Diagnostic accuracy of electrocardiography and thoracic radiography in the assessment of left atrial size in cats: Comparison with transthoracic 2-dimensional echocardiography

Abstract

Background: Left atrial (LA) enlargement (LAE) is a morphologic expression of the severity and chronicity of left ventricular (LV) diastolic dysfunction, volume overload, and increased atrial pressure and has diagnostic, therapeutic, and prognostic importance in cats. The noninvasive gold standard for assessing LA size is 2-dimensional echocardiography (2DE). Hypothesis: ECG and thoracic radiography may be used to predict LAE in cats. Animals: Twenty-one healthy control cats and 31 cats with cardiomyopathy were prospectively studied. Methods: 2DE studies, including determination of the maximum LA dimension (LAD) and area (LAA), were performed prospectively in all cats and compared to the assessment of LA size based on thoracic radiography and indices obtained from a 6-lead ECG. Results obtained from healthy cats were used to generate discrimination limits suggestive of LAE as defined by LAD > 1.57 cm and LAA > 2.75 cm 2. Results: In cats with LAE, P wave duration and PR interval were prolonged and radiographic LA vertebral heart size (LA-VHS) was increased (P < .001). Conclusion and Clinical Importance: ECG and thoracic radiography are reasonably specific but less sensitive predictors of LAE in cats. Copyright © 2007 by the American College of Veterinary Internal Medicine.