Ischaemia and infarction
Acute pericarditis
Widespread concave ST elevation with PR depression — and no reciprocal change to speak of.
What you see
- Concave ('saddle-shaped') ST elevation in most leads, not confined to a coronary territory.
- PR segment depression — the most specific sign, and often the earliest.
- PR elevation and ST depression in aVR.
- Sinus tachycardia; the ST changes evolve over days to widespread T inversion.
Why it looks like that
Inflammation of the epicardial surface produces a diffuse injury current rather than a regional one, and atrial involvement shifts the PR segment. Because the whole heart is affected, there is no territory left over to generate reciprocal change.
What to do
- High-dose NSAID or aspirin with colchicine for three months — colchicine halves the recurrence rate.
- Echocardiography to look for effusion and tamponade.
- Look for a cause: viral, post-MI (Dressler's), uraemic, autoimmune, tuberculous, malignant.
The trap
Benign early repolarisation looks similar and is far more common in young men. The discriminator is PR depression and the ST-height to T-height ratio in V6: greater than 0.25 favours pericarditis. Regional elevation with reciprocal depression is an infarct, whatever the age of the patient.
More in ischaemia and infarction
Anterior STEMI
Convex ST elevation across the anterior chest leads — the LAD occlusion you cannot afford to sit on.
Inferior STEMI
ST elevation in II, III and aVF with reciprocal change in aVL — and a right ventricle you must check before giving nitrates.
Posterior myocardial infarction
Tall R waves and ST depression in V1–V3 — a STEMI viewed from behind, and easy to call NSTEMI by mistake.
Wellens' syndrome
Deep or biphasic T waves in V2–V3 in a pain-free patient — critical LAD stenosis waiting to declare itself.