INTRODUCTION The acute coronary syndromes (ACS) represent a pathological, diagnostic, and risk continuum from unstable angina through myocardial infarction (MI) with or without ST-segment elevation. The management strategies and outcomes of patients who present with symptoms of acute coronary ischemia depend upon where they fall within this spectrum. The ability to accurately diagnose and risk-stratify this group of patients at presentation and to provide continuous risk evaluation thereafter is critical, not only for patient outcome but also for efficiency of care. As the health care environment has evolved, our focus has also evolved from traditional categorical diagnosis to baseline and long-term risk stratification, and to methods that allow continuous risk assessment. Unfortunately, as shown by Lee and colleagues in 1986, the ability of physicians to accurately risk-stratify patients based on clinical factors alone is limited and subject to wide variability among physicians [1]. Neither experience nor practice setting of the physician significantly affects predictions of outcome [2].