Dilated Cardiomyopathy

Overview

Dilated cardiomyopathy is a disease of the heart muscle in which the main pumping chamber, the left ventricle, becomes enlarged and its walls thin out. The heart muscle weakens progressively, and the enlarged chamber can no longer pump blood forward with enough force. Over time, this leads to heart failure.

Dilated cardiomyopathy is the most common type of cardiomyopathy and one of the leading causes of heart failure. It can occur at any age but is more frequently diagnosed in middle-aged men. In some patients a clear cause is identified. In others, no definitive cause is found despite thorough investigation, and the condition is described as idiopathic.

With early diagnosis and appropriate treatment, heart function can improve meaningfully in many patients. Treatment is long-term, but consistent medication use and lifestyle changes can slow the progression of the disease and preserve a good quality of life.

Symptoms

Dilated cardiomyopathy may produce no symptoms in its early stages. As the heart becomes less able to pump effectively, symptoms develop. These closely overlap with the symptoms of heart failure.

• Shortness of breath. This is one of the most common symptoms. It may begin only with exertion, such as climbing stairs or walking briskly. As the disease progresses, breathlessness can occur at rest or when lying flat. Waking from sleep due to breathlessness and needing to sit upright to breathe comfortably are important signs of worsening heart failure.
• Fatigue and weakness. When the body receives less blood than it needs, a persistent and often debilitating sense of exhaustion develops. Tasks that were previously manageable may become increasingly difficult.
• Swelling in the legs and ankles. When the heart cannot pump adequately, fluid accumulates in the lower body. Swelling in the legs, ankles, and sometimes the abdomen may develop and tends to worsen as the day progresses.
• Palpitations or irregular heartbeat. An enlarged heart muscle is more prone to rhythm disturbances. The heart may feel as though it is racing, fluttering, or beating irregularly. Atrial fibrillation is a common rhythm problem in dilated cardiomyopathy.
• Dizziness or lightheadedness. Reduced blood flow to the brain can cause feelings of unsteadiness or dizziness. Brief loss of consciousness can also occur in some cases.
• Cough. A persistent cough that worsens when lying flat, sometimes producing pink or frothy mucus, can indicate fluid building up in the lungs.
• Abdominal discomfort or bloating. Fluid accumulation in the liver and abdominal cavity can cause a feeling of fullness or discomfort in the abdomen.

When to Seek Medical Care

See a doctor if you notice any of the following.

• Shortness of breath during activity or at rest
• Swelling in the legs or ankles
• Unexplained and worsening fatigue
• Palpitations or a sensation of irregular heartbeat
• A gain of several pounds over a short period

Call emergency services immediately if you experience any of the following.

• Sudden and severe shortness of breath or inability to breathe when lying flat
• Sudden, severe chest pain
• Fainting or nearly fainting
• A very rapid or markedly irregular heartbeat

Causes

Dilated cardiomyopathy has several possible causes. In some patients the cause is clearly identifiable. In others, no definitive explanation is found despite thorough testing.

• Inherited gene changes. Approximately one-third of dilated cardiomyopathy cases are hereditary. If a close family member has had dilated cardiomyopathy or unexplained heart failure, other family members may be at risk and should be evaluated.
• Heart muscle inflammation. Viral infections can directly damage the heart muscle. Even after the infection resolves, lasting weakness and enlargement of the heart can remain. Coxsackievirus B, influenza, and COVID-19 are among the viruses known to affect the heart muscle.
• Heart attack and coronary artery disease. When blood supply to the heart muscle is reduced or cut off, the muscle sustains damage. A heart attack affecting a large area of heart muscle can weaken it significantly, leading to dilated cardiomyopathy.
• Long-term heavy alcohol use. Sustained excessive alcohol consumption directly weakens the heart muscle over time. When alcohol is stopped, heart function can improve substantially in many patients.
• Chemotherapy medications. Certain chemotherapy drugs, particularly those in the anthracycline group, can damage the heart muscle. Cardiac monitoring before and after these treatments is important.
• Pregnancy. Peripartum cardiomyopathy, which develops in the final months of pregnancy or shortly after delivery, is a form of dilated cardiomyopathy. It can occur in women with no prior history of heart disease.
• Thyroid disorders. An overactive or underactive thyroid can disrupt the heart's rhythm and pumping function. Treating the thyroid condition often allows the heart to recover.
• Diabetes. Long-term poorly controlled diabetes can affect both the heart muscle and the coronary arteries.
• Autoimmune diseases. Conditions such as lupus can target the heart muscle and lead to dilated cardiomyopathy.

Risk Factors

Certain factors increase the likelihood of developing dilated cardiomyopathy.

• Family history of dilated cardiomyopathy or early-onset heart failure. Having a first-degree relative with this condition significantly raises the risk.
• Male sex. Dilated cardiomyopathy is more commonly diagnosed in men than in women.
• Long-term heavy alcohol use. Years of excessive drinking gradually weakens the heart muscle.
• A previous heart attack. Particularly large heart attacks can leave lasting damage that leads to dilated cardiomyopathy over time.
• Uncontrolled high blood pressure. Persistent high blood pressure increases the heart's workload and can contribute to muscle weakening.
• Pregnancy. The increased circulatory demands of pregnancy can, in some women, contribute to the development of dilated cardiomyopathy.
• Certain chemotherapy agents. Treatment with cardiotoxic drugs increases the risk and requires cardiac monitoring.

Diagnosis

The diagnosis of dilated cardiomyopathy involves a combination of clinical assessment, imaging, and laboratory tests. The goal is not only to confirm the diagnosis but also to identify the underlying cause, since treating the cause directly can allow the heart to recover in some patients.

• Medical history and physical examination. The doctor asks in detail about when symptoms began, what makes them worse, and the overall health history. Family history of dilated cardiomyopathy, heart failure, or unexplained cardiac death at a young age is specifically important and should always be mentioned. Alcohol use, prior heart attack, chemotherapy history, and other conditions are reviewed. On examination, the doctor listens to the heart and lungs, assesses neck vein distension, and checks for leg swelling.
• Echocardiogram (heart ultrasound). This is the most important test for diagnosing dilated cardiomyopathy. It shows how much the left ventricle has enlarged and how thin the walls have become. It measures the ejection fraction, which is the percentage of blood the heart pumps out with each beat. A normal ejection fraction is above 50 percent. In dilated cardiomyopathy, this value is typically below 40 percent. Valve function and the space around the heart are also assessed.
• Electrocardiogram (ECG). Records the heart's electrical activity. Various changes may be found in dilated cardiomyopathy, including atrial fibrillation and other rhythm disturbances, conduction problems such as left bundle branch block, and electrical traces of a previous heart attack. The pattern of findings can help point toward the underlying cause.
• Holter monitor. A portable ECG device worn for 24 hours or longer that continuously records the heart rhythm during daily activity. It captures rhythm disturbances, such as atrial fibrillation, that come and go and may not be present during a standard ECG. It is particularly important in patients who experience palpitations, dizziness, or brief blackouts.
• Cardiac MRI. This provides the most detailed assessment of the heart muscle. It precisely measures chamber dimensions and ejection fraction. Using a technique called late gadolinium enhancement, it can identify areas of fibrosis or scarring within the heart muscle. This information is important for assessing the extent of damage and long-term risk, and it helps distinguish cardiomyopathy caused by a heart attack from other causes.
• Blood tests. BNP and NT-proBNP are markers that reflect the degree of stress on the heart and help assess the severity of heart failure. Troponin elevation indicates active heart muscle injury. Tests for thyroid function, iron levels, blood sugar, kidney health, and autoimmune markers are ordered to search for treatable underlying causes.
• Coronary angiography or coronary CT angiography. To determine whether the dilated cardiomyopathy is caused by blocked coronary arteries, the heart's arteries may need to be imaged. In coronary angiography, a thin catheter passed through a blood vessel in the groin or wrist delivers contrast dye directly into the coronary arteries for real-time X-ray imaging. Coronary CT angiography is a less invasive alternative that uses contrast dye and a CT scanner.
• Genetic testing. When a hereditary cause is suspected, genetic testing may be recommended. Several gene changes associated with dilated cardiomyopathy have been identified. A positive result supports the diagnosis and indicates that first-degree family members should be evaluated.

Treatment

Treatment of dilated cardiomyopathy aims to relieve symptoms, improve or preserve heart function, slow the progression of the disease, and prevent serious complications. Most patients require a combination of medications, device therapies, and lifestyle changes.

Medications

Medications are the cornerstone of treatment for dilated cardiomyopathy. When used consistently, they can improve ejection fraction, reduce heart failure hospitalizations, and extend life.

• ARNI (angiotensin receptor-neprilysin inhibitor). This medication widens blood vessels, reduces the workload on the heart, and slows adverse remodeling of the heart muscle. Clinical trials have shown it reduces hospitalizations and death related to heart failure more effectively than ACE inhibitors or ARBs. It is now the preferred first-line treatment in eligible patients.
• ACE inhibitors and ARBs. Used in patients who cannot take an ARNI. They reduce blood pressure and slow further enlargement of the heart. If ACE inhibitors cause a troublesome dry cough, an ARB is an effective substitute.
• Beta-blockers. These slow the heart rate and reduce the force of contractions, lowering the heart's oxygen demand. They are started at a low dose and increased gradually. Over time they can meaningfully improve the ejection fraction and are an essential component of heart failure treatment.
• Aldosterone antagonists. These help regulate sodium and fluid balance and provide additional protection in patients with significant heart function impairment. Kidney function and potassium levels need to be monitored regularly.
• SGLT2 inhibitors. Originally developed for diabetes, these drugs were found to have a powerful protective effect in heart failure and have been incorporated into standard treatment. They reduce heart failure hospitalizations and cardiovascular death even in patients without diabetes.
• Diuretics. These remove excess fluid from the body and relieve breathlessness and leg swelling. They provide rapid symptomatic relief but do not alter the course of the underlying disease and are therefore used alongside the medications above.
• Blood thinners. An enlarged and poorly pumping heart carries an increased risk of clot formation inside the chambers. Blood-thinning medication is often necessary, particularly when atrial fibrillation is also present. Warfarin or newer oral anticoagulants may be used depending on individual risk.
• Medications for rhythm disturbances. When atrial fibrillation or other rhythm problems are present, medications to control heart rate or restore a normal rhythm may be added.

Device Therapies

• Implantable cardioverter-defibrillator (ICD). This small device is implanted under the chest skin and connected to the heart by thin wires. It continuously monitors the heart rhythm. If it detects a life-threatening rhythm such as ventricular fibrillation or ventricular tachycardia, it delivers an electrical shock to restore a normal rhythm. An ICD is highly effective at preventing sudden cardiac death in patients with an ejection fraction below 35 percent. It remains in place permanently and the battery is replaced when needed.
• Cardiac resynchronization therapy (CRT). In advanced dilated cardiomyopathy, the right and left ventricles sometimes beat in an uncoordinated way, reducing pumping efficiency. A CRT device uses multiple electrodes to stimulate both ventricles simultaneously, restoring coordination. This can improve the ejection fraction and significantly relieve symptoms such as breathlessness and fatigue. A combined CRT-D device, which provides both resynchronization and defibrillation, is often preferred.

Advanced Treatments

• Left ventricular assist device (LVAD). In patients whose heart function has deteriorated severely despite all medical and device therapies, an LVAD may be considered. This mechanical pump is implanted alongside or inside the heart and takes over the work of the left ventricle, actively moving blood forward to the body. It can be used as a bridge to transplantation while a suitable donor heart is awaited, or as a long-term treatment option in patients who are not transplant candidates.
• Heart transplantation. In end-stage dilated cardiomyopathy that does not respond to any other treatment, heart transplantation may be considered. The waiting time for a suitable donor heart varies significantly. After transplantation, lifelong immunosuppressive medications are required to prevent the body from rejecting the new heart.

Treating the Underlying Cause

In dilated cardiomyopathy, addressing the underlying cause can lead to meaningful recovery of heart function. Stopping alcohol entirely in alcohol-related cases can result in significant improvement in pumping function. Treating a thyroid disorder removes an additional strain on the heart. In autoimmune-related cases, medications that regulate the immune system may be recommended. When chemotherapy is identified as the cause, the responsible drug may need to be stopped or changed in discussion with the oncology team.

Complications

When dilated cardiomyopathy is not adequately treated or controlled, serious complications can develop over time.

• Heart failure. This is the most common and most significant complication. As the heart continues to weaken, it may gradually lose the ability to meet the body's needs. Breathlessness, swelling, and fatigue worsen progressively.
• Sudden cardiac arrest. The heart's electrical system can be disrupted by the structural changes in dilated cardiomyopathy, leading to life-threatening rhythm disturbances. The risk is particularly significant in patients with a very low ejection fraction.
• Atrial fibrillation and other rhythm disturbances. Rhythm problems are common in an enlarged heart. Atrial fibrillation causes palpitations and substantially increases the risk of clot formation and stroke.
• Heart valve problems. As the heart enlarges, the mitral valve in particular may no longer close properly, allowing blood to leak backward. This increases the workload on the heart further.
• Blood clots and stroke. Blood moves more slowly through an enlarged and poorly pumping heart, increasing the risk of clot formation, particularly in the upper chambers. Clots that reach the brain can cause a stroke.

Lifestyle

Dilated cardiomyopathy is a long-term condition. Lifestyle changes support medical treatment, relieve symptoms, and reduce the risk of complications and further deterioration.

Salt and Fluid Intake

Salt causes the body to retain fluid, increasing the strain on the heart. Reducing daily salt intake can significantly relieve breathlessness and swelling in patients with heart failure. Processed foods, canned goods, and fast food tend to be high in sodium. Reading food labels and choosing lower-sodium options is helpful. Ask your doctor for a specific daily salt target. In some patients, total fluid intake may also need to be monitored.

Daily Weight Monitoring

Weighing yourself at the same time each morning and recording the result is one of the most practical ways to detect fluid buildup before symptoms worsen. A gain of two to three pounds or more over a short period can indicate that fluid is accumulating. If this happens, contact your doctor. Ask your care team at what point a weight gain should prompt you to call or seek care.

Physical Activity

Remaining completely inactive is not the right approach in dilated cardiomyopathy. Regular light to moderate activity, such as short walks, can support heart function and improve overall wellbeing in many patients. However, the type and amount of exercise that is appropriate depends on your current heart function and should be determined by your doctor. High-intensity and competitive sport should generally be avoided. Cardiac rehabilitation programs offer a safe, supervised environment for physical activity and are strongly recommended after a major cardiac event or hospitalization.

Medications

Dilated cardiomyopathy typically requires long-term and often lifelong medication use. Taking medications consistently is essential. Do not stop any medication without speaking with your doctor first, even if you feel well. Missing doses or stopping treatment can lead to rapid deterioration. If a side effect is troubling you, talk to your doctor rather than stopping the medication on your own. Always inform any other treating physician about your heart medications before a new drug is started.

Smoking and Alcohol

Smoking directly damages the blood vessels and the heart muscle. Stopping is one of the most beneficial steps a person with dilated cardiomyopathy can take. Effective support is available through your doctor or pharmacist.

Alcohol is a direct cause of one form of dilated cardiomyopathy and can worsen others. Stopping alcohol completely or reducing consumption significantly can lead to meaningful improvement in heart function in some patients. Talk with your doctor about what is appropriate for your specific situation.

Informing Family Members

When dilated cardiomyopathy has a hereditary cause, first-degree relatives, including parents, siblings, and children, are recommended to undergo cardiac evaluation. The disease can be present without causing symptoms in its early stages. Screening allows early detection, and early treatment leads to significantly better long-term outcomes. Discuss this with your cardiologist.

Regular Follow-up

Dilated cardiomyopathy requires ongoing monitoring. Repeat echocardiograms, ECGs, and blood tests are used to assess how the heart is responding to treatment and whether adjustments are needed. Do not miss follow-up appointments. Contact your doctor promptly or seek emergency care if any of the following develop.

• Shortness of breath that returns or worsens
• Difficulty breathing when lying flat
• Swelling in the legs or ankles that is new or increasing
• A gain of several pounds over a short period
• Palpitations or a sensation of irregular heartbeat
• Dizziness or fainting
• Chest pain or pressure

Preparing for Your Appointment

Coming prepared to an appointment for dilated cardiomyopathy helps your doctor make a more accurate assessment and choose the most appropriate treatment for you.

What You Can Do

• Write down when symptoms began and how they have changed over time.
• Mention any family history of dilated cardiomyopathy, heart failure, or unexplained cardiac death at a young age.
• List all medications, supplements, and herbal products you are currently taking.
• Be honest about your alcohol and smoking habits.
• Mention any prior chemotherapy or cancer treatment.
• Bring any home weight or blood pressure readings you have recorded.
• Write your questions down before the appointment.

Questions You May Wish to Ask Your Doctor

• What is causing my dilated cardiomyopathy?
• Is this condition inherited and should my family members be screened?
• What is my ejection fraction and what does that number mean?
• Which medications do I need and for how long?
• Do I need an implantable device?
• What type and amount of exercise is safe for me?
• How much salt and fluid should I consume each day?
• Which symptoms should prompt me to seek emergency care?
• How often do I need follow-up appointments?

Questions Your Doctor May Ask You

• When did your symptoms begin and how have they progressed?
• Is there a family history of dilated cardiomyopathy or early-onset heart failure?
• How much alcohol do you drink and for how long?
• Have you received chemotherapy in the past?
• Do you have high blood pressure, diabetes, or a thyroid condition?
• Have you had a heart attack?
• What medications are you currently taking and are you taking them regularly?
• Does breathlessness worsen when you lie flat?