Evaluation of left atrial and atrioventricular function in enhanced rat HFpEF models

The assessment of left atrial (LA) function in heart failure with preserved ejection fraction (HFpEF) rat models remains suboptimal, limiting its clinical translation. This study aims to evaluate LA strain and atrioventricular function in HFpEF model using speckle-tracking echocardiography (STE) with an optimized imaging approach.

A dual-hit model (high-fat diet + Nω-nitro-L-arginine methyl ester, HD+NAME) and high salt-sensitive induced HFpEF model (Dahl/SS) were established to comprehensively evaluate LA and atrioventricular function using STE. An approach involving modified LA imaging view and dedicated LA analysis software was applied to assess LA function.The general parameter,layer-specific strain,E/e’/LASr ratio( left atrial stiffness index, LASI) and E/early diastolic circumferential strain rate(CSRe) ratio were compared between groups. Additionally, the correlation between atrioventricular compliance parameters and exercise endurance, atrial histopathological changes were performed. Compared to the control group, HFpEF rats in the Dahl/SS group and the HD+NAME group exhibited left ventricular (LV) remodeling and diastolic dysfunction. LA reservoir strain was significantly reduced(P＜0.05), while conduit strain showed no significant difference(P＞0.05). Endocardial circumferential strain was significantly decreased in the HFpEF groups(P＜0.05),while the LASI ,E/CSRe were markedly higher in the HD+NAME group.Histological analysis revealed significant cardiomyocyte hypertrophy and fibrosis in the LA tissue. LASr,CSRe,LASI and E/CSRe were significantly correlated with left atrial histopathological remolding.

The modified LA view combined with STE provides an effective and comprehensive assessment of LA and atrioventricular compliance functions, which closely correlate with histopathological remodeling of the atrium.