Stroke Thrombectomy: Removing Clot on First Attempt Is Key

June 29, 2021

For patients with acute ischemic stroke who undergo thrombectomy, an increase in the number of attempts to retrieve the clot is associated with a higher risk for an unfavorable outcome, a new study shows.

An increase in attempts at clot retrieval was also associated with an increase in emboli to new territory and greater infarct growth, which could explain the worse outcomes.

The study was published online in Neurology on June 23.

"Achieving successful recanalization with the fewest number of clot retrieval attempts, ideally with a single pass, appears to be a new goal, redefining procedural success in stroke endovascular therapy and underlining the need to develop a new generation of devices designed to increase the rate of complete revascularization at the first attempt," the authors, led by Wagih Ben Hassen, MD, Université de Paris, Paris, France, conclude.

"These findings highlight the need for a randomized trial to define the appropriate therapeutic strategy when a first clot retrieval attempt is unsuccessful," they add.

However, they also point out that successful recanalization, even after multiple attempts, is still better than no recanalization. They note that in this study, when recanalization was obtained after a third attempt, 45% of patients still had a favorable outcome, so they do not believe operators should give up after a specified number of attempts.

"[O]ne should rather draw attention to the potential impact of multiple CRA [clot retrieval attempts] and encourage operators to use the best technique available to achieve full recanalization with a minimal number of maneuvres," they write.

For the study, the researchers examined data from two prospective registries that included consecutive patients with anterior acute ischemic stroke with a large-vessel occlusion who were treated with mechanical thrombectomy. The study included 419 patients for whom recanalization was successful and who underwent pretreatment and 24-hour posttreatment diffusion-weighted imaging.

Results showed that symptomatic intracranial hemorrhage rates increased with the number of clot retrieval attempts. Among patients for whom recanalization was achieved after one retrieval attempt, the rate was 5.8%; for those needing two attempts, it was 8.4%; for those needing three attempts, 6.1%; and for those needing four or more attempts, 10%.

Favorable functional outcome, defined as a Modified Rankin Scale score ≤2, decreased with each additional clot retrieval attempt among the patients for whom recanalization was successful. Favorable outcomes were achieved among 62% of those needing just one attempt, vs 55% among those needing two attempts, 49% of those requiring three attempts, and 42% of those requiring four or more attempts.

Occurrence of emboli migrating to a new territory was highly correlated to increasing number of clot retrieval attempts. This occurred in 1% of those requiring one attempt, 2.8% of those needing two attempts, 14.3% of those requiring three attempts, and 28.2% of those undergoing four or more attempts at clot retrieval.

Infarct growth volume also increased linearly with the number of clot retrieval attempts.

"Achieving successful recanalization is important but so is the way used to achieve it," the authors note. "If the thrombectomy device placement is suboptimal, ie, if a stent retriever does not fully cover the arterial clot or if the aspiration catheter cannot be positioned immediately adjacent to the site of occlusion, it is more important to try to reposition the device or to change the technique rather than carry on with a suboptimal retrieval attempt.

"Similarly, if a combined technique (aspiration + stent retriever) appears most likely to produce a successful result, then it should be used as the first technique and not be tried after a single device attempt," the investigators write.

They suggest that these findings raise the question of the optimal timing for changing thrombectomy technique when the first attempt is unsuccessful. "Should the operator switch immediately to another technique (changing from contact aspiration to combined aspiration + stent retriever for example) or continue with the same technique for a second or a third attempt?" they ask.

They point out that the limit on the number of attempts before changing strategy is highly variable among centers and operators and that no guidelines are currently available. They note that a randomized trial is needed to address this issue and to define the best strategy after a first attempt fails.

A Call to Arms

Commenting on the study for Medscape Medical News, J. Mocco, MD, system vice chair director of the cerebrovascular center at Mount Sinai Health System, New York City, said, "Ben Hassen et al should be congratulated on their thorough analysis of outcomes following stroke thrombectomy."

But he added that "a great deal of caution should be taken in interpreting these data."

Noting that the authors themselves acknowledge that successful recanalization, even after multiple attempts, is still better than no recanalization, Mocco said: "It would be a great disservice to patients to conclude that these results suggest one should stop attempting to open the vessel after three attempts have been made."

He noted that this article is a call to arms for the thrombectomy community to continue improving. "As techniques and technologies advance, we should target one-pass recanalization as our goal...not just eventual recanalization."

He added that this study also emphasizes the importance of expertise in performing stroke thrombectomy.

"It matters how experienced and well trained a practitioner is, as each attempt to open the blood vessel carries decreased likelihood of a good outcome," he said.

The study received no targeted funding. The authors have disclosed no relevant financial relationships.

Neurology. Published online June 23, 2021. Abstract

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