What lies behind the extensive ST-segment changes in cardiac arrest?

Interpretation of electrocardiographic changes after cardiac arrest is critical. If the electrocardiogram is consistent with ST-segment elevation myocardial infarction, primary coronary angiography is indicated. However, the presence of ST-segment depression in eight or more surface leads, together with ST-segment elevation in the aVR and/or V1, could be a sign of multivessel ischaemia or left main coronary artery disease if haemodynamic instability is present.