MRI Investigation of the Association of Left Atrial and Left Atrial Appendage Hemodynamics with Silent Brain Infarction.

Background: Left atrial (LA) myopathy is thought to be associated with silent brain infarctions (SBI) through changes in blood flow hemodynamics leading to thrombogenesis. 4D‐flow MRI enables in‐vivo hemodynamic quantification in the left atrium (LA) and LA appendage (LAA). Purpose: To determine whether LA and LAA hemodynamic and volumetric parameters are associated with SBI. Study Type: Prospective observational study. Population: A single‐site cohort of 125 Participants of the multiethnic study of atherosclerosis (MESA), mean age: 72.3 ± 7.2 years, 56 men. Field Strength/Sequence: 1.5T. Cardiac MRI: Cine balanced steady state free precession (bSSFP) and 4D‐flow sequences. Brain MRI: T1‐ and T2‐weighted SE and FLAIR. Assessment: Presence of SBI was determined from brain MRI by neuroradiologists according to routine diagnostic criteria in all participants without a history of stroke based on the MESA database. Minimum and maximum LA volumes and ejection fraction were calculated from bSSFP data. Blood stasis (% of voxels <10 cm/sec) and peak velocity (cm/sec) in the LA and LAA were assessed by a radiologist using an established 4D‐flow workflow. Statistical Tests: Student's t test, Mann–Whitney U test, one‐way ANOVA, chi‐square test. Multivariable stepwise logistic regression with automatic forward and backward selection. Significance level P < 0.05. Results: 26 (20.8%) had at least one SBI. After Bonferroni correction, participants with SBI were significantly older and had significantly lower peak velocities in the LAA. In multivariable analyses, age (per 10‐years) (odds ratio (OR) = 1.99 (95% confidence interval (CI): 1.30–3.04)) and LAA peak velocity (per cm/sec) (OR = 0.87 (95% CI: 0.81–0.93)) were significantly associated with SBI. Conclusion: Older age and lower LAA peak velocity were associated with SBI in multivariable analyses whereas volumetric‐based measures from cardiac MRI or cardiovascular risk factors were not. Cardiac 4D‐flow MRI showed potential to serve as a novel imaging marker for SBI. Level of Evidence: 3 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]