Characteristic findings in amyloid cardiomyopathy
• N-terminal pro brain natriuretic peptide (NT-proBNP): normal levels exclude cardiac amyloid. Elevated levels of NT-proBNP and cardiac troponin T are predictors of poor survival, especially if they do not decrease with therapy.
• Electrocardiogram: reduced voltage as a result of replacement of myocardium by amyloid.
• Two-dimensional echocardiography has a high sensitivity for detecting amyloid deposits, which can cause a restrictive cardiomyopathy. Symmetric thickening of the left ventricular wall (>12 mm) or thickening of the interventricular septum may lead to an erroneous diagnosis of concentric left ventricular hypertrophy or asymmetric septal hypertrophy. Hypokinesis may suggest prior “silent” infarction. The combination of increased myocardial “sparkling” echogenicity and increased septal thickness (>6 mm) is 60% sensitive and 100% specific for the diagnosis of amyloidosis.
• Cardiac magnetic resonance imaging (MRI) shows delayed (late) subendocardial gadolinium enhancement.
