Myocarditis electrocardiogram

The presence of ST segment elevation in patients with myocarditis can mimic pericarditis and myocardial infarction. Arrhythmias and heart block may also be observed in myocarditis patients. Myocarditis can be distinguished from pericarditis by the presence of PR depression in the patient with pericarditis.

• The ECG findings in myocarditis are similar to those in pericarditis and myocardial infarction. Myocarditis should be suspected in patients who are at low risk for ischemic heart disease and MI and in those patients with normal coronary arteries on coronary angiography.^[1][2]
• The ECG findings most commonly seen in myocarditis are:^[3][4][5][6]
  • Sinus tachycardia
  • Diffuse T wave inversions
  • ST segment elevation without reciprocal depression. This helps in differentiating myocarditis from infarction particularly when EKG changes are diffuse.
  • Low voltage of the QRS complexes may be observed.
  • Arrhythmias such as atrial and ventricular ectopic beats, atrial and ventricular tachycardias and atrial fibrillation may also be present and are common in Chagas heart disease.
  • Heart block is frequently observed in giant cell myocarditis and cardiac sarcoidosis.
  • These EKG changes may persist for several months before they resolve spontaneously.

• The EKG below shows diffuse ST segment elevation without reciprocal ST depression in a patient with myocarditis.

• The EKG below shows diffuse T wave inversion in a patient with myocarditis.

• The EKG below shows diffuse ST elevation in a patient with myocarditis and pericarditis.

• Despite its worrisome appearance, ST segment elevation suggestive of myocardial infarction is usually self-limited with no overt sequelae. In contrast, the presence of either left bundle branch block, q waves suggestive of old infarct or high degree AV block are associated with a poor long term prognosis and are associated with the development of cardiac failure and cardiac transplantation.^[7][8]

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