An early diastolic third sound is often heard. The heart is usually enlarged, and the ECG frequently shows low voltage. Arrhythmias are common. Two-dimensional echocardiography may be helpful in the diagnosis of cardiac amyloidosis. The cardiac walls are often thickened and show a characteristic granular, speckled appearance.
Echocardiographic data can also provide prognostic information.
In a large group of patients with amyloid heart disease, survival was negatively influenced by greater wall thickness and reduced systolic function, which were seen on two-dimensional echocardiography. Enhanced diffuse myocardial uptake of technetium-99m pyrophosphate in radionuclide scintigraphy has also been reported in patients with cardiac amyloidosis. Clues to the nature of a restrictive cardiomyopathy may be provided by the presence of other signs of the underlying disease process. The presence of a small heart favors a diagnosis of constrictive pericarditis. The conditions may also be distinguished hemodynamically because constrictive pericarditis may involve the two ventricles equally and produce a so-called plateau of filling pressures.