Prevalence of Cardiomyopathy in Apparently Healthy Cats

Subclinical cardiomyopathy (CM) sometimes is identified after abnormalities are detected during auscultation of apparently healthy cats. Little is known regarding the prevalence of CM in this population. Furthermore, the clinical importance of auscultatory abnormalities in apparently healthy cats is unclear. In order to estimate the prevalence of murmurs and CM, we prospectively evaluated a sample of apparently healthy cats. Cats with systemic hypertension or hyperthyroidism were excluded. 103 cats were subject to physical and echocardiographic examinations which were performed by two different investigators; the echocardiographer was unaware of the physical findings. Left ventricular wall thickness was determined by two-dimensional echocardiography in short- and long-axis planes. Left ventricular hypertrophy (LVH) was defined as an end-diastolic wall thickness greater than or equal to 6 mm. Cats with LVH but without left ventricular dilation were considered to have hypertrophic CM (HCM). Cardiomyopathy was identified in 16 cats (15.5%; 95% CI: [9.2, 24.0]); 15 had HCM and one had arrythmogenic right ventricular cardiomyopathy. Murmurs were detected in 16 cats (15.5%; 95% CI: [9.2; 24.0]); of these cats, 5 had CM. Of 15 cats with HCM, 11 had segmental LVH, three cats had diffuse LVH, and one cat had borderline LVH and marked systolic anterior motion of the mitral valve. The sensitivity and specificity of murmurs for detection of a CM was 31% and 87%, respectively. The prevalence of feline subclinical CM in Southwest Virginia is near 16%; approximately a third of these cats had murmurs. In apparently healthy cats, a cardiac murmur is an insensitive marker of the presence of CM.