Introduction Large multicenter cohorts of thrombolysed stroke patients consistently report a sex disparity in functional outcome that is not age-dependent. Explanations for these sex-dependent outcomes differences are poorly understood. Patients with robust cerebral collaterals have been shown to have better outcomes after mechanical thrombectomy for acute middle cerebral artery occlusions. We hypothesize that differences in collateral circulation contribute to the observed sex disparity in stroke functional outcomes.

Methods Consecutive patients with middle cerebral artery occlusions undergoing mechanical thrombectomy at a tertiary care, urban, academic comprehensive stroke center were retrospectively evaluated. Brain CT angiography was graded by a neuroradiologist using a standardized grading scheme (0 = 0% collateral reconstitution of the affected ischemic area, 1 = <50% collateral reconstitution, 2 = 50–100% collateral reconstitution, 3 = 100% collateral reconstitution). Other independent variables consisted of age, admission and discharge NIHSS, TICI 2b/3 recanalization, and IV-tPA administration. The dependent variable was the modified Rankin score at 90 days.

Results From June 2013 to November 2016, 42 males and 26 females met the inclusion criteria. Males had higher rates of poor collaterals (0-1) than females (64.3% vs. 53.8%). Males also had lower rates of favorable collaterals (2-3) than females (35.7% vs. 46.2%). The odds ratio of collateral scores of 0-1 for males compared with females was not significant (OR =1.54, 95% CI = 0.57-4.18). Fisher’s two-tailed t-test of the sample data also did not show significance at a p-value of.45 (p < 0.05).

Conclusion Although this pilot study did not prove a significant association between poor collateral scores (0-1) and patient sex, there were higher rates of poorer collaterals and lower rates of favorable collaterals among men. Differences in collateral circulation would not appear to explain why women have poorer outcomes after post-thrombectomy, or a clear trend towards poorer collaterals among women would be expected. An analysis of a larger patient sample might yield a stronger association; for now, the sex disparity in stroke functional outcomes among thrombolysed patients remains unclear.

Disclosures: K. Keppetipola: None. M. Davison: None. S. Dua: None. B. Ouyang: None. M. Chen: None.