Abstract TP199: Prominent Laterality of the Posterior Cerebral Artery on MR Angiography Before Mechanical Thrombectomy in Patients With the Middle Cerebral Artery Occlusion Predicts Long-Term Functional Outcome

Abstract

Background and Purpose: Well-developed collateral flow is reported to be associated with a reduction of infarct volume, successful reperfusion, and better functional outcome in acute ischemic stroke (AIS). Relatively increased visualization of posterior cerebral artery (PCA) ipsilateral to the ischemic lesion on MR angiography (MRA), a sign of prominent PCA laterality (PCAL), represents the development of collateral flow from PCA to middle cerebral artery (MCA) territory. However, the prognostic value of PCAL on functional outcome in AIS patients having MCA occlusion and undergoing mechanical thrombectomy, is not well known. Methods: We retrospectively reviewed initial MRA scans of pre-morbidly independent patients treated with mechanical thrombectomy for M1-segment occlusion from September 2017 to May 2022. PCAL was defined as better visualization of ipsilateral PCA, compared to contralateral PCA, by one or more segments on MRA. We divided patients into two groups, those presenting PCAL and not, and compared the background characteristics, in-hospital management, and functional outcome between the two groups. Factors associated with favorable outcome (mRS score 0-2) at 3 months after onset were assessed using multivariate logistic regression analysis. Results: In total, 172 patients (76 female [44%], median age 77 [IQR 74.5-78.0] years, median NIHSS score 16 [15-18]) were included. Of these, 86 patients (50%) presented PCAL on initial MRA. There is no significant difference between the two groups in age, sex, major vascular risk factors, NIHSS on admission, DWI-ASPECTS, onset-to-recanalization time (OTR), and preclinical modified Rankin scale. Multivariate logistic regression analysis showed an adjusted odds ratio of 2.11 for a favorable outcome in patients with PCAL (95% CI: 0.986 to 4.53, P=0.054). When focused on the cases with OTR >6 hours (n=53), PCAL was independently associated with favorable outcome (OR 5.77, 95% CI: 1.28 to 26.0, P=0.022). Conclusion: PCAL on initial MRA in patients with M1-segment occlusion predicts favorable long-term functional outcome after mechanical thrombectomy, especially in the case taking longer time from onset to recanalization.