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Mechanical Thrombectomy Efficacious in Distal Medium Vessel Occlusion

Researchers found that higher NIHSS scores on admission and a successful first-pass effect were predictors of reaching early neurological improvement.

Data from the TOPMOST study suggest that mechanical thrombectomy (MT) for posterior circulation is a safe and feasible therapy option for patients that experienced stroke attributed to primary distal medium vessel occlusion (DMVO) of the posterior cerebral artery (PCA) of the P2 or P3 segment when compared to standard medical treatment (SMT) with or without intravenous thrombectomy (IVT).

The mean difference in National Institute of Health Stroke Scale (NIHSS) score decrease from admission between MET and SMT cohorts was –1.5 points (95% CI, 3.2 to −0.8; P = .06). The largest effects of MT were seen in the subgroup of patients with NIHSS scores of 10 or higher at admission, with a mean difference of –5.6 (95% CI, −10.9 to −0.2; P = .04), as well as patients without IVT (mean difference, −3.0 [95% CI, −5.0 to −0.9]; P = .005).

"This study suggested that, although rarely performed at comprehensive stroke centers, mechanical thrombectomy for posterior circulation DMVO is a safe, and technically feasible treatment option for occlusions of the P2 or P3 segment of the PCA compared with standard medical treatment with or without IVT,” wrote first author Lukas Meyer, MD, radiology resident, University Medical Center Hamburg-Eppendorf, and colleagues.

Meyer and colleagues analyzed data from 184 propensity score-matched patients in participating centers throughout Europe, the US, and Asia, between January 2010 and June 2020. The patients had a median age of 74 years (interquartile range [IQR], 62-81) and 95 (51.6%) were women. Posterior circulation DMVOs were located in the P2 segment of the PCA in 149 patients (81.0%) and in the P3 segment in 35 patients (19.0%).

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The researchers found that the SMT cohort received significantly more IVT (53 of 92; 57.6%) than the MT cohort (37 of 92; 40.2%; P = .01). The median time from onset to groin puncture was 197 minutes (IQR, 148-277) in the MT cohort. The median time from onset to imaging was 141 minutes (104-216) and to IVT application was 151 minutes (IQR, 120-201) in the SMT cohort. 

The MT cohort had a mean NIHSS score decrease from admission of 3.9 points (95% CI, –5.4 to –2.5) while the SMT cohort had a mean decrease of 2.4 points (95% CI, –3.2 to –1.6). 

The researchers performed multivariable logistic regression analysis and found that higher NIHSS scores on admission (adjusted OR [aOR], 1.19 [95% CI, 1.08-1.31]; P <.001) and a successful first-pass effect (aOR, 2.32 [95% CI, 1.03-5.20]; P = .04) were independent factors in reaching early neurological improvement (ENI) in the MT cohort. Within the SMT cohort, P3 occlusions (aOR, 4.25 [95% CI, 1.27-14.22]; P = .02), and IVT were independently associated with reaching ENI (aOR, 2.69 [95% CI, 0.98-7.37]; P = .054).

Excellent functional outcomes (modified Rankin Scale [mRS] score ≤1) were observed in 51 patients (66.2%) in the MT cohort and 31 patients (54.4%) in the SMT cohort at 90-day follow-up. Overall, mRS score distributions in the MT cohort (median, 1; IQR, 0-2) points and SMT cohort (median, 0; IQR, 1-2.5; P = .26) did not differ significantly at 90-day follow-up. 

Symptomatic intracranial hemorrhage and symptomatic intracerebral hemorrhage each occurred in 4 patients (4.3%) in each treatment cohort. The overall mortality in both cohorts was 4.9% (n = 9) during hospital stay and 13.4% (n = 18) at 90-day follow-up, including 3 patients in the MT cohort who died from a non-stroke-related cause. Mortality rates did not differ significantly between the treatment groups (P ≥.4). Patients with an NIHSS score of 10 or higher on admission, an mTICI score of 2a or lower, or SMT treatment with ineligibility for IVT had the highest relative mortality rates.

“A randomly-controlled trial that compares MT with SMT is warranted to evaluate the use of thrombectomy for posterior circulation DMVO and to resolve clinical equipoise in acute therapeutic decision-making,” Meyer and colleagues concluded.

Meyer L, Stracke CP, Jungi N, et al. Thrombectomy for primary distal posterior cerebral artery occlusion stroke: The TOPMOST Study. JAMA Neurol. Published online February 22, 2021. doi: 10.1001/jamaneurol.2021.0001