C08 - Echocardiographic Evaluation of Aortic Root Size in Cats with Hypertrophic Cardiomyopathy

Background: In addition to left ventricular hypertrophy (LVH), enlargement of the mitral valve is commonly observed in hypertrophic cardiomyopathy (HCM) in cats. Whether aortic root size (ARS) is increased in HCM is unknown. Hypothesis/

Objectives: To determine ARS in cats with HCM and compare ARS to control cats and cats with hyperthyroidism (HT4) and systemic hypertension (SH). We hypothesized that cats with HCM have increased ARS. Animals: 180 client-owned cats.

Methods: Retrospective echocardiographic observational study. Ten two-dimensional echocardiographic variables characterizing ARS were measured (linear dimension of the aortic valve (AV), the sinus of Valsalva (SV), the sinotubular junction (STJ), the ascending aorta (AAo), and the sinus height (SH) in systole and diastole). Results were compared using standard univariate and multivariate statistical tests for group comparison.

Results: 130 cats with HCM, 15 with HT4, and 15 with SH were studied. Univariate analysis revealed a difference (P<.01) between HCM and control only for the STJ measured in diastole and systole (median, 7.44 vs. 7.03 mm and 7.70 vs. 6.90 mm, respectively), the SV in systole (9.99 vs. 9.67 mm), and the AV in systole (7.06 vs. 6.66 mm). However, multivariable analysis only found age (P<.001), body weight (BW, P<.001), and presence of SH (P<.001) but not HCM and HT4 associated with ARS. Conclusions and Clinical Importance: Cats with HCM do not have aortic root enlargement beyond that expected by BW and aging while ARS is consistently increased in cats with SH. These data are helpful differentiating causes of LVH in cats by echocardiography.