This is a common disease of unknown cause which affects the heart muscle, causing deterioration of the function of the myocardium. Thus, cardiomyopathy patients are often at risk of arrhythmia and/or sudden cardiac death, as well as eventual heart failure.
This disease is classified into two main types:
A- Primary/intrinsic cardiomyopathy Weakness in the muscle of the heart that is not due to external causes, which is further divided into:
1- Genetic: This cardiomyopathy exhibits an autosomal dominant inheritance. This means that this illness may run in families and can affect more than one member of a family. There are some common types that are inherited in this way, such as:
i- Hypertrophic cardiomyopathy: The heart muscle becomes thickened and stiff. As a result, the heart muscle cannot pump the blood out from the left ventricle to the body.
ii- Arrhythmogenic right ventricular cardiomyopathy (ARVC): Although this affects the right side of the heart, it may affect function of both sides. For example, there may be fibro-fatty replacement of the right ventricular myocardium and structural and functional abnormalities of the right ventricle associated with this disorder, which may diagnosed by electrocardiographic depolarisation/repolarisation changes. Moreover, this type causes sudden death or arrhythmias of right ventricular origin.
iii- Mitochondrial myopathy: A type of myopathy due to mitochondrial disease.
2- Mixed:
i- Dilated cardiomyopathy or DCM: This causes dilation and impaired function of one or both ventricles in the heart. The heart then cannot pump blood because it becomes weakened and enlarged. This disease may affect other organs such as the lungs or liver due to decreased heart function and may cause non-ischemic cardiomyopathy.
ii- Restrictive cardiomyopathy (RCM) is an uncommon cardiomyopathy in which the walls become rigid and the heart is restricted from stretching and filling with blood properly.
3- Acquired:
i- Takatsubo cardiomyopathy, also known as broken heart syndrome, is a type of non-ischemic cardiomyopathy. This type occurs due to a sudden temporary weakening of the myocardium by emotional stress, which may cause acute heart failure, lethal ventricular arrhythmias and ventricular rupture.
B- Secondary/extrinsic cardiomyopathy In which the cause is outside the myocardium itself:
1- Diabetic cardiomyopathy: An illness associated with diabetes affecting the heart muscle. It causes inability of the heart to circulate blood through the body and leads to heart failure.
2- Alcoholic cardiomyopathy is a type of dilated cardiomyopathy. This type occurs due to chronic long-term abuse of alcohol and leads to heart failure.
3- Ischemic cardiomyopathy is the major cause of coronary artery disease. This type occurs due to weakness in the muscle of the heart due to inadequate oxygen delivery to the myocardium.
Symptoms and signs:
1- Chest pain is common
2- Some severe cases are associated with heart failure, arrhythmias, and systemic embolisation.
3- ECG abnormalities are often present, flat or inverted T waves are most common as well as low-voltage QRS complexes.
4- Chest radiographs may be normal or may show congestive heart failure with pulmonary oedema or cardiomegaly.