Chronic Atrial Fibrillation and Low Cognitive Function
To the Editor:
We read with great interest the article by Kilander et al1 recently published in Stroke. We would like to support their conclusions by presenting data obtained from our clinical experience. We analyzed the relationship between atrial fibrillation and cognitive function in the elderly patients admitted to our Medical Unit for the Acute Care of the Elderly (Poliambulanza Hospital, Brescia, Italy). During the period from November 1997 through July 1998, 600 patients were consecutively admitted. For the aim of the study we excluded 331 patients: those aged <70 years with previous cerebrovascular events (TIA and minor or major stroke); with terminal, wasting diseases or severe metabolic disorders (chronic renal or liver failure, malignant neoplasm, chronic inflammatory or infectious diseases of a severe degree); and those who were demented or with a score of <20 on Folstein’s Mini Mental Status Examination (MMSE).
The remaining 269 patients (mean age, 80.4±5.8 years; 69% W) were stratified according to ECG features into 3 groups: (1) those with sinus rhythm (n=214; 79.5%), (2) those with paroxysmal atrial fibrillation (ie, ≥1 episodes of arrhythmia lasting <48 hours) (n=13; 4.8%), and (3) those with chronic atrial fibrillation (ie, arrhythmia lasting >6 months) (n=42; 15.7%). Cognitive status as assessed by MMSE was found to be significantly different in the 3 groups: group 1, 26.3±2.9; group 2, 25.2±2.5; and group 3, 24.3±2.9 (by ANOVA, F2,266=8.15, P=0.0004). The Table⇓ shows the association of atrial fibrillation with cognitive impairment: patients with sinus rhythm were considered the reference group; patients with an MMSE score of <24 were considered to have cognitive impairment. In analogy to the study of Kilander and colleagues,1 we found a significant association between chronic atrial fibrillation and cognitive impairment (ie, elderly patients with chronic atrial fibrillation had a 3.3-fold higher risk of cognitive impairment than those with sinus rhythm); the association held after controlling for all the confounders associated with cognitive impairment in a crude analysis (age, education, and depression) and for hypertension and diabetes. In conclusion, chronic atrial fibrillation is an independent correlate of low cognitive function. Although the pathogenetic link between chronic atrial fibrillation and cognitive impairment is still unclear, the results obtained by Kilander and colleagues1 and our own observations might support the use of anticoagulant therapy whenever indicated. This might prevent not only major cerebrovascular accidents but also the less obvious clinical outcome of cognitive function loss.
- Copyright © 1999 by American Heart Association
Kilander L, Andren B, Nyman H, Lind L, Boberg M, Lithel H. Atrial fibrillation is an independent determinant of low cognitive function. Stroke.. 1998;29:1816–1820.
We thank Drs Rozzini, Sabatini, and Trabucchi for their response to our article. Interestingly, our finding of a relationship between atrial fibrillation and low cognitive function was replicated in an older population with acute somatic disorders. However, it remains to be established whether a causal relation exists between atrial fibrillation and cognitive impairment, and if so, by which mechanisms. They may be separate phenomena—both indicating general atherosclerosis—or atrial fibrillation may contribute to cognitive impairment by atherothrombotic or hemodynamic mechanisms. Richards and colleaguesR1 have reported that men at risk of cardiovascular disease who received primary preventive treatment with low-dose aspirin and/or warfarin performed better in cognitive tests than the placebo group. It is of great importance to further examine this hypothesis in larger, randomized trials.