What are the electrocardiographic (ECG) findings seen in PE?

  • ECG findings are also variable and neither sensitive or specific
  • A normal ECG is seen in up to 18% of cases
  • Abnormalities seen include:
    • Sinus tachycardia (most common – 44%)
    • Atrial arrhythmias (most frequently atrial fibrillation)
    • Classic S1Q3T3 (10%)
      • Deep S-wave in lead I, Q-wave in III and an inverted T-wave in III
    • Complete or incomplete right bundle branch block (15%): rSR’ in V1
      • Associated with increased mortality
    • Acute right ventricular strain (34%)
      • T-wave inversion in the right precordial leads (V1-4) and the inferior leads (II, III, aVF)
        Associated with high pulmonary artery pressures
    • Right axis deviation (15%):
      • May be extreme deviation – between 0 and -90°
    • Non-specific ST-segment and T-wave changes:
      • ST-elevation and depression
      • T-wave inversion

An ECG in pulmonary embolism demonstrates:

  • S1Q3T3 pattern – an S wave in lead I, Q wave and an inverted T wave in lead III
  • Sinus tachycardia

An ECG in pulmonary embolism demonstrates:

  • Incomplete or complete RBBB (rSR’ in V1)
  • T wave inversion in V1-V3 – mimics anterior ischemia
  • Sinus tachycardia

An ECG in pulmonary embolism demonstrates:

  • Right axis deviation
  • Right bundle branch block (rSR’ in V1)
  • Deep T wave inversion in V1-V3
  • Sinus tachycardia