When you have an infection, your immune system produces special cells to fight off disease. If the infection affects your heart, the disease-fighting cells enter the heart. However, the chemicals produced by an immune response can damage the heart muscle. As a result, the heart can become thick, swollen, and weak. This leads to symptoms of heart failure.
Other causes of myocarditis may include:
Allergic reactions to certain medicines or toxins (alcohol, cocaine, certain chemotherapy drugs, heavy metals, and catecholamines)
Treatment is aimed at the cause of the problem, and may involve:
Anti-inflammatory medicines to reduce swelling
Diuretics to remove excess water from the body
If the heart muscle is weak, your health care provider will prescribe medicines to treat heart failure. Abnormal heart rhythms may require the use of other medicines. You may also need a device such as a pacemaker, or an implantable cardioverter-defibrillator to correct an irregular heartbeat. If a blood clot is in the heart chamber, you will also receive blood thinning medicine.
Rarely, a heart transplant may be needed if the heart muscle has become very weak or you have other health problems.
Your outcome can vary, depending on the cause of the problem and your overall health. Some people may recover completely. Others may have lasting heart failure.
Treat conditions that cause myocarditis promptly to reduce the risk.
Liu P, Baughman KL. Myocarditis. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 70.
McKenna W. Diseases of the myocardium and endocardium. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 60.
Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.