Pathogenetic classifications of unstable angina as a guideline to individual patient management and prognosis.
Although it is widely recognized that unstable angina is a syndrome encompassing a variety of clinical and pathophysiologic entities, clinical trials and guidelines for management still consider patients with unstable angina as a single homogeneous group. When first recognized as a potentially threatening coronary syndrome, unstable angina was thought to be caused by extremely severe coronary obstructions that culminated in the syndrome of angina at rest, when coronary flow reserve is practically exhausted. It is now clear that the severity of coronary atherosclerosis in stable and unstable angina is, on the average, similar; and it appears that the features of "instability" are largely determined by dynamic obstructions superimposed on a widely variable fixed obstruction. Current clinical classifications, although based on purely descriptive symptoms, and angiographic classifications, based solely on coronary anatomy, independently identify subgroups of patients with unstable angina who have clearly distinct prognoses. The pathophysiologic classification proposed in this article considers both the severity of the underlying coronary fixed obstructions (as evidenced by the reduction of coronary flow reserve and by coronary anatomy) and the tendency for dynamic stenoses to develop (as evidenced by the pathophysiologic interpretation of symptoms and by the response to therapy). Since this classification combines elements of currently used clinical and angiographic classifications with a pathophysiologic interpretation, it can be applied easily in clinical practice and may provide more rational groupings of patients for both management and prognosis assessment.
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D000787:Angina Pectoris / Q000145:classification*; D000789:Angina, Unstable / Q000145:classification* / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology; D017023:Coronary Angiography; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000473:pathology; D005080:Exercise Test; D006801:Humans; D011379:Prognosis