The intermediate coronary syndrome

Abstract

T HE term “intermediate coronary syndrome” was first used by Graybiel in 1955.’ He defined this syndrome as “an acute attack complicating coronary heart disease in which evaluation of the pain distinguishes it from the angina1 syndrome, and evaluation of the other clinical findings distinguishes it from myocardial infarction.” He was primarily interested in defining a clinical syndrome and not in its “obscure pathophysiologic mechanisms.” Prolonged duration was considered the most important characteristic of the pain of this syndrome to distinguish it from typical angina. Pain arising without obvious cause, such as spontaneous rest pain or pain with mild stress that would ordinarily be easily tolerated by the patient, was another typical feature. During subsequent years, the intermediate coronary syndrome was lumped together with other coronary syndromes, such as preliminary pain,* impending myocardial infarction3 acute coronary insufficiency,4 preinfarction angina,5 and accelerating angina,6 under the umbrella term “unstable angina,“7 in an attempt to develop an acceptable uniform nomenclature. Though unstable angina has become accepted and is now widely used in medical literature, some authors have decried the generality of the term and have attempted to break it down into more precise subgroups.’ The classification that has become most recognized has been that of Conti et a1.,9 who suggested a division of unstable angina into three subgroups. Group I would include patients with angina on effort of recent onset. Group II would be patients with angina on effort whose pattern was changing or progressing. Group III patients would be those who had angina at rest, with pain generally lasting 15 min or more during an episode. This group would include those with rest pain as an initial symptom and those whose rest pain followed an earlier course of stable angina. A high-risk subcategory, which can be designated group IIIa, is made up of those patients whose rest pain is refractory to medical treatment after 24-48 hr of hospitalization. Group III unstable angina closely resembles the intermediate coronary syndrome of Graybiel. For purposes of simplicity, the two will be considered to be the same for this article.