Presentation collateral patterns and outcomes after endovascular thrombectomy for large vessel occlusion stroke

Background Endovascular thrombectomy (EVT) revolutionized large vessel occlusion (LVO) stroke. However, treatment decisions and prognostication are challenging without advanced imaging. We sought to determine the relationship of simple CTA collateral patterns and outcomes after EVT. Methods We identified patients with anterior LVO who underwent guideline based EVT from a single center from 2019-2020. Inclusion criteria were available CTA and 90-day modified Rankin Scale (mRS). Arterial-phase CTA collaterals were categorized as malignant, other, or symmetric. Results Among 74 patients, the median age was 75 and 49% were female. Collaterals were symmetric (36%), malignant (24%), or other (39%). Comparing collateral patterns there were no differences in demographics, presentations, time from last well, good reperfusion, or intracerebral hemorrhage. Median NIHSS was 18 for malignant, 19 for other, and 11 for symmetric (p=0.02). Intracranial ICA occlusions were present in 28% of malignant, 3% of other, and 11% of symmetric (p=0.04). Ninety-day mRS ≤2 was achieved in 17% of malignant, 38% of other, and 67% of symmetric. Collateral pattern was a significant determinant of 90-day mRS ≤2 (aOR=6.62, 95%CI=2.24,19.53; p=0.001) in a multivariable model including age, NIHSS, baseline mRS, thrombolysis, LVO location, and good reperfusion. Conclusions Simple CTA collateral pattern is a robust determinant of 90-day outcomes after EVT. Further prospective studies are needed to understand how collateral pattern can guide EVT treatment decisions and long-term prognosis.