and 16 hours after the onset of their symptoms were largely spared from the consequences of their stroke," said Albers, the trial's principal investigator.

"These astounding results will have an immediate impact in the clinic and will help us save many lives," Walter Koroshetz, MD, director of the National Institute of Neurological Disorders and Stroke, said in an NIH news release. "I really cannot overstate the size of this effect."

The American Heart Association has issued new acute-stroke treatment guidelines that reflect what the study found.

Patients in the study were followed for 90 days after their strokes. (After this time period, stroke patients typically experience little additional recovery.) By 90 days, 26 percent of the patients in the control group had died and 16 percent had devastating disability. In contrast, only 14 percent of the patients who received thrombectomies had died, and 8 percent had severe disability. The combined plunge in these feared outcomes, from 42 percent of patients to 22 percent, represents the biggest improvement seen in any stroke-treatment trial to date, said Albers.

Albers noted one caveat: "Our trial's excellent results reflect our selection of patients most likely to benefit," he said. "Only about half of the patients we screened with the brain-imaging software had enough salvageable brain tissue to enter the study. For the others, the procedure was considered unlikely to be effective."

'It saved my life'

As a result of the trial's findings, thrombectomy procedures for late-arriving patients will probably double, said Albers. "It used to be that by five or six hours after a stroke, we had to say 'I'm so sorry, you arrived too late to be treated,'" he said. "But this is a new world."

Dodd is profoundly grateful that she was sent to Stanford to become a part of the study. By the time her husband and high school-age son drove up from Salinas, she was already out of surgery. Seven days later, she was discharged.

A year later, she is almost fully recovered after a combination of her thrombectomy, intensive rehabilitation and personal gumption. Dodd, who sports a tattoo reading, "I can, and I will," is talking, walking and driving as before. "I am literally standing on this Earth as a wife and a mother because of that procedure," she said. "It saved my life."