A serious infection of the heart may too often go untreated, because many patients present with a nonspecific illness characterized by fatigue, mild dyspnea, and myalgias. A few patients present acutely with fulminant congestive heart failure (CHF) secondary to widespread myocardial involvement. Many cases of myocarditis are such that the patient rarely seeks medical attention during acute illness. These cases may have transient ECG abnormalities. The appearance of cardiac-specific symptoms occurs primarily in the subacute virus-clearing phase; therefore, patients commonly present 2 weeks after the acute viremia. Fever is present in 20% of patients. Other symptoms include fatigue, myalgias and arthralgias, and malaise. Chest discomfort is reported in 35% of patients. The pain is most commonly described as a pleuritic, sharp, stabbing precordial pain. It may be substernal and squeezing and, therefore, difficult to distinguish from that typical of ischemic pain. Dyspnea and shortness of breath at rest may be noted. Palpitations are common.
Small and focal areas of inflammation in electrically sensitive areas may be the etiology in patients whose initial presentation is sudden death. An antecedent viral syndrome is present in more than one half of patients with myocarditis. Syncope in a patient with a presentation consistent with myocarditis should be carefully approached because it may signal high-grade AV block or risk for sudden death.