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Potential benefit cannot be ruled out for endovascular thrombectomy in acute ischemic stroke patients with substantial ischemic cores, according to a secondary analysis of the .

Those who received mechanical thrombectomy were more likely to show functional independence at 90 days (modified Rankin Scale [mRS] score 0-2) than if they had gotten medical management alone (31% vs 14%, OR 3.27, 95% CI 1.11-9.62).

But after accounting for baseline differences in SELECT -- such as the latter group waiting longer to get treatment and presenting with larger ischemic cores -- the difference was no more (adjusted OR 3.95, 95% CI 0.62-25.35), reported Amrou Sarraj, MD, of University of Texas McGovern Medical School in Houston, in .

Nevertheless, the authors reported other signals of benefit for endovascular therapy:

• Better functional outcomes across mRS categories: common OR 2.12 (95% CI 1.05-4.31)
• Less infarct growth: 44 vs 98 mL (P=0.006)
• Smaller final infarct volume: 97 vs 190 mL (P=0.001)

"These data do not provide a definitive answer as to which modality should be used for identifying patients with large cores who would benefit from EVT [endovascular thrombectomy]," Sarraj's group concluded. "These data provide hypothesis-generating evidence that patients with large cores visible on CT or CTP [CT perfusion] may achieve a reasonable rate of functional independence after EVT."

Similar drops in the odds of functional independence were noted for every 10 cm³ increase in core volume (adjusted OR 0.58, 95% CI 0.39-0.87) and every hour of treatment delay (adjusted OR 0.60, 95% CI 0.36-0.99).

None of the 10 endovascular thrombectomy recipients with baseline core volumes >100 cm³ had a favorable outcome. The investigators estimated the probability of functional independence when thrombectomy occurred more than 12 hours after last known well at <10%.

It may be that "the influence of time is more pronounced with increased ischemic core volume," Sarraj and colleagues suggested.

A pooling of the SELECT and TREVO studies previously suggested that patients with large core strokes may not get the same benefits of endovascular therapy as those with smaller ischemic cores.

For now, U.S. guidelines exclude stroke patients with ASPECTS 0-5 from the level 1 recommendation for endovascular thrombectomy, Bruce Campbell, MBBS, PhD, of Royal Melbourne Hospital, Australia, pointed out in an .

"Excluding patients from thrombectomy based purely on low ASPECTS, which encompasses a wide range of core volumes, risks excluding patients who have relatively small core volumes and the potential to benefit," Campbell warned.

SELECT was a prospective cohort study of patients with anterior circulation large vessel occlusions presenting up to 24 hours from stroke onset.

The present analysis was based on the 105 participants who had large ischemic cores on CT (ASPECTS scores ≤5) and/or CT perfusion scanning (≥50 cm³). Median age was 66 and 43% of the cohort were women.

Only 40 people had large cores on both imaging modalities.

Among those who underwent endovascular therapy, 81% had successful reperfusion (mTICI 2b or higher). However, successful reperfusion was not significantly associated with functional independence, Sarraj's group found.

"A key consideration in patients with a large ischemic core is that mRS scores of 0 to 2 may not be the best definition of treatment success. If a patient achieves an mRS score of 3 and lives at home with some assistance to cook or clean, that is highly preferable to dying or requiring nursing home care (mRS scores, 5-6)," according to Campbell.

Sarraj and colleagues acknowledged that on top of not being randomized, their study lacked MRI assessment and didn't actually enroll any patients with ASPECTS 0-2.

Their finding of no difference in symptomatic intracerebral hemorrhage between groups should be taken with a grain of salt as well, since the analysis was underpowered, Campbell added.

Ongoing trials like SELECT 2, TENSION, LASTE, and TESLA are expected to provide information on whether mechanical thrombectomy really does benefit people with large ischemic cores.

Another open question is the best imaging modality to identify such large cores.

"If ASPECTS is used, it is therefore best interpreted in the light of more volumetrically quantitative and spatially informative imaging, such as CT perfusion imaging or diffusion-weighted MRI results," the editorialist suggested.

"Taken together, Sarraj et al and the other studies indicate that some patients within 6 hours of onset are likely to benefit if they have an ischemic core up to at least 150 mL in size," he wrote. "The key modifying considerations are the patient's functional status, location of the core, and the expected time to reperfusion."

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