Clot removal device results in dramatically improved outcomes in acute ischemic stroke, study finds

In patients with acute ischemic stroke who received a clot-busting drug, removing the obstructing blood clot with a stent retriever device significantly reduced post-stroke disability and increased the number of patients who were independent in daily function after three months, according to a study led by a UCLA investigator.

The findings represent the first new treatment for acute ischemic stroke in 20 years, since the development of the clot-busting drug tPA, said study global principal investigator Dr. Jeffrey Saver, director of the UCLA Stroke Center and a professor of neurology at the David Geffen School of Medicine at UCLA.

"These findings are a paradigm shift, a new era in stroke care and we are ecstatic," Saver said. "We will be able to treat many more patients, who will have much better outcomes. This is a once-in-a-generation advance in acute stroke care."

The findings appear in the New England Journal of Medicine.

The study, the Solitaire With the Intention For Thrombectomy as PRIMary Endovascular Treatment (SWIFT PRIME), was conducted at 39 hospitals in the United States, Canada and Europe. The study enrolled 196 patients, although it was originally slated to enroll 833. Because of early positive results in this and other stent retrieval studies, SWIFT PRIME was halted early, Saver said.

The study tested a second generation stent clot retrieval device called Solitaire. The first-generation devices tested previously had shown no benefit over medical therapy alone, which Saver said was disappointing.

The study tested the Solitaire on patients within six hours of symptom onset. The 196 patients were randomized to either tPA alone or tPA with stent retrieval of the clot, with 98 patients comprising each group. Saver said the study showed the clot removal devices outperformed tPA alone. Three months after the stroke, 60 percent of the patients who received tPA along with clot retrieval were functionally independent and free from disability, compared to 35 percent of the patients who received tPA only.

tPA is an effective treatment, but it only reopens vessels about 30 percent of the time, Saver said. In SWIFT PRIME, which focused on clots in large vessels, the stent retriever device opened the artery 88 percent of the time.

The preclinical research used to help develop the Solitaire device was performed at UCLA by Dr. Reza Jahan, a professor of radiology at the David Geffen School of Medicine at UCLA and a member of the UCLA Stroke Center, who also served as global neurointerventional advisor for the trial.

"This device reopened arteries much more frequently with less injury to the vessel," Jahan said. "The Solitaire also caused less bleeding and was able to more easily engage and entangle clots."

About one in 10 ischemic stroke patients can be taken to a catheter lab in time to perform the clot retrieval. This means that about 60,000 stroke patients a year could benefit from the two-pronged treatment approach of the drug tPA plus the stent retriever device.

"While these findings won't help all stroke patients, it will help those who have the most disabling strokes," said UCLA study site principal investigator Dr. Sidney Starkman, co-director of the UCLA Stroke Center and professor of emergency medicine and neurology at the David Geffen School of Medicine at UCLA. "Right now, they get tPA and it helps a third of them, but the other two thirds end up disabled or don't survive the stroke."

UCLA has a long history developing and testing stent retrieval devices, Saver said. In 2000, the first clot retrieval device, a corkscrew coil retriever, was invented at UCLA, with Starkman as that study's initial principal investigator.

"We are very happy to see this more than decade-long research program result in an important advance for stroke patients," said Saver.

SWIFT PRIME was one of three positive stent retrieval studies presented in February at the International Stroke Conference.

Stroke is the fifth leading cause of death in the United States and is a major cause of adult disability. About 800,000 people in the United States have a stroke each year. One American dies from a stroke every four minutes, on average.