What is Dilated Cardiomyopathy ? Dilated cardiomyopathy is a disorder of the heart muscle, in which the abnormally enlarged lower chambers (ventricles) of the heart fail to pump adequate amount of blood, leading to heart failure.

• Dilated cardiomyopathy is often caused by coronary artery disease and myocarditis.
• The earliest symptoms are shortness of breath and fatigue on exertion.
• Electrocardiography and echocardiography help diagnose dilated cardiomyopathy.
• Dilated cardiomyopathy is generally treated with drugs that treat its cause.

Dilated cardiomyopathy is prevalent in the age group 20 – 60 years, but not strictly restricted to it. Men are more prone to this condition than women; and blacks, more than whites; the ratio of incidence being 3 : 1 in both cases. Every year, approximately 50 – 80 people out of every million develop dilated cardiomyopathy.

Causes of Dilated Cardiomyopathy

Coronary artery disease is the most common cause of dilated cardiomyopathy. Coronary artery disease impairs blood supply to the heart muscle, causing irreversible damage and death of the muscle, consequent to which, the blood pumping capacity of the heart becomes severely diminished. The remaining healthy heart muscle stretches (hypertrophies) to make up for the reduced capacity since stretched and taut heart muscle can pump with more force (much like a stretched rubber band). However, after a while, the hypertrophied heart muscle can no longer keep up this compensatory action, resulting in dilated cardiomyopathy leading to heart failure.

Myocarditis or inflammation of the heart muscle due to an infection can also result in dilated cardiomyopathy. When a viral infection is the cause, it is called viral cardiomyopathy. Coxsackie B virus infection is a common cause of viral cardiomyopathy in the U.S. Dilated cardiomyopathy can also result from a bacterial infection. The weakening of the heart muscle by the infection causes the muscles to stretch and thicken in a compensatory attempt, resulting in dilated cardiomyopathy, and often heart failure.

Obesity, diabetes, thyroid disease and persistent tachycardia (rapid heart rate) are also known to result in dilated cardiomyopathy.

Some substances such as, cocaine, and alcohol (especially when combined with poor nutrition), antidepressants, and a few chemotherapy drugs too cause this condition.

Extra stress to the heart during pregnancy and auto immune diseases like rheumatoid arthritis also may lead to dilated cardiomyopathy.

When dilated cardiomyopathy cannot be attributed to any identifiable cause, it is termed idiopathic dilated cardiomyopathy.

Symptoms

Shortness of breath and fatigue on exertion are the earliest symptoms of dilated cardiomyopathy. Heart failure due to the weak pumping action of the heart causes these symptoms.

A sudden fever may be the first symptom of the development of cardiomyopathy due to viral or bacterial myocarditis.

Palpitations or pronounced beating of the heart felt by the patient, is a sign of a dangerous (often fatal) abnormal heart rhythm (arrhythmias), caused by the damaged heart.

Due to the enlargement of the heart, there may be incomplete closing of the heart valves, leading to leakage and regurgitation of blood, further impairing the pumping action of the heart. Heart murmurs that can be picked up by through a stethoscope can identify this condition. The two atrioventrcular valves connecting the ventricles to atrium, namely, mitral valve and tricuspid valve are the most affected, because, it is often the ventricles of the heart that are abnormally enlarged.

The enlarged walls and the reduced pumping action of the heart, together precipitates the ideal condition for the formation of clots on the heart walls. When these clots become detached and travel through the blood vessels (emboli), they can cause partial or complete blockage of those vessels, resulting in damage to various organs. A block in the arteries supplying the brain can lead to stroke.

Irrespective of the cause of dilated cardiomyopathy, a severely damaged heart eventually precipitates symptoms of heart failure such as rapid heart rate and fluid retention in the limbs and lungs, finally culminating in death.

Diagnosis

The symptoms exhibited by the patient and physical examination can help diagnose cardiomyopathy. It is always followed by more accurate diagnostic tests to determine the cause as well as the extent of the disease.

• Electrocardiography (ECG) measures the electrical activity of the heart and can point out any abnormality but it is inconclusive at best.
• Echocardiography projects a real time image of the heart, giving a clear picture of its size and pumping action, making it the ideal diagnostic test for dilated cardiomyopathy,
• Magnetic resonance imaging (MRI), may help to identify the cause of dilated cardimyopathy as it gives very accurate and detailed pictures of the heart.
• Cardiac catheterization is a procedure in which a thin catheter is inserted into a major vein and guided into the heart. It can help assess more accurately, the pumping action of the heart as well as the pressure existing in the chambers of the heart. It can also collect a sample of the heart muscle for biopsy to determine whether the cardiomyopathy is due to any viral or bacterial infection. The extent of damage caused to the heart by coronary heart disease also can be correctly determined by this procedure.

Prognosis

Prognosis is very bleak, with less than 30% of those who suffer from dilated cardiomyoparthy surviving beyond five years from the onset of the disease. Also, half of the fatalities are sudden deaths, caused due to an abnormal heart rhythm which suddenly worsens. Statistics indicate that women survive for twice as long as men and whites twice as long as blacks.

Treatment Of Dilated Cardiomyopathy

1. The main focus of the medical treatment is on treating the underlying cause.
2. Drugs usually prescribed include ACE inhibitors, angiotensin II receptor blockers, beta-blockers, spironolactone or eplerenone, and low-dose digoxin. They help reduce symptoms and improve heart function thus prolonging life.
3. Antiarrhythmic drugs such as beta blockers and Amiodarone are used to prevent abnormal heart rhythm. They are given in small doses, gradually increasing the dosage by small amounts, as an overdose could have an adverse effect on the pumping action of the heart, further affecting the rhythm.
4. Pace makers may help correct abnormal electrical circuitry in the heart. Patients at greater risk of sudden death can get a cardioverter-defibrillator pacemaker implanted to regulate their heart function.
5. Warfarin, an anti coagulant, always forms an integral part of the treatment since the overly stretched walls of a sluggish heart is an ideal site for clot formation.
6. Avoiding physical strain and mental stress which may worsen heart function is a part of general treatment. Cutting sodium intake and use of diuretics may not prolong life but may improve the quality of life by reducing swelling and discomfort due to excess fluid collection in the lungs.
7. In spite of the risks involved in heart transplantation, it is often considered a viable option for persons with dilated cardiomyopathy, as this condition is almost always fatal, unless its cause can be correctly identified and successfully treated before severe heart failure occurs.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery

Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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