Diagnosis

Your doctor will perform a physical exam and ask questions about your personal and family medical history. He or she will use a device called a stethoscope to listen to your heart and lungs. You may be referred to a heart specialist (cardiologist) for testing.

Tests

Tests your doctor might order include:

• Blood tests. These tests give your doctor information about your heart. They also may reveal if you have an infection, a metabolic disorder or toxins in your blood that can cause dilated cardiomyopathy.
• Chest X-ray. Your doctor may order a chest X-ray to check your heart and lungs for changes or problems in the heart's structure and size, and for fluid in or around your lungs.
• Electrocardiogram (ECG or EKG). An electrocardiogram records electrical signals as they travel through your heart. Your doctor can look for patterns that may be a sign of an arrhythmia or problem with the left ventricle. Your doctor may ask you to wear a portable ECG device (Holter monitor) to record your heart rhythm for a day or two.
• Echocardiogram. This is the main test for diagnosing dilated cardiomyopathy. Sound waves produce images of the heart, allowing your doctor to see whether your left ventricle is enlarged. An echocardiogram can also reveal how much blood is pumped out of the heart with each beat and whether blood is flowing in the right direction.
• Exercise stress test. During this test, you walk on a treadmill or ride a stationary bike while attached to an ECG. Exercise testing can help reveal the cause and severity of dilated cardiomyopathy. If you're unable to exercise, you may be given medication to mimic the effect of exercise on your heart.
• CT or MRI scan. These imaging tests can show the size and function of your heart's pumping chambers.
• Cardiac catheterization. During this procedure, a long thin tube (catheter) is inserted in a blood vessel, usually in your groin, and guided to your heart. Dye may flow through the catheter to help your coronary arteries appear more clearly on X-ray. During cardiac catheterization, your doctor can measure pressure in your heart and collect a sample of tissue to check for muscle damage (biopsy).
• Genetic screening or counseling. If your doctor can't identify the cause of dilated cardiomyopathy, he or she may suggest screening of other family members to see if the disease is inherited in your family.