This ECG was recorded in a middle-aged male with prolonged chest pain. It shows sinus rhythm with hyperacute ST segment elevation in the inferior leads (II, III, aVF), and in V6 (and to a lesser extent in V5). These changes imply extensive evolving inferior infarction with extension laterally. In addition there is widespread ST depression in the anterior leads, which could imply anterior (usually LAD) ischaemia, or could represent true posterior infarction.
In this case the culprit vessel was a very large circumflex artery, and there was true infero-posterior infarction with some lateral extension.