Cardiomyopathy

Types of Cardiomyopathy

• Dilated Cardiomyopathy (DCM):
  • The most common type. The heart's main pumping chamber (left ventricle) becomes enlarged (dilated) and weakened, leading to reduced pumping ability.
  • Can be idiopathic (unknown cause), inherited, or caused by chronic alcohol abuse, viral infections, uncontrolled high blood pressure, or coronary artery disease.
• Hypertrophic Cardiomyopathy (HCM):
  • The heart muscle, especially the walls of the ventricles, becomes abnormally thick (hypertrophied). This thickening makes it harder for the heart to pump blood and can block blood flow out of the heart.
  • Often inherited.
• Restrictive Cardiomyopathy (RCM):
  • The heart muscle becomes stiff and less elastic, meaning it can't relax properly and fill with blood between beats. The pumping ability may be normal initially, but filling is impaired.
  • Often caused by infiltrative diseases like amyloidosis, hemochromatosis, or sarcoidosis.
• Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC/ARVD):
  • A rare genetic disorder where the muscle tissue in the right ventricle is replaced by fatty and fibrous tissue. This disrupts the heart's electrical signals and leads to arrhythmias and sudden cardiac arrest.
• Unclassified Cardiomyopathies: Other types that don't fit into the main categories.

Causes

• Inherited Genes:
  • Many types, especially hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy, are inherited from parents.
  • Genetic mutations can affect the proteins that build heart muscle or organize its electrical activity.
• Coronary Artery Disease (CAD) and Heart Attack:
  • CAD can lead to dilated cardiomyopathy by reducing blood flow to the heart muscle, weakening it over time.
  • A prior heart attack can cause scarring that weakens a portion of the heart muscle.
• Chronic High Blood Pressure (Hypertension):
  • Uncontrolled hypertension forces the heart to work harder, leading to thickening (hypertrophy) and eventual weakening.
• Long-Term Alcohol Abuse: Can directly damage heart muscle cells, leading to dilated cardiomyopathy.
• Viral Infections:
  • Certain viral infections (e.g., coxsackievirus B, parvovirus B19, HIV) can cause myocarditis (inflammation of the heart muscle), which can lead to dilated cardiomyopathy.
• Diabetes: Poorly controlled blood sugar can contribute to heart muscle damage.
• Obesity: Increases the workload on the heart and is linked to metabolic syndrome, which contributes to heart disease.
• Thyroid Disease: Both hyperthyroidism and hypothyroidism can affect heart function.
• Infiltrative Diseases (for Restrictive Cardiomyopathy):
  • Amyloidosis: Abnormal protein deposits in the heart muscle.
  • Hemochromatosis: Iron overload in the heart muscle.
  • Sarcoidosis: Inflammatory cells infiltrate the heart.
• Certain Medications:
  • Some chemotherapy drugs (e.g., anthracyclines).
  • Some cancer drugs, like certain targeted therapies or immune checkpoint inhibitors.
  • Certain illicit drugs (e.g., cocaine, amphetamines).
• Pregnancy (Peripartum Cardiomyopathy): A rare form of dilated cardiomyopathy that develops during the last month of pregnancy or within five months after delivery.

Symptoms

• Shortness of Breath (Dyspnea): Especially with exertion or when lying flat (orthopnea), or waking up with shortness of breath (paroxysmal nocturnal dyspnea).
• Fatigue: Persistent tiredness.
• Swelling (Edema): In the legs, ankles, and feet, and sometimes the abdomen (ascites) due to fluid retention.
• Coughing or Wheezing: Due to fluid buildup in the lungs.
• Chest Pain or Pressure: Especially in hypertrophic cardiomyopathy with exertion.
• Dizziness, Lightheadedness, or Fainting (Syncope): Due to reduced blood flow to the brain or arrhythmias.
• Heart Palpitations: Sensations of a rapid, pounding, or fluttering heartbeat.
• Bloating or Fullness in the Abdomen: Due to fluid retention.
• Weight Gain: Due to fluid retention.

Diagnosis

• Medical History and Physical Exam: The doctor will ask about symptoms, family history of heart disease or sudden death, and risk factors. The exam may reveal heart murmurs, abnormal heart sounds, lung crackles (fluid), or leg swelling.
• Echocardiogram (Echo):
  • The most common and important test. Uses sound waves to create moving images of the heart.
  • Shows heart size, chamber function, thickness of heart walls, valve function, and pumping efficiency (ejection fraction). Essential for classifying the type of cardiomyopathy.
• Electrocardiogram (ECG/EKG): Records electrical signals in the heart. Can detect abnormal heart rhythms, signs of heart muscle damage, or thickening.
• Chest X-ray: Can show if the heart is enlarged or if there is fluid in the lungs.
• Blood Tests:
  • BNP (B-type Natriuretic Peptide): Elevated levels can indicate heart failure.
  • Cardiac Enzymes: To rule out a heart attack.
  • Thyroid Function Tests.
  • Iron Studies (for hemochromatosis), genetic tests (for inherited forms), viral studies, etc.
• Cardiac MRI (Magnetic Resonance Imaging): Provides detailed images of the heart muscle structure, scar tissue, and function. Very useful for diagnosing specific types and causes.
• Cardiac Catheterization and Coronary Angiography:
  • Invasive procedure to measure pressures in the heart chambers and visualize coronary arteries to rule out blockages as a cause of heart muscle weakness.
• Genetic Testing: Recommended for inherited forms of cardiomyopathy, both for diagnosis and family screening.
• Myocardial Biopsy (Heart Muscle Biopsy): (Rarely used) A small piece of heart muscle is taken for examination, usually when infiltrative diseases or myocarditis are suspected.

Treatment

• Medications:
  • ACE Inhibitors or ARBs (Angiotensin Receptor Blockers): Reduce blood pressure and the heart's workload, improving pumping ability.
  • Beta-Blockers: Slow heart rate, reduce blood pressure, and improve heart function.
  • Diuretics ("Water Pills"): To reduce fluid retention and swelling.
  • Aldosterone Antagonists: (e.g., spironolactone, eplerenone) Help remove excess fluid and may improve heart function.
  • Digoxin: Can improve the pumping ability of the heart and slow the heart rate in heart failure.
  • Blood Thinners (Anticoagulants): (e.g., warfarin, DOACs) To prevent blood clots, especially in dilated cardiomyopathy with reduced ejection fraction or atrial fibrillation.
  • Antiarrhythmics: To control irregular heart rhythms.
  • Specific Medications for Hypertrophic Cardiomyopathy: (e.g., mavacamten, disopyramide) Reduce obstruction or improve heart muscle relaxation.
• Implantable Devices:
  • Pacemaker: For slow heart rates or to synchronize heart contractions (Cardiac Resynchronization Therapy - CRT).
  • Implantable Cardioverter-Defibrillator (ICD): For high-risk patients to prevent sudden cardiac death by delivering an electrical shock to correct dangerous arrhythmias.
• Procedures/Surgery:
  • Septal Myectomy: (For obstructive HCM) Surgical removal of a small part of the thickened heart muscle to relieve obstruction.
  • Alcohol Septal Ablation: (For obstructive HCM) Injecting alcohol into an artery supplying the thickened septum to thin the muscle.
  • Ventricular Assist Devices (VADs): Mechanical pumps implanted in the chest to help the heart pump blood, as a bridge to transplant or destination therapy.
  • Heart Transplant: For end-stage cardiomyopathy that is severe and unresponsive to other treatments.
• Lifestyle Modifications:
  • Sodium Restriction: To manage fluid retention.
  • Fluid Management: As advised by doctor.
  • Regular, Moderate Exercise: As tolerated and advised by doctor.
  • Weight Management.
  • Avoid Alcohol and Illicit Drugs.
  • Manage Underlying Conditions: (e.g., blood pressure, diabetes, thyroid disease).

Living With Cardiomyopathy

The difference between a stable decade and a series of hospital stays usually comes down to a few routines: taking the right combination at full dose, weighing yourself daily, knowing which symptoms cannot wait, and getting relatives checked.

Four drug classes, taken together and at target

For cardiomyopathy with a weakened pump, four classes are used together: a beta-blocker such as carvedilol, metoprolol succinate, or bisoprolol; an ACE inhibitor, ARB, or sacubitril-valsartan; spironolactone; and an SGLT2 inhibitor such as dapagliflozin or empagliflozin, which helps even without diabetes. Each is started low and raised every few weeks toward the dose proven in trials, and feeling better at a low dose is a reason to keep going, not to stop. Potassium and kidney function are checked after each increase. The heart failure page covers the fluid rules.

Hypertrophic cardiomyopathy runs on different rules

When the muscle is thick rather than weak, the goal is a slower, fuller heartbeat: beta-blockers or verapamil are the mainstays, dehydration and heavy alcohol are avoided because they worsen the outflow obstruction, and medications that drop blood pressure sharply, including some for erectile dysfunction, are used cautiously. Fainting during exertion is treated as an emergency, since it can precede a dangerous rhythm.

Daily weight and the two-pound rule

Weigh yourself each morning before breakfast. A gain of two to three pounds overnight or five pounds in a week is fluid, not fat, and is the signal to call so a diuretic such as furosemide can be adjusted before breathlessness sets in. Our early signs of heart failure article lists the other changes worth reporting. In Florida's heat, diuretics plus sweating cause dizziness and kidney strain; our humidity and heart health guide covers adjusting.

Rhythm, clots, and the device question

Atrial fibrillation is common in every type of cardiomyopathy and usually calls for a blood thinner such as apixaban; palpitations with lightheadedness or fainting are evaluated urgently for ventricular tachycardia. A defibrillator is considered when the ejection fraction stays low after three months of full treatment, or earlier in inherited forms with high-risk features, and a shock from one is a reason to be seen the same day.

Family screening and reversible causes

First-degree relatives of anyone with hypertrophic, arrhythmogenic, or unexplained dilated cardiomyopathy are offered an ECG and echocardiogram, and genetic testing when a variant is found. Treating sleep apnea, hemochromatosis, thyroid disease, and alcohol use disorder can partly or fully restore heart function. Our cardiovascular team coordinates care between cardiology visits. The NHLBI and MedlinePlus publish patient guidance on living with cardiomyopathy.

If you have cardiomyopathy and are not on all four medication classes, or have not weighed yourself this week, schedule a visit.