Evaluation of left atrial reservoir function and sphericity index in patients with mitral valve disease: a cardiac magnetic resonance imaging study

To assess the performance of biplane area-length method in measuring left atrial (LA) volume and sphericity index and to investigate the correlation of LA reservoir function and sphericity index with atrial fibrosis on cardiac magnetic resonance imaging (MRI) in patients with mitral valve disease (MVD). Forty-eight patients with MVD undergoing cardiac MRI scan were enrolled in this retrospective study. LA reservoir function, measured as maximum volume (LAV_max), minimum volume (LAV_min) and ejection fraction (LAEF), and sphericity index were quantified using the biplane area-length method and standard short-axis approach, respectively. Comparisons of LA reservoir function and sphericity index between the two different methods were performed, as well as between positive (n = 17, 35%) and negative atrial wall fibrosis groups (n = 31, 65%). There was no difference in the values of LAV_max index and sphericity index between the two different methods. The biplane area-length method had poor performance in assessing LAV_min index and LAEF compared to standard short-axis approach, with an underestimation of 13.5% for LAV_min index and an overestimation of 27% for LAEF. Patients with positive atrial fibrosis had larger LAV_max index, LAV_min index and sphericity index, and lower LAEF levels in comparison to the negative atrial fibrosis group. The biplane area-length method has good performance in assessing LA sphericity index for patients with MVD, not in LA reservoir function. Patients with positive atrial fibrosis tend to suffer from more adverse LA remodelling.