Association of left atrial function with vascular brain injury: The Atherosclerosis Risk in Communities study.

Background and purpose: Lower left atrial (LA) function is associated with higher dementia risk and may be mechanistically linked through vascular brain injury, an established correlate for higher dementia risk. Using data from the Atherosclerosis Risk in Communities study, we assessed the cross-sectional association between LA function and brain magnetic resonance imaging (MRI) markers of vascular brain injury.

Methods: We included 1488 participants who were free of prevalent dementia, stroke, or atrial fibrillation and who underwent a two-dimensional echocardiogram and brain MRI in 2011-2013 (mean [± standard deviation] age 76 [± 5] years, 60% female, 27% Black). LA function measures (reservoir, conduit, contractile strain) were assessed in quartiles. Brain MRI measures included cerebral microbleeds, brain infarcts, and white matter hyperintensity (WMH) volume. Logistic regression was used for dichotomous outcomes. Linear regression was used for WMH volume.

Results: Overall, 343 (23%) and 344 participants (23%) had ≥1 cerebral microbleed or brain infarct. After multivariable adjustments, the lowest LA reservoir and conduit strain quartiles (vs. highest quartile) were associated with higher odds of the presence of ≥1 cerebral microbleed (odds ratios [95% confidence intervals] 1.78 [1.42-2.22] and 1.52 [1.22-1.90]). Compared to the highest quartile, participants in the lowest LA conduit strain quartile had 1.51 (95% confidence interval 1.22-1.88) times higher odds of having ≥1 brain infarct. Lower LA contractile strain was associated with lower odds of brain infarcts. No association with WMH volume was noted.

Conclusions: We found that LA reservoir and conduit strain were associated with cerebral microbleeds and brain infarcts. Lower LA function may be linked to dementia risk via vascular brain injury. Prospective studies are needed to confirm these findings.