Performance of Different Echocardiographic Measurements of Left Atrial Size in Dogs by Observers with Different Levels of Experience

SIMPLE SUMMARY: Assessing enlargement of the left atrium (one of the four cardiac chambers) is extremely important for gaining information about dogs’ heart disease, their prognosis, and directing treatment. However, people with different levels of experience may be required to make this assessment, and we don’t know how observers with different experiences perform in making this assessment. In this study, five observers with different levels of experience evaluated the left atrium of 36 dogs in a blinded fashion (i.e., unaware of each other measurements, or of the identity of the dog), compared to two cardiologists. We then used statistical analysis to evaluate repeatability, reproducibility, accuracy of the measurements, and the capacity of correctly identifying left atrial enlargement. We found that the measurements performed by observers with more experience where more similar to the cardiologists’ measurements, and that combining more than one technique for measuring the left atrium can improve accuracy of the identification of left atrial enlargement. ABSTRACT: Assessment of left atrial (LA) sizes in dogs informs clinical staging, risk assessment, treatment decisions, and prognosis. The objective of this study was to assess the diagnostic performance of observers with different levels of experience measuring the LA with three different techniques. Echocardiographic images from 36 dogs with different degrees of left atrial enlargement (LAE) were retrospectively retrieved, anonymized and measured in a blinded fashion by a veterinary student, a first-year cardiology resident, a third-year cardiology resident, and two board-certified veterinary cardiologists. The LA to aortic root ratio (LA:Ao), LA antero-postero diameter indexed to body weight (LAiAPD) and left atrial area were measured. Inter- and intra-observer intraclass correlation coefficients (ICCs) were calculated for all three variables. Bland–Altman plots and accuracy in identification of LAE were calculated for the three least experienced observers using LA:Ao and LAiAPD. Intra- and interobserver ICCs were greater than 0.9 for every variable. The observer with least experience had significant positive bias and a tendency to overestimate larger measurements using LA:Ao, but not using LAiAPD. The accuracy of identification of LAE also increased with the increasing level of experience and was higher for LAiAPD compared to LA:Ao. Combining both methods for identification of LAE, further increased accuracy.