Correlation between left ventricular hypertrophy, myocardial fibrosis, and left atrial function in non-obstructive hypertrophic cardiomyopathy: insights from CMR-FT imaging.

Nonobstructive hypertrophic cardiomyopathy (NOHCM) is associated with left ventricular (LV) hypertrophy and myocardial fibrosis, which progressively impair left atrial (LA) function. This study evaluated the impact of LV hypertrophy and fibrosis on LA dysfunction using cardiac magnetic resonance (CMR) imaging and feature-tracking (FT) strain analysis in 99 NOHCM patients, who were stratified into four groups based on the extent of late gadolinium enhancement (LGE): no fibrosis (LGE < 7%), mild fibrosis (7% ≤ LGE < 15%), moderate fibrosis (15% ≤ LGE < 30%), and severe fibrosis (LGE ≥ 30%). LA functional parameters, including reservoir strain (εs), conduit strain (εe), and pump strain (εa), showed significant reductions with increasing LGE burden (P < 0.05), with functional decline detectable even in mild fibrosis cases despite preserved LV ejection fraction. LV morphological and functional indices, such as global peak wall thickness (GPWT), LV end-systolic volume (LVESV), and LGE percentage, negatively correlated with LA strain metrics (r = -0.2 to -0.7, P < 0.05). Strain analysis demonstrated high reproducibility (ICC > 0.75). These findings highlight the clinical significance of CMR-FT as a sensitive and reliable tool for early detection of LA dysfunction in NOHCM patients, even before significant LV structural changes occur. The ability of CMR-FT to identify subtle changes in LA mechanics could provide valuable insights for risk stratification and guide early intervention strategies, ultimately improving clinical outcomes in this patient population.