Abstract A002: Association of Cerebral Amyloid Angiopathy Neuroimaging Markers and Boston Criteria with the Safety and Efficacy of Thrombolysis in Patients with Acute Ischemic Stroke: Results from the AcT Trial

Introduction: Cerebral amyloid angiopathy (CAA) is thought to increase the risk of post thrombolytic intracranial bleeding, yet CAA neuroimaging markers and MRI criteria have not been systematically evaluated in large acute stroke trials. We therefore examined the association of various iterations of the Boston CAA criteria and their constituent markers with hemorrhagic risks and functional outcomes after intravenous thrombolysis in the Alteplase compared to Tenecteplase (AcT) trial. Methods: This post-hoc study included AcT participants who underwent follow-up brain MRI (n = 482). Blinded raters recorded lobar cerebral microbleeds (CMBs), cortical superficial siderosis (CSS), white-matter-hyperintensity (WMH) multispot sign, and centrum-semiovale enlarged perivascular spaces, and classified “possible” and “probable” CAA according to radiological Boston criteria iterations 1.0, 1.5, and 2.0. Multivariable logistic or ordinal regressions, adjusted for age, sex, baseline NIHSS, onset-to-needle time, thrombolytic agent, diabetes mellitus, hypertension, and endovascular therapy assessed associations with primary safety endpoints: 90-day mortality, symptomatic intracerebra l hemorrhage, any ICH, and Heidelberg hemorrhage grade, and secondary functional endpoints (modified Rankin Scale mRS 0–1 and ordinal mRS shift). Results: CSS emerged as the dominant harmful marker: each increment independently increased 90-day mortality (adjusted odds ratio aOR 1.42, 95%CI1.18–1.71), heightened the risk of sICH (aOR 3.88, 2.87–5.26) and any intracranial hemorrhage (aOR 1.91, 1.22–2.98), worsened hemorrhage severity on the Heidelberg scale, reduced the likelihood of excellent functional recovery (aOR 0.70, 0.64–0.77) and shifted the entire mRS distribution toward greater disability (adjusted common OR 1.74, 1.58–1.91). Boston 1.0 and 1.5 “probable”criteria increased the odds of any intracranial hemorrhage (aOR 2.57 and 2.39), whereas Boston 1.5 “possible” criteria were associated with worsened disability (acOR 2.34, 1.30–4.22). Conclusions: In thrombolyzed patients with acute ischemic stroke, CSS burden is strongly and consistently associated with higher risk of severe hemorrhage, disability and death, making it the most actionable CAA marker when weighing thrombolytic risk. Meeting Boston 1.0 or 1.5 “probable” radiologic criteria, increases hemorrhagic risk, but meeting the latest 2.0 criteria does not.