Stages of Pericarditis. Pericarditis is classically associated with ECG changes that evolve through four stages. Stage 1 – widespread STE and PR depression with reciprocal changes in aVR (occurs during the first two weeks); Stage 2 – normalisation of ST changes; generalised T wave flattening (1 to 3 weeks); Stage 3 – flattened T waves become inverted (3 to several weeks)

