Dilated cardiomyopathy (DCM) is a condition where the heart becomes enlarged and weakened, making it harder for the heart to pump blood effectively. Over time, this can lead to heart failure and other serious complications such as irregular heart rhythms or blood clots. It is one of the most common causes of heart failure and a leading reason for heart transplantation around the world. 

While DCM can affect anyone, it most often appears in adults between the ages of 20 and 60 and tends to affect men slightly more than women. Understanding its causes, symptoms, and treatment options can help people with DCM live longer and healthier lives. 

In dilated cardiomyopathy, one or both of the heart’s main pumping chambers (ventricles) become stretched and thin. Because the heart muscle is weaker, it cannot pump blood as forcefully as it should. This leads to a reduced ejection fraction (the percentage of blood pumped out with each heartbeat), usually below 40%. 

Over time, the heart may continue to enlarge, increasing the risk of heart failure, irregular rhythms, and blood clots. Unlike heart disease caused by blocked arteries, DCM happens even when the coronary arteries are normal. 

Dilated cardiomyopathy affects about 1 in 250 people. It accounts for more than one-third of all cases of heart failure with reduced ejection fraction. 

• Age: Most common between ages 20 and 60 

• Gender: Slightly more common in men 

• Leading cause of heart transplant in both adults and children 

Because DCM can run in families, early screening and diagnosis can help protect relatives at risk. 

Dilated cardiomyopathy can have many different causes, and sometimes no clear cause is found. It can result from a combination of genetic, environmental, and lifestyle factors. 

Common causes 

• Genetic causes: About half of all cases run in families and are linked to gene changes that affect heart muscle structure. 

• Viral infections: Certain viruses can inflame the heart muscle (myocarditis), leading to damage and enlargement. 

• Alcohol and toxins: Heavy alcohol use, certain chemotherapy drugs, and drug use (such as cocaine) can weaken the heart. 

• Autoimmune and inflammatory diseases: Conditions like lupus, rheumatoid arthritis, or sarcoidosis can affect the heart. 

• Hormonal and metabolic disorders: Thyroid problems, diabetes, or vitamin deficiencies (such as low thiamine or selenium) may contribute. 

• Pregnancy-related (peripartum) cardiomyopathy: In rare cases, DCM can occur during or shortly after pregnancy. 
• Rapid or abnormal heart rhythms: Long-term fast heart rates can stretch and weaken the heart muscle. 

Risk factors 

• Family history of cardiomyopathy or sudden cardiac death 

• Viral or autoimmune illnesses 

• Long-term heavy drinking 

• Uncontrolled high blood pressure or diabetes 

• Obesity or poor diet 

• Exposure to toxins or chemotherapy drugs 

In many cases, no single cause is identified, which doctors refer to as idiopathic dilated cardiomyopathy. 

Dilated cardiomyopathy develops gradually. When the heart muscle is injured—by a virus, genetic mutation, or toxin—the affected cells cannot contract normally. To make up for the lost strength, the heart stretches and enlarges, allowing it to hold more blood. However, this temporary fix actually makes the problem worse over time. 

As the heart expands, the muscle walls become thinner and weaker, leading to poor blood flow and fluid buildup in the lungs and body. The heart’s electrical system can also become unstable, increasing the risk of irregular rhythms and sudden cardiac arrest. 

The process often follows this pattern: The progression typically begins with an initial injury to the heart muscle, followed by gradual enlargement of the chambers, a weakening of the pumping action, and eventually the appearance of heart failure symptoms and rhythm disturbances. 

Symptoms of dilated cardiomyopathy can range from mild to severe and often develop slowly. Many people don’t realize they have it until the heart becomes significantly weakened. 

Common symptoms 

• Shortness of breath, especially with activity or when lying flat 

• Tiredness or weakness 

• Swelling in the feet, ankles, or abdomen 

• Sudden weight gain from fluid buildup 

• Coughing, especially at night 

• Difficulty concentrating or feeling lightheaded 

Other possible symptoms 

• Irregular or rapid heartbeat (palpitations) 

• Chest discomfort 

• Fainting or feeling dizzy 

• Stroke-like symptoms from blood clots 

If you notice increasing shortness of breath, swelling, or fainting spells, it’s important to contact a healthcare provider promptly. 

Doctors diagnose DCM using a combination of medical history, physical exam, and specialized tests. Because its symptoms overlap with other heart conditions, testing helps confirm the diagnosis and rule out other causes. 

Tests used to diagnose DCM 

• Echocardiogram: An ultrasound of the heart that shows enlarged chambers and reduced pumping function. 

• Electrocardiogram (ECG): Records the heart’s electrical activity to detect irregular rhythms or damage. 

• Cardiac MRI: Provides detailed images of the heart’s structure and any scarring. 

• Blood tests: Check for thyroid problems, infections, or markers of heart failure (such as BNP or NT-proBNP). 

• Chest X-ray: Shows if the heart is enlarged or if fluid has built up in the lungs. 

• Coronary angiography: May be done to rule out blockages in the heart’s arteries. 

• Genetic testing: Recommended if a family history of DCM or sudden cardiac death is present. 

In rare cases, doctors may perform a heart biopsy to identify inflammation or unusual conditions like sarcoidosis. 

Several conditions can mimic DCM, and doctors must rule these out before confirming the diagnosis: 

• Ischemic heart disease (caused by blocked arteries) 

• High blood pressure–related heart changes 

• Valvular heart disease 

• Hypertrophic or restrictive cardiomyopathy 
• Pericardial diseases (like constrictive pericarditis) 

The goals of treatment are to help the heart work more efficiently, reduce symptoms, and prevent complications like heart failure, blood clots, and sudden cardiac death. 

Lifestyle and general measures 

• Limit salt intake to reduce swelling 

• Avoid alcohol and recreational drugs that can weaken the heart 

• Maintain a healthy weight and exercise safely as advised by your doctor 

• Take medications consistently and attend all follow-up appointments 

• Stay up to date on vaccinations, especially flu and pneumonia 

Medications 

• ACE inhibitors or ARBs: Help relax blood vessels and reduce the heart’s workload 

• Beta-blockers: Slow the heart rate, improve pumping, and lower the risk of irregular rhythms 

• Diuretics: Reduce fluid buildup and relieve swelling 

• Aldosterone blockers: Help remove excess salt and fluid 

• SGLT2 inhibitors: Newer drugs shown to improve heart failure outcomes 

• ARNI (sacubitril/valsartan): A combination medication that can further improve survival 

Devices and advanced treatments 

• Implantable cardioverter-defibrillator (ICD): Prevents sudden cardiac death from dangerous arrhythmias 

• Cardiac resynchronization therapy (CRT): Helps the heart’s chambers beat in sync for better efficiency 

• Left ventricular assist device (LVAD): A mechanical pump used in severe heart failure 

• Heart transplantation: Considered for people with end-stage disease who do not respond to other treatments 

Blood-thinning medication 

People with irregular rhythms or evidence of blood clots may need anticoagulants to reduce the risk of stroke. 

Without treatment, DCM can lead to several serious complications: 

• Chronic heart failure and fluid buildup 

• Irregular heart rhythms (arrhythmias) 

• Stroke or blood clots from sluggish blood flow 

• Heart valve leakage (especially mitral or tricuspid regurgitation) 

• Cardiogenic shock in advanced stages 

Regular follow-up and adherence to treatment can greatly reduce these risks.

The outlook for DCM varies. Some people experience significant improvement with medication and lifestyle changes, while others may develop progressive heart failure. 

• With modern therapies, many patients live 10 years or longer after diagnosis. 

• Early diagnosis and adherence to treatment can improve survival and quality of life. 

• Genetic testing and family screening can help identify at-risk relatives before symptoms start. 

While not all cases of DCM can be prevented, many steps can reduce the risk: 

• Avoid excessive alcohol and recreational drug use 

• Treat high blood pressure, diabetes, and thyroid problems early 

• Get prompt care for viral infections that affect the heart 

• Eat a balanced diet rich in fruits, vegetables, and lean proteins 

• Exercise regularly under medical supervision 

• Have regular heart checkups, especially if you have a family history of DCM 

Living with DCM means finding the right balance between medical care, lifestyle habits, and emotional well-being. 

• Follow your treatment plan closely and never stop medications without your doctor’s advice. 

• Monitor symptoms daily, such as weight changes, swelling, or shortness of breath. 

• Stay active safely, with low-impact exercise like walking or cycling. 

• Eat a heart-healthy diet that’s low in sodium and processed foods. 

• Seek support from family, friends, or heart failure support groups. 

With the right care, many people with dilated cardiomyopathy live full, active lives for years. 

Dilated cardiomyopathy is a serious but manageable condition. By recognizing symptoms early, following medical advice, and making healthy lifestyle choices, people with DCM can reduce their risk of complications and improve their quality of life. Advances in medications, devices, and heart transplants continue to offer hope for those living with this condition. 

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