Introduction

• Endomyocardial disorders involve the endocardium and the underlying myocardium to varying extents.
• The disorders are poorly characterized and may, in some cases, represent variations of a single etiology.
• Feline endomyocardial diseases include: unclassified cardiomyopathy, restrictive cardiomyopathy  Heart: restrictive cardiomyopathy, excess moderator band cardiomyopathy, endocardial fibroelastosis, and non-septic endomyocarditis Heart: myocarditis. 

Pathogenesis

Etiology

• Etiology of endomyocardial diseases in cats is unknown.  The early onset of some of the cardiomyopathies suggests a congenital disorder Congenital heart disease: overview, but the range of ages at presentation (8 months to 19 years in 1 study) argues against this.
• Endomyocarditis is thought to be an acquired inflammatory disorder, but no cause has been identified.

Pathophysiology

• Thickening of the endocardium and myocardium by deposition of fibrous tissues results in marked loss of ventricular compliance.  In most cases, only the left ventricle is involved.  The decreased compliance produces diastolic dysfunction, leading to congestive heart failure Heart: congestive heart failure.

Timecourse

• The subclinical onset of the disease is generally undetected.  Thus, the duration of the disease, and the nature of disease progression is unknown. Once congestive heart failure develops, prognosis is generally poor.  Unclassified cardiomyopathy often fails to respond well to standard therapy.

Diagnosis

Treatment

Outcomes