Little Benefit From Adding Aspiration to Thrombectomy for Stroke

A first-line thrombectomy approach that combines contact aspiration and stent retrieval techniques does not significantly improve the reperfusion rate compared to stent retrieval alone in patients with acute ischemic stroke and large-vessel occlusion, a newly published study shows.

Dr Bertrand Lapergue

However, the trial was likely underpowered, so the question of whether the combined approach provides additional benefit has not been definitively answered, lead study author Bertrand Lapergue, MD, PhD, director, Stroke Center, Neurology Division, Hôpital Foch, Suresnes, France, told Medscape Medical News.

Until it is, neurosurgeons should continue to use the strategy they’re most comfortable with, be that contact aspiration (CA), stent retrieval (SR), or a combination of these two, said Lapergue.

The study, first presented at the European Stroke Organisation Congress (ESOC) in 2019 and reported at that time by Medscape Medical News, was published online September 28 in JAMA.

Research shows that endovascular mechanical thrombectomy leads to better functional outcomes compared to medical therapy for patients with acute ischemic stroke due to large-vessel occlusion. Mechanical thrombectomy strategies include use of devices such as stent retrievers and contact aspiration catheters.

Reperfusion is a strong predictor of clinical outcomes, as reflected in scores on the expanded Thrombolysis In Cerebral Infarction (eTICI) visual scale. Scores range from grade 0 (0% reperfusion) to grade 3 (100% reperfusion).

Grade 2b50 indicates reperfusion of 50% to 66% of the territory, and grade 2c indicates reperfusion of 90% to 99% of the territory.

The initial Contact Aspiration vs Stent Retriever for Successful Revascularization (ASTER) trial showed that removal of a blood clot using negative-pressure aspiration was as effective as using a stent retriever. But there has been some suggestion that CA and SR techniques together would provide a synergistic effect that would lead to an even better reperfusion rate.

The open-label blinded ASTER2 trial evaluated this combination approach. The study included 405 patients with anterior circulation large-vessel occlusion strokes who presented within 8 hours of symptom onset at 11 comprehensive stroke centers in France.

These patients were randomly assigned to undergo contact aspiration and stent retrieval combined (experimental intervention group) or the standard stent retrieval technique alone (control group).

The two groups were well balanced. The mean age was 73.4 years, and 54.3% were women. The mean baseline National Institutes of Health Stroke Scale (NIHSS) score was 16.2.

Imaging showed that most patients (85.2%) had an isolated middle cerebral artery occlusion.

The primary outcome was the rate of an eTICI score indicating near complete (grade 2c) or complete (grade 3) reperfusion at the end of the endovascular procedure. This outcome has been linked to relatively good clinical outcomes and less disability.

The researchers adjusted for randomization stratification variables that included age (<70 vs ≥70 years), intravenous thrombolysis, occlusion site (isolated middle cerebral artery vs terminus internal carotid artery), and treatment center.

The analysis showed that eTICI 2c/3 reperfusion did not differ significantly between the two groups (64.5% for the combined approach vs 57.9% for the stent retriever alone; adjusted odds ratio [OR]: 1.33; 95% CI, 0.88 – 1.99; P = .17).

Lapergue said he and his colleagues were surprised and “a little bit disappointed” by this outcome. He said the study was likely underpowered to detect smaller benefits of the combined approach.

He noted that another French trial, Adaptative Endovascular Etrategy to the CloT MRI in Large Intracranial Vessel Occlusion (VECTOR), could provide a more definitive answer as to whether CA should be added to SR for patients eligible for thrombectomy.

All but two of 14 secondary efficacy endpoints showed no significant difference between groups. Two did favor the experimental intervention. These were both reperfusion outcomes after the assigned initial allocated treatment: eTICI 2b50/2c/3 (86.2% vs 72.3%; adjusted OR, 2.54; 95% CI, 1.51 – 4.28); P < .001) and eTICI 2c/3 (59.6% vs 49.5%; adjusted OR, 1.52; 95% CI, 1.02 – 2.27; P = .04).

“If you look at the data, you find that direct angiographic criteria of efficacy of the combined strategy (eTICI 2C/3 and 2b/2c/3 after first line) were significant,” said Lapergue. “This suggests the combined strategy is better at the beginning of the intervention.”

A subgroup analysis suggested that the combined approach might be more beneficial “in cases of large burden clot,” something that is being studied further, said Lapergue.

Additional rescue therapies were needed for patients in the stent retrieval–alone group (26.7% vs 19.2%), but the procedure times did not differ significantly.

There was no significant difference between the groups in mean change of NIHSS score from admission to 24 hours or in degree of disability on the Modified Rankin Scale score at the 3- and 12-month follow-up. There was also no significant difference in health-related quality of life at 12 months.

There were no significant differences in safety outcomes except that the rate of type 2 parenchymal hematoma was lower in the combination group (3.1%) than in the control group (8.6%). Lapergue doesn’t think this is important, given the fact that there were no other differences in safety endpoints.

Procedure-related adverse events occurred in 25.1% in the combination group and in 24.3% of the control group. The most frequent event was vasospasm, followed by embolization in a new territory, arterial dissection, and arterial perforation.

There was no significant difference in mortality.

Exciting Era

Asked to comment, Mitchell S. V. Elkind, MD, immediate past president of the American Heart Association and professor of neurology and epidemiology at Columbia University Vagelos College of Physicians and Surgeons, New York City, praised the trial for being “well designed” and “methodologically robust” and said that it is part of “an exciting era” in stroke therapy.

“It’s a great example of how interventional therapy for acute stroke has really come into its own in the last few years,” said Elkind.

“Now that there are high-quality trials that have consistently demonstrated the benefits of mechanical thrombectomy overall, the target has begun to shift to evaluating specific devices and methods for opening blocked vessels,” he said.

Elkind noted that although the trial interventionalists themselves couldn’t be blinded, the outcomes were assessed in a blinded fashion, which “increases the credibility of the findings.”

And although the study didn’t prove a benefit to combined therapy, “it suggests there could be benefit,” Elkind concluded.

The study was sponsored by Foch Hospital, the University of Versailles Saint-Quentin-en-Yvelines. Research grants were provided by Penumbra, Stryker, MicroVention, and the French health ministry Programme Hospitalier Recherche Clinique. Lapergue received grants from Stryker Neurovascular, Penumbra, Balt, and MicroVention during the conduct of the study, nonfinancial support for travel from Medtronic, and personal fees as speaker honoraria from Penumbra outside the submitted work. Elkind has disclosed no relevant financial relationships.

JAMA. Published online September 28, 2021. Abstract

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