Multi-ethnic study of atherosclerosis: association between left atrial function using tissue tracking from cine MR imaging and myocardial fibrosis.

PURPOSE: To investigate the association between left atrial ( LA left atrium ) function and left ventricular myocardial fibrosis using cardiac magnetic resonance (MR) imaging in a multi-ethnic population.
MATERIALS AND METHODS: For this HIPAA-compliant study, the institutional review board at each participating center approved the study protocol, and all participants provided informed consent. Of 2839 participants who had undergone cardiac MR in 2010-2012, 143 participants with myocardial scar determined with late gadolinium enhancement and 286 age-, sex-, and ethnicity-matched control participants were identified. LA left atrium volume, strain, and strain rate were analyzed by using multimodality tissue tracking from cine MR imaging. T1 mapping was applied to assess diffuse myocardial fibrosis. The association between LA left atrium parameters and myocardial fibrosis was evaluated with the Student t test and multivariable regression analysis.
RESULTS: The scar group had significantly higher minimum LA left atrium volume than the control group (mean, 22.0 ± 10.5 [standard deviation] vs 19.0 ± 7.8, P = .002) and lower LA left atrium ejection fraction (45.9 ± 10.7 vs 51.3 ± 8.7, P < .001), maximal LA left atrium strain ( Smax maximum LA strain ) (25.4 ± 10.7 vs 30.6 ± 10.6, P < .001) and maximum LA left atrium strain rate ( SRmax maximum LA strain rate ) (1.08 ± 0.45 vs 1.29 ± 0.51, P < .001), and lower absolute LA left atrium strain rate at early diastolic peak ( SRE LA strain rate at early diastolic peak ) (-0.77 ± 0.42 vs -1.01 ± 0.48, P < .001) and LA left atrium strain rate at atrial contraction peak ( SRA LA strain rate at atrial contraction peak ) (-1.50 ± 0.62 vs -1.78 ± 0.69, P < .001) than the control group. T1 time 12 minutes after contrast material injection was significantly associated with Smax maximum LA strain (β coefficient = 0.043, P = .013), SRmax maximum LA strain rate (β coefficient = 0.0025, P = .001), SRE LA strain rate at early diastolic peak (β coefficient = -0.0016, P = .027), and SRA LA strain rate at atrial contraction peak LA strain rate at atrial contraction peak (β coefficient -0.0028, P = .01) in the regression model. T1 time 25 minutes after contrast material injection was significantly associated with SRmax maximum LA strain rate (β coefficient = 0.0019, P = .016) and SRA LA strain rate at atrial contraction peak (β coefficient = -0.0022, P = .034).
CONCLUSION: Reduced LA left atrium regional and global function are related to both replacement and diffuse myocardial fibrosis processes. Clinical trial registration no.: NCT00005487 © RSNA, 2014 Online supplemental material is available for this article.