Probable lecanemab-associated pontine hemorrhage following cardiovascular intervention: Clinical implications for lecanemab use

We report a 76-year-old patient with mild cognitive impairment and APOE ε3/ε3 genotype who developed a rare pontine hemorrhage following treatment with lecanemab, an anti-amyloid-β monoclonal antibody for Alzheimer's disease. She was initially on clopidogrel and rivaroxaban; rivaroxaban was discontinued prior to lecanemab initiation. After two infusions, lecanemab was paused due to angina. She then underwent coronary stenting and was placed on dual antiplatelet therapy (aspirin and clopidogrel). Pontine hemorrhage occurred after twenty days. This case highlights heightened bleeding risk when lecanemab is combined with intensified antithrombotic therapy, even without APOE ε4 or significant cerebral small vessel disease load.