Feline Restrictive Cardiomyopathy

Feline restrictive cardiomyopathy refers to that group of primary myocardial disorders that are not typical of feline DCM or feline HCM. Morphologically the heart is characterized by a normal to reduced contractility, no thickening of the interventricular septum or LV free wall, a normal to small left ventricular cavity potentially with a thickened endocardium, and marked atrial enlargement (often bilateral).

The history and physical examination are identical to those of feline HCM. The diagnosis relies on the echocardiographic examination. Doppler echocardiography demonstrates abnormal transmitral flow, classically a restrictive filling pattern. In addition, left atrial enlargement and mitral valve insufficiency are common. These cats are also at risk for thrombus formation and thromboembolic events.

The most effective therapy for this disorder remains unknown. The underlying disorder is that of diastolic dysfunction. ACE inhibitor therapy is used if contractility is reduced. Furosemide is used in the presence of CHF. These patients are at risk for thromboembolic events, hence prophylaxis is warranted.

The prognosis is unknown but generally very poor.