The Use of Contrast-Enhanced Echocardiography in the Evaluation of Feline Left Ventricular Wall Thickness

Introduction/Objectives Accurate measurement of feline left ventricular (LV) wall thickness is challenging due to endocardial and myocardial irregularities, false tendons, and prominent papillary muscles. In human medicine, contrast-enhanced echocardiography (C-Echo) is used to improve LV wall delineation and is more accurate, repeatable, and reliable than standard echocardiography (S-Echo). Our objective was to compare C-Echo and S-echo measurements of feline LV wall thickness (LVWT) and determine repeatability, reproducibility, and reliability of each modality. Animals Fifty client-owned cats were prospectively enrolled. Materials and Methods Cats underwent S-Echo and C-Echo after intravenous injection of contrast agent. Methods were compared using Bland-Altman and Passing-Bablok regression. Inter- and intra-operator reproducibility, repeatability, and reliability were quantified using intraclass correlation (ICC), repeatability coefficients (RC), and coefficients of variation (CV). Results Standard echocardiography and C-Echo differed significantly for all segments with a median difference of 0.56 mm (range: –1.4 to 4.9 mm; P < 0.0001). Regression showed proportional bias (slope 1.21, CI 1.11–1.31) with minimal systematic bias (intercept –0.26, CI –0.64 to 0.12). Intra- and inter-operator reproducibility was excellent for both modalities (ICC 0.90–0.94 for S-Echo; 0.86–0.99 for C-Echo), while RCs were lower for C-Echo (0.28–0.61 mm) than S-Echo (0.89–1.03 mm), and CVs were lower for C-Echo (intra-observer 5.86%, inter-observer 3.03%) than S-Echo (7.43% and 7.64%). Limitations Accuracy of S-Echo and C-Echo compared with a reference standard not assessed. Conclusions Contrast-enhanced echocardiography is feasible and provides excellent LV wall visualization with lower LVWT measurements and superior repeatability, reproducibility, and reliability.