What is the Difference Between Myocarditis and Cardiomyopathy?

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Myocarditis and cardiomyopathy are two distinct but related conditions that affect the heart. The main differences between them are:

  • Definition: Myocarditis is an inflammation of the heart muscle, while cardiomyopathy is a chronic disease that affects the heart's muscle and its ability to pump blood.
  • Cause: Myocarditis is typically caused by an infection or an autoimmune response, leading to inflammation of the heart muscle. Cardiomyopathy, on the other hand, can be caused by various factors, including genetic disorders, systemic diseases like lupus, and even myocarditis.
  • Progression: Myocarditis usually resolves within a few weeks or months but can lead to cardiomyopathy in some cases. In long-term follow-up of acute myocarditis patients, approximately 20% diagnosed with myocarditis will eventually develop chronic cardiomyopathy.
  • Symptoms: Myocarditis can cause symptoms such as chest pain, palpitations, and fatigue. Cardiomyopathy, depending on the type, can lead to heart failure, arrhythmias, or other complications.
  • Diagnosis: The diagnosis of myocarditis is based on histological, immunological, and immune-histochemical criteria. Cardiomyopathy may be diagnosed through a combination of physical examination, medical history, blood tests, electrocardiography (ECG), and imaging studies.
  • Treatment: The treatment of myocarditis depends on the cause and the patient's symptoms. In some cases, treating the underlying cause, such as an infection, may be sufficient. In other cases, additional therapies may be needed. Cardiomyopathy treatment may require medications, lifestyle changes, or, in severe cases, heart surgery or transplantation.

Comparative Table: Myocarditis vs Cardiomyopathy

Myocarditis and cardiomyopathy are both disorders that affect the heart, but they have distinct differences in their definitions, causes, and manifestations. Here is a table summarizing the differences between the two:

Feature Myocarditis Cardiomyopathy
Definition Myocarditis is an inflammation of the myocardium, typically caused by infectious agents, systemic diseases, drugs, and toxins, with viral infections being the most common cause in developed countries. Cardiomyopathy is defined as a structural or functional abnormality of the myocardium that is not due to hypertension or pulmonary vascular disease. It is usually classified as dilated cardiomyopathy (DCM), hypertrophic obstructive cardiomyopathy (HOCM), or restrictive cardiomyopathy.
Causes Infection with Coxsackie B virus or adenovirus is the most common cause of myocarditis. Many other viruses, as well as bacterial infections, mycoplasma, fungi, protozoa, spirochetes, and rickettsia have also been reported to cause myocarditis. The cause of cardiomyopathy can be genetic, acquired, or unknown (idiopathic). Some cases of cardiomyopathy are related to myocarditis, but not all.
Symptoms The clinical symptoms associated with myocarditis are highly variable and may range from chest pain, palpitations, and heart failure to cardiogenic shock and death. Symptoms of cardiomyopathy can include fatigue, shortness of breath, chest pain, and palpitations, as well as complications such as atrial and ventricular tachyarrhythmias, atrioventricular valve regurgitation, and embolic events.
Diagnosis Diagnosis of myocarditis relies on clinical suspicion, histologic or immunohistologic evidence, as well as laboratory tests such as troponin and creatine phosphokinase levels. Diagnosis of cardiomyopathy involves a detailed clinical history, physical examination, echocardiogram, and other imaging studies.
Treatment Treatment for myocarditis depends on the severity and cause of the condition, and may include antiviral medications, anti-inflammatory therapies, or other supportive measures. Treatment for cardiomyopathy depends on the specific type and severity of the condition, and may include medications, lifestyle modifications, devices such as pacemakers, or even heart transplantation.

In summary, myocarditis is an inflammatory disorder of the heart, while cardiomyopathy is a structural or functional abnormality of the myocardium. The causes, symptoms, diagnosis, and treatment of these conditions differ, with myocarditis typically being caused by infections and cardiomyopathy having a more diverse range of causes and manifestations.