Myocarditis: Difference between revisions

==Clinical features and prognosis of myocarditis==

In symptomatic patients, the cardiac presentation is frequently one of acute heart failure , although a syndrome mimicking acute myocardial infarction or a tachyarrhythmia, including sudden death, or high-grade heart block may occur. If the epicardium is involved, the syndrome of myopericarditis develops, often with pleuritic chest pain and pericardial effusion. Severe illness with systemic manifestations of viral disease and heart failure, often referred to as ‘fulminant myocarditis’, may resolve without symptoms but may also lead to heart failure in a limited number of patients. Prognosis seems relatively good compared to ‘Acute Myocarditis’, presenting with heart failure as the main symptom <cite>McCarthy</cite>. See Figure 3. Most people with myocarditis who present with acute dilated cardiomyopathy have relatively mild disease that resolves with few short-term sequelae, but certain clinical clues signify those at high risk for more difficulty (Table 2). Rash, fever, peripheral eosinophilia, or a temporal relation with recently initiated medications or the use of multiple medications suggest a possible hypersensitivity myocarditis. Giant-cell myocarditis should be considered in patients with acute dilated cardiomyopathy associated with thymoma, autoimmune disorders, ventricular tachycardia, or high-grade heart block. An unusual cause of myocarditis, such as cardiac sarcoidosis, should be suspected in patients who present with chronic heart failure, dilated cardiomyopathy and new ventricular arrhythmias, or second-degree or third-degree heart block or who do not have a response to standard care. Many symptomatic cases of postviral or lymphocytic myocarditis present with a syndrome of heart failure and dilated cardiomyopathy. In  patients who develop heart failure, fatigue and decreased exercise capacity are the most common initial manifestations. However, diffuse, severe myocarditis, if rapid in evolution, can result in acute myocardial failure and cardiogenic shock. Signs of right ventricular failure include increased jugular venous pressure, hepatomegaly, and peripheral edema. The decline in right ventricular function "protects" the left side of the circulation so that signs of left ventricular failure may not be seen. If, however, there is predominant left ventricular involvement, the patient may present with the symptoms of pulmonary congestion: dyspnea, orthopnea, pulmonary rales, and, in severe cases, acute pulmonary edema. Chest pain is usually associated with concomitant pericarditis. However, myocarditis can mimic myocardial ischemia and/or infarction both clinically and on the electrocardiogram, particularly in younger patients. Myocarditis may present with unexpected sudden death, presumably due to ventricular tachycardia or fibrillation. A number of other arrhythmias may be seen. Sinus tachycardia is more frequent than serious atrial or ventricular arrhythmias, while palpitations secondary to premature atrial or, more often, ventricular extrasystoles are common. The electrocardiogram may be normal or abnormal in myocarditis. However, the abnormalities are nonspecific unless there is pericardial involvement. The changes that may be seen include nonspecific ST abnormalities, single atrial or ventricular ectopic beats, complex ventricular arrhythmias (couplets or nonsustained ventricular tachycardia), or, rarely, atrial tachycardia or atrial fibrillation. High grade heart block is uncommon in lymphocytic myocarditis, but common in cardiac sarcoidosis and idiopathic giant cell myocarditis. Myocarditis can, in some patients, exactly simulate the ECG pattern of acute pericarditis or acute MI. Like acute MI, myocarditis may be associated with regional ST elevations and Q waves. Myocarditis should be suspected in young patients who present with a possible MI but have a normal coronary angiogram. The chest radiograph is variable, ranging from normal to cardiomegaly with or without pulmonary vascular congestion and edema. Considerable biventricular cardiomegaly may be associated with the total absence of pulmonary congestion due to the presence of right ventricular failure and/ or moderate or severe tricuspid regurgitation. Cardiac enzyme elevations are seen in some but not all patients with myocarditis. Persistent elevations in cardiac enzymes are indicative of ongoing necrosis.

==Diagnosis and treatment of myocarditis==