To study antiplatelet use for prevention of ischemic stroke in patients with cerebral amyloid angiopathy.

Patients with cerebral amyloid angiopathy (CAA) and concurrent ischemic stroke (IS) presents a therapeutic challenge on the use of antiplatelet agent. The risk and benefit of antiplatelet agents for stroke prevention in these patients is not well described.

We conducted a prospective, observational study of patients with probable or definitive CAA consistent with modified Boston criteria on either aspirin 81mg-325mg daily or no aspirin seen at a single academic center from 2011 to 2018, and followed until 2020 for incident IS and intracranial hemorrhage (ICH). Those with a history of cardiopulmonary bypass procedures, inflammatory CAA, major brain surgery or radiation, coagulopathy (defined as INR>1.5, platelet<50K), and use of anticoagulants were excluded. Paired 2-tailed t-tests were performed with statistical significance being p<0.05.

We identified 152 patients with CAA. After exclusion criteria, 38 patients were included in the cohort. Mean age was 74 years old, 32% were female, 39% were on aspirin. Over a mean follow-up of 2.7 years, 13 IS and 17 ICH occurred. Incidence of IS was 27% vs 36% in patients on vs off aspirin, respectively with relative risk (RR) 0.74 (95% CI 0.276-1.991, p=0.55). Incidence of ICH was 20% vs 50% in patients on vs off aspirin, respectively with RR 0.40 (95% CI 0.136-1.174, p=0.096) though less patients with ICH on aspirin vs off aspirin had superficial siderosis (79% vs 88%) and a history of ICH (50% vs 67%).

We observed that aspirin lowers the risk of ischemic stroke without increasing the risk of ICH in patients with CAA, though the study did not achieve statistical significance. Our study is limited by small sample size and observational design; a larger multicenter study with more expanded time window is ongoing.