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Extensive anterior STEMI on a 12-lead ECG

ST elevation across V1-V6 and in I and aVL, with reciprocal depression in III and aVF.

What to look for

An occlusion of the proximal left anterior descending artery, before its first diagonal branch, injures the septum, the anterior wall and the high lateral wall. So you see ST elevation across the chest leads and in I and aVL, with reciprocal ST depression of 1 mm or more in the inferior leads.

Examples

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.

Example 1 · 12-lead · 10 seconds
IaVRV1V4IIaVLV2V5IIIaVFV3V6II25 mm/s · 10 mm/mV
Rate
100/min
Rhythm
RegularSinus: upright in II, biphasic in V1, one before every QRS
PR
0.16 s
QRS
0.08 s, narrow
Axis
38°, normal
QTc
0.42 s
ST up
I, aVL, V1, V2, V3, V4, V5, V6 (lateral and septal and anterior)
ST down
III, aVR, aVF (reciprocal)
T inverted
III
Example 2 · 12-lead · 10 seconds
IaVRV1V4IIaVLV2V5IIIaVFV3V6II25 mm/s · 10 mm/mV
Rate
63/min
Rhythm
RegularSinus: upright in II, biphasic in V1, one before every QRS
PR
0.16 s
QRS
0.09 s, narrow
Axis
81°, normal
QTc
0.42 s
ST up
I, aVL, V1, V2, V3, V4, V5, V6 (lateral and septal and anterior)
ST down
III, aVR, aVF (reciprocal)
T inverted
III
Also
Pathological Q waves (40 ms or wider) in aVL

Don't confuse it with

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

Where the criteria come from

Others in the STEMI and occlusion MI group