More than one clot retrieval attempt after stroke causes decline in functional outcomes

Repeated attempts to retrieve a clot in patients with acute stroke increased both the rate of emboli to new territory and infarct growth volume, with an impact on functional outcomes even when recanalization was successful.

Researchers published the findings in Neurology.

“These findings highlight the need for a study to determine the appropriate strategy to use when the first attempt at retrieving a blood clot is unsuccessful, since each additional attempt reduced the odds of a favorable outcome,” Wagih Ben Hassen, MD, of the French National Institute for Health and Medical Research in Paris, said in a press release.

Research recently identified the number of clot retrieval attempts as a marker of clinical outcome, regardless of final recanalization success, with a “detrimental” effect of more clot retrieval attempts on 3-month functional outcomes, whereas the ability to achieve complete recanalization on the first clot retrieval attempt correlated with a favorable outcome and reduced mortality. However, the impact of more clot retrieval attempts on functional outcomes “is not straightforward and has not yet been explained,” according to the researchers.

“Additional [clot retrieval attempts] could result in an increased per procedural clot fragmentation, leading to emboli to new (initially unaffected) territory, associated with [infarct growth] and potentially explaining the detrimental effect of [clot retrieval attempts] on functional outcome,” Hassen and colleagues wrote. “In this study, we aimed to elucidate the link between the number of [clot retrieval attempts] and the functional outcome in a successfully recanalized population.”

The researchers obtained data from two pooled, multicentric prospective registries of patients with consecutive anterior acute ischemic stroke caused by large vessel occlusion who were treated with mechanical thrombectomy between January 2016 and January 2019. Specifically, Hassen and colleagues included patients who received pretreatment and post-treatment at 24 hours with diffusion-weighted imaging and successful recanalization, which was defined as expanded Thrombolysis in Cerebral Infarction Scale (eTICI) scores of 2B, 2C or 3. They evaluated emboli to new territory and measured infarct growth using voxel-based segmentation after diffusion-weighted imaging coregistration. Hassen and colleagues also examined correlations between the number of clot retrieval attempts, emboli to new territory, infarct growth and outcomes at 3 months.

The study included 419 patients in whom successful recanalization was achieved (43.9% men; mean age, 68 years).

Hassen and colleagues found that emboli to new territory “strongly correlated” with a greater number of clot retrieval attempts, with 23 cases (5.5%) in the entire study population, two cases (1%) in the group with one clot retrieval attempt, three cases (2.8%) in the group with two clot retrieval attempts, seven cases (14.3%) in the group with three clot retrieval attempts and 11 cases (28.2%) in the group with four or more clot retrieval attempts.

Patients with emboli to new territory experienced higher infarct growth volume compared with the group with no emboli to new territory (P = .01). Patients with one clot retrieval attempt demonstrated the lowest infarct growth volume (P = .001) and the lowest rates of emboli to new territory (P = .01). Infarct growth increased linearly with the number of clot retrieval attempts, according to the study results.

“In multivariable linear regression, number of [clot retrieval attempts] and [emboli to new territory] were associated with [infarct growth] among poor collateral status, blood glucose level and initial NIH [stroke scale] score independently from time metrics (procedure time or onset-to-recanalization time),” Hassen and colleagues wrote.

Poor functional outcome, which the researchers defined as a 3-month modified Rankin scale score of greater than 2, increased with each new clot retrieval attempt, according to the study results. Specifically, symptomatic intracranial hemorrhage rates rose with the number of clot retrieval attempts; patients with one retrieval attempt had the lowest rate of symptomatic intracranial hemorrhage (5.8%), compared with rates of 8.4% in the group with two clot retrieval attempts, 6.1% in the group with three clot retrieval attempts and 10% in the group with four or more clot retrieval attempts. Favorable functional outcomes also declined with each additional clot retrieval attempt among the group of patients who were successfully recanalized. Infarct growth served as an independent predictor of unfavorable outcomes (OR = 1.05) per 1 mL increase in infract growth, according to binary logistic regression analysis.

“Achieving successful removal of blood clots and clearing these blood vessels with the fewest number of attempts, and ideally with a single pass, appears to be the new goal,” Ben Hassen said in the press release. “This underlines the need to develop a new generation of devices designed to increase the rate of complete success at the first attempt.”

Reference:

American Academy of Neurology. After stroke, more than one try to remove blood clots may be tied to worse outcome. Available at: https://www.aan.com/PressRoom/Home/PressRelease/4904. Accessed June 23, 2021.