Echocardiographic assessment of aortic root size in 220 apparently healthy adult cats

The size of the aortic root (ARS) is of clinical relevance particularly in cats with suspected systemic hypertension and in the echocardiographic diagnosis of left atrial (LA) enlargement using the LA dimension to aortic annulus ratio. There are no prospective data on ARS in healthy cats. The study objective was to determine reference values and 95% prediction intervals for two-dimensional (2D) echocardiographic variables of ARS in cats. We hypothesized that ARS in healthy cats is primarily dependent on body weight (BW) and age. Study type was retrospective, cross-sectional, observational, and clinical cohort. 220 apparently healthy client-owned adult cats were enrolled and 2D echocardiograms analyzed. Systolic and diastolic dimensions of the aortic valve, the sinus of Valsalva, the sinotubular junction, the ascending aorta, and sinus height were evaluated. Reference values and 95% prediction intervals were determined using raw data and values after allometric transformation (Y=a x Mb). The effect of BW, sex, breed, and age was determined. Proportionality constants (α) and allometric scaling exponents (b) were computed for all variables and reference values and 95% prediction intervals for the study sample determined. BW and age, but not sex and breed, were independent predictors of ARS. Cats >12 years old had significantly (adjusted P2–6, and >6–12 years old. The effects of BW and age must be considered for decision-making when using echocardiographic ARS variables in clinical practice.