How do you counsel patients who develop DVT or atrial fibrillation requiring anticoagulation when being treated with lecanemab or donanemab?

I believe until further data/studies are available, I would prefer not to use anticoagulation (at least long term) without comprehensive discussion among other treating physicians depending on the indication. The lecanemab appropriate use recommendations (Cummings et al., PMID 37357276) recommend against the use of anticoagulation in these patients until further data is available. The FDA also recommends caution with concomitant anti-amyloid therapy and anticoagulation (labeling-package insert, ...

Anticoagulation has an increased risk of ARIA H even without the E4 allele. I would not use warfarin but would carefully use apixaban, with counseling about risk.

Previous answer (January 09 2025):

I would be concerned only with patients with E4 homozygous state.