ECG rhythms Conduction, ST and QT
Anterior ST elevation ECG
Anterior ST elevation (V1–V4). ST elevation in contiguous anterior leads meets the Fourth Universal Definition cut-offs for a man over 40 — at least 2 mm in V2–V3 and at least 1 mm in V1 and V4 — with a narrow QRS and ongoing pain: an acute anterior injury pattern.
A 30-second recording of the heart model, played in real time. Run live starts the engine itself with this rhythm.
Computed by the TracingsMD heart model (Junkers engine): simulated for education, not a patient recording and not for diagnosis.
Measured on this recording
| Ventricular rate | 84/min |
|---|---|
| PR | 158 ms |
| QRS | 84 ms |
| QT | 335 ms |
| QTc (Bazett) | 397 ms |
| QTc (Fridericia) | 375 ms |
| ST at J+60 ms | V2 +0.28 · V3 +0.31 · V1 +0.15 · V4 +0.19 · III +0.00 mV |
What it is
ST elevation in the anterior chest leads (V1–V4) from acute injury of the septum and anterior wall of the left ventricle, usually from occlusion of the left anterior descending (LAD) coronary artery. The fourth universal definition of myocardial infarction describes ischemic ST elevation as new ST elevation at the J point in two contiguous leads, without left ventricular hypertrophy or left bundle branch block: at least 1 mm (0.1 mV) in most leads, with higher cut-offs in V2–V3 (2 mm in men aged 40 or more, 2.5 mm in men under 40, 1.5 mm in women).
How to read this strip
| Rate | 60–100/min. |
|---|---|
| Rhythm | Regular sinus. |
| P waves | Normal. |
| PR | Normal. |
| QRS | Narrow. |
| ST–T | ST elevation in V1–V4. |
Causes
- Acute occlusion of the LAD (plaque rupture with thrombus).
- Less often: coronary spasm, spontaneous coronary artery dissection (more common in younger women), coronary embolism, cocaine use.
What to consider
- Suspected STEMI is time-critical: the aim is immediate reperfusion, usually primary PCI (fibrinolysis when PCI cannot be done in time), through the local STEMI pathway.
- A large anterior infarction can cause heart failure, cardiogenic shock and ventricular arrhythmias: monitor continuously with a defibrillator at hand.
- New conduction disease (right bundle branch block, left anterior fascicular block, Mobitz II or complete heart block) in anterior infarction signals extensive septal damage, a worse outlook and a possible need for pacing.
- Consider mimics (left ventricular hypertrophy, early repolarization, pericarditis, left ventricular aneurysm, Brugada pattern) and compare with earlier ECGs, but do not let this delay reperfusion when the symptoms and ECG fit; Takotsubo syndrome can only be told apart by coronary angiography.
- Critical LAD disease can also appear without classic ST elevation: de Winter T waves (upsloping ST depression with tall T waves in V1–V6) during pain, or Wellens T waves (deep or biphasic T waves in V2–V3) after the pain settles. Treat de Winter T waves as a STEMI equivalent; Wellens T waves need urgent angiography, and stress testing should be avoided.
Key point
Anterior ST elevation is most often an LAD occlusion. Treat it as STEMI and activate the cath lab without waiting for troponin.
Not to be confused with
- Inferior ST elevation — II, III and aVF are not elevated; the ST elevation is in V1–V4.
- Left bundle branch block — The QRS is narrow. LBBB widens the QRS to 120 ms or more, with broad notched R waves in I, V5 and V6.
- Normal 12-lead ECG — The ST segments in V1–V4 are clearly raised above the baseline.