Dilated cardiomyopathy

Definition

Dilated cardiomyopathy is a disease of the heart muscle (myocardium), primarily affecting your heart's main pumping chamber (left ventricle). The left ventricle becomes enlarged (dilated) and can't pump blood to your body with as much force as a healthy heart can.

Dilated cardiomyopathy doesn't necessarily cause symptoms, but for some people the disease is life-threatening. Dilated cardiomyopathy is a common cause of heart failure, the inability of the heart to supply the body's tissue and organs with sufficient blood. The disease may also cause irregular heartbeats (arrhythmia), blood clots or sudden death.

Dilated cardiomyopathy may affect people of all ages, including infants and children, but it's most often diagnosed in middle age.

Symptoms

If you have dilated cardiomyopathy, you're likely to experience signs and symptoms when the disease has caused heart failure or arrhythmias. Signs and symptoms of dilated cardiomyopathy include:

• Fatigue and weakness
• Shortness of breath (dyspnea) when you're active or lying down
• Reduced ability to exercise
• Lightheadedness, dizziness or fainting
• Persistent cough or wheezing
• Swelling (edema) in your legs, ankles and feet
• Swelling of your abdomen (ascites)
• Sudden weight gain from fluid retention
• Lack of appetite and nausea
• Difficulty concentrating or decreased alertness
• Sensation of rapid, fluttering or pounding heartbeats (palpitations)

Causes

If you're like more than half the people with dilated cardiomyopathy, the cause of your condition can't be determined. Such cases are usually called idiopathic dilated cardiomyopathy. An estimated 30 percent to 50 percent of people with idiopathic dilated cardiomyopathy may carry a genetic mutation that causes the disease. Researchers have identified numerous genes associated with dilated cardiomyopathy and continue to search for more.

A number of other factors can change and enlarge your left ventricle. These additional causes of dilated cardiomyopathy include:

• High blood pressure (hypertension)
• Hardening and narrowing of arteries (atherosclerosis)
• Heart valve problems
• Damage to the heart muscle from a previous heart attack
• Chronic rapid heart rate (tachycardia)
• Chronic, excessive alcohol consumption
• Certain chemotherapy drugs for treating cancer
• Abuse of cocaine
• Viral or bacterial infections affecting the heart
• Metabolic disorders, such as thyroid disease or diabetes
• Abnormal metabolism of iron (hemachromatosis)
• Nutritional deficiencies of essential vitamins and minerals
• Inflammation of heart muscle from immune system disorders
• Metals and other toxic compounds, such as lead, mercury and arsenic
• Neuromuscular disorders, such as muscular dystrophy
• Pregnancy (peripartum cardiomyopathy)

When to seek medical advice

If you experience fatigue, shortness of breath or other symptoms of dilated cardiomyopathy, see your doctor. Call 911 or your local emergency number if you feel chest pain that lasts more than a few minutes or have severe difficulty breathing.

If a member of your family has been diagnosed with dilated cardiomyopathy, talk to your doctor about having you or other family members screened for dilated cardiomyopathy. This early intervention may benefit people with inherited forms of dilated cardiomyopathy who have no apparent signs or symptoms.

Tests and diagnosis

If you exhibit signs and symptoms associated with heart failure or arrhythmia — such as shortness of breath, fatigue, fluid retention or others — your doctor conducts a series of tests to assess the quality of heart function, identify possible causes of your illness and determine a course of treatment. For some of the exams, your doctor may refer you to a heart specialist (cardiologist) or specialized technicians.

Most assessments cannot be used alone to diagnose dilated cardiomyopathy, but they are important for piecing together clues. The results of some tests may determine what additional tests your doctor orders. Your doctor is likely to conduct assessments roughly in the following order.

Physical examination
Your doctor reviews your lifestyle habits (such as exercise, diet, smoking history and alcohol use), recent changes in weight, a chronology of recent signs and symptoms you've observed, and the history of heart disease and other medical conditions in your family.

Your doctor conducts a thorough physical examination, which may reveal signs such as irregular heartbeats, abnormal heart sounds (heart murmurs), the accumulation of fluids in the lungs, swelling in the legs or feet, or coolness in the limbs due to poor blood circulation.

Blood tests
Your doctor may order a series of blood tests that may show evidence of poor heart function or factors that can cause dilated cardiomyopathy. These may tests may reveal:

• Elevated levels of a protein called brain natriuretic peptide (BNP) that may indicate possible heart failure or stress on the heart
• Bacterial or viral infection
• Metabolic disorders
• Elevated levels of metals or toxic elements
• Evidence of hemachromatosis

X-ray
Your doctor may order a chest X-ray to assess your heart and lungs. Although these images don't provide enough information alone for making a diagnosis, they can reveal abnormalities in the heart's structure and size and can detect fluid in or around your lungs. The chest X-ray can provide a baseline record of your heart from which to assess subsequent changes associated with your condition.

Electrocardiogram (ECG)
An electrocardiogram — also called an ECG or EKG — records electrical signals as they travel through your heart. Your doctor can look for patterns among these signals that indicate abnormal heart rhythm and problems with the left ventricle.

Echocardiography
An echocardiogram uses sound waves to produce images of the heart. This common test enables your doctor to assess your ventricles squeezing and relaxing and valves opening and closing in rhythm with your heartbeat.

The echocardiogram is the primary tool for diagnosing dilated cardiomyopathy. If you have dilated cardiomyopathy, your doctor will be able to observe enlargement of the left ventricle. An echocardiogram can also reveal how much blood is ejected from the heart with each beat and whether blood is flowing in the right direction.

Exercise test
Your doctor may have you perform an exercise test, either walking on a treadmill or riding a stationary bike. Devices attached to you during the test help your doctor measure your heart rate and oxygen use. This type of test can enable your doctor to assess the severity of problems caused by dilated cardiomyopathy.

CT scan or MRI
In some situations your doctor may order a computerized tomography (CT) scan or a magnetic resonance imaging (MRI) scan of your heart. These tests can assess the size and function of your heart's pumping chambers and can sometimes provide clues to suggest unusual disorders that cause dilated cardiomyopathy.

Cardiac catheterization
Your doctor may order a procedure called cardiac catheterization, which is used primarily for identifying factors that may cause dilated cardiomyopathy. A long, narrow tube is threaded through a blood vessel and into the heart with the use of X-ray technology to guide the cardiologist. The procedure can to be used to:

• Inject a dye into coronary arteries that enable your doctor to see them on an X-ray
• Measure pressure in each chamber of the heart
• Obtain muscle tissue (biopsy) for laboratory tests to identify infected or damaged heart muscle

Screening for familial dilated cardiomyopathy
If your doctor can't identify the cause of dilated cardiomyopathy, he or she may suggest screening of other family members to determine if the disease is inherited in your family.

No single test can determine if you carry a disease-related gene mutation. However, a thorough and detailed multigenerational family history may reveal who's most at risk of dilated cardiomyopathy or whether there's evidence of other conditions that may contribute to the disease. Genetic testing is performed in some situations, usually as part of a research study.

Your doctor may advise family members to get a complete physical examination, echocardiogram and ECG. These tests may reveal enlargement of the left ventricle and poor blood outflow from the heart before any signs or symptoms of the disease are apparent. Subsequent monitoring and early treatment may provide long-term health benefits.

Complications

Enlargement of the left ventricle and its inability to pump blood efficiently can cause any of the following complications:

• Poor outflow of blood from the left ventricle may lead to heart failure.
• Enlargement of the left ventricle may result in incomplete closure of heart valves and subsequent backward flow of blood.
• Fluid buildup in the lungs, abdomen, legs and feet.
• Changes in the structure of the heart and changes in pressure on the heart's chambers can cause heart rhythm problems (arrhythmia).
• Sudden cardiac arrest.
• Pooling of blood (stasis) in the left ventricle can lead to blood clots, which may enter the bloodstream, cut off the blood supply to vital organs, and cause stroke, heart attack or damage to other organs.

Treatments and drugs

The goals of treatment for dilated cardiomyopathy are to treat an underlying cause if it's known, improve blood flow, reduce symptoms and prevent further damage to the heart.

Medications
Doctors usually treat dilated cardiomyopathy with a combination of medications. Depending on your symptoms, you might need two or more of these drugs. Several types of drugs have proved useful in the treatment of heart failure and dilated cardiomyopathy. These medications include:

• Angiotensin-converting enzyme (ACE) inhibitors. These drugs help people with dilated cardiomyopathy live longer and feel better. ACE inhibitors are a type of vasodilator, a drug that widens or dilates blood vessels to lower blood pressure, improve blood flow and decrease the workload on the heart. Examples include enalapril (Vasotec), lisinopril (Prinivil, Zestril) and captopril (Capoten). ACE inhibitors also blunt some of the effects of hormones that promote salt and water retention.

  ACE inhibitors cause an irritating cough in some people. It may be best to put up with the cough, if you can, to gain the medication's benefits. Discuss this side effect with your doctor. Switching to another ACE inhibitor or an angiotensin II receptor blocker may relieve the problem.

• Angiotensin II (A-II) receptor blockers (ARBs). These drugs, which include losartan (Cozaar) and valsartan (Diovan), have many of the beneficial effects of ACE inhibitors, but they don't cause a persistent cough. They may be an alternative for people who can't tolerate ACE inhibitors.
• Other vasodilators. For people who can't take ACE inhibitors or ARBs due to poor kidney function, the combination medications of hydralazine and nitrates can be used as vasodilators.

• Beta blockers. This class of drug also improves survival and reduces the risk of sudden cardiac death and abnormal heart rhythms in people with dilated cardiomyopathy. Beta blockers may reduce signs and symptoms of heart failure and improve heart function.

  A beta blocker slows your heart rate, reduces blood pressure and prevents some of the harmful effects of stress hormones, substances produced by your body that can make heart failure worse and can trigger abnormal heart rhythms. Examples of beta blockers include carvedilol (Coreg), metoprolol (Toprol XL) and bisoprolol (Zebeta).

• Diuretics. Often called water pills, diuretics make you urinate more frequently and keep fluid from collecting in your body. The drugs also decrease fluid in your lungs, so you can breathe more easily. Commonly prescribed diuretics for heart failure include bumetanide (Bumex) and furosemide (Lasix).

  Because some diuretics make your body lose potassium and magnesium, your doctor may also prescribe supplements of these minerals. If you're taking a diuretic, your doctor will likely monitor levels of potassium and magnesium in your blood through regular blood tests.

• Aldosterone antagonists. These drugs include spironolactone (Aldactone) and eplerenone (Inspra). They are primarily potassium-sparing diuretics, but they have additional properties that help the heart work better, may reverse scarring of the heart and may help people with severe heart failure live longer. Unlike some other diuretics, spironolactone can raise the level of potassium in your blood to dangerous levels.
• Digoxin (Lanoxin). This drug, also referred to as digitalis, increases the strength of your heart muscle contractions. It also tends to slow the heartbeat. Digoxin reduces heart failure symptoms and improves your ability to live with dilated cardiomyopathy.
• Anticoagulants. Your doctor may prescribe anticoagulants, which prevent blood clots. These include aspirin and warfarin (Coumadin).

Devices
Implantable devices that may correct irregular heartbeats include:

• Biventricular pacemakers use electrical shocks to coordinate contractions between the left and right ventricle.
• Implantable cardioverter-defibrillators (ICDs) monitor heart rhythm and deliver electrical shocks when needed to control abnormal, rapid heartbeats, including those that cause cardiac arrest. They can also function as pacemakers.

Heart transplant
You may be a candidate for a heart transplant if medications and other treatments are no longer sufficient to manage heart failure due to dilated cardiomyopathy.

Prevention

If you eliminate lifestyle habits that can contribute to dilated cardiomyopathy, you may prevent or minimize effects of the disease:

• If you smoke, quit.
• Don't drink alcohol, or drink in moderation.
• Don't use cocaine or other illicit drugs.
• Eat a healthy diet.
• Maintain a healthy weight.
• Follow an exercise regimen recommended by your doctor.

Lifestyle and home remedies

If you have dilated cardiomyopathy, these self-care strategies may improve your treatment outcome:

• Talk to your doctor about what kind of exercise and activities would be safe and beneficial for you.
• Take your medications as directed.
• Seek psychotherapy or other treatment to quit smoking or to recover from alcohol or drug abuse.