Survival and Prognostic Factors in Cats with Restrictice Cardiomyoathy : A Review of 103 Cases

Restrictive cardiomyopathy (RCM), which approximately accounts for 20% of referred feline (CMs), is a primary myocardial disorder characterized by diastolic dysfunction and a poor prognosis. Large studies focusing on RCM in the cat are scant. The aims of this retrospective study were to describe epidemiological characteristics and to analyze prognostic factors affecting survival in cats with RCM. The clinical archives of the Clinica Veterinaria Gran Sasso (Italy) and of the cardiology unit of DIMEVET (University of Milan, Italy) from 1997 to 2015 were reviewed for all cats diagnosed with RCM based on an echocardiographic exam. The diagnosis was based on distinctive echocardiographic phenotype of left atrial/biatrial enlargement, normal left ventricular (LV) wall thickness, and restrictive LV filling pattern with pulsed Doppler echocardiography. Inclusion criteria were any patient with a complete case record and an echocardiographic diagnosis of RCM. Cats diagnosed with another form of cardiomyopathies CMs, with congenital heart disease, with hypertension or hyperthyroidism or those with incomplete case records were excluded. Follow-up status and cause of death were determined by reviewing the medical records or by phone interviews with the owners. One hundred three cats (61 male and 42 female) were included in the study with a mean age of 10 years (SD 4.45) and a median weight of 3.8 kg (IQR 3.2-5 kg); most of the cats were domestic shorthair (67%) or Persians (18%). Almost all cats were showing clinical signs (96%). Dyspnea was the most common clinical sign, being evident in 82.5% of the cats. Dyspnea was attributable to pleural effusion (PE) in 50 cats, pulmonary edema in 22 cats and both in 13 cats. Hind limb paresis or paralysis due to aortic thromboembolism was evident in 14 cats. Follow-up information was available for 67 cats. Median survival time (MST) in cats with RCM was 133 days. A statistically significant different (p=0.004) MST was identified in cats with dyspnea (68 days) and in cats without dyspnea (731 days). Likewise a statistically significant (p=0.004) different MST was identified in cats with PE (68 days) and in cats without PE (186 days). MST of cats with dyspnea/PE is in this study significantly shorter than MST in cats without dyspnea/PE. The present results confirmed that cats with RCM had short survival time (MST 133 days), but worse prognosis should be prospected to the owner in cats with dyspnea or PE. Better prognosis may be prospected only in cats without dyspnea.