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Ischemic cardiomyopathy is usually suspected if a patient shows symptoms of heart failure following the diagnosis of coronary artery disease or a heart attack.
The first step that a physician will take when diagnosing an ischemic cardiomyopathy is to ask about the patient’s personal and family medical history. Any previous heart attack or coronary revascularization surgery, such as coronary artery bypass graft surgery, is important because of its association with ischemic cardiomyopathy. Similarly, a previous diagnosis of coronary artery disease will help the physician better identify the cause of symptoms.
The American Heart Association has issued guidelines to help physicians correctly diagnose ischemic cardiomyopathy as a potential cause of heart failure. According to these guidelines, all patients with heart failure who suffer from chest pain, patients with chest pain of unknown origin, and patients who have suspected or confirmed coronary artery disease should have a coronary arteriogram. During this test, a special dye is injected into the coronary arteries that is visible under x-ray. This is followed by a chest x-ray. This test allows physicians to see potential blockages in the coronary arteries on the surface of the heart.
A number of noninvasive tests may also be used to detect the shape and size of the heart, as well as measure various elements of cardiac health. These include:
- Blood tests. Certain blood tests can help rule out a recent heart attack and can otherwise help determine the presence of risk factors for atherosclerosis (e.g., cholesterol, blood sugar, CRP).
- Electrocardiogram. A painless test that measures the heart’s electrical activity, helping to assess for arrhythmia and/or evidence of a past heart attack.
- 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. A painless test that uses sound waves to visualize the structures and functions of the heart. A live 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, pumping ability and ejection fraction, 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). Measurements may also be taken of the thickness of the ventricles. During this test, a Doppler ultrasound may be done to evaluate cardiac blood flow, pressure inside the heart and the severity of stiffness of the heart muscle.
- Non-invasive evaluation of myocardial viability. If a patient is a candidate for a revascularization procedure, such as coronary artery bypass or angioplasty, a number of tests might be used to detect hibernating myocardium. This is heart muscle that is not functioning properly, but can be revived by re-establishing good blood flow. Tests used to measure this include dobutamine stress echocardiography, positron emission tomography (PET) and contrast enhanced magnetic resonance imaging (MRI). Patients with mostly scar tissues are considered for medical treatment alone whereas those with substantial viability may improve with revascularization.
- 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.
- Cardiac magnetic resonance imaging (MRI). A painless test that uses magnetic fields and a computer to produce high-resolution cross-sectional or three-dimensional images of the heart. It can also differentiate a scar from viable heart tissues.
In some cases, the physician may need to order more invasive tests, such as a cardiac catheterization or a biopsy of the heart.
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