History
Patients with myocarditis have a clinical history of acute decompensation of heart failure, but they have no other underlying cardiac dysfunction or have low cardiac risk. The diagnosis is usually presumptive, based on patient demographics and the clinical course (eg, spontaneous recovery following supportive care).
Patients may present with mild symptoms of chest pain (in concurrent pericarditis), fever, sweats, chills, and dyspnea.
In viral myocarditis, patients may present with a history of recent (within 1-2 wk) flulike syndrome of fevers, arthralgias, and malaise or pharyngitis, tonsillitis, or upper respiratory tract infection.
Population studies suggest that adults may present with few symptoms, rather than the acute toxic state of cardiogenic shock or frank heart failure (fulminant myocarditis) that is often associated with myocarditis. (In fulminant myocarditis, sudden and severe diffuse cardiac inflammation is typically fatal when the condition is unrecognized and left untreated, from cardiogenic shock, ventricular arrhythmias, or multiorgan system failure. [20] )
Symptoms of palpitations or syncope, or even sudden cardiac death, may develop, due to underlying ventricular arrhythmias or atrioventricular block (especially in giant cell myocarditis).
Adults may present with heart failure years after an initial index event of myocarditis (as many as 12.8% of patients with idiopathic dilated cardiomyopathy had presumed prior myocarditis in one case series).
Physical Examination
Patients with myocarditis usually present with signs and symptoms of acute decompensation of heart failure (eg, tachycardia, gallop, mitral regurgitation, edema) and, in those with concomitant pericarditis, with pericardial friction rub. Specific findings in special cases are as follows:
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Sarcoid myocarditis: Lymphadenopathy, also with arrhythmias, sarcoid involvement in other organs (up to 70%)
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Acute rheumatic fever: Usually affects heart in 50-90%; associated signs, such as erythema marginatum, polyarthralgia, chorea, subcutaneous nodules (Jones criteria)
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Hypersensitive/eosinophilic myocarditis: Pruritic maculopapular rash and history of using offending drug
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Giant cell myocarditis: Sustained ventricular tachycardia in rapidly progressive heart failure [1]
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Peripartum cardiomyopathy: Heart failure developing in the last month of pregnancy or within 5 months following delivery
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Myocarditis. Hematoxylin and eosin staining. Low power. This image shows numerous lymphocytes with associated myocyte damage. Photo courtesy of Dr Donald Weilbaecher.
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Myocarditis. Hematoxylin and eosin staining. High power. Toxoplasmosis (numerous purple granular-like structures within a myocyte) is demonstrated.
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Myocarditis. Hematoxylin and eosin staining. High power. Lymphocytes, histiocytes, and a multinucleated giant cell representing sarcoidosis (a diagnosis of exclusion) is shown.
