Cardiomyopathy

About Cardiomyopathy

Cardiomyopathy refers to diseases of the heart muscle, causing the heart muscle to become enlarged, thick, or rigid. The condition makes it harder for the heart to fill with blood, pump blood throughout the body and maintain a normal electrical rhythm.  The three most common types of cardiomyopathy are dilated, hypertrophic, and restrictive, and can be acquired (develops due to another disease, condition or factor), or inherited. Cardiomyopathy can affect people of all ages and races. The forms of cardiomyopathy include:

The most common type of dilated cardiomyopathy is Ischemic cardiomyopathy. The heart’s ability to pump blood is decreased because of enlargement (dilation) of the left ventricle usually related to coronary artery disease or blockages in the arteries supplying the heart with blood and oxygen. Often related to prior myocardial infarction/heart attack.

Hypertrophic cardiomyopathy typically occurs due to genetic disease or mutation in the cardiac muscle proteins.  The abnormal proteins result in the heart chamber (left ventricle) becoming thicker than normal and not relaxing (filling with blood) between beats.  The resulting stiffness is termed nonobstructive hypertrophic cardiomyopathy. In addition, the heart may contract in such a way as to block outflow of blood to the body, reducing the amount of blood taken in and pumped out to the body with each heartbeat.  This is called obstructive hypertrophic cardiomyopathy.

A variety of mutations are associated with enlargement of the left ventricle and failure to pump an adequate supply of blood to the body and compiled these mutations are termed other genetic or familial cardiomyopathies. These diseases are generally characterized by the absence of other common causes of heart failure such as coronary artery disease.

Transthyretin (trans-thy-re-tin) amyloid cardiomyopathy (ATTR-CM) is an infiltrative disease (amyloidosis) that is often underdiagnosed and potentially fatal disease of the heart muscle. In ATTR-CM, a protein called transthyretin that normally circulates in the bloodstream becomes misshapen and builds up in the heart, nerves, and other organs. When these amyloid deposits build up in the heart, the walls can become stiff, making the left ventricle unable to properly relax and fill with blood – called diastolic dysfunction. As the condition progresses, the heart can become unable to adequately squeeze to pump blood out of the heart, leading to heart failure.

Other infiltrative cardiomyopathies can be caused by a variety of metabolic diseases. The heart’s ventricles become rigid because abnormal tissue replaces the normal heart muscle. Consequently, the ventricles cannot relax normally and fill with blood, and the atria become enlarged. Blood flow in the heart is reduced over time. This can lead to problems such as heart failure or arrhythmias.

Similarly, cardiomyopathy can be developed by toxic causes such as therapeutic treatments and other medicines, environmental agents, illicit substances and natural toxins.  These may or may not be transient and are termed toxic cardiomyopathy.

The cause of cardiomyopathy may or may not be able to be identified.  Cardiomyopathy without an identified cause is termed Idiopathic cardiomyopathy and is generally characterized by the absence of other common causes of heart failure such as coronary artery disease.