Review Question - QID 107034

This patient's clinical presentation is consistent with cardiac amyloidosis (CA), which is diagnosed by cardiac biopsy.

CA should be suspected in patients presenting with congestive heart failure, concentrically thickened ventricles, and non-elevated blood pressures. Decreased voltage on EKG in the setting of thickened ventricles on echocardiogram further point towards a diagnosis of CA. Patients frequently present with evidence of non-cardiac amyloid deposition, including tingling in the hands and feet (neural deposits) and foamy urine (renal deposits). Treatment is aimed at symptom management (diuretics) and decreasing further amyloid deposition with drugs such as cyclophosphamide and dexamethasone.

Wexler et al. review the approach to cardiomyopathy. They note that, although cardiomyopathies are a diverse group of diseases, treatment is usually aimed at symptom-reduction and decreasing rates of hospitalization. Commonly recommended interventions include decreased alcohol intake, smoking cessation, weight loss, and a low-sodium diet.

Quarta et al. discuss the two types of cardiac amyloidosis. One form, "Amyloid formed from Light Chains Amyloidosis," is caused by plasma cell dysfunction. A second form, transthyretin-related amyloidosis, is caused by a defect in the TTR protein that leads to protein degradation. It is not known why TTR breakdown causes amyloidosis.

Figure A shows an EKG with inappropriately low voltage compared to the corresponding ventricular thickness of echocardiogram. Figure B shows an echocardiogram of a patient with cardiac amyloid; note the concentric thickening of the ventricles. Illustration A shows a cardiac biopsy from a patient with cardiac amyloid. The red, fluffy areas are amyloid deposits stained with congo red.

Incorrect Answers:
Answers 1-3: Stress testing is used to evaluate myocardial perfusion. Although amyloid deposits in cardiac vessels may lead to decreased perfusion, cardiac biopsy is needed for conclusive diagnosis of CA. Exercise stress testing is the most common form of stress testing. Dobutamine stress testing is generally performed when it is not possible for the patient to exercise. Nuclear stress testing is generally performed when a patient has pre-existing EKG abnormalities that make interpretation of new ischemic EKG changes impossible.
Answer 5: Pulmonary function tests are useful for diagnosing asthma, COPD, and other lung diseases. This patient's shortness of breath is cardiac in origin.