Diagnosis

A definitive diagnosis is possible with echocardiography (a dilated, relatively thin-walled left ventricle with reduced contractility).

Among acquired feline heart disorders, dilated cardiomyopathy and hypertrophic cardiomyopathy used to be the most common disorders, and the diagnostic challenge was to distinguish between these two forms of cardiomyopathy. Since the introduction of routine supplementation of taurine to the feline commercial diets, dilated cardiomyopathy has become a rare disorder. Thus, the hypertrophic (concentric hypertrophy) form is the most common type of cardiomyopathy presently occurring in the cat.

Other potentially useful diagnostic aids:

a) Radiology:

• Pleural effusion is often present and obscures the cardiac silhouette
• A diffusely enlarged, rounded heart is often noted. However the sensitivity and specificity of this finding are relatively low (especially specificity) in that many cases of hypertrophic cardiomyopathy can show this type of radiographic picture
• Typical findings of congestive heart failure may be present (see the Thoracic Radiography Tutorial)

b) Electrocardiography: may reveal

• A normal ECG
• Tall R waves in lead II
• Ventricular ectopy

c) Blood Work: may reveal

• Evidence of reduced cardiac output as discussed in the Bloodwork Clinical Evaluation of Heart Disease section
• Serum taurine levels may be low
• Muscle enzyme elevation if thromboembolism occurs
• Troponin I is likely elevated
• NT-proBNP is likely elevated