Cardiac MRI-based strain analysis for the assessment of left atrial dysfunction in patients with atrial fibrillation.

Atrial fibrillation (AF) involves changes in atrial myocardium and early left atrial (LA) dysfunction, which are difficult to identify using conventional static measurements. This study aimed to investigate the value of cardiac magnetic resonance feature tracking (CMR-FT) derived LA strain parameters for assessing LA dysfunction in AF patients and to identify sensitive indicators for early detection of impaired LA function.This retrospective study included 113 AF patients and 52 age- and sex-matched healthy controls. LA structural (LAD, LAVI) and functional parameters (LAEF, εs, εe, εa) were measured. AF patients were divided into AF1 (abnormal LAVI/LAEF, n = 92) and AF2 (normal LAVI/LAEF, n = 21). Group comparisons, correlation analysis, ROC analysis, and univariate and multivariate logistic regression analyses were performed.AF patients showed significantly increased LAD and LAVI, decreased LAEF, and impaired LA strain (all P < 0.001). Even in the AF2 subgroup with normal LAVI/LAEF, LA strain remained significantly impaired (all P < 0.001). LA strain was positively correlated with LVEF and LAEF, and negatively correlated with LAD and LAVI (all P < 0.001). εs showed the strongest correlation with total LAEF (r = 0.902). ROC analysis showed high efficacy for identifying LA dysfunction (AUC > 0.80), with εs achieving the highest AUC (0.917).CMR-FT enables non-invasive quantitative assessment of LA function. LA strain is more sensitive than conventional static parameters for detecting established LA dysfunction in AF patients, although patients already exhibited structural remodeling and reduced LVEF. The small AF2 subgroup limits the robustness of early-detection claims. εs is a promising imaging biomarker for assessing LA dysfunction.