Identifying and measuring severity of coronary artery stenosis. Quantitative coronary arteriography and positron emission tomography.

Q uantifying severity of coronary artery stenosis is becoming increasingly important for many reasons, including evaluation of interventions such as cholesterol control, stress management, pharmacological agents, percutaneous transluminal coronary angioplasty, thrombolysis, and bypass surgery; clinical decisions on medical versus mechanical treatment of coronary artery stenoses; judgment of adequacy of noninvasive diagnostic techniques; understanding the role of fluid dynamics in localizing atheroma at specific sites of an artery exposed to the same risk factors throughout its length; and in silent coronary artery disease, as the only basis for choosing medical or mechanical intervention to prevent sudden death or acute myocardial infarction. There are two fundamental ways of describing stenosis severity based on anatomic and physiological approaches.1 These anatomic and physiological methods are related but provide independent complementary data; each is essential forjudging severity and regression or progression or for making clinical decisions and will be briefly reviewed.