Ischemic cardiomyopathy is a condition characterized by enlargement of the main pumping chamber of the heart caused by ischemic heart disease, usually coronary artery disease. Among patients with ischemic cardiomyopathy, the heart muscle is either permanently damaged, usually due to a heart attack, or "hibernating" due to the prolonged lack of oxygen-rich blood. Ischemic cardiomyopathy is a form of dilated cardiomyopathy, a general term used to describe forms of heart disease in which the pumping chambers (ventricles) of the heart have expanded. The name ischemic cardiomyopathy comes from the following:
Ischemic refers to episodes of cardiac ischemia that occur when the heart is not getting enough oxygen-rich blood. The most common cause of cardiac ischemia is coronary artery disease caused by atherosclerosis, or hardening of the arteries. In this condition, the arteries that supply the heart muscle with blood are blocked by plaque deposits, thus limiting the flow of oxygen-rich blood to the heart muscle.
Cardiomyopathy is any disease of the heart muscle. It is most often used to refer to a heart that is abnormally enlarged, thickened and/or stiffened.
Treatment for an ischemic cardiomyopathy depends on the extent of the coronary artery disease, the extent of damage to the heart muscle and the severity of symptoms. In most cases, medications are effective treatments. In severe cases that do not respond to medication or other forms of medical therapy, a heart transplant may be necessary.
About ischemic cardiomyopathy
An ischemic cardiomyopathy is a chronic disorder caused by a lack of oxygen-rich blood flowing to the heart muscle. This condition is generally cause by one of two underlying factors, which in turn are often related to one another:
Coronary artery disease. Coronary artery disease is characterized by hardening of the arteries (atherosclerosis) that supply the heart muscle with the oxygen-rich blood needed for it to pump efficiently. In CAD, the coronary arteries are gradually blocked with fatty plaque deposits that narrow the artery, thus reducing the flow of blood to the heart muscle (myocardium). In severe cases of coronary artery disease, the heart muscle is starved of oxygen (cardiac ischemia), forcing it work extra hard. Over time, the main pumping chamber of the heart (e.g., the left ventricle) expands and is unable to efficiently pump oxygen-rich blood to the rest of the body.
Heart attack. A heart attack may be caused when plaque deposits in the coronary artery rupture, resulting in the formation of a blood clot that reduces blood flow to the heart muscle. As a result, the heart muscle may be permanently damaged and no longer able to function properly. Alternatively, the heart muscle may be stunned, or technically speaking, "hibernating," in which case the damage may be somewhat reversed with appropriate therapy.
It's important to note, however, that not all patients with coronary artery disease will develop ischemic cardiomyopathy. A number of factors are associated with increased risk for ischemic cardiomyopathy, in addition to atherosclerosis. These include diabetes, high blood pressure (hypertension), high cholesterol or a history of smoking.
Cardiomyopathy is the most common cause of heart failure in the United States. Although older men are most commonly affected, atherosclerosis is also a serious health concern for men and women of all ages, especially if risk factors (e.g., obesity, tobacco use) are present.
Signs and symptoms
Symptoms of an ischemic cardiomyopathy are consistent with heart failure and include:
Shortness of breath, especially when physically active
Trouble breathing while lying down
Fluid buildup (edema) in the legs, and in severe cases, the abdomen (ascites)
Angina (chest pain), pressure or discomfort
Strong, fast or “galloping” heartbeat (palpitations)
Tiredness or weakness
Difficulty concentrating
Changes in urination patterns
Coughing
The physician may also detect signs of heart failure, which include:
An abnormal heart murmur
A crackling sound of fluid in the lungs (rales), which is a sign of pulmonary congestion
A rapid heartbeat (tachycardia) or other abnormal heart rhythms (arrhythmias)
Swelling and fluid retention (edema) in the liver or gastrointestinal tract (in advanced stages of heart failure)
Bulging neck veins
Hypertrophy or enlargement of the heart
Liver malfunction
Other signs that may be detected by a physician include high blood pressure and a rapid pulse.
Diagnosis methods
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.
Treatment and prevention
Treatment for ischemic cardiomyopathy often begins with treating the underlying coronary artery disease and taking steps to relieve the burden on the heart. An important first step is to make healthy lifestyle changes, such as eating a heart-healthy diet and quitting smoking.
In conjunction with lifestyle improvements, the physician may also choose to use medications. Significant advances have been made in the treatment of ischemic cardiomyopathy with medications to manage symptoms and help the heart beat more effectively. Possible medications include:
Aspirin. Daily aspirin has been shown to reduce the risk of blood clots and lower the level of inflammation in the heart.
Beta blockers. These reduce the workload of the heart, help protect against abnormal rhythms (arrhythmias), and block a part of the adrenalin system.
ACE inhibitors. These tone down the adrenalin system, reduce the size of the heart, strengthen the heart muscle and lower blood pressure, thus reducing the workload on the heart.
Angiotensin II receptor blockers. These also tone down the adrenalin system, shrink the enlarged heart, strengthen the heart muscle and lower the blood pressure, thus reducing the workload on the heart. These are often used as alternatives to ACE inhibitors in patients who cannot tolerate ACE inhibitors.
Aldosterone blockers. These are used to dampen a part of the adrenalin system.
Inotropes. In selected instances, digoxin may be prescribed to strengthen the contractions on the heart, which has been shown to reduce hospitalizations for heart failure.
Anticoagulants. Coumadin is indicated to reduce the risk of embolism in patients who develop a thrombus within the heart and or atrial fibrillation. Both conditions are not uncommon in patients with ischemic cardiomyopathy.
An implantable cardioverter defibrillator (ICD) is indicated in patients who are considered at high risk of death due to severe ventricular arrhythmias, which may cause sudden cardiac death.
Cardiac resynchronization therapy (CRT) may also be recommended. In this therapy, a special pacemaker is implanted that simultaneously paces different segments of the left ventricle. This allows for more synchronous pumping that can increase the efficiency of the heart. These devices are sometimes recommended for patients who have an ejection fraction of 35 percent or less. They are frequently combined with an ICD.
A significant number of patients with ischemic cardiomyopathy may also benefit from therapies that reestablish blood flow to the heart. These procedures may include coronary angioplasty with or without either coronary stenting (a minimally invasive procedure), or bypass surgery (an invasive procedure). Whether these procedures can be done strongly depends on the condition of the patient and evaluation of the heart (muscles and coronary arteries). In very severe cases, heart transplantation is an option.
Because ischemic cardiomyopathies are complications of heart disease, the best prevention strategy is to avoid heart disease.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about ischemic cardiomyopathy:
Have I been diagnosed with ischemic cardiomyopathy?
What type of tests can you recommend to better evaluate my condition?
Will changing my lifestyle affect my condition in any way?
Will this condition require surgery? How urgently?
Can this condition be controlled with medication?
Could any medications I am currently taking interfere with or complicate my condition in any way?
Could I require a heart transplant as a result of my ischemic cardiomyopathy?
Are there any activities I should not participate in as a result of this condition?
Could ischemic cardiomyopathy affect my ability to have children in the future?
