Clinical Outcomes of Isolated Subarachnoid Hemorrhage after Mechanical Thrombectomy

BACKGROUND AND OBJECTIVES: Subarachnoid hemorrhage (SAH) after mechanical thrombectomy (MT) occurs in about 4.51-7.23% of cases. This study evaluates the impact of isolated SAH after MT on clinical outcomes. METHODS: This was a retrospective analysis of patients who underwent mechanical thrombectomy for acute ischemic stroke between January 2017-December 2024 at a single center in the United States. Cases were patients with SAH on their post-operative imaging, while controls were patients who did not exhibit signs of hemorrhagic conversion on their imaging. Patients with contrast leakage, intraparenchymal hemorrhage or subdural hemorrhage were excluded. Propensity-score weighting was used to adjust for confounders. RESULTS: A total of 471 patients were included. 12.14% (n= 51) were cases and 89.16% (n= 420) were controls. After propensity score weighting, patients who developed SAH after MT did not have increased risk for higher NIHSS on discharge (log beta= 0.004 (95% CI:-0.334, 0.343), P= 0.98 or increased length of stay (log beta=-0.081 (-0.302, 0.14), P= 0.472). Rates of 30-day readmission (OR: 0.61, 95% CI: 0.14-2.68, P= 0.513) and 90-day functional dependence (OR: 0.69, 95% CI: 0.28-1.68, P= 0.412) did not differ among patients who developed SAH and those who did not. CONCLUSION: In our retrospective study, isolated SAH after MT was not associated with increased risk for higher NIHSS on discharge, increased LOS, 30 day readmission or 90 day functional dependence. Further prospective studies with larger sample sizes could aim to validate these findings.