Cardiomyopathy Explained: Causes, Symptoms, And Treatments

The American Heart Association broadly categorizes cardiomyopathy as primary or secondary, but with frequent overlap (via a 2021 review of studies in the International Journal of Molecular Sciences). Primary cardiomyopathy is primarily restricted to the heart; however, in secondary cases the heart condition develops as part of a systemic disorder that affects other organs. Of the three main type of cardiomyopathy, reports Johns Hopkins Medicine, dilated cardiomyopathy occurs most frequently and is distinguished by a heart that is enlarged and stretched, thus impairing its ability to pump out blood. 

It is more common in men and can occur in adults of all ages as well as in children. Rarely inherited, dilated cardiomyopathy can be caused by alcohol abuse, infections, or illicit drugs. Hypertrophic cardiomyopathy is associated with thickening of the left ventricle (lower chamber), which may impede blood flow to the body. It is the most common inherited from of cardiomyopathy and can occur at any age, continues Johns Hopkins Medicine. People with hypertrophic cardiomyopathy may develop arrythmias (irregular heartbeat), which can cause sudden death. The third major type of cardiomyopathy — restrictive cardiomyopathy — is marked by stiffness of the heart muscle that compromises its ability to relax and fill up with enough blood to pump out. It is the least common type in the United States and "often occurs due to an underlying problem, such as amyloidosis, hemochromatosis, scleroderma, or sarcoidosis" (via Johns Hopkins Medicine).  

Arrhythmogenic right ventricular dysplasia (ARVD) is a rare form of cardiomyopathy that causes irregular heart rhythms and can trigger sudden cardiac arrest in young athletes. 

As explained by the National Heart, Lung, and Blood Institute, some types of cardiomyopathies occur as a result of gene mutations that cause the heart to form and develop abnormally. These gene mutations can be passed down through families from generation to generation. Hypertrophic cardiomyopathy (one of the three major types of the disease) as well as arrhythmogenic cardiomyopathy are usually inherited. Rather than being genetic in origin, other forms of cardiomyopathy are acquired, i.e., they are secondary to another condition or disorder (via the Mayo Clinic). Although the cause of cardiomyopathy is often never determined, some conditions can lead to the development of the disease. 

Cardiovascular conditions implicated include long-term high blood pressure, heart damage from a heart attack, prolonged rapid heartbeat, heart valve issues, and excessive accumulation of iron in the heart (hemochromatosis). Other precipitating conditions are metabolic disorders (e.g., diabetes, obesity, or thyroid disease), connective tissue disease (e.g., Rheumatoid arthritis, lupus), and certain infections, including Covid-19 and, in particular, infections that cause cardiac inflammation. 

Cardiomyopathy can also develop from rare disorders such as amyloidosis (abnormal buildup of proteins in organs) and sarcoidosis (clumps of inflammatory cells – granulomas – form in organs including the heart and lungs), continues the Mayo Clinic. Unhealthy lifestyle habits such as long-term alcohol abuse, poor diet, cocaine, amphetamines, and anabolic steroids, complications around pregnancy, and cancer treatments (e.g., chemotherapy, radiation) may also lead to cardiomyopathy.

As with prevalence, the signs and symptoms of cardiomyopathy vary with the type (via a 2021 review of studies in the International Journal of Molecular Sciences). Symptoms of hypertrophic cardiomyopathy may be related to abnormal heart rhythms (arrythmia) and can include difficulty breathing (especially when physically active), chest pain, heart palpitations, or fainting. Some people with hypertrophic cardiomyopathy may have only a few or no symptoms for an extended time. Common symptoms of dilated cardiomyopathy include shortness of breath and fatigue as well as swelling in the ankles, feet, legs, abdomen, and veins in the neck, reports the American Heart Association. The dilation, or widening, of the heart weakens its contractions, potentially resulting in heart failure. 

As with hypertrophic cardiomyopathy, people with restrictive cardiomyopathy may be asymptomatic or may experience only minimal symptoms (via WebMD). Symptoms can occur at any age and can become more severe as the heart progressively worsens. They include shortness of breath, fatigue, inability to exercise, swollen legs and feet, chest pain, weight gain, fainting, palpitations, nausea, bloating, and reduced appetite. 

The medical treatment for cardiomyopathy is determined by any underlying disorders that preceded the development of the disease as well as by the particular type of cardiomyopathy, explains the Centers for Disease Control and Prevention (CDC). The main goals of treatment are to manage symptoms, delay the progression of the disease, and prevent severe outcomes such as sudden death. 

A variety of medications may be used to treat symptoms and underlying conditions, reports the Cleveland Clinic. For example, blood thinners such as warfarin (Coumadin) can help prevent blood clots while beta blockers such as propranolol (Inderal) lower blood pressure. Other medications are used to treat high cholesterol levels. Sometimes surgically implanted devices may be necessary to improve heart function. 

Patients with irregular heartbeats may need a pacemaker or implantable cardioverter defibrillator (ICD) to monitor heart rhythms and deliver electrical impulses as needed. In other patients, a left ventricular assist device (LVAD) may be used to improve blood flow through the heart. Non-surgical therapies include ablation procedures that destroy areas of heart tissue, notes the Mayo Clinic. Septal ablation targets segments of thickened heart muscle to improve blood flow through the heart while radiofrequency ablation is used to treat irregular heart rhythms. Open-heart surgery or a heart transplant are last resort treatments for severe cases of cardiomyopathy. 

Complications of cardiomyopathy can damage the heart and the brain, reports the NIH. Some people with the disease may experience arrythmias whereby disruption of the heart's electrical system causes the heart to beat too fast, too slow, or at irregular intervals. In other people with cardiomyopathy, the heart valves may become damaged. These valves have flaps that regulate blood flow in the right direction by opening and shutting with each heartbeat. Sometimes the heart is so weakened or damaged that it cannot pump sufficient blood and oxygen to the brain, kidneys, and other organs. This can lead to a potentially fatal condition called cardiogenic shock. Moreover, pooling of the blood in the heart can trigger the formation of blood clots which can impede blood flow to the brain and possibly cause a stroke. 

If not treated, the inability of the heart to pump enough blood to the body can result in life-threatening heart failure, notes the Mayo Clinic. In some cases of cardiomyopathy, the heart may abruptly stop beating, causing cardiac arrest and sudden death. 

Cardiomyopathy is a serious, life-threatening type of heart disease that worsens over time, reports the Cleveland Clinic. Nevertheless, treatment with medicines, surgery, or other modalities can improve outlook and quality of life. The prognosis varies among the three major types of the disease. According to Medscape, many people with dilated cardiomyopathy progress to heart failure. If heart function continues to deteriorate, mechanical circulatory support (e.g., LVAD, artificial heart) or a heart transplant may be required. Higher death rates from heart failure are associated with certain risk factors, including increasing age, male sex, and severe congestive heart failure (CHF). 

While more than half of patients with severe heart failure die each year, those with mild heart failure have a much better outlook. Death rates for people with hypertrophic cardiomyopathy are also high, though they have markedly improved over the past four decades, notes Medscape. The death rate for this type is considerably higher in younger patients, especially children. In many cases, death occurs suddenly and without any warning signs. 

It is often related to sports or any intense activity. People with hypertrophic cardiomyopathy are at high risk of recurrent heart failure. Among the major types of cardiomyopathies, restrictive cardiomyopathy has the worst prognosis, especially in children with heart failure (via Medscape). In people with this type of cardiomyopathy, the heart progressively deteriorates along with potential complications such as blood clots and pulmonary hypertension (high blood pressure in the arteries leading from the heart to the lungs). The five-year death rate for restrictive cardiomyopathy is 70%.