Amyloidosis is a group of diseases characterized by the deposition of abnormal fibrillar proteins(amyloid) in tissues and organs throughout the body.
Amyloidosis can be classified as primary, secondary, or familial depending on the type of precursor protein that forms the amyloid fibril amyloidosis is a rare systemic disease caused by the abnormal production of immunoglobulin light chains by a plasma cell dyscrasia. Cardiac involvement is common in this disease and results in a restrictive cardiomyopathy because of the deposition of amyloid fibrils within the myocardium.
Although diastolic dysfunction is common with cardiac amyloid, systolic dysfunction may also occur, especially late in the course of the disease. The electrocardiogram typically reveals low voltage of the QRS complexes. Abnormal Q waves, especially in the anterior leads, may simulate myocardial infarction . The echocardiogram often reveals increased wall thickness , small ventricular cavity size, enlarged atria, and thickened valve leaflets. The myocardium often has a sparkling, granular appearance that is thought to be sec ondary to myocardial infiltration with the abnormal protein. A diagnosis of cardiac amyloid in a patient with clinical and echocardiographic findings typical of this disease can often be established by detecting amyloid deposits in tissue obtained from a fat pad or rectal e biopsy. If such methods are inconclusive, myocardial biopsy may be required .
The prognosis of patients with primary cardiac amyloid is extremely poor, with a median survival of less than 6 months if symptoms of congestive heart failure are present.Chemotherapy with high-dose intravenous melphalan followed by autologous stem cell rescue has been shown to improve the manifestations of amyloid disease in patients without significant cardiac involvement.
Current studies are now under way to determine if this therapy may be beneficial in selected patients with cardiac involvement.