Case: ECG and pulmonary embolism – a pattern you must recognize

 A woman in her 60s was admitted with increasing shortness of breath. The ECG showed:

• Sinus tachycardia (109/min)

• Right axis deviation

• Incomplete right bundle branch block (QRS < 120 ms)

• T-wave inversions in aVR, III, and V1–V5

This ECG pattern is classic for acute pulmonary embolism and reflects right heart strain. T-wave inversions may also be seen in leads II and aVF, although not in this case.

Many associate pulmonary embolism with the S1Q3T3 pattern:

• S wave in lead I

• Q wave in lead III

• T-wave inversion in lead III

However, this pattern is neither sensitive nor specific for pulmonary embolism and should be interpreted with caution.

CT thorax was performed due to suspicion of pulmonary embolism and confirmed bilateral central emboli.

Differential diagnosis: Could this represent LAD occlusion (Wellens pattern)?

T-wave inversions in the precordial leads can also suggest acute coronary syndrome, but in this case several points argued against it:

• The patient presented only with dyspnea and no chest pain, lowering the likelihood of acute coronary syndrome.

• LAD-related T-wave inversions often show preserved positive T-waves in leads III and V1.

• In pulmonary embolism, T-wave inversions also involve these leads, as in this case.

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 Learning points

• An ECG showing right heart strain, tachycardia, and widespread T-wave inversions should always raise suspicion of acute pulmonary embolism.

• The S1Q3T3 pattern may be present but is neither sensitive nor specific; the broader pattern of right heart strain and precordial T-wave inversions is more important.

• T-wave inversions in the precordial leads can mimic acute LAD occlusion. Differentiation requires attention to clinical presentation and lead distribution.

• In patients with dyspnea without chest pain, pulmonary embolism is more likely than acute coronary syndrome.

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Conclusion

This ECG pattern is crucial to recognize. Prompt identification of pulmonary embolism can be life-saving by ensuring the correct diagnosis and timely treatment.

Reference:

Kosuge M. et al. Electrocardiographic Differentiation Between Acute Pulmonary Embolism and Acute Coronary Syndromes on the Basis of Negative T Waves. Am J Cardiol. 2007.