Table 1.

World Health Organization criteria^* for diagnosis of definite acute MI, possible acute MI or old MI

Type of evidence	Criteria
History	The history is typical if severe, prolonged chest pain is present. Sometimes the history is atypical, and the pain may
	be mild or even absent, or other symptoms may be predominant
Electrocardiography (ECG)	Unequivocal changes in ECG are the development of abnormal, persistent Q or QS waves, and evolving injury
	current lasting longer than 1 day. When the ECG shows these unequivocal changes, the diagnosis may be made
	on the basis of ECG alone. In other cases the ECG may show equivocal changes, consisting of a stationary injury
	current, a symmetrical inversion of the T-wave, a pathological Q-wave in a single ECG record, or conduction
	disturbances
Serum enzymes	Unequivocal changes consist of serial change, or initial rise and subsequent fall of the serum level. The change
	must be properly related to the particular enzyme, and to the delay time between onset of symptoms and blood
	sampling. Elevation in cardio-specific isoenzymes is also considered unequivocal change. Equivocal change
	consists of an enzyme pattern in which an initially elevated level is not accompanied by a subsequent fall - the
	curve of enzyme activity is not obtained

^*Revised 1994 for the MONICA study [1].