Myocarditis is the inflammation of the heart muscle (myocardium) that leads to a disease process presenting with various clinical signs and symptoms. It usually occurs in a healthy individual that can lead to heart failure and arrhythmia. Myocarditis is equivalent to inflammatory cardiomyopathy in clinical context. Various infectious agents, such as viruses (enterovirus, adenovirus), bacteria (mycobacteria, chlamydia), fungi (Candida, Aspergillus), parasites (schistosomiasis, larva migrans), protozoans (Trypanosoma cruzi, Toxoplasma gondii), autoimmunity (influenza vaccine, postinfectious), allergens (penicillin, tricyclic antidepressants) and toxins (alcohol, chemotherapeutic drugs) are implicated in the etiology of myocarditis. In about 50% cases, myocarditis is idiopathic. While in developed nations, viral etiology is common, bacterial, fungal and protozoal etiology is more common in developing countries.
Lieberman has classified myocarditis into fulminant myocarditis, acute myocarditis, chronic active myocarditis and chronic persistent myocarditis. In acute myocarditis, myocardial inflammation is followed by left ventricular or right ventricular pathology. Chronic myocarditis is also subsequent to persistence of chronic inflammation after a chronic infection.(1)
What Is The Treatment Objective For Myocarditis?
The diagnosis of myocarditis is based on medical history, clinical examination, laboratory tests, electrocardiography, echocardiography, diagnostic catheterization, magnetic resonance imaging, computed topography, scintigraphy, and endomyocardial biopsy.
The objective of treatment of myocarditis is to provide supportive care to prolong life and to reduce congestion and improve cardiac hemodynamics in heart failure. The question whether myocarditis is treatable or not depends on the underlying etiology. Various chronic viral infections, autoimmune or post infectious myocarditis are treatable.
Supportive care to manage heart failure or arrhythmia is independent of the underlying etiology and is the same for all the patients suffering from them. Specific treatment depends on the underlying etiology, clinical symptoms and the disease course.
Since most of the cases of viral myocarditis are mild, the recovery is with simple supportive care along with slow rehabilitation and evidence based medical therapy. Further, echocardiography should be performed in future to evaluate the resolution of myocarditis. Vaccinations are given to prevent influenza, measles, mumps, rubella, and poliomyelitis. Bed rest is necessary during the active disease course. Lifestyle modifications with diet (low salt diet) and exercise (low intensity exercises and avoidance of high intensity exercises) is suggested for patients with myocarditis to avoid exacerbation of symptoms of heart failure.
It is important to treat the underlying cause as well as remove the cause, if possible, such as alcohol or cardiotoxic drugs. Supportive therapy for symptoms of acute heart failure includes nitroglycerin/nitroprusside, diuretics, and angiotensin-converting enzyme. In some cases, where severe decompensation has taken place, there might be need for inotropic agents (milrinone, dobutamine). ACE inhibitors, aldosterone receptor antagonists and beta blockers are given for long term management, although they cannot be given initially due to hemodynamic imbalance. It is recommended to use anticoagulants prophylactically just like other heart failure cases. Immunosuppressive agents are used for underlying systemic autoimmune disease (sarcoid myocarditis, giant cell myocarditis). NSAIDs are contraindicated in the acute phase due to risk of exacerbation of inflammatory process initially.
Surgical intervention is required in some patients, especially those with complete heart block, lymphocytic myocarditis, tachyarrhythmia, giant cell myocarditis or ventricular ectopy. Monitoring is important part of myocarditis management. Initially, monitoring should be done at 1-3 months interval followed by gradual re-adaptation to physical exercise. Mild cases of myocarditis recover completely, although some develop dilated cardiomyopathy.(2)
Patients with myocarditis can present with symptoms similar to myocardial infarction, arrhythmias and/or heart failure that develops within days. Additionally, they may show non-specific symptoms unrelated to cardiac origin. Cardiac involvement is only suspected as a differential diagnosis when cardiac symptoms, such as dyspnea, edema, tachycardia, angina and palpitations persist for a longer duration following a resolving underlying infection. Viral myocarditis is preceded by a recent history (within 1-2 weeks) of flu like symptoms, including fever, malaise, sore throat, upper respiratory tract infection, arthralgia and tonsillitis. An underlying ventricular arrhythmias or atrioventricular block may lead to symptoms of palpitations, syncope or even sudden cardiac death.(1)
- https://emedicine.medscape.com/article/156330-overview#showall 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370379/