Evaluation of myocardial function by strain echocardiography in cats with hypertrophic cardiomyopathy phenotypes

Hypertrophic cardiomyopathy (HCM) is the most common cardiac disease in cats, and early detection of myocardial dysfunction remains challenging using conventional echocardiography alone. This study evaluated myocardial function using two-dimensional speckle-tracking echocardiography and investigated the diagnostic value of left ventricular global longitudinal strain (LVGLS), right ventricular longitudinal strain (RVLS), left atrial reservoir strain (LARS), and strain-volume curve analysis for differentiating HCM phenotypes in cats.

A retrospective observational study was conducted on 40 client-owned cats categorized into three groups: Healthy controls (n = 15), cats with a hypertrophic phenotype and normal left atrial size (n = 13), and cats with a hypertrophic phenotype accompanied by left atrial enlargement (n = 12). Comprehensive echocardiographic examinations included conventional measurements together with LVGLS, RVLS, LARS, circumferential strain, and strain-volume curve analysis. Group comparisons and correlations between strain-derived and conventional echocardiographic parameters were analyzed using appropriate statistical methods, with significance set at p < 0.05.

Cats with HCM and left atrial enlargement exhibited significantly lower LVGLS and LARS than healthy cats, indicating impaired ventricular systolic deformation and reduced atrial reservoir function. RVLS did not differ significantly among groups, suggesting relative preservation of right ventricular systolic function during the early stages of disease. Strain-volume curve analysis demonstrated progressive flattening and rightward displacement in affected cats, reflecting impaired myocardial deformation despite preserved conventional systolic indices such as fractional shortening. Moderate correlations were observed between LVGLS and radial strain, whereas LARS showed inverse correlations with indices of left ventricular hypertrophy. These findings indicate that strain-derived parameters provide complementary functional information beyond conventional echocardiographic measurements.

Multi-chamber strain echocardiography integrating LVGLS, RVLS, LARS, and strain-volume curve analysis provides a comprehensive assessment of myocardial mechanics in cats with HCM. This approach improves characterization of hypertrophic phenotypes, facilitates earlier recognition of myocardial dysfunction, and may enhance disease staging and clinical decision-making in feline cardiology.