The term acute coronary syndrome encompasses the complete spectrum of clinical syndromes characterised by acute coronary ischaemia and includes unstable angina, non-ST elevation myocardial infarction (NSTEMI), and ST elevation myocardial infarction (STEMI).
Patients presenting with ST segment elevation or new left bundle branch block on an electrocardiogram are diagnosed with STEMI, indicative pathologically as a transmural myocardial infarction usually arising from complete occlusion of an epicardial coronary artery. These patients require urgent reperfusion, either by fibrinolytic therapy or primary angioplasty. The European Society of Cardiology and the American College of Cardiology/American Heart Association have issued guidelines for the management of this distinct group.