Case Study

Restrictive Cardiomyopathy vs Dilated Cardiomyopathy in an 11 year old MN Devon Rex cat

The patient presented on 6/22/15 with lethargy and diarrhea. Radiographs showed pleural fissure lines and scalloping lung margins, and a possible mass in the left thorax. Thoracocentesis performed 6/23/15. 100ml of pink, opaque fluid was aspirated. SG of the fluid was 1.026 and protein 4g/100ml.

Physical exam revealed a gallop rhythm, respiratory rate 60 and increased respiratory effort.

Image Interpretation

There is severe left atrial enlargement. Left auricular function is depressed and there is spontaneous echo contrast seen within the auricular body. The mitral valve appears normal, though mild mitral regurgitation is present. Left ventricular wall thickness is normal. There is mild left ventricular dilation. Left ventricular systolic function is moderately depressed. Left ventricular diastolic function is difficult to assess due to fusion of transmitral E and A waves, though the maximum velocity of the combined waves (> 1 m/s) suggests elevated left-sided filling pressure. The aorta and aortic valve are normal. There is severe right atrial dilation. The tricuspid valve appears normal, though mild tricuspid regurgitation is present. TR velocity does not suggest the presence of pulmonary hypertension. There is severe right ventricular dilation. The pulmonary artery and pulmonic valve are normal. Trace pericardial effusion is present. Mild pleural effusion can be seen. No cardiac masses are evident.
LA/Ao – 2.4
IVSd – 3.7 mm
LVIDd – 16.0 mm
LVPWd – 3.0 mm
LVIDs – 12.8 mm
FS – 21.8%
LVOT Vmax – 0.7 m/s
RVOT Vmax – 0.7 m/s
TR – 2.5 m/s

DX

Severe biatrial dilation, severe right ventricular dilation, mild left ventricular dilation, moderate global myocardial dysfunction – r/o restrictive cardiomyopathy vs. dilated cardiomyopathy (primary vs. taurine-deficient).

Outcome

While I think that this is unlikely to be taurine deficiency cardiomyopathy, I think it would be a good idea to obtain a plasma taurine level (submit to UC Davis) and supplement with taurine (250 mg BID pending the blood level), as this is a potentially reversible disease if present.
Recommendeded cardiac therapy includes Lasix (1-2 mg/kg BID), enalapril (0.25 mg/kg BID), pimobendan (0.25 mg/kg BID), and clopidogrel (1/4 of 75 mg tab SID). A recheck radiograph and renal profile are recommended in 5-7 days.

Comments

This examination demonstrates severe cardiac disease. The presence of severe biatrial enlargement suggests restrictive cardiomyopathy; however, the moderately depressed global systolic function is more suggestive of dilated cardiomyopathy. It’s likely that the patient was originally affected by restrictive cardiomyopathy which has now progressed to late stage disease with secondary myocardial dysfunction. While I can’t comment on the presence of a mass in the thorax, as I have not seen the radiographs, it is clear based on this exam that the pleural effusion is secondary to congestive heart failure, and it’s possible that the area suspicious for a mass is actually consolidated lung secondary to cardiac decompensation. In addition to recurrence of CHF, there is high risk for the development of a cardiogenic thrombus, as there is decreased left atrial function and spontaneous contrast consistent with developing thrombus formation in the left auricle. Unfortunately, given how advanced the disease is, long term prognosis is likely poor.