• Chest x-ray. A painless radiation-based imaging test that offers the physician a picture of the general size, shape, and structure of the heart and lungs.
  
  
• Echocardiogram. The most common test used to diagnose cardiomyopathy, echocardiogram is a painless test that uses sound waves to visualize the structures and functions of the heart. A moving image of the patient’s beating heart is displayed on a video screen, where a physician can study the heart’s thickness, size and function. From this image, a physician can measure the heart’s size and pumping, which tend to be abnormal in people with cardiomyopathies. The image also shows the motion pattern and structure of the four heart valves, revealing any potential leakage (regurgitation) or narrowing (stenosis). During this test, a Doppler ultrasound may be done to evaluate cardiac blood flow and the relaxation properties of the heart (known as diastolic function).
  
  
• Computed tomography (CT) scan. Also known as a CAT scan, this painless test allows for multiple x-rays to be taken from different angles around the patient. With the help of a computer, a three-dimensional image can be created.
  
  
• Blood tests. A recently developed test is capable of measuring the levels of the cardiac hormone brain natriuretic peptide (BNP). BNP is naturally produced by cardiac muscle, but excessive amounts are present in response to heart failure. Iron levels are measured when hemochromatosis is suspected.

In some cases, the physician may need to order more invasive tests, such as a biopsy of the heart, to tell the difference between a restrictive cardiomyopathy and constrictive pericarditis. It is important that constrictive pericarditis (which simulates restrictive cardiomyopathy) be ruled out. This is because constrictive pericarditis can be cured by surgery, whereas restrictive cardiomyopathy can only be controlled with medications. Rarely, surgery may be needed to confirm a diagnosis.