Abstract
Large studies focusing on restrictive cardiomyopathy (RCM) in the cat are scarce. The aims of this retrospective study were to describe epidemiological characteristics and to analyse prognostic factors affecting survival in cats with RCM. The clinical archives of the Gran Sasso Veterinary Clinic (Milan, Italy) and of the cardiology unit of the Department of Veterinary Medicine (University of Milan, Italy) from 1997-2015 were reviewed for all cats diagnosed with RCM based on an echocardiographic examination (left atrial/biatrial enlargement, normal left ventricle wall thickness, normal or mildly decreased systolic function and restrictive left ventricle filling pattern with pulsed Doppler echocardiography). The study population comprised 90 cats (53 male, 37 female) with an echocardiographic diagnosis of RCM. Most were domestic shorthairs (n = 60) with a mean ± SD age of 10.0 ± 4.3 years and a median weight of 3.8 kg (interquartile range 3.2-5 kg). Most cats were symptomatic (n = 87). The most common clinical sign was respiratory distress (n = 75). Follow-up was available for 60 cats and the median survival time (MST) was 69 days (95% confidence interval [CI] 0-175 days). Cardiac-related death occurred in 50 cats. In the multivariate Cox analysis only respiratory distress showed a statistically significant effect on survival. The cats without respiratory distress showed an MST of 466 days (95% CI 0-1208); cats with respiratory distress showing an MST of 64 days (95% CI 8-120; P = 0.011). RCM can be considered an end-stage condition associated with a poor prognosis, with few cats not showing clinical signs and surviving >1 year. Most cats died of cardiac disease within a very short time.
Highlights
Restrictive cardiomyopathy (RCM) can be considered an end stage condition associated with a poor prognosis, with few cats not showing clinical signs and surviving longer than a year: most cats died for cardiac disease in a very short time
Follow-up was available on 60 cats and the median survival time (MST) was 69 days
Cardiac-related death occurred in 50 cats (83%), 5 cats were still alive at last follow-up and 5 cats had died from unrelated cardiac causes (3 neoplasia and 2 chronic kidney disease)
Summary
Restrictive cardiomyopathy (RCM) is a myocardial disorder characterized by myocardial stiffness, severe diastolic dysfunction (restrictive physiology) and an overall poor prognosis.[1,2,3,4] It is not clear if some of the RCM cases may be considered the end result of other forms of cardiomyopathy (CM), mainly hypertrophic cardiomyopathy (HCM) and myocarditis.[2,5,6,7,8,9,10] As serial echocardiographic exams are seldom available for review to substantiate changes in the echocardiographic appearance, it is difficult to quantify or identify if different separate etiologies contribute to a common end-stage pattern. RCM is often morphologically sub-classified into two forms: myocardial and endomyocardial.[1] Echocardiography allows classification and is at the moment the most common tool for diagnosis. Both forms of RCM are characterized by atrial enlargement, normal left ventricular (LV) wall thickness, normal or mildly decreased systolic function. Restrictive LV filling pattern with pulsed Doppler echocardiography; in the endomyocardial form, thick hyperechoic tissues bridge the LV lumen.[1,2,3,4,8] Large studies focusing on RCM in the cat are scant.[2,3] The aims of this retrospective study were to describe epidemiological characteristics and to analyze prognostic factors affecting survival in cats with RCM Both forms of RCM are characterized by atrial enlargement, normal left ventricular (LV) wall thickness, normal or mildly decreased systolic function. and restrictive LV filling pattern with pulsed Doppler echocardiography; in the endomyocardial form, thick hyperechoic tissues bridge the LV lumen.[1,2,3,4,8] Large studies focusing on RCM in the cat are scant.[2,3] The aims of this retrospective study were to describe epidemiological characteristics and to analyze prognostic factors affecting survival in cats with RCM
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