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Mechanical Thrombectomy Shows Functional Benefit for Large Vessel Occlusion

Favorable outcome, defined as modified Rankin Scores of 0-2, was achieved in patients presenting with ASPECTS of 2-5 regardless of treatment with mechanical thrombectomy in the early or extended windows.

Newly published retrospective data from the Stroke Thrombectomy and Aneurysm Registry (STAR) showed a more than 5-in-1 chance of achieving functional independence 90 days after treatment with mechanical thrombectomy (MT) in patients with large vessel occlusion (LVO) presenting with an Alberta Stroke Program Early Computed Tomography Score (ASPECTS) of 2-5.

The findings also indicated that patients within this range who reported successful recanalization were 5 times more likely to achieve a favorable 90-day outcome compared with those who were unsuccessful. Led by Eyad Almallouhi, MD, neuroendovascular surgery fellow, Medical University of South Carolina, the data showed no difference in 90-day outcome when comparing those presenting in the early (≤6 hours) vs extended window (6-24 hours from symptom onset).

STAR includes databases from 28 thrombectomy-capable stroke centers in the US, Europe, and Asia, with this specific analysis that included 2345 patients treated with MT who presented with an occlusion in the internal carotid artery (ICA) of M1 segment of the middle cerebral artery. Of these, 2132 had ASPECTS greater than 6 and 213 with ASPECTS of 2-5. Favorable 90-day outcome, the primary outcome, was defined as modified Rankin Scale (mRS) scores of 0-2.

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ASPECTS is a 10-point scoring system that detects changes on the baseline CT scan, with 10 indicating normal and 0 indicating ischemic changes in all the regions included in the score. At 90 days, 47 of the 213 patients (22.1%) with an ASPECTS of 2-5 demonstrated functional independence compared to 771 of the 2132 patients (36.2%) with ASPECTS of 6 to 10.

In total, 176 patients (82.6%) with ASPECTS of 2-5 achieved successful recanalization after MT. Of these, favorable outcome at 90 days was reported in 45 patients (25.6%), compared with only 2 of 37 patients (5.4%) in the unsuccessful recanalization group (P = .007). Notably, there was no significant difference between the 2 groups in 90-day mortality (successful recanalization: 54 of 176 [30.7%] vs unsuccessful recanalization: 16 of 37 [43.2%]; P = .14).

When dividing patients with ASPECTS of 2-5 into early (n = 123) and extended (n = 90) windows, investigators found no significance difference in 90-day favorable outcome (30 of 123 [24.4%] vs 17 of 90 [18.9%]; P = .34) or 90-day mortality (46 of 123 [37.4%] vs 24 of 90 [26.7%]; P = .10). The study authors wrote that that this "reflects that both of these factors are independently associated with outcomes, suggesting that patients with a larger infarct volume may potentially still achieve benefits associated with MT even beyond 6 hours from symptom onset."

A multivariable analysis that included all patients who presented with an ICA or M1 occlusion an underwent MT showed that both a low ASPECTS and receiving treatment in the extended window were associated with lower odds of achieving a favorable 90-day outcome (low ASPECTS: OR, 0.60 [95% CI, 0.38-0.85]; P = .002; extended window: OR, 0.69 [95% CI, 0.55-0.88]; P = .001). These findings, although concluded after controlling for age, location of occlusion, admission National Institutes of Health Stroke Scale (NIHSS) score, intravenous thrombolysis, and successful recanalization were not significant (OR, 0.85 [95% CI, 0.39-1.78]; P = .64).

Younger age (OR, 1.04 [95% CI, 1.03-1.05]; P <.001), lower admission NIHSS score (OR, 1.12 [95% CI, 1.10-1.14]; P <.001), intravenous thrombolysis (OR, 1.32 [95% CI, 1.07-1.63], and modified Thrombolysis in Cerebral Ischemic score of 2B or more (OR, 6.64 [95% CI, 4.56-9.66]; P <.001), were all factors associated with favorable 90-day mRS score.

A secondary analysis using Cochran-Mantel-Haenszel test found the association between an ASPECTS of 2-5 and favorable outcome to not be modified by the thrombectomy center in which the MT was performed. Overall, the percentage of these patients compared to those with ICA or M1 occlusion ranged from 4.4% (5 of 113) and 15.2% (48 of 316; P = .12).

REFERENCE
Almallouhi E, Kasab SA, Hubbard Z, et al. Outcomes of mechanical thrombectomy for patients with stroke presenting with low Alberta stroke program early computed tomography score in the early and extended window. JAMA Netw Open. 2021;4(12):2137708. doi:10.1001/jamanetworkopen.2021.37708.