It appears that we have now come full circle in our definition of symptomatic ischemic heart disease. Before the 1930s, 2 manifestations, stable angina and AMI, were recognized. Patients in the gray zone between stable angina and AMI that we now call UA were described 75 years ago and at first appeared to be quite rare. Over the next half-century, they were recognized with increasing frequency, and by 25 years ago, about one half of all patients with NSTE-ACS were considered to have UA. However, use of ever more sensitive biomarkers of myocardial necrosis, especially cTn, has steadily chipped away at the fraction of patients with NSTE-ACS without MI who therefore are still considered to have UA.
In the 70s terms such as “intermediate coronary syndrome” and “pre-infarction angina” were commonplace and conveyed a sense of urgency. The increasing sensitivity of cardiac biomarkers has gradually chipped away at those designations. They have all but vanished now with the advent of the more sensitive troponin assays.