Atrial cardiomyopathy associates preferentially with cortical rather than non-cortical brain infarcts

Background Atrial cardiomyopathy, characterized by structural and electromechanical abnormalities of the left atrium, has been associated with ischemic stroke. However, its relationship with specific brain infarct subtypes remains unclear. Purpose To determine whether markers of atrial cardiomyopathy are independently associated with incident brain infarct subtypes related to a probable embolic aetiology. Methods We studied participants from the Atherosclerosis Risk in Communities (ARIC) Study who attended Visit 5 (2011–2013) and had brain MRI at Visit 5 with at least one follow-up brain MRI through 2025. At Visit 5, the following were assessed: Left atrial (LA) structure and function, using echocardiographic volume and strain parameters, electrocardiographic P-wave parameters, and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Incident infarcts were identified on follow-up brain MRI using standardized ARIC protocols and classified as cortical or non-cortical. Multivariable logistic regression was used to evaluate associations with incident brain infarcts, and Poisson regression was used to assess infarct burden. Results Among 780 participants (mean [SD] age 74 [5] years at Visit 5, 58% women, 27% Black), at least one incident cortical infarct was detected in 78 individuals (10%), 37 of whom had >1 infarct. At least one non-cortical infarct was detected in 158 individuals (20%). In multivariable models adjusted for CHA₂DS₂-VA score, sex, smoking, creatinine and left ventricular ejection fraction, lower LA conduit function (expressed as absolute value) was independently associated with incident cortical infarcts (OR per 1-SD decrease 1.39, 95% CI 1.04-1.89, p=0.03; Figure 1). Each 1-SD decrease in the absolute value of LA conduit strain was associated with a 67% higher expected number of cortical infarcts (incidence rate ratio 1.67, 95% CI 1.22–2.29, p =0.001). LA conduit < 11.0%, a cut-off proposed by a previous ARIC analysis,1 was present in 25% of patients and was associated with a 112% increase in the risk of incident cortical infarcts (OR 2.12, 95% CI 1.30-3.45, p<0.01). Findings were consistent in sensitivity analyses restricted to participants free of prevalent atrial fibrillation. No significant associations were observed for non-cortical infarcts (Figure 1). Conclusions Among multiple markers of atrial cardiomyopathy, impaired LA conduit is associated with MRI-defined brain infarcts with a probable embolic origin and greater infarct burden. These findings support a specific link between atrial cardiomyopathy and cardioembolic brain infarcts.