What is Dilated Cardiomyopathy?
Dilated Cardiomyopathy (DCM) is a condition that affects the heart muscle, leading to an enlargement of one or both of the heart’s pumping chambers and causing them to work less efficiently. In this condition, the heart’s ability to pump out blood (known as the left ventricular ejection fraction, or LVEF) is less than 40%. Some people with Dilated Cardiomyopathy may show symptoms related to heart failure, but others may not have any signs of the condition. The term “primary” DCM means that the cause is unknown, whereas “secondary” DCM means that the disease has a known cause.
Usually, DCM gradually gets worse, often leading to heart failure and sometimes death. Heart transplantation is often required for survival, as patient outcomes generally aren’t promising without a transplant.
While there are many causes for DCM and they all affect how well the heart pumps blood, not everyone with DCM will experience symptoms. Some people’s bodies can compensate for the initial changes, so they may not notice any issues. But over time, the bigger and weaker heart chambers lead to worsening heart function, irregular heart rhythms, blood clots, and eventually heart failure. Early identification and treatment of these patients can improve their chances for a better health outcome.
What Causes Dilated Cardiomyopathy?
Dilated cardiomyopathy (DCM) is a condition where the heart becomes enlarged and it’s often difficult to pinpoint a clear reason behind it. This unknown cause is often referred to as idiopathic. It’s also common to see DCM passed down in families or appearing due to certain genetic changes. Yet, if no distinct genetic connection is found, these situations too are considered idiopathic. Notably, changes in various genes, including those responsible for the structure and function of the heart muscle, are often associated with DCM.
Other triggers for DCM could be due to a heart infection (from viruses, Chagas disease, or Lyme disease), blood supply issues to the heart, high blood pressure, certain medications, excessive alcohol intake, HIV, heart changes during pregnancy or certain infiltrating diseases. It’s important to note that damage to the heart due to clogged arteries, known as ischemic cardiomyopathy, is the most common reason for heart failure. Nonetheless, it’s typically classified as a distinct condition, separate from DCM, unless it occurs in patients with hidden artery disease.
There’s also a less common but increasingly reported type of heart condition known as stress cardiomyopathy or ‘Broken heart syndrome’. This usually happens after severe emotional or physical stress and is believed to be a response to a sudden rush of stress hormones in the body. It is characterized by temporary bulging of the left lower chamber of the heart but is usually considered a distinct condition, separate from primary DCM.
Risk Factors and Frequency for Dilated Cardiomyopathy
Dilated Cardiomyopathy (DCM) is a condition that is more commonly found in men than women. It’s estimated to affect about 36 out of every 100,000 people. It results in about 10,000 deaths and causes around 46,000 hospitalizations each year in the United States. However, these numbers might be lower than the reality, as several people may have the condition without showing any symptoms, leading to it being undiagnosed even with heart dysfunction.
- DCM is more common in men.
- It’s estimated that about 36 out of 100,000 people have this condition.
- Each year in the US, DCM leads to about 10,000 deaths and 46,000 hospitalizations.
- The actual numbers might be higher because many people show no symptoms and remain undiagnosed, even though their heart isn’t functioning properly.
Signs and Symptoms of Dilated Cardiomyopathy
Dilated cardiomyopathy, or DCM, typically appears in people aged 20 to 60, but it can also affect children or the elderly. Although many people with DCM may not experience symptoms for an extended period, symptoms eventually emerge due to left ventricle (LV) systolic dysfunction. It’s important to have a thorough examination to identify any related systemic disease or secondary causes.
Common symptoms include overnight breathlessness, wheezing while lying down, leg swelling, and shortness of breath. Other less specific symptoms can be fatigue, feeling unwell, and weakness. More severe situations may result in complications like blood clots, heart rhythm problems, or even sudden cardiac death. The physical signs, which are usually similar to those seen with congestive heart failure, are often not specific to other causes of heart muscle disease.
- Overnight breathlessness
- Wheezing while lying down
- Leg swelling
- Shortness of breath
- Fatigue
- Feeling of illness
- Weakness
- Possible complications: blood clots, heart rhythm problems, sudden cardiac death
- Signs similar to congestive heart failure
An examination might reveal sounds of fluid in the lungs, higher venous pressures in the neck, swelling in the limbs, and an extra heart sound. The point of maximum impulse (PMI) may have shifted sideways, and heart murmurs due to ventricle enlargement and annulus dilation may be present. You may also observe enlarged neck veins, large upward and downward waves and a positive hepatojugular reflux, which is an abnormal increase in jugular vein size when pressure is applied to the liver.
Testing for Dilated Cardiomyopathy
If your doctor suspects that you may have a type of heart disease called dilated cardiomyopathy, they have to rule out other potential causes before making a definitive diagnosis. Various tests and procedures can help to find the reversible causes of this condition. For instance, blood tests might check your thyroid function, HIV status, electrolyte balance, and iron levels which can help rule out specific conditions like hemochromatosis. If drug or alcohol abuse is a concern, a urine test and an alcohol level blood test might also be ordered. In certain family cases, genetic testing could also be useful.
A particular blood test called the serum B-type natriuretic peptide (BNP) test may be conducted if the diagnosis is unclear. Low levels of BNP assist in excluding heart failure, and also provide important information about prognosis.
Other conditions such as hypothyroidism and anemia should also be ruled out. Imaging tests like a chest X-ray can help identify an enlarged heart and signs of fluid accumulation and congestion in the lungs. An electrocardiogram (EKG) may be used to detect irregular heart rhythm and other heart-related issues.
In terms of prognosis, if your oxygen consumption is less than 14 ml/kg/min, this could suggest a poor outcome.
An echocardiogram is especially key in diagnosing dilated cardiomyopathy. This test provides a clear view of the size of your heart, how well it’s functioning, any issues with heart valves, the presence of blood clots, and can help in distinguishing this condition from other types of heart disease.
A coronary angiography, which provides detailed images of your heart’s blood vessels, might be carried out, especially if there’s no known history of coronary artery disease (CAD). This helps to check for hidden heart disease that could be causing the problem. A heart biopsy is rarely needed but might be carried out if an infiltrative cause is suspected. However, this procedure carries some risks and the findings are often not specific.
Treatment Options for Dilated Cardiomyopathy
The management and treatment of Dilated Cardiomyopathy (DCM), an enlarged and weakened heart, typically follow standard guidelines for heart failure. This means any underlying conditions causing the disease are first addressed, and then specific treatments for heart failure are used.
For patients facing an intense flare-up of heart failure, medications called IV loop diuretics are given to reduce excess fluid in the body. Patients with stable, chronic disease often need to take oral diuretics to maintain a balanced fluid level in their body.
Patients with DCM benefit from medications like Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). These treatments are designed to help heart failure with a reduced ability to pump blood. Other suitable treatments for DCM patients include drugs like spironolactone or eplerenone, which block aldosterone hormone receptors and are recommended for people dealing with moderate to severe heart failure and pump dysfunction.
Other medications like beta-blockers and a combination of isosorbide dinitrate and hydralazine can also increase survival rates in those with serious heart failure.
For the prevention of blood clots in patients with artificial heart valves, a heart rhythm disorder called atrial fibrillation, or a known blood clot in the heart wall, anticoagulation medications can be used. They can lower the risk of stroke; however, they also come with an increased risk of bleeding.
Patients who don’t respond to traditional therapies might need to consider advanced treatment options like heart transplantation or the use of a device called a Left Ventricular Assist Device (LVAD) to help the heart pump blood.
Options like a device called an Implantable Cardioverter Defibrillator (ICD) for preventing sudden cardiac death, and Cardiac Resynchronization Therapy (CRT) to help ensure the heart’s chambers beat as they should can also be explored.
Heart transplantation can be an option for severe cases like shock triggered by inadequate blood flow, life-threatening heart rhythm problems, heavy reliance on drugs to force the heart to contract properly, and continuous dependence on a blood-pumping device. However, the process is hindered by the lack of available heart donors.
What else can Dilated Cardiomyopathy be?
These are some conditions that doctors need to consider when diagnosing heart problems:
- Cardiac tamponade (pressure on the heart caused by fluid in the sac surrounding the heart)
- Acute pericarditis (inflammation of the pericardium, which is the sac-like structure around the heart)
- Hypertrophic cardiomyopathy (abnormal thickening of the heart muscle)
- Restrictive cardiomyopathy (stiff heart muscles that restrict the heart’s filling with blood)
The doctor will need to carefully evaluate all these possibilities to make an accurate diagnosis.
What to expect with Dilated Cardiomyopathy
In general, the outlook for patients with dilated cardiomyopathy, a condition where the heart’s ability to pump blood is weakened, is uncertain. Most patients often end up developing chronic heart failure. A number of these individuals may need a heart transplant or a device to assist their heart, which can also lead to more health complications.
The progression to heart failure is influenced by the heart’s pumping efficiency and the cause of the cardiomyopathy. Around half of the patients diagnosed with this condition unfortunately pass away within 5 years. The outlook tends to be worse for those with serious heart failure diagnosis, men, those with kidney failure, and patients who have symptoms even when not being physically active or are unable to exercise.
Medical professionals are now commonly using “Peak VO2 levels” (a measure of the body’s ability to use oxygen during maximum effort) to predict survival rates. Patients with higher VO2 levels generally have a better chance of survival than those with lower levels. By receiving the best possible medical treatment, patients with mild chronic heart failure can maintain a reasonably good quality of life.
Possible Complications When Diagnosed with Dilated Cardiomyopathy
Common heart conditions include:
- Congestive heart failure
- Stroke (Cerebrovascular accident)
- Valvular heart disease (issues with the heart valves)
- Abnormal heart rhythms
- Sudden cardiac death
- Thromboembolism (blood clots in the blood vessels)
Recovery from Dilated Cardiomyopathy
People with dilated cardiomyopathy need thorough guidance about their diet. Cutting down on both salt and water is crucial in order to avoid symptoms. These patients should keep active or join a heart rehab program. Regular participation in such a program can lower the risk of death by 20%, alleviate symptoms, and lessen the chance of unwanted heart-related events.
Preventing Dilated Cardiomyopathy
Teaching patients about the importance of taking their medication as prescribed, sticking to dietary guidelines, and attending regular check-ups is crucial to the treatment of a heart condition known as dilated cardiomyopathy. Understanding and following these steps can help manage the condition effectively.
