A stent retriever that an operator can expand and contract mid-procedure resulted in a revascularization rate better than that seen in the trials of already approved, self-expanding stents, according to data presented at the International Stroke Conference.
The devices, called Tigertrievers—which have not yet been approved by the US Food and Drug Administration (FDA)—also resulted in lower levels of disability after three months compared to standard retrievers in the study of acute ischemic stroke patients with large vessel occlusion, researchers said. The study was funded by the device manufacturer, Rapid Medical.
An independent expert said the device has potential but more data are needed.
When using the devices, the operator can slide a button to either widen or compress the wire netting area, to align the device with the vessel dimensions and to adjust the radial force as needed for penetration of the clot and to minimize tension on the vessel wall.
The device was developed to improve upon self-expanding retrievers currently in the marketplace, which have not achieved successful reperfusion about 27 percent of the time, said Jeffrey L. Saver, MD, FAAN, professor of neurology at the David Geffen School of Medicine at UCLA.
Researchers enrolled 160 patients in a lead-in phase and a main phase of the study. Sixteen of the sites were in the US, and one was in Israel, where a single patient was enrolled. Eighty percent of patients had a modified Rankin score of zero before their stroke. Almost all of the others had a score of one.
The investigators compared outcomes to the pivotal trials for the existing stent retrievers already on the market, including the Solitaire and Trevo retrievers.
The patients treated with the operator-adjustable stent retriever had successful revascularization—a grade of 2b or better on the modified Thrombolysis in Cerebral Infarction (TICI) scale—in 84.6 percent of cases, after one to three passes. In the trials of the self-expanding stent retrievers on the market, 73.4 percent had this outcome.
This met a superiority threshold (p=0.0001), said co-primary investigator Rishi Gupta, MD, a vascular neurologist at the Wellstar Health System in Atlanta. In 57.8 percent of the adjustable retriever cases, successful revascularization was achieved on the first pass.
At 90 days, 58 percent of the patients treated with the adjustable retriever had an mRS of zero to two, considered a good outcome. In the trials of the retrievers already on the market, 43 percent had this outcome.
Symptomatic intracranial hemorrhage at 24 hours or mortality at 90 days was seen in 18.1 percent of the adjustable retriever patients, compared to 20.4 percent of those in the trials of the retrievers already on the market, Dr. Saver said.
“The Tigertriever is a highly effective and safe device to remove thrombus in patients with large vessel occlusion who are eligible for mechanical thrombectomy," Dr. Gupta said.
Pooja Khatri, MD, MSc, FAAN, professor of neurology and director of the vascular neurology division at the University of Cincinnati, said the findings show potential, but she reserved judgment about the device.
“The device looks reasonably safe and efficacious," Dr. Khatri said. “It shows potential for being better than prior devices, but that is hard to know with any certainty at this point. The comparison to historical controls is an apples-to-oranges comparison."
She added that outcomes tend to improve over time, and that analyses that go beyond strictly what is needed for FDA approval are needed.
“We will want to see more analyses ultimately, such as comparison to historical controls with adjustment for important prognostic variables, ideally at the patient level with advanced methods," Dr. Khatri said. “The real-world experiences of our interventional colleagues will be critical, too, of course."
Dr. Khatri said she hoped re-occlusion rates could be reported in the future, imagining that the device could reduce re-occlusion rates due to the control of radial force and less vessel wall damage, but could also increase it if the operator applies too much radial force.
Investigators said they will be able to explore this using vessel imaging studies done at 24 hours.
Dr. Saver disclosed receiving hourly payments and travel reimbursement for service as a scientific consultant advising on rigorous trial design and conduct for Medtronic, Cerenovus, Stryker, Boehringer Ingelheim, and Abbott. Dr. Khatri disclosed that her department has received funds from Cerenovus (grant), Lumosa (consulting), and Diamedica (consulting) on her behalf. She also received funds from Bayer (trial lead), UpToDate (royalties), and Basking (consulting).
Link Up for More Information:
ISC Abstract LB10: Saver JL, Gupta R, Gross B, et al. A new class of radially-adjustable stentrievers for acute ischemic stroke: Primary results of the multicenter Tiger trial.