Dementia in patients with atrial fibrillation and the value of the Hachinski ischemic score

AIM: To assess the prevalence of vascular dementia, mixed dementia andAlzheimer's disease in patients with atrial fibrillation, and to evaluate theaccuracy of the Hachinski ischemic score for these subtypes of dementia.METHODS: A nested case-control study was carried out. A total of 103 of 784consecutive patients evaluated for cognitive status at the Ambulatory GeriatricClinic had a diagnosis of atrial fibrillation. Controls without atrialfibrillation were randomly selected from the remaining 681 patients using a 1:2matching for sex, age and education.RESULTS: The prevalence of vascular dementia was twofold in patients with atrial fibrillation compared with controls (21.4% vs 10.7%, P = 0.024). Alzheimer'sdisease was also more frequent in the group with atrial fibrillation (12.6% vs7.3%, P = 0.046), whereas mixed dementia had a similar distribution. TheHachinski ischemic score poorly discriminated between dementia subtypes, withmisclassification rates between 46% (95% CI 28-66) and 70% (95% CI 55-83). Inpatients with atrial fibrillation, these rates ranged from 55% (95% CI 32-77) to 69% (95% CI 39-91%). In patients in whom the diagnosis of dementia was excluded, the Hachinski ischemic score suggested the presence of vascular dementia in 11%and mixed dementia in 30%.CONCLUSIONS: Vascular dementia and Alzheimer's disease, but not mixed dementia,are more prevalent in patients with atrial fibrillation. The discriminativeaccuracy of the Hachinski ischemic score for dementia subtypes in atrialfibrillation is poor, with a significant proportion of misclassifications.