Current is directed away from the normal myocardium(negative deflection) toward the ischemic myocardium(more positive deflection) during systole.

As a result the leads facing the ischemic myocardium represent upward or more positive deflection or ST-segment Elevation and sometimes Tall (hyperacute) T wave due to Myocardial ischemia. In normal myocardium, ST-segment is isoelectric or baseline.

Non-ischemic Causes of ST-segment elevation are following:

  1. Acute pericarditis
  2. Early repolarization pattern
  3. Left Ventricular Hypertrophy (V1-V3)
  4. Left Bundle Branch Block (V1-V3only)
  5. Myocarditis
  6. Hypothermia (Osborn wave)
  7. Hyperkalemia
  8. Hypercalcemia
  9. Brugada pattern
  10. Intracranial hemorrhage and
  11. After DC cardioversion.

Non-ischemic Causes of prominent T wave inversion include:

  • Juvenile T wave pattern
  • Early repolarization
  • Cardiomyopathy
  • Cerebrovascular accidents
  • Ventricular hypertrophy
  • Bundle Branch Block
  • Apical Hypertrophic cardiomyopathy
  • Wolf-Perkinson-White Syndrome
  • Post-tachycardia T wave pattern
  • Idiopathic global T wave inversion syndrome and
  • Memory T Wave.(intermittent bundle branch block, Ventricular pacing or Ventricular pre-excitation).