Case Study

Hypertrophic Cardiomyopathy (HCM) in a 17 year old FS cat

The patient has had weight loss of 1-2 pounds in the last month, diminished appetite, and eats about ½ his normal intake. Diagnosis of IRIS stage 2 CRF in May 201 . Current medications include amlodipine 1.25 mg PO SID and just began mirtazapine 3.75 mg PO every other day. There is a history of a grade 3/6 murmur of at least 6 years duration. The patient is asymptomatic for cardiac disease.

BW: Crea 2.5 with no changes in phosphorus and low normal potassium. BUN 33. T4 WNL in May 2015

DX

hypertrophic cardiomyopathy (HCM)

Image Interpretation

There is severe left atrial enlargement. The mitral valve leaflets appears normal, however, mild to moderate mitral regurgitation is present. There is mild symmetrical hypertrophy of the left ventricular walls. The walls appear irregular with regions of hyperechogenicity, suggestive of myocardial fibrosis. Left ventricular systolic function measures within the normal reference range, however, is less than expected in a cat with myocardial hypertrophy. The aorta and aortic valve are normal. Right atrial and right ventricular dimensions are normal. The tricuspid valve is normal. The pulmonary artery and pulmonic valve are normal. Very mild pericardial effusion is present, as is trace pleural effusion. No cardiac masses are seen.
LA – 19.9 mm
LA/Ao – 2.3
IVSd – 6.2 mm
LVIDd – 15.5 mm
LVPWd – 6.6 mm
LVIDs – 9.1 mm
FS – 41%
LVOT Vmax – 1.10 m/s
RVOT Vmax – 1.19 m/s

Outcome

This examination demonstrates hypertrophy of the left ventricular walls, consistent with HCM. The disease is advanced, as there is severe secondary left atrial enlargement, mild left ventricular systolic dysfunction, and possible left ventricular myocardial fibrosis. The radiographs show a mild interstitial infiltrate caudal to the heart in the region of the caudal vena cava that likely represents mild cardiogenic pulmonary edema, and his echocardiogram demonstrates very mild pericardial and trace pleural effusion, all changes consistent with mild congestive heart failure. It is unclear whether the congestive heart failure is naturally occurring, or whether it is secondary to subcutaneous fluid administration.
The concurrent presence of renal disease significantly complicates the prognosis for the patient’s cardiac disease, as therapy for his heart disease may worsen his renal disease and vice versa. Therapy for congestive heart failure is required at this time; however, caution must be used to avoid adversely affecting the kidneys.