Association between atrial fibrillation and silent cerebral infarctions: a systematic review and meta-analysis

Abstract

Background: Atrial fibrillation (AF) is a common cause of stroke. Silent cerebral infarctions (SCIs) are known to occur in the presence and absence of AF, but the association between these disorders has not been well-defined.

Purpose: To estimate the association between AF and SCIs and the prevalence of SCIs in stroke-free patients with AF.

Data sources: Searches of MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE from inception to 8 May 2014 without language restrictions and manual screening of article references.

Study selection: Observational studies involving adults with AF and no clinical history of stroke or prosthetic valves who reported SCIs.

Data extraction: Study characteristics and study quality were assessed in duplicate.

Data synthesis: Eleven studies including 5317 patients with mean ages from 50.0 to 83.6 years reported on the association between AF and SCIs. Autopsy studies were heterogeneous and low-quality; therefore, they were excluded from the meta-analysis of the risk estimates. When computed tomography (CT) and magnetic resonance imaging (MRI) studies were combined, AF was associated with SCIs in patients with no history of symptomatic stroke (odds ratio, 2.62 [95% CI, 1.81 to 3.80]; I(2) = 32.12%; P for heterogeneity = 0.118). This association was independent of AF type (paroxysmal vs. persistent). The results were not altered significantly when the analysis was restricted to studies that met at least 70% of the maximum possible quality score (odds ratio, 3.06 [CI, 2.24 to 4.19]). Seventeen studies reported the prevalence of SCIs. The overall prevalence of SCI lesions on MRI and CT among patients with AF was 40% and 22%, respectively.

Limitation: Most studies were cross-sectional, and autopsy studies were heterogeneous and not sufficiently sensitive to detect small lesions.

Conclusion: Atrial fibrillation is associated with more than a 2-fold increase in the odds for SCI.

Primary funding source: Deane Institute for Integrative Research in Atrial Fibrillation and Stroke, Massachusetts General Hospital.

Appendix Figure. Summary of evidence search and selection

AF = atrial fibrillation; SCI = silent cerebral infarction. * Once relevant papers were identified through electronic search, their reference lists were manually searched to identify any additional relevant papers. Twenty-nine full-text articles were reviewed from reference lists, and 1 was found to be relevant.

Figure 1. Association between AF and SCIs according to the method of SCI diagnosis in 9 studies

AF = atrial fibrillation; CT = computed tomography; MRI = magnetic resonance imaging; SCI = silent cerebral infarction. *Studies that used an acceptable method to control for ≥5 of the following 6 variables were considered to be at minimal risk of bias: age, sex, hypertension, hyperlipidemia, diabetes mellitus, and presence of significant carotid stenosis. Studies that did not control for ≥2 variables were considered at moderate risk of bias. †For the purpose of this meta-analysis, we used the reported odds ratio for the association between AF and SCI lesions >5 mm. ‡Paroxysmal AF. §Persistent AF.

Figure 2. Prevalence of SCIs in patients with AF according to the method of SCI diagnosis

AF = atrial fibrillation; CT = computed tomography; MRI = magnetic resonance imaging; SCI = silent cerebral infarction.