Diagnosis

Your doctor will perform a physical examination and ask questions about your personal and family medical history. You'll also be asked when your symptoms occur — for example, whether exercise brings on your symptoms. If your doctor thinks you have cardiomyopathy, several tests may be done to confirm the diagnosis, including:

• Chest X-ray. An image of your heart will show whether it's enlarged.
• Echocardiogram. This test uses sound waves to create images of the heart, which show its size and its motions as it beats. This test checks your heart valves and helps your doctor determine the cause of your symptoms.
• Electrocardiogram (ECG). In this noninvasive test, electrode patches are attached to your skin to measure electrical signals from your heart. An ECG can show disturbances in the electrical activity of your heart, which can detect abnormal heart rhythms and areas of injury.
• Treadmill stress test. Your heart rhythm, blood pressure and breathing are monitored while you walk on a treadmill. Your doctor might recommend this test to evaluate symptoms, determine your exercise capacity and determine if exercise triggers abnormal heart rhythms.

• Cardiac catheterization. A thin tube (catheter) is inserted into your groin and threaded through your blood vessels to your heart. Pressure within the chambers of your heart can be measured to see how forcefully blood pumps through your heart. Dye can be injected through the catheter into your blood vessels to make them more visible on X-rays (coronary angiogram). A cardiac catheterization can reveal blockages in your blood vessels.

  During this test, doctors can remove a small tissue sample (biopsy) from your heart for analysis in the laboratory.

• Cardiac MRI. This test uses magnetic fields and radio waves to create images of your heart. Your doctor might order a cardiac MRI if the images from your echocardiogram aren't helpful in making a diagnosis.
• Cardiac CT scan. You lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest to assess heart size and function and the heart valves.

• Blood tests. Several blood tests might be done, including those to check your kidney, thyroid and liver function and to measure your iron levels.

  One blood test can measure B-type natriuretic peptide (BNP), a protein produced in your heart. Your blood level of BNP might rise when your heart is in heart failure, a common complication of cardiomyopathy.

• Genetic testing or screening. Cardiomyopathy can be passed down through families (inherited). Ask your doctor if genetic testing is right for you. He or she might recommend family screening or genetic testing for your first-degree relatives — parents, siblings and children.