Several changes seen in the ECG may indicate the presence of a previous myocardial infarction, especially if QR confounders are absent.
ECG changes - one or more of the following:
(1) Q wave in leads V2 or V3 >= 0.02 seconds
(2) QS complex in V2 or V3
(3) Q wave >= 0.03 seconds AND >= 0.1 mV deep in any 2 leads of a contiguous lead grouping of leads I, II, aVL, aVF, or V4 to V6
(4) QS complex in any 2 leads of a contiguous lead grouping of leads I, II, aVL, aVF, or V4 to V6
(5) R wave >= 0.04 sec in V1-V2 AND R/S >= 1 AND concordant positive T wave AND no conduction defect
Contiguous lead groups:
(1) I and aVL
(2) V1-V6
(3) II, III and aVF
Other findings suggestive of previous myocardial infarction:
(1) Q wave >= 0.02 and < 0.03 seconds AND >= 0.1 mV deep AND accompanied by inverted T waves in the same lead group
