Anti-amyloid treatment in Alzheimer disease: updated implications for patients with cerebral amyloid angiopathy and other cerebrovascular conditions.

Anti-amyloid treatment (AAT) with monoclonal antibodies represents a major therapeutic advance in early Alzheimer disease (AD), but its introduction has important and underappreciated implications for vascular neurology. Because many patients with AD also have cerebral amyloid angiopathy and other cerebrovascular pathology, AAT influences stroke diagnosis, acute reperfusion therapy, and long-term antithrombotic management. Clinical trials of lecanemab and donanemab enrolled highly selected patients with minimal baseline cerebrovascular pathology, limiting generalizability to real-world populations with prevalent vascular comorbidity. Amyloid-related imaging abnormalities, particularly vasogenic edema and microhemorrhages, constitute a central safety concern and may clinically mimic acute ischemic stroke, complicating emergency decision-making and increasing the risk of inappropriate intravenous thrombolysis (IVT). Emerging reports of intracerebral hemorrhage following IVT in treated patients underscore the need for revised acute stroke pathways and support consideration of mechanical thrombectomy when otherwise indicated, although AAT-specific safety data are lacking. Beyond the hyperacute phase of stroke, concomitant use of anticoagulants or dual antiplatelet therapy raises unresolved questions regarding hemorrhagic risk, particularly in patients with atrial fibrillation or those requiring complex antithrombotic regimens. Alternative strategies, including left atrial appendage closure, may be considered in selected patients, although evidence in AAT recipients remains limited. As AAT enters routine practice, multidisciplinary collaboration, dedicated imaging protocols, and prospective safety registries will be essential to integrate disease-modifying AD treatment with safe and effective cerebrovascular care.