The definitions of acute coronary syndrome, myocardial infarction, and unstable angina.

The acute coronary syndrome encompasses a spectrum of conditions that include acute myocardial infarction, unstable angina pectoris, and, to some extent, sudden cardiac death. Recently, the diagnosis of myocardial infarction has been redefined by The Joint European Society of Cardiology/American College of Cardiology Committee. However, the conceptual meaning of the term myocardial infarction has not been changed. Thus, the current diagnoses of myocardial infarction as well as of unstable angina are clinical syndromes based on symptoms, electrocardiogram, and sensitive biochemical markers.