What is the risk and when is it greatest?

Our own database in east London shows that about 30% of patients with acute myocardial infarction and 20% with unstable angina experience a major event (death or non-fatal coronary syndrome) during the first year after hospital admission. Risk, however, is not a linear function of time, and as fig 1 shows, 66% of all major events during the first six months after myocardial infarction occur in the first 30 days. Moreover, the determinants of risk may change with time, acute phase arrhythmias and myocardial rupture in the first 48 hours giving way to reinfarction, heart failure, and secondary arrhythmias later after presentation. Thus assessment of risk, using strategies tailored to address its changing determinants, is an essential part of the management of acute coronary syndromes and must be applied at an early stage to identify successfully patients with most to benefit. Recognition of this fact has rendered obsolete old arguments about the appropriate timing of stress testing and other non-invasive tests which must be performed as early as possible (certainly before discharge) to be of significant value for risk stratification.