Amyloid Deposition and Infiltrative Cardiomyopathy

A 63-year-old African American man presented with orthopnea and pedal edema that had worsened during the past 4 months. Macroglossia was noted.

The ECG showed loss of anterior forces and low voltage; echocardiography revealed infiltrative cardiomyopathy. Eosinophilic, fibrous tissue was noted on a biopsy of material from the tongue (A); bone marrow examination (B) demonstrated 5% plasma cells.

Dr Muhammad Wasif Saif of the National Cancer Institute, Bethesda, Md, writes that primary amyloidosis is a clonal disorder of plasma cells that may be associated with multiple myeloma. Amyloidosis is more common in white men; multiple myeloma more frequently affects black men. This patient did not have multiple myeloma; his laboratory test results, including electrophoresis and erythrocyte sedimentation rate, were within normal limits.

Cardiac involvement occurs in 25% of patients with primary amyloidosis. The disease presents as either congestive heart failure or conduction abnormalities and is fatal in nearly 50% of patients.¹

It is often difficult to differentiate between infiltrative cardiomyopathy secondary to amyloid deposition and ischemic cardiomyopathy. Other conditions in the differential include restrictive or hypertrophic cardiomyopathy, constrictive pericarditis, and valvular heart disease.

Immunoelectrophoresis of the serum and urine and echocardiography can assist in the diagnosis. In persons older than 50 years, a finding of cardiac infiltration is virtually pathognomonic for amyloidosis. Amyloid fibrils (particularly transthyretin) infiltrate the myocardium and impair ventricular contraction and relaxation.

Treatment of amyloidosis includes melphalan and prednisone; diuretics provide supportive therapy for cardiac involvement. Digitalis, which has been associated with sudden fatal arrhythmia, is contraindicated as are calcium channel blockers because of their association with significant negative inotropic effects. Amyloid has recurred in patients who have received a heart transplant.

REFERENCE:1. Kyle RA, Gertz MA, Greipp PR, et al. Long-term survival (10 years or more) in 30 patients with primary amyloidosis. Blood. 1999;93:1062-1066.