Clinical, epidemiological and echocardiographic features and prognostic factors in cats with restrictive cardiomyopathy: A retrospective study of 92 cases (2001-2015).

Abstract

BACKGROUND: Restrictive cardiomyopathy (RCM) is a common primary cardiomyopathy of cats. However, little information is available regarding prognostic variables in large populations of cats with RCM. OBJECTIVES: To characterize the epidemiological, clinical, and echocardiographic features of cats with RCM and to document their survival times and risk factors for cardiac death (CD). ANIMALS: Ninety-two cats with RCM. METHODS: Retrospective study. Diagnosis of RCM was based on echocardiographic and Doppler criteria. Median survival time to CD and adjusted hazard ratios (HR) were estimated by the Kaplan-Meier method and multivariate Cox models, respectively. RESULTS: The feline population (median age [interquartile range], 8.6&#x2009;years [4.1-12.4]; body weight, 4.0&#x2009;kg [3.3-4.7]) included 83 cats (90%) with the myocardial RCM form and 9 (10%) with the endomyocardial fibrosis RCM form. Most RCM cats (64/92, 70%) were symptomatic at the time of diagnosis, with dyspnea related to congestive heart failure in 57 of 64 cats (89%). The median survival time of the 69 cats with the myocardial RCM form and available follow-up was 667&#x2009;days (range, 2-3710&#x2009;days) considering CD. Independent of age, biatrial enlargement, and arrhythmias, increase of the left atrium (LA)-to-aorta (Ao) ratio (hazard ration [HR], 2.5 per 0.5-unit increase; 95% confidence interval [CI], 1.5-4.2; P&#x2009;<&#x2009;.001) and presence of severe LA enlargement (end-diastolic LA : Ao &#x2265;2; HR, 3.4; 95% CI, 1.3-8.7; P&#x2009;=&#x2009;.01) were significantly associated with shorter time to CD. CONCLUSIONS AND CLINICAL IMPORTANCE: Cardiac death is common in RCM cats, and LA enlargement seems independently associated with decreased survival time in these cats.