Comparative evaluation of left atrial size in healthy cats measured by two-dimensional echocardiography and cardiovascular MRI

Objectives This study aimed to assess left atrial (LA) size in healthy cats using cardiovascular MRI (cMRI) and to compare this with LA size assessed by two-dimensional echocardiography. The hypothesis was that cMRI would accurately determine LA size in domestic cats. Methods A prospective comparative study was performed. Six healthy cats were selected for the study. Standard two-dimensional echocardiography was performed with and without general anaesthesia. cMRI was conducted under general anaesthesia. A comprehensive analysis of LA mass and function measurements was performed to determine the consistency and correlation of LA size and function indicators between two-dimensional echocardiography and cMRI. Results Our study found that intraobserver variability for cMRI measurements was lower than that for two-dimensional echocardiography. Compared with cMRI, echocardiography under anaesthesia significantly overestimated maximal LA volume (LAVmax_2D, P <0.01) and significantly underestimated minimal LA volume (LAVmin_2D, P <0.01). The LAVmin measured by two-dimensional echocardiography exhibited the highest consistency (intraclass correlation coefficient = 0.857) and correlation ( R = 0.75, P <0.01) with LAVmin measured by cMRI. The linear regression equation was LAVmin_ cMRI = 0.891 × LAVmin_2D + 0.304. Conclusions and relevance cMRI represents a reproducible method for assessing LA mass in domestic cats. This study underscored the importance of echocardiography in veterinary cardiology, and the LAVmin measured by two-dimensional echocardiography may reflect the true LAVmin.