ST-Segment Elevation

ECG Lead Involvement

Evolution of ST and T Waves

PR-Segment Depression

Pericarditis

Concave upward

All leads involved except aVR and V₁

ST remains elevated for several days; after ST returns to baseline, T waves invert

Yes, in majority

Acute ST Elevation MI

Convex upward

ST elevation over infarcted region only; reciprocal ST depression in opposite leads

T waves invert within hours, while ST still elevated; followed by Q wave development

No