The use of contrast-enhanced echocardiography in the evaluation of feline left ventricular wall thickness.

INTRODUCTION/

OBJECTIVES

Accurate measurement of feline left ventricular wall thickness (LVWT) 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 left ventricular 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 LVWT and determine repeatability, reproducibility, and reliability of each modality.

ANIMALS, MATERIALS AND

METHODS

Fifty client-owned cats were prospectively enrolled in the study. Cats underwent S-Echo and C-Echo after intravenous injection of contrast agent. Methods were compared using Bland-Altman and Passing-Bablok regression. Interoperator and intra-operator reproducibility, repeatability, and reliability were quantified using intraclass correlation coefficients, repeatability coefficients, and coefficients of variation.

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, confidence interval: 1.11-1.31) with minimal systematic bias (intercept: -0.26, confidence interval: -0.64 to 0.12). Intra-operator and interoperator reproducibility was excellent for both modalities (intraclass correlation coefficient: 0.90-0.94 for S-Echo; 0.86-0.99 for C-Echo), while repeatability coefficients were lower for C-Echo (0.28-0.61 mm) than for S-Echo (0.89-1.03 mm), and coefficients of variation were lower for C-Echo (intra-observer: 5.86%, inter-observer: 3.03%) than for S-Echo (7.43% and 7.64%).

STUDY LIMITATIONS: Accuracy of S-Echo and C-Echo compared with a reference standard was not assessed.

CONCLUSIONS

Contrast-enhanced echocardiography is feasible and provides excellent left ventricular wall visualization with lower LVWT measurements and superior repeatability, reproducibility, and reliability.