QS waves in V1-V3 with persistent ST elevation and small T waves (each under about a third of its QRS): an old anterior infarct, not an acute one.
After a big anterior infarct, the ST elevation can stay for weeks or for good, over a thinned, scarred wall. The clues it's old: QS waves (no R at all) in V1-V3, an ST that matches old ECGs and doesn't change, no reciprocal depression, and T waves that are small for their QRS. An acute anterior STEMI has big T waves for its QRS. Smith's rule: if the T wave is 0.36 or more of its QRS in any of V1-V4, think acute. A prior ECG or the patient's history is the best tiebreaker, and a new infarct can still land on an old aneurysm.
Each is a standard 12-lead: 2.5 seconds of each lead in four columns, with 10 seconds of lead II along the bottom, drawn to scale (25 mm a second, 10 mm a millivolt). The measurements are under each one.
ST elevation across V1-V4, from an occluded left anterior descending artery.
ST elevation across V1-V6 and in I and aVL, with reciprocal depression in III and aVF.
Concave ST elevation in V2-V5 with a notched J point and tall, slightly lopsided T waves, no reciprocal depression, and a V6 ST under a quarter of its T wave's height. A normal variant, mostly in the young.
Wide, deep Q waves in III and aVF (40 ms or more) with no acute ST elevation: the scar of an infarct that has already happened.
The ECG tool in the app gives you a new 12-lead every time and walks you through reading it: rate, QRS, axis, then where the ST is up and down. It's part of the Paramedic level, and you can try 5 ECGs a day free.
Try the 12-lead drill
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