Asymptomatic Hypertrophic Cardiomyopathy: Diagnosis and Therapy.

Hypertrophic cardiomyopathy (HCM) affects 15% of cats, and prevalence increases with age. Although many cats with HCM have normal life expectancy, some cats die suddenly, or develop congestive heart failure or arterial thromboembolism (ATE). High-risk cats can be recognized by left atrial enlargement on echocardiography, which can be missed on physical examination, as a heart murmur is often absent. Alternatively, plasma biomarkers can be measured as an initial screening test; echocardiography is indicated in cats with plasma NT-probrain natriuretic peptide concentrations exceeding 100 pmol/L. High-risk cats should be treated with clopidogrel to reduce the risk of ATE.

Familial cardiomyopathy in Norwegian Forest cats.

Norwegian Forest cats (NFCs) are often listed as a breed predisposed to cardiomyopathy, but the characteristics of cardiomyopathy in this breed have not been described. The aim of this preliminary study was to report the features of NFC cardiomyopathy based on prospective echocardiographic screening of affected family groups; necropsy findings; and open-source breed screening databases. Prospective examination of 53 NFCs revealed no murmur or left ventricular (LV) outflow tract obstruction in any screened cat, though mild LV hypertrophy (defined as diastolic LV wall thickness ≥5.5mm) was present in 13/53 cats (25%). Gross pathology results and histopathological sections were analysed in eight NFCs, six of which had died of a cardiac cause. Myocyte hypertrophy, myofibre disarray and interstitial fibrosis typical of hypertrophic cardiomyopathy were present in 7/8 cats, but endomyocardial fibrosis suggestive of restrictive cardiomyopathy was also present in the same cats. Pedigree data analysis from 871 NFCs was supportive of a familial cardiomyopathy in this breed.