There are five main types of cardiomyopathy: dilated, hypertrophic, restrictive, arrhythmogenic, and stress-induced (takotsubo). Each one weakens the heart muscle in a different way, changing its size, thickness, or stiffness. Some are inherited, some develop from other conditions, and some are temporary. A person can even have more than one type at the same time.
Dilated Cardiomyopathy
Dilated cardiomyopathy (DCM) is the most common form. The lower chambers of the heart, called the ventricles, stretch out and become larger. As they expand, their walls thin and weaken, and the heart loses its ability to pump blood efficiently. A healthy heart pushes out roughly 55 to 70 percent of its blood with each beat. In DCM, that drops below 40 percent, which means your organs and muscles receive less oxygen-rich blood than they need.
DCM has a strong genetic component. The most frequently involved gene is one that codes for titin, a giant protein that acts like a molecular spring inside heart muscle cells. Mutations in that gene show up in about 25 percent of families with inherited DCM and 18 percent of cases where no family history is identified. Another gene linked to DCM, called LMNA, accounts for roughly 8 percent of cases and tends to come with heart rhythm problems and conduction disease.
Not all DCM is inherited, though. Heavy alcohol use, viral infections of the heart, uncontrolled high blood pressure, and certain chemotherapy drugs can all trigger it. In many cases no clear cause is ever found, which doctors call “idiopathic.” Symptoms typically include fatigue, shortness of breath during activity, swollen legs, and difficulty lying flat at night. Because the heart is enlarged, it can also develop irregular rhythms.
Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy (HCM) is essentially the opposite structural problem. Instead of stretching, the heart muscle grows abnormally thick. That thickened wall can partially block the path blood takes out of the heart, forcing it to work harder with every beat. HCM is far more common than many people realize. A large U.S. study covering 2016 to 2023 found a prevalence of about 1 in 327 people, making it one of the most common genetic heart conditions.
Doctors diagnose HCM when the heart wall measures 15 millimeters or thicker on imaging, with no other explanation for the thickening (like long-standing high blood pressure or intense athletic training). Some specialists suspect HCM at slightly lower thicknesses, around 12 to 14 millimeters, particularly when other evidence points toward it.
Many people with HCM have no symptoms and live normal lives. Others experience chest pain, shortness of breath, dizziness, or fainting, especially during exercise. The condition carries a small risk of dangerous heart rhythms, which is why it occasionally makes headlines as a cause of sudden cardiac arrest in young athletes. For people at higher risk, an implantable device that monitors and corrects abnormal rhythms can be lifesaving.
Restrictive Cardiomyopathy
Restrictive cardiomyopathy (RCM) is rare and works differently from the other types. The ventricles don’t enlarge or thicken. Instead, the heart muscle stiffens. A stiff ventricle can’t relax properly between beats, so it fills with much less blood than it should. Even a small amount of incoming blood causes pressure inside the chamber to spike. Over time, the upper chambers (atria) stretch out because blood backs up waiting to enter the rigid ventricles.
RCM can result from conditions that deposit abnormal substances in the heart muscle. Amyloidosis, where misfolded proteins accumulate in tissues, is one of the more recognized causes. Iron overload (hemochromatosis), scar tissue from radiation therapy, and certain storage diseases can also stiffen the heart. Symptoms tend to mirror general heart failure: swelling in the legs and abdomen, fatigue, and breathlessness. Because the heart’s pumping strength may remain close to normal early on, RCM can be tricky to detect until the stiffness becomes significant.
Arrhythmogenic Cardiomyopathy
In arrhythmogenic cardiomyopathy, normal heart muscle is gradually replaced by fatty or scar tissue. This most commonly affects the right ventricle, though it can involve the left ventricle or both. The patches of abnormal tissue disrupt the electrical signals traveling through the heart, creating short circuits that lead to irregular rhythms. These rhythm disturbances can range from brief palpitations to life-threatening episodes.
The condition is typically inherited and caused by mutations in genes that code for proteins holding heart muscle cells together. It tends to show up in adolescents and young adults, and intense exercise can accelerate the disease. Diagnosis involves a combination of imaging to look for structural changes in the ventricle, electrical testing to identify characteristic abnormalities in the heart’s rhythm patterns, and sometimes a small tissue biopsy confirming that fibrous or fatty tissue has replaced muscle.
Because the primary danger is sudden cardiac arrest from an abnormal rhythm, treatment focuses on controlling those rhythms. People diagnosed with arrhythmogenic cardiomyopathy are generally advised to avoid competitive or high-intensity exercise, since vigorous activity appears to worsen the progression of muscle replacement.
Takotsubo (Stress) Cardiomyopathy
Takotsubo cardiomyopathy stands apart from the others because it is temporary. It strikes suddenly, usually after intense emotional or physical stress, such as the death of a loved one, a serious accident, or a major surgery. The bottom portion (apex) of the left ventricle balloons outward and stops contracting, while the base of the heart squeezes harder to compensate. This gives the heart a distinctive shape on imaging that resembles a Japanese octopus trap, which is where the name comes from.
During an episode, the heart’s pumping ability can drop dramatically, and the symptoms, including chest pain and shortness of breath, closely mimic a heart attack. The critical difference is that takotsubo is reversible. Heart function typically recovers within one to four weeks, with most studies reporting recovery times between about 11 and 24 days. Some patients experience an “inverted” pattern where the base of the heart balloons instead of the apex, but this is less common.
Peripartum Cardiomyopathy
Peripartum cardiomyopathy is a form of heart failure that develops in the final month of pregnancy or up to five months after delivery, when no other cause of heart failure can be identified. It most commonly appears in the last weeks before birth or the first weeks afterward. The heart dilates and weakens in a pattern similar to DCM, but the trigger is related to the unique cardiovascular stress of pregnancy.
Risk factors include being over 30, carrying multiples, having preeclampsia, and a history of high blood pressure. Some people recover heart function fully within months, while others develop lasting heart failure. Subsequent pregnancies carry a risk of recurrence, particularly for those whose heart function did not fully return to normal.
Genetic vs. Acquired Causes
Broadly, cardiomyopathies fall into two camps: those you’re born predisposed to and those caused by something external. Genetic cardiomyopathies, including most cases of HCM and arrhythmogenic cardiomyopathy, run in families and follow inheritance patterns that give each child of an affected parent roughly a 50 percent chance of carrying the gene variant. Genetic testing can identify at-risk family members before symptoms appear.
Acquired cardiomyopathies develop from damage or stress to previously healthy heart muscle. Chronic alcohol use, viral infections, uncontrolled diabetes, thyroid disorders, nutritional deficiencies, and exposure to certain toxins can all cause the heart to enlarge, stiffen, or weaken over time. In practice, many cases involve both: a person may carry a genetic vulnerability that only becomes apparent when an external stressor pushes the heart past its limits.
How Cardiomyopathy Is Managed
Treatment depends on the type and severity. For milder cases, medications that reduce the heart’s workload, control blood pressure, and prevent fluid buildup are the foundation. Many people with cardiomyopathy take a combination of drugs that help the heart pump more efficiently and prevent it from remodeling further.
When the heart’s pumping fraction drops below 35 percent and symptoms persist, an implantable device that detects and corrects dangerous rhythms may be recommended. This is particularly relevant for people with dilated or arrhythmogenic cardiomyopathy, where the risk of sudden cardiac arrest is elevated. For those with very advanced heart failure that doesn’t respond to other treatments, a mechanical pump or heart transplant becomes an option.
Lifestyle adjustments matter across all types. Limiting salt intake helps manage fluid retention. Moderate physical activity is encouraged for most cardiomyopathies, with the notable exception of arrhythmogenic cardiomyopathy and certain forms of HCM where intense exertion carries real risk. Avoiding alcohol is especially important when it may have contributed to the condition, since the heart can sometimes partially recover once the toxic exposure stops.