A dilated cardiomyopathy (DCM) is a condition where the heart muscle is enlarged and weakened to the point where it cannot pump adequate oxygen-rich blood to the body. DCM can occur in anyone but it is most commonly found among adult men. DCM is the most common cause of heart failure.
A number of conditions may cause DCM, including:
Coronary artery disease
Viral infections
Alcoholism
Genetic factors
In some cases, there is no known cause (idiopathic).
Dilated cardiomyopathy is the most common type of cardiomyopathy and derives its name for the following reasons:
Dilated refers to the dilation or enlargement of one or both lower chambers of the heart ventricles. The dilation frequently begins in the heart’s main pumping chamber, the left ventricle. This chamber is responsible for pumping oxygen-rich blood from the heart to the rest of the body. As it grows, it starts to weaken. Its weakened condition often leads to heart failure.
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.
Symptoms of DCM generally vary depending on the severity of the condition. In the early stages, the patient may not experience any symptoms as the heart adjusts to the disease. However, if left untreated, DCM can result in arrhythmia, blood clots and heart failure. Therefore, later stages of DCM can present symptoms such as fainting, palpitations, chest pain, fatigue and shortness of breath.
Treatment for DCM usually begins by attempting to treat the underlying condition. If it is caused by coronary artery disease, for example, the physician may first attempt to treat that condition with medications and lifestyle changes. However, a significant number of dilated cardiomyopathies have no known cause, so physicians must attempt to alleviate symptoms and stop the progressive degeneration of the heart. This approach might include strategies that aim to do the following:
Strengthen the heart
Decrease the heart’s workload
Allow the heart to shrink in size
Lower blood pressure (if necessary)
Control abnormal heart rhythms (arrhythmias)
A pacemaker or implantable cardioverter defibrillator may be surgically inserted to control arrhythmias that do not respond to medication. As a last resort, a heart transplantation may be considered. Other techniques to treat this condition are currently being developed.
About dilated cardiomyopathy
Also known as a congestive cardiomyopathy, a dilated cardiomyopathy (DCM) is a condition in which one or both ventricles of the heart becomes enlarged (dilated). This condition often begins in the left ventricle, which is the heart’s main pumping chamber. If it is left untreated, it may also affect the right ventricle. Over time, the entire heart may become enlarged.
Dilated cardiomyopathy can be a life-threatening condition. Aside from the heart’s inability to effectively pump oxygen-rich blood around the body, dilated cardiomyopathy also increases the risk of numerous health conditions, including:
Blood clots. The extra volume of blood flowing to and from the heart means that the blood flows more slowly. The allows blood clots to form easily and raises the risk of an embolism occurring.
Arrhythmia. Abnormal heart rhythms are common in patients with dilated cardiomyopathy. The change in heart structure affects the way that the electrical signals regulating the heartbeat travel through the heart. This may result in tachycardia (increased heartbeat) or bradycardia (decreased heartbeat).
Heart valve problems. Other structures in the heart may struggle to cope with the extra size of the ventricles and the extra blood that is being processed. This may cause problems with the heart’s valves. The valves most often affected are the mitral valve between the left atrium and the left ventricle, and the tricuspid valve between the right atrium and the right ventricle. This can lead to further worsening of heart failure and reduction of effective heart output.
The end result of untreated dilated cardiomyopathy is usually heart failure. Heart failure occurs when the heart is unable to cope with the body’s demand for oxygen-rich blood. This eventually causes complications with the lungs and other parts of the body. Heart failure may lead to cardiac arrest, where the heart stops pumping altogether.
Dilated cardiomyopathy can occur to anyone at any age, although it is more common in people aged 20 to 60 years, according to the National Institutes of Health. It occurs more often in men than women. In some cases, there is an underlying cause for a patient’s dilated cardiomyopathy, which may or may not be treatable. However, in a significant number of cases, no cause can be found. In this instance, it is referred to as idiopathic cardiomyopathy.
Potential causes of dilated cardiomyopathy
Although there are many conditions that may result in dilated cardiomyopathy, up to half of all dilated cardiomyopathy cases are thought to be hereditary, possibly resulting from a gene mutation passed from parent to child.
Laboratory studies have revealed the presence and role of certain genes involved in the growth of heart muscle. A faulty gene, for example, may not be able to limit heart muscle growth, thereby setting in motion the process of dilated cardiomyopathy and other conditions that can enlarge the heart.
Aside from genetic factors, there are several other conditions and factors that may result in dilated cardiomyopathy, including:
Coronary artery disease (CAD). The coronary arteries supply the heart with the blood necessary for it to function. CAD is a chronic disease in which blood flow is obstructed through the coronary arteries. As a result, the heart is unable to work as effectively as it should. This can lead to dilated cardiomyopathy.
High blood pressure. Poorly controlled or untreated high blood pressure can put unnecessary strain on the heart, leading to dilated cardiomyopathy.
Excessive alcohol consumption. Alcohol damages the heart muscle over time. The Texas Heart Institute estimates that 30 percent of dilated cardiomyopathy cases are related to heavy drinking. This high proportion of cases may also be linked to the fact that heavy drinkers frequently neglect other aspects of their health, particularly nutrition, which is another risk factor for dilated cardiomyopathy.
Other toxic substances. Aside from alcohol, there are several other substances that are toxic to the heart and may lead to dilated cardiomyopathy. These may include illegal drugs, such as cocaine or methamphetamine, or certain powerful medications used to treat cancer.
Viral infections. Although rare, there are several viruses that have been linked to cardiomyopathy. Additionally, viral infections may cause myocarditis, inflammation of the heart muscle which may contribute to the risk of developing dilated cardiomyopathy.
AIDS. Studies have shown that people with AIDS have a significant risk of developing dilated cardiomyopathy.
Barth syndrome. This is a rare and relatively unknown genetically linked cardiac disease, that has been known to cause dilated cardiomyopathy. It usually affects male children in their first year of life.
Signs and symptoms of dilated cardiomyopathy
Individuals with a dilated cardiomyopathy may not initially notice any symptoms. This is because the heart is able to adjust itself to compensate for increased blood volume or decreased ability to pump for many years.
However, as the heart begins to fail, serious symptoms may present themselves. Typically, a dilated cardiomyopathy is first recognized by heart failure and its signs and symptoms. These including:
Shortness of breath or inability to exercise
Persistent cough
Congestion of the lungs
Swelling (edema) of the feet and lower legs
Swelling or distention of the abdomen
Fatigue and weakness
Rapid, forceful, uncomfortable or obviously irregular heartbeat (palpitations)
Patients who experience arrhythmia caused by their cardiomyopathy may also experience symptoms such as rapid, forceful or uncomfortable heartbeats (palpitations), dizziness or fainting.
In more serious cases, individuals may experience cardiac arrest or sudden cardiac death.
Diagnosis methods for dilated cardiomyopathy
Dilated cardiomyopathy may be suspected if a patient visits a physician complaining of increasing fatigue and difficulty exercising.
The first step that a physician will take when diagnosing dilated cardiomyopathy is to obtain the patient’s personal and family medical history. In particular, the physician will look for family members who have this or other cardiac disorders, such as myocarditis. The patient will be given a complete physical examination with particular focus on the heart and lungs. The physician will listen for crackles in the patient’s lungs, a heart murmur or other unusual sounds. The physician will also take the patient’s pulse rate and blood pressure.
To help diagnose any cardiac abnormalities, the physician may order one or more tests to look for the cause of the patient’s symptoms. These tests include the following:
Echocardiogram. A painless test that uses sound waves to visualize the structures and functions of the heart. A moving image of the patient’s beating heart is played 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). During this test, a Doppler ultrasound may be done to evaluate cardiac blood flow.
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.
Electrocardiogram (EKG). A painless test that measures the heart’s electrical activity, aiding in the assessment of any abnormal heart rhythms (arrhythmias) or an enlarged heart.
Stress tests. These come in various forms, but the most common includes exercising on a treadmill or stationary bike while an EKG measures the heart’s electrical activity. The patient will be asked to exercise until a target heart rate is reached. The heart is then monitored while it is under this stress.
CAT scan (computed axial tomography). Also known as a CT 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. It may reveal a larger-than-normal heart.
“Fast” MRI (magnetic resonance imaging). Advances in MRI scans have resulted in crisper resolutions of blood flow, ejection fraction, stroke volume (the amount of blood ejected with each heartbeat) and scar tissue in the heart.
In some cases, the physician may need to order more invasive tests, such as a biopsy of the heart, to tell the difference between a dilated cardiomyopathy and similar forms of heart disease. A cardiac catheterization, with a left ventriculogram, may also be necessary.
Treatment and prevention
Currently, there is no cure for dilated cardiomyopathy. However there are many available treatment methods that can both alleviate symptoms and treat underlying any underlying conditions that may be causing or aggravating the cardiomyopathy. In some cases, these treatments may reverse the process of dilated cardiomyopathy.
If symptoms are severe at the time of diagnosis, patients may need to be hospitalized for a period of time. When their condition has been stabilized, long-term treatment will be discussed. Treatment for dilated cardiomyopathy often focuses on reversing the underlying condition if possible. Some patients with cardiomyopathy can remain stable for long periods of time.
For patients with mild to moderate dilated cardiomyopathy, treatment plans may include health lifestyle changes, medications and/or surgery. Medications that may be prescribed fall into the following classes:
Diuretics treat symptoms of heart failure by helping to flush fluids and minerals – primarily sodium – from the body.
ACE inhibitors minimize the effort the heart must make to pump blood and help to prevent further dilation or enlargement of the ventricle. This helps to relieve symptoms and, more importantly, directly increases the chance for long-term survival by reducing the stress on the heart muscle.
Angiotensin II receptor blockers work slightly differently than ACE inhibitors, but may also be used to increase the patient’s chance of survival by reducing the stress on the heart muscle.
Beta blockers have also been shown to increase the patient’s chance of survival, as well as to limit the number of hospitalizations for heart failure and improve symptoms. They can improve the ejection fraction by protecting the heart from high levels of hormones in the blood. These hormones may initially help the failing heart, but can then contribute to its progressive dysfunction.
Aldosterone inhibitors have recently been shown to prolong life when used along with standard medications. The landmark RALES study (Randomized Aldalactone Evaluation Study) found that, in patients with advanced heart failure already taking diuretics or ACE inhibitors, the addition of low-dose aldosterone inhibitor led to enhanced heart function and significant reduction in mortality.
Digoxin strengthens the heart muscle and helps slow the heart rhythm. This is used to treat certain rapid arrhythmias such as atrial fibrillation are present.
Vasodilators are sometimes recommended to lower a patient's blood pressure. This can make it easier for the heart to pump effectively by decreasing its workload.
Anticoagulant medications prevent the blood from clotting, and can help prevent embolisms in patients with dilated cardiomyopathy.
Ongoing studies are investigating whether some statins (a type of cholesterol reducing drug) exhibit a positive effect in dilated cardiomyopathy. Previous research with statins has already shown benefit on the coronary arteries of individuals with heart disease.
Physicians may recommend other treatment methods depending on the severity of the cardiomyopathy. For example, patients who survive sudden cardiac death or in who are at risk of death due to severe arrhythmias may benefit from a pacemaker or implantable cardioverter defibrillator (ICD). These devices are used to control the electrical impulses that make the heart beat.
Heart resynchronization therapy (biventricular pacing) is a type of pacemaker device that ensures activation of different portions of the heart at the same time, resulting in more efficient heart contractions. Many studies have shown that this procedure improves heart function and symptoms in certain suitable selected patients.
Heart transplantation may be necessary for patients in the advanced stages of heart disease who have a poor response to medical treatment and in whom the underlying problem could not be reversed or modified. Advanced dilated cardiomyopathy is the most common reason for heart transplantation, according to the National Institutes of Health.
Some patients with severe heart failure awaiting a heart transplant may be treated with a ventricular assist device. This is a mechanical pump that assists the failing heart that is implanted in open heart surgery.
In many cases, a physician will recommend lifestyle changes that may ease the symptoms of dilated cardiomyopathy. These may be recommended in conjunction with medication- or device-based treatment methods and generally include healthy lifestyle choices such as eating a heart-healthy diet, quitting smoking, getting regular exercise and limiting one’s alcohol use. Individuals should abstain from the use of any recreational drugs, such as cocaine.
Since dilated cardiomyopathy can be inherited, prospective parents should inform their physician of any family history of congenital heart disease. Genetic counseling, special prenatal/delivery care and other services may be recommended, depending on the nature of this problem and other heart problems.
Peripartum and alcoholic cardiomyopathies
Specific types of dilated cardiomyopathies include peripartum cardiomyopathy and alcoholic cardiomyopathy. Peripartum cardiomyopathy is a rare type of dilated cardiomyopathy that is due to complications from pregnancy. One of several gestational heart-related conditions, it most often occurs in women over the age of 30 during the last three months of their pregnancy or within four to six months after delivery. It can be a serious or even life-threatening risk for the mother and can also put her unborn child at risk.
Like other forms of dilated cardiomyopathy, the symptoms of peripartum cardiomyopathy include swelling (edema) in the lower legs, shortness of breath and other symptoms of heart failure. Because these symptoms are so similar to normal changes experienced during pregnancy, early diagnosis may be difficult. Although half of the women diagnosed with this condition recover fully or almost fully over time, there are some cases in which lifelong medications or even heart transplantation surgery are necessary. Women who are diagnosed with this condition are encouraged to consult with their physician and genetic counselors about future pregnancies.
Alcoholic cardiomyopathy is a type of dilated cardiomyopathy caused by excessive alcohol use. It is most common among middle-aged men. In some cases, the heart will be able to heal if diagnosis is made early and the patient stops drinking. In other cases, the condition continues for life. The symptoms of alcoholic cardiomyopathy, as well as its treatment, are similar to other forms of dilated cardiomyopathy. However, this form has a known prevention strategy – limiting one’s consumption of alcohol.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to dilated cardiomyopathy (DCM):
Why do you suspect that I have dilated cardiomyopathy?
What is the difference between DCM and other forms of cardiomyopathy?
Can you determine the cause of my cardiomyopathy?
What tests will be done to diagnose the condition?
How severe is my cardiomyopathy?
What are my treatment options for my condition?
What are the risks associated with these treatments?
If I am placed on mediations, what type will you prescribe?
How long will I need to stay on the medications?
When can I expect to see results from the treatment?
Can lifetyle changes reverse my heart condition?
Do I have any restrictions with DCM?
What signs indicate a medical emergency with my condition?
What is my prognosis with this condition?
How will DCM affect pregnancy or childbirth?
What are the chances my children will inherit DCM?
How can my children be monitored for the condition?
