Senile cardiac amyloidosis with myocardial dysfunction. Diagnosis by endomyocardial biopsy and immunohistochemistry.

Senile cardiac amyloid discovered at autopsy is usually regarded as an incidental finding. However, in immunohistochemical studies of autopsy material, three distinct forms of senile cardiovascular amyloid have been characterized, including a systemic form that diffusely infiltrates the cardiac ventricles. The systemic form can be identified immunohistochemically with use of antiserum to human prealbumin. We diagnosed senile systemic amyloidosis causing cardiac dysfunction in five men (57 to 72 years old) by using antiserum to prealbumin in myocardial biopsy tissue. Clinically, the five patients were indistinguishable from patients with nonsecretory immunoglobulin-derived primary amyloidosis with cardiac involvement; only immunohistochemical staining of myocardial tissue distinguished between the two entities. This distinction is important, because the treatment and prognosis of the two disorders are different. We recommend immunohistochemical staining of myocardial tissue for prealbumin in patients with biopsy-proved cardiac amyloid in whom no monoclonal immunoglobulin light chain is detectable in the serum or urine.