Afib associated with cognitive impairment, dementia regardless of stroke history

Atrial fibrillation (AF) was associated with a higher risk for cognitive impairment and dementia, with or without a history of clinical stroke, a meta-analysis found.

Twenty-one studies were included in the meta-analysis, seven that looked at the association of AF with cognitive impairment or dementia after stroke and 14 that examined the association between AF and cognitive impairment or dementia in a broader population, including patients with or without a history of stroke.

The review appeared in the March 5 Annals of Internal Medicine.

In a combined analysis, AF was significantly associated with cognitive impairment (relative risk [RR], 1.40; 95% CI, 1.19 to 1.64). There was significant heterogeneity among studies, mainly from variability among prospective studies and possibly due to variances in outcome measures. So researchers incorporated a random-effects model and did several sensitivity analyses and found that pooled estimates were virtually the same for prospective and cross-sectional studies. Restricting the analysis to studies of dementia, which is more reliably diagnosed than cognitive impairment, eliminated the significant heterogeneity without changing the pooled estimate substantially (RR, 1.38; 95% CI, 1.22 to 1.56).

Limiting the analysis to the eight studies that defined cognitive impairment as a mini-mental state exam (MMSE) score of 24 or less or cognitive decline as a reduction in MMSE score of 3 points or more did not appreciably change the results (RR, 1.38; 95% CI, 1.11 to 1.71). Investigating subtypes of dementia did not reveal any significant association between AF and Alzheimer's disease (RR, 1.22; 95% CI, 0.96 to 1.56); however, the association was significant for vascular dementia (RR, 1.72; 95% CI, 1.27 to 2.32).

Limiting the analysis to participants without a history of stroke and studies that adjusted for stroke in multivariate analyses did not appreciably affect the primary results (RR, 1.34; 95% CI, 1.13 to 1.58), nor did restricting the analysis to studies that specifically excluded patients with a history of stroke (RR, 1.37; 95% CI, 1.08 to 1.73).

Seven studies reported an association between AF and cognitive impairment or dementia after stroke (RR, 2.70; 95% CI, 1.82 to 4.00). Although prospective and cross-sectional studies showed overlapping risk estimates, the association was stronger in prospective studies (RR, 3.01; 95% CI, 1.96 to 4.61).

The researchers wrote, “On the basis of this systematic review and meta-analysis of all available data, future research should carefully distinguish between types of dementia, and investigators should consider cognitive function as a new outcome to be assessed in interventional studies for the treatment of AF.”