Dilated Cardiomyopathy

What happens in dilated cardiomyopathy

In DCM, the heart muscle fibers weaken and the left ventricle stretches to a larger, more rounded shape. The ejection fraction (the share of blood pumped out with each beat) falls below the normal range of about 50 to 70 percent. To compensate, the body retains salt and water and releases stress hormones, which help in the short term but strain the heart further over time. The result is heart failure with reduced ejection fraction.

Stretching of the ventricle can pull the mitral valve open, causing leakage (mitral regurgitation). Scarring and stretching also predispose to abnormal heart rhythms.

Causes

Genetic

Gene variants are found in a substantial share of people with DCM, particularly when it runs in families. Genes include TTN (titin, the most common), LMNA, MYH7, RBM20, FLNC and others. LMNA and FLNC variants carry a high risk of dangerous arrhythmias. First-degree relatives should be offered screening.

Acquired

• Alcohol: long-term heavy drinking (alcoholic cardiomyopathy); often improves if alcohol is stopped.
• Myocarditis: inflammation, usually after a viral infection.
• Chemotherapy: anthracyclines (doxorubicin), trastuzumab and some newer cancer drugs.
• Pregnancy: peripartum cardiomyopathy, in late pregnancy or the months after birth.
• Persistent fast heart rhythms such as uncontrolled atrial fibrillation (tachycardia-induced, often reversible).
• Drugs: cocaine and methamphetamine.
• Endocrine and nutritional causes: thyroid disease, severe thiamine or selenium deficiency.
• Autoimmune and infiltrative diseases: sarcoidosis, among others.
• Neuromuscular diseases: Duchenne and Becker muscular dystrophy.

When coronary artery disease causes a similar picture, it is called ischemic cardiomyopathy and is managed somewhat differently.

Symptoms

Symptoms often develop gradually:

• breathlessness on exertion, later at rest
• breathlessness lying flat or waking up gasping at night
• fatigue and reduced exercise capacity
• swelling of the ankles, legs and belly
• rapid weight gain from fluid
• palpitations
• dizziness or fainting
• chest discomfort

Some people have no symptoms and are diagnosed from an abnormal ECG or echocardiogram, or through family screening.

Diagnosis

• Echocardiogram: shows the enlarged ventricle and measures ejection fraction.
• ECG: may show rhythm problems or conduction delays.
• Blood tests: BNP or NT-proBNP (heart strain markers), kidney function, electrolytes, thyroid function, iron studies.
• Cardiac MRI: assesses scarring and inflammation, which helps identify the cause and arrhythmia risk.
• Coronary angiography or CT to rule out blocked arteries.
• Genetic testing, especially with a family history or certain features.
• Holter monitoring for arrhythmias.
• Endomyocardial biopsy in selected cases.

Treatment

Medicines

Guideline-directed medical therapy for heart failure with reduced ejection fraction uses four main classes, which together reduce hospital admission and death:

• ARNI (sacubitril/valsartan), or an ACE inhibitor or ARB
• beta blockers (carvedilol, metoprolol succinate, bisoprolol)
• mineralocorticoid receptor antagonists (spironolactone, eplerenone)
• SGLT2 inhibitors (dapagliflozin, empagliflozin)

Diuretics relieve fluid buildup. Anticoagulants are used with atrial fibrillation or a clot in the heart.

Devices

• Implantable cardioverter-defibrillator (ICD): protects against sudden cardiac death from dangerous rhythms, considered when the ejection fraction remains 35 percent or less despite treatment, or with high-risk genes.
• Cardiac resynchronization therapy (CRT): a special pacemaker that coordinates the ventricles in people with certain ECG patterns.

Treating the cause

• stopping alcohol and drugs
• controlling fast rhythms
• adjusting cancer treatment with cardio-oncology input
• treating thyroid disease or nutritional deficiency

Advanced heart failure

Left ventricular assist devices (LVADs) and heart transplantation are options for advanced disease.

Lifestyle

• limit salt, as advised
• weigh yourself daily and report rapid gains
• stay active with cardiac rehabilitation
• avoid alcohol, especially if it contributed
• get flu, COVID-19 and pneumococcal vaccines

Outlook

Outlook has improved considerably with modern treatment. Many people with DCM improve on medicines, and some recover normal or near-normal heart function, particularly with reversible causes such as alcohol, tachycardia, peripartum cardiomyopathy or myocarditis. Others have progressive heart failure. Regular follow-up, taking medicines consistently and family screening are key.

Frequently asked questions

What is dilated cardiomyopathy?

Dilated cardiomyopathy is a heart muscle disease in which the left ventricle becomes enlarged and weakened, so it cannot pump blood effectively. It is a common cause of heart failure and can be inherited or caused by alcohol, infection, medicines or pregnancy.

What are the symptoms of dilated cardiomyopathy?

Symptoms include breathlessness with activity or when lying down, fatigue, swelling of the legs and ankles, rapid weight gain, palpitations, dizziness and fainting. Some people have no symptoms early on.

Can dilated cardiomyopathy be reversed?

Sometimes. When the cause is alcohol, a fast heart rhythm, pregnancy, myocarditis or thyroid disease, treating it can lead to substantial recovery. Even in other cases, heart failure medicines often improve heart function.

What is the life expectancy with dilated cardiomyopathy?

It varies widely depending on the cause, severity and response to treatment. Many people live for decades with good treatment, and some recover heart function. Outlook is worse with advanced heart failure or high-risk genetic forms. A cardiologist can give an individual estimate.

Is dilated cardiomyopathy hereditary?

It can be. Gene variants are found in a substantial share of people, especially when relatives are affected. First-degree relatives are usually advised to have an echocardiogram and ECG, and genetic testing when a variant is found.