Feline Cardiomyopathy Study Guide

Overview and Clinical Importance

Feline cardiomyopathies represent the most common form of acquired heart disease in cats, affecting approximately 1 in 7 cats (approximately 15%) in the general population. These primary myocardial disorders cause structural and functional abnormalities of the heart muscle, leading to congestive heart failure (CHF), arterial thromboembolism (ATE), and sudden death. Understanding the classification, diagnosis, and management of feline cardiomyopathies is essential for NAVLE success and clinical practice.

Cardiomyopathies are classified by phenotype (structural and functional characteristics) rather than etiology, as the underlying cause remains unknown in most cases. The ACVIM Consensus Statement (2020) provides the current classification framework used in clinical practice and board examinations.

Classification of Feline Cardiomyopathies

Feline cardiomyopathies are classified based on echocardiographic phenotype. The primary phenotypic categories include hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). HCM accounts for approximately 60% of cases, while RCM and nonspecific cardiomyopathy (NCM) comprise 20-30%. DCM and ARVC are rare.