Quantification of Left Atrial Size and Function in Cardiac MR in Correlation to Non-Gated MR and Cardiovascular Risk Factors in Subjects without Cardiovascular Disease: A Population-Based Cohort Study

Background: In magnetic resonance imaging (MRI), the comparability of gated and non-gated measurements of the left atrial (LA) area and function and their association with cardiovascular risk factors have not been firmly established. Methods: 3-Tesla MRIs were performed on 400 subjects enrolled in the KORA (Cooperative Health Research in the Augsburg Region) MRI study. The LA maximum and minimum sizes were segmented in gated CINE four-chamber sequences (LA(max) and LA(min)) and non-gated T1 VIBE-Dixon (NGLA). The area-based LA function was defined as LAaf = (LA(max) − LA(min))/LA(max). Inter-and intra-reader reliability tests were performed (n = 31). Linear regression analyses were conducted to link LA size and function with cardiovascular risk factors. Results: Data from 378 subjects were included in the analysis (mean age: 56.3 years, 57.7 % male). The measurements were highly reproducible (all intraclass correlation coefficients ≥ 0.98). The average LA(max) was 19.6 ± 4.5 cm(2), LA(min) 11.9 ± 3.5 cm(2), NGLA 16.8 ± 4 cm(2) and LAaf 40 ± 9%. In regression analysis, hypertension was significantly associated with larger gated LA(max) (β = 1.30), LA(min) (β = 1.07), and non-gated NGLA (β = 0.94, all p ≤ 0.037). Increasing age was inversely associated with LAaf (β = −1.93, p < 0.001). Conclusion: LA enlargement, as measured in gated and non-gated CMR is associated with hypertension, while the area-based LA function decreases with age.