The four chronological stages of EKG changes in an acute Q-wave MI.

1.) Appearance of peaked or "hyperacute" T waves.

2.) ST segment elevation

3.) Appearance of abnormal Q waves.

4.) T wave inversion (accompanied by decrease in ST elevation).

n.b. These changes are not seen in acute Posterior MI.

References: Chou, pp.124-132; Thaler, p.203