OVERVIEW

What is idiopathic cardiomyopathy?

Cardiomyopathy can be divided into idiopathic cardiomyopathy (also known as primary cardiomyopathy), which has no identifiable cause, and secondary cardiomyopathy (also called specific cardiomyopathy), which is clearly associated with other diseases. The cause of idiopathic cardiomyopathy is unknown, but it is currently believed to be related to genetic and environmental factors. Recent perspectives also suggest a possible link to viral infections.

Idiopathic cardiomyopathy often develops insidiously and progresses gradually, leading to abnormal changes in heart structure and function, eventually resulting in heart failure. Early stages may show no obvious symptoms, but as the disease progresses, symptoms of pump failure (congestive heart failure) often appear, such as exertional dyspnea and paroxysmal nocturnal dyspnea.

How is idiopathic cardiomyopathy classified?

Based on clinical manifestations and pathological structural changes, idiopathic cardiomyopathy can be classified into dilated cardiomyopathy (also called congestive cardiomyopathy), hypertrophic cardiomyopathy, and restrictive cardiomyopathy, with the first two being more common.

• Dilated cardiomyopathy: A common cause of heart failure, characterized by enlargement of the left ventricle or the entire heart and reduced systolic function. As the disease progresses, myocardial cell necrosis and endocardial calcification occur, leading to impaired pumping function, restricted left ventricular emptying, and gradual heart enlargement, causing relative insufficiency of the atrioventricular valves and ultimately congestive heart failure.

• Hypertrophic cardiomyopathy: Characterized by myocardial hypertrophy, most commonly affecting the left ventricle and interventricular septum, resulting in asymmetric or concentric ventricular hypertrophy. It is often linked to genetic factors, typically autosomal dominant inheritance, with 60%–70% of cases having a family history.

• Restrictive cardiomyopathy: Characterized by primary myocardial and/or endocardial fibrosis, increased myocardial stiffness, leading to impaired filling of one or both ventricles (reduced diastolic function), while systolic function and ventricular wall thickness remain mostly normal. It mainly manifests as impaired diastolic function, reduced ventricular compliance, decreased venous return, and subsequently reduced ejection fraction and cardiac output.

Is idiopathic cardiomyopathy serious?

The prognosis of idiopathic cardiomyopathy is poor, with the majority of patients dying from heart failure, and some experiencing sudden cardiac death.

SYMPTOMS

What are the common manifestations of idiopathic cardiomyopathy?

• In the early stages, idiopathic cardiomyopathy may present no specific symptoms or only nonspecific manifestations such as fatigue.

• As cardiac function declines, symptoms of heart failure gradually appear:

  • Early signs may include reduced exercise tolerance and increased heart rate;

  • Exertional dyspnea, where varying degrees of physical activity trigger breathlessness or difficulty breathing, which improves with rest;

  • Paroxysmal nocturnal dyspnea, worsening when lying flat and improving upon sitting up;

  • Severe dyspnea may be triggered by factors such as colds, straining during bowel movements, or emotional stress, leading to orthopnea, rapid breathing, restlessness, frequent coughing, and the production of large amounts of pink, frothy sputum;

  • Patients with severe arrhythmias may experience paroxysmal palpitations, transient vision loss (amaurosis), or even syncope and sudden death.

What severe consequences can idiopathic cardiomyopathy cause?

• Severe heart failure can lead to loss of work capacity and significantly reduce the quality of daily life;

• Cardiac enlargement and structural changes in the heart chambers and valves may result in malignant arrhythmias, thromboembolism, and in severe cases, sudden death;

• Idiopathic cardiomyopathy ultimately progresses to heart failure. In some patients, heart failure is difficult to control, and drug therapy is ineffective, necessitating heart transplantation. Heart failure is the primary cause of death in this disease.

CAUSES

What causes idiopathic cardiomyopathy?

The exact cause of idiopathic cardiomyopathy remains unclear. Research suggests its development may be associated with the following factors:

• The chronic phase or subsequent damage caused by viral myocarditis.

• Localized immune-mediated myocardial injury triggered by certain protozoa, such as Toxoplasma.

• Autoimmune antigen-antibody reactions in the heart induced by infections, toxins, or other factors.

• Familial or hereditary factors.

• Activation of apoptosis programs due to genetic mutations.

DIAGNOSIS

Under what circumstances should idiopathic cardiomyopathy be considered?

After excluding other heart diseases (such as coronary heart disease, congenital heart disease, rheumatic heart disease, inherited metabolic disorders, secondary cardiomyopathy, and chronic constrictive pericarditis), the following conditions should raise suspicion of idiopathic cardiomyopathy:

• Symptoms of heart failure at various stages, such as exertional dyspnea, paroxysmal nocturnal dyspnea, or lower limb edema, without evidence of other heart diseases.

• Unexplained episodes of syncope.

• Unexplained systemic (or pulmonary) arterial embolism.

• Unexplained cardiomegaly, especially spherical enlargement observed on imaging.

• Unexplained ECG changes, such as ST-segment and T-wave abnormalities, or various arrhythmias.

What tests are needed to diagnose idiopathic cardiomyopathy?

• Echocardiography is currently the most commonly used diagnostic tool for cardiomyopathy, providing multi-planar visualization of ventricular structure, myocardial thickness, valve abnormalities, and myocardial motion.

  • Dilated cardiomyopathy: Echocardiography reveals left ventricular enlargement, thinning of the ventricular wall, reduced wall motion, and decreased cardiac output.

  • Hypertrophic cardiomyopathy: Echocardiography shows increased interventricular septal thickness (ratio of septal thickness to left ventricular posterior wall thickness ≥ 1.30 in diastole) and systolic anterior motion of the mitral valve.

  • Restrictive cardiomyopathy: Echocardiography demonstrates reduced ventricular cavity size, restricted ventricular filling, significant right atrial enlargement with a small right ventricle, and diffuse endocardial thickening.

• Cardiac magnetic resonance imaging (MRI) provides detailed analysis of regional myocardial systolic and diastolic function, measures myocardial blood flow, and assesses the extent of myocardial fibrosis. With higher objectivity and reproducibility, it has become the gold standard for cardiomyopathy diagnosis.

• Endomyocardial biopsy: This invasive procedure allows pathological evaluation of endocardial or myocardial fibrosis, amyloidosis, or other abnormalities. Due to its high risk, widespread use is limited.

TREATMENT

Which department should be consulted for idiopathic cardiomyopathy?

If idiopathic cardiomyopathy is suspected, the cardiology department should be visited.

How should idiopathic cardiomyopathy be treated?

There is no specific treatment for idiopathic cardiomyopathy, and symptomatic treatment is the main approach to delay the progression of heart failure and reduce complications.

• Basic drug therapy for heart failure includes angiotensin-converting enzyme inhibitors (ACEIs), diuretics, and positive inotropic agents.

• Some patients with idiopathic cardiomyopathy may develop arrhythmias: those with tachyarrhythmias can be treated with beta-blockers to improve long-term prognosis, while severe cases may undergo electrophysiological therapy or implantable defibrillator therapy as needed; severe bradyarrhythmias may require pacemaker implantation.

• Patients with hypertrophic obstructive cardiomyopathy who respond poorly to drug therapy may consider surgical resection of the hypertrophic myocardium to relieve symptoms.

• Patients with restrictive cardiomyopathy may consider surgical removal of fibrotic and thickened endocardium to alleviate the condition.

• Those with altered valve structures may undergo artificial valve remodeling or replacement as appropriate.

• For severe heart failure patients with poor response to drug therapy, heart transplantation may be considered.

• Prevention of thromboembolic complications is important, and oral anticoagulants or antiplatelet drugs may be used when necessary.

DIET & LIFESTYLE

Can patients with idiopathic cardiomyopathy work normally?

In the early stages of idiopathic cardiomyopathy, patients with relatively preserved heart function can engage in light physical work. As the disease progresses and heart function declines, they gradually lose their ability to work and become unable to perform regular jobs.

Can patients with idiopathic cardiomyopathy exercise?

Those with good cardiac function can engage in moderate physical activity and do not need strict bed rest. However, physical exercise increases cardiac load and heart rate, which may trigger acute heart failure in patients with poor heart function. Therefore, patients with idiopathic cardiomyopathy are advised to exercise cautiously.

Are there any dietary precautions for patients with idiopathic cardiomyopathy?

Patients with idiopathic cardiomyopathy should maintain a light diet, avoid overly salty foods, and eat more fruits and vegetables.

What lifestyle precautions should patients with idiopathic cardiomyopathy take?

• Avoid excessive stress and maintain emotional stability;

• Avoid catching cold and prevent flu. Adjust clothing according to seasonal changes;

• Avoid contact with people who have colds to prevent infection;

• Ensure adequate rest and avoid overexertion;

• Follow medical advice for regular check-ups and take medications on time;

• Seek immediate medical attention if sudden complications such as chest pain, hemoptysis, breathlessness, difficulty breathing, hemiplegia, or coma occur.

PREVENTION

How to Prevent Idiopathic Cardiomyopathy?

The cause of idiopathic cardiomyopathy is unknown. Daily prevention mainly focuses on maintaining a healthy lifestyle, such as regular routines, a balanced diet, and improving physical fitness. Individuals with a family history may undergo genetic testing and regular health check-ups.