Thromboprophylaxis in atrial fibrillation and association with cognitive decline: systematic review

Abstract

Objective: atrial fibrillation (AF) is associated with dementia. If AF-related cognitive decline is driven by cerebral embolic events, thromboprophylaxis may impact on this. This systematic review assessed the association between cognitive impairment and AF thromboprophylaxis.

Methods: two independent reviewers searched CINAHL, EMBASE, MEDLINE, PsycINFO, Web of Science Core Collection and Cochrane Library from inception until 12 November 2014. Eligible studies compared AF thromboprophylaxis to control with an outcome measure of cognition or dementia. Where data allowed, meta-analyses describing between-group differences in cognitive test scores or rates of incident dementia were performed.

Results: nineteen studies were eligible. For two prospective studies (one randomised controlled trial, RCT) comparing anticoagulation against antiplatelet therapy, change in Mini-Mental Score Examination (MMSE) score from baseline to last follow-up (maximal duration: 5.9 years) suggested a difference favouring anticoagulation (mean difference: 0.90, 95% CI: 0.29-1.51), in keeping with a trend seen in the single RCT (mean difference MMSE: 0.80, 95% CI: -0.07 to 1.67). Pooled odds ratio (OR) suggested no association with incident dementia, comparing anticoagulant to antiplatelet therapy (two studies, OR: 1.23, 95% CI: 0.80-1.91) or no treatment (three studies, OR: 0.89, 95% CI: 0.47-1.69).

Conclusion: our analyses show no definitive evidence of cognitive benefit or harm from anticoagulation. We demonstrated a potential benefit of anticoagulation in comparison to antiplatelet over time. Larger scale studies with longer follow-up are needed to determine the true cognitive impact of AF thromboprophylaxis.

Keywords: anticoagulation; atrial fibrillation; cognitive impairment; dementia; older people; systematic review.