What is ‘S1Q3T3 sign’?

S₁Q₃T₃ sign is Seen in ECG

R.W.Koster, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

• Image – points to note
• S wave present in lead -I
• Q wave and inverted T wave in lead III

S₁Q₃T₃ sign reflects

[A] Right atrial strain
[B] Right ventricular strain
[C] Left ventricular strain
[D] Pulmonary artery strain

S₁Q₃T₃ sign

S₁Q₃T₃ sign

1. Prominent S wave in lead I
2. Q wave and inverted T wave in lead III
3. This is a sign of acute cor pulmonale
4. Suggests – acute pressure and volume overload of the right ventricle because of pulmonary hypertension
5. Reflects right ventricular strain

S₁Q₃T₃ findings on ECG and diagnosis of pulmonary embolism

S₁Q₃T₃ findings on ECG – is present in 15% to 25% of patients ultimately diagnosed with pulmonary emboli

S₁Q₃T₃ findings on ECG and acute cor pulmonale 

Any cause of acute cor pulmonale can result in the S₁Q₃T₃ findings on ECG,

1. Pulmonary embolism
2. Acute bronchospasms
3. Pneumothorax

Pulmonary embolism – findings on ECG

S₁Q₃T₃ findings on ECG

Other ECG findings noted during the acute phase of a PE include

1. New right bundle branch block (complete or incomplete)
2. Rightward shift of the QRS axis
3. ST-segment elevation in V₁ and aVR
4. Generalized low amplitude QRS complexes
5. Atrial premature contractions
6. Sinus tachycardia
7. Atrial fibrillation/flutter
8. T wave inversions in leads V₁-V₄

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