DOES THE PRESENCE AND SITE OF MYOCARDIAL-ISCHEMIA ON PERFUSION SCINTIGRAPHY PREDICT THE OCCURRENCE AND SITE OF FUTURE MYOCARDIAL-INFARCTIONIN PATIENTS WITH STABLE CORONARY-ARTERY DISEASE

Several angiographic studies have demonstrated that nearly two thirds of acute myocardial infarctions (AMI) result from coronary artery occl usion at sites with a coronary diameter stenosis of less than or equal to 50%.(1-7) Potential reasons are that nonobstructive atheroscleroti c lesions outnumber more severe stenotic lesions, and that angiography frequently underestimates the severity and extent of coronary atheros clerosis.(8) Furthermore, angiographically severe stenoses are more li kely to have collaterals than milder stenoses; therefore, an overt acu te coronary syndrome is more Likely when occlusive thrombosis complica tes a mildly obstructive plaque. Stress myocardial perfusion scintigra phy may fail to detect non-flow-limiting mild coronary stenoses, thus precluding accurate prediction of future AMI. These stenoses may, howe ver, become flow limiting during physical or pharmacologic stress, fro m paradoxical vasoconstriction due to endothelial dysfunction, thereby enhancing the likelihood of their detection by stress perfusion scint igraphy.(9,10) To date, the ability of myocardial perfusion scintigrap hy to predict the site of occurrence of future AMI has not been examin ed systematically. This study was performed to determine whether myoca rdial perfusion scintigraphy could predict the site and occurrence of future AMI in a cohort of patients with known or suspected coronary ar tery disease.