Time in Therapeutic Range of Anticoagulation Among Patients with Atrial Fibrillation and Cerebral Amyloid Angiopathy

Atrial fibrillation (AF) and cerebral amyloid angiopathy (CAA) present risks of ischemic stroke and intracerebral hemorrhage (ICH). Vitamin K antagonist use is associated with fluctuations in international normalized ratio (INR), which predispose to a higher bleeding risk. Patients with a diagnosis of AF and ICH while on a vitamin K antagonist were identified using the Rochester Epidemiology Project. Sixty patients were identified (mean age 81.3 years; 24 men). Thirty-three (55%) exhibited characteristics consistent with possible (n = 25) or probable (n = 8) CAA. Mean time in therapeutic range in the 30 days preceding ICH was 55.4%, with no difference between CAA and non-CAA patients. Mean time spent above therapeutic range (INR > 3.0) was 17.7%, with no difference between CAA and non-CAA patients. Following ICH, 21 (35%) died within 30 days, with total mortality at 76.7% after 176.4 person-years of follow-up (mean 2.9 years). Time in therapeutic range in the 30 days prior to ICH had no significant impact on 7-day mortality, nor risk of recurrent ICH or ischemic stroke. Patients with warfarin-related ICH were often outside of the therapeutic range within the month preceding hemorrhage but more frequently were subtherapeutic. Even with careful avoidance of supratherapeutic INR, vitamin K antagonist use in CAA patients is unlikely to have a major effect in preventing ICH and must be used with caution.