S1Q3T3 Pattern

Report:

Sinus rhythm 70/min

S1Q3T3 pattern

Comment:

The pattern is the classical McGinn-White one of large pulmonary embolism or acute cor pulmonale of any ætiology. Even lead 3 ST segment elevation seen in this trace occurred in a pulmonary embolism series in 28% cases20. It is also a normal variant: chance of significant pathology in otherwise healthy individuals – and without tachycardia - is minuscule.

This individual was unwell enough to be sent to CCU after the (negative) lung scan, which was just as well (below, Fig 27a).

The unusual feature of his acute inferior infarction was that the reciprocal ST depression was confined to a single lead, aVL. More leads were taken and the (not entirely unexpected) right ventricular infarction was documented (Fig 27b, with right-sided chest leads).

The obvious question is whether the S1Q3T3 pattern had anything to do with the developing inferior MI and, especially, right ventricular involvement. It is unanswerable, since no old ECGs are available. It may well have been a normal variant in this case, except for lead 3, where ST elevation is less expected in normal subjects (and we know there was no pulmonary embolism). I think it’s the RV infarction: the ECG cannot distinguish between cor pulmonale and RV injury. Paradoxically normal heart rate probably reflects the latter.

27a. Acute inferior MI with curious lack of reciprocal depression in the anteroseptal leads.

27b. Right-sided chest leads confirm RV infarction. 28. 48 year old man injured in a single-car MVA, confused and shocked.

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