Cardiomyopathy is a term that means a weakness of the heart muscle. There are many causes of cardiomyopathy. Some cancer treatments may cause cardiomyopathy. Other common causes include blocked arteries due to a heart attack, heavy alcohol use, and uncontrolled high blood pressure.
To diagnose a cardiomyopathy, a test (echocardiogram or MUGA scan) is performed to measure ejection fraction. If the ejection fraction is below normal, a cardiomyopathy is present. There are different degrees of cardiomyopathy, and the ejection fraction is used to categorize the severity of a cardiomyopathy. An ejection fraction < 30% is considered severe heart muscle weakness, an ejection fraction of 30% – 40% or 45% is a moderate weakness of the heart muscle, and an ejection fraction of 40%-50% (on a MUGA scan) or 45%-55% (on an echocardiogram) is considered a mild cardiomyopathy.
Some patients have no heart symptoms and a normal examination by their health care provider, even though they have a cardiomyopathy. Patients who have a cardiomyopathy are at risk for heart failure.
Heart failure is diagnosed when a patient experiences symptoms from a cardiomyopathy, your health care provider detects extra fluid in your system during a physical examination, or extra fluid is observed on a chest X ray or CT scan. Common symptoms of heart failure include breathlessness with little effort and edema (swelling).
Mild breathlessness is a common symptom, but if you have risk factors for cardiomyopathy (chemotherapy, left chest radiation, high blood pressure, artery problems), and are noticing breathlessness when you do ordinary things like walking, you should talk to your health care provider. A physical examination can detect heart failure, and if there is a concern a test will be ordered to measure your ejection fraction.
Some symptoms are more likely to be from heart failure than others. Edema when you first wake up, which is worse each subsequent morning, can be from heart failure. Edema at the end of the day (i.e. after you have been on your feet for a long time), but never in the morning, is less likely to be from heart failure. Your doctor uses a physical examination to confirm heart failure. Sometimes tests such as a chest X-ray, or a blood test can help confirm heart failure.