A new device to remove obstructing blood clots can significantly improve outcomes for people who suffer a certain type of stroke, according to a study led by a UCLA investigator.
In patients with acute ischemic stroke — in which a clot blocks the blood supply to part of the brain — who received a clot-busting drug, removing the obstructing blood clot with a stent retriever device significantly reduced post-stroke disability and increased the percentage of patients who were independent in daily function after three months.
The findings represent the first new treatment for acute ischemic stroke in 20 years, since the development of the clot-busting drug tPA, said Dr. Jeffrey Saver, the study’s global principal investigator and director of the UCLA Stroke Center.
“These findings are a paradigm shift — a new era in stroke care — and we are ecstatic,” said Saver, who is also a professor of neurology at the David Geffen School of Medicine at UCLA. “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 April 17 in the New England Journal of Medicine.
The study, called 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 people. It was originally slated to enroll 833, but was halted early because of early positive results in this and other stent retrieval studies, 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 new study tested the Solitaire on patients within six hours of the onset of stroke symptoms. The 196 patients were randomly assigned to be treated with either tPA alone or tPA along with stent retrieval of the clot, with 98 people in each group. Saver said the study showed the clot-removal devices outperformed tPA alone. Three months after having a stroke, 60 percent of the people who received clot retrieval as well as tPA were functionally independent and free from disability, compared to 35 percent of those who received tPA only.
For patients with a large clot, tPA only reopens vessels 25 to 30 percent of the time, Saver said. In the study, the stent retriever device opened the artery 88 percent of the time, even when there was a large clot.
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.
“This device reopened arteries much more frequently with less injury to the vessel,” said Jahan, who also served as global neurointerventional adviser for the trial.
“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.
“While this won’t help all stroke patients, the ones it will help have the most disabling strokes,” said Dr. Sidney Starkman, the UCLA study site principal investigator and co-director of the UCLA Stroke Center
“Right now, they get tPA and it helps a third of them, but the other two-thirds end up dependent on others for help or they die,” said Starkman, who is also professor of emergency medicine and neurology at the David Geffen School of Medicine at UCLA.
UCLA has a long history developing and testing stent retrieval devices, Saver said. The first clot retrieval stent device, a coil retriever, was invented at UCLA, and several major clinical trials of clot retrieval devices have been led by UCLA Stroke Center doctors.
“We are very happy to see this decade-long research program result in an important advance for stroke patients,” said Saver.
The study 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.
The SWIFT PRIME trial was funded by Medtronic, which manufactures the Solitaire device.
- Kim Irwin