Cardiomyopathy refers to several diseases that affect the myocardium (heart muscle) and are associated with mechanical and/or electrical dysfunction. In cardiomyopathy, abnormal heart function results from weakness or structural changes in the myocardium.
There are four main types of cardiomyopathy as defined by the American Heart Association (AHA): arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, and restrictive cardiomyopathy. They are then categorized into two groups: primary or secondary. Primary cardiomyopathies may be genetic (inherited) or acquired (develop the condition). Secondary cardiomyopathies result from an underlying condition such as diabetes, thyroid disorders, chronic alcohol consumption, infection, or drugs/toxins (e.g., heavy metals, anthracyclines, cocaine). Clinical presentation varies from asymptomatic (without symptoms) to sudden cardiac death.
Therapies for cardiomyopathy aim to reduce the symptoms of heart failure and the risk of complications such as arrhythmia (irregular heartbeat or abnormal heart rhythm). Treatments may involve drugs, implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) to regulate the heartbeat and reduce the risk of fatal arrhythmias. In some cases, heart transplant may be necessary. General measures that may reduce mortality and prevent future occurrences of heart failure include controlling blood pressure and weight (through diet and exercise), reducing alcohol and sodium consumption, and quitting smoking.
Amyloidosis, arrhythmia, arrhythmogenic right ventricular cardiomyopathy, arrhythmogenic right ventricular dysplasia, ARVC, ARVD, broken heart syndrome, CAD, cardiac resynchronization therapy, congestive heart failure, coronary artery disease, CRT, dilated cardiomyopathy, diuresis, endomyocardial fibrosis, familial hypertrophic cardiomyopathy, HCM, heart disease, heart failure, hypertrophic cardiomyopathy, ICD, implantable cardioverter-defibrillator, ischemic cardiomyopathy, myocardium, peripartum cardiomyopathy, postnatal cardiomyopathy, pregnancy-induced hypertension (preeclampsia), primary cardiomyopathy, restrictive cardiomyopathy, sarcoidosis, secondary cardiomyopathy, stress cardiomyopathy.
types of the disease
There are four main types of cardiomyopathy as defined by the American Heart Association (AHA): arrhythmogenic right ventricular cardiomyopathy (ARVC), dilated cardiomyopathy, hypertrophic cardiomyopathy (HCM), and restrictive cardiomyopathy. Dilated cardiomyopathy may result from multiple causes and is the most common form of cardiomyopathy that affects the overall population of North America. HCM is genetic in origin, and is the most common cause of sudden death in athletes. Restrictive cardiomyopathy and ARVC are considered to be rarer forms of the disease.
The different types of cardiomyopathy are further classified by the AHA as primary or secondary. Primary cardiomyopathies cannot be attributed to other conditions (such as heart disease). Instead, they may be caused by genetic (inherited) factors, acquired factors, or a combination of genetic and acquired traits. Acquired causes of cardiomyopathy include inflammatory cardiomyopathy (myocarditis), post- or peripartum cardiomyopathy, and stress cardiomyopathy (broken heart syndrome). Secondary cardiomyopathy occurs as a result of another condition, such as an infection or a metabolic disease (e.g., diabetes or coronary heart disease).
Arrhythmogenic right ventricular cardiomyopathy (ARVC): Arrhythmogenic right ventricular cardiomyopathy (ARVC, formerly known as arrhythmogenic right ventricular dysplasia or ARVD) is a genetic disease that causes the myocardium to become fatty and fibrous. Though it mainly affects the right ventricle of the heart, it may also affect the left ventricle. In contrast to other forms of cardiomyopathy, ARVC seldom results in heart failure. However, it does cause abnormal heart function such as arrhythmia (abnormal heartbeat), which may be fatal.
Dilated cardiomyopathy: In dilated cardiomyopathy, the myocardium becomes weak, enlarged, and unable to pump blood efficiently. The prevalence of dilated cardiomyopathy in the United States is 36 per 100,000. It is considered the most common form of cardiomyopathy. After coronary artery disease (CAD) and hypertension (high blood pressure), dilated cardiomyopathy is the third most common cause of heart failure in the United States.
There are several types of dilated cardiomyopathy, which are caused by multiple factors (primary or secondary). The three types of dilated cardiomyopathy include ischemic cardiomyopathy, peripartum cardiomyopathy, and stress cardiomyopathy.
Ischemic cardiomyopathy is the most common form of dilated cardiomyopathy. It is most often caused by CAD or high blood pressure; however, viral infections, other heart diseases, or genetics may also contribute to ischemic cardiomyopathy.
Peripartum cardiomyopathy is usually diagnosed in women in their last month of pregnancy, or in the first five months following birth (also called postpartum cardiomyopathy). Although it is rare (affecting one in 1,000-4,000 live births), peripartum cardiomyopathy is more prevalent in women who are over age 30, obese, have pregnancy-induced hypertension (preeclampsia), or multiple births.
Excessive alcohol use may also cause dilated cardiomyopathy.
Hypertrophic cardiomyopathy (HCM): In hypertrophic cardiomyopathy (HCM), the myocardium is thickened. As a result, it becomes difficult for the heart to pump blood. Nearly one-half of deaths due to HCM occur during or after physical activity. Sudden death occurs due to lethal heart rhythm disturbances (ventricular fibrillation and ventricular tachycardia). It is the most common cause of sudden cardiac death in athletes as a result of structural heart changes in response to intense training. Because HCM is typically an inherited disorder, it is also called familial HCM. It is estimated that one of 500 people has the gene for HCM. However, it may also be acquired resulting from high blood pressure or aortic stenosis (narrowing or obstruction of the aortic valve causing restricted blood flow). Symptoms of HCM include chest pain, shortness of breath, dizziness, palpitations, and fatigue.
Restrictive cardiomyopathy: In restrictive cardiomyopathy, the heart is unable to function properly, due to stiffness of the myocardium. The heart is usually normal size (or slightly larger), but the myocardium of one or both ventricles (cavities or chambers) cannot relax after each heartbeat because of stiffness in the heart. Instead, the ventricles are restricted and do not fill with enough blood. Restrictive cardiomyopathy may have a genetic cause, or it may result from another myocardial disease.
Other: Stress cardiomyopathy (also known as broken heart syndrome or Takotsubo cardiomyopathy) is triggered by sudden intense physical or emotional stress (e.g., death of a loved one, fear, extreme anger). The clinical presentation is similar to that of a heart attack. The most common symptoms are chest pain, shortness of breath, and low blood pressure.