Background: Patients with atrial fibrillation usually are elderly and may have cognitive dysfunction. These patients may receive less effective oral anticoagulation, resulting in more vascular events and bleeding.
Methods and results: In an analysis of cognitive function associated with the time in therapeutic range (TTR) in the Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events, 2510 patients (mean age, 71+/-9.5 years) from 27 countries completed the Mini-Mental State Examination (MMSE). Of these patients, 171 (6.8%) had an MMSE score <24, suggesting dementia, and 194 (7.7%) had intermediate scores of 24 to 25. Low MMSE scores were correlated with a low TTR. Even mild cognitive impairment was associated with a TTR below the median (<65%). Patients with an MMSE score <26 had more vascular events (6.7% versus 3.6% per 100 patient-years; P=0.002) and more bleeding (9.6% versus 7% per 100 patient-years; P=0.04). After controlling for TTR, the MMSE no longer conferred increased risk, suggesting that if improved anticoagulation was provided, vascular events and bleeding would be reduced. Other independent factors associated with a TTR <65% were region of the world, recent initiation of vitamin K antagonist, type of anticoagulant, and concurrent use of amiodarone or insulin. After adjustment for these factors, lower MMSE scores still predicted a reduced TTR.
Conclusions: Cognitive dysfunction is common in elderly patients with atrial fibrillation and is related to less effective anticoagulation and more vascular events. The MMSE identifies patients with atrial fibrillation in whom extra efforts are needed to maintain effective anticoagulation and improve outcomes. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00243178.