MYOCARDIAL PERFUSION AND VENTRICULAR-FUNCTION MEASUREMENTS DURING TOTAL CORONARY-ARTERY OCCLUSION IN HUMANS - A COMPARISON WITH REST AND EXERCISE RADIONUCLIDE STUDIES

Background The purpose of this investigation was to compare the magnit ude of change in myocardial perfusion and function during exercise wit h that obtained during total coronary artery occlusion. Radionuclide s tudies are widely used for the diagnosis and determination of prognosi s in patients with suspected or known coronary artery disease. These s tudies are based on the premise that the relative deficit of coronary blood flow, which is induced by exercise and recognized as increased d emand, relates to the jeopardy experienced by the decrease or sudden a bsolute interruption of coronary blood how that is recognized as decre ased supply and is associated with coronary stenosis or total coronary artery occlusion. The magnitude of exercise-induced perfusion and fun ction abnormalities compared with those induced by total coronary arte ry occlusion in humans has not been previously reported. Methods and R esults We prospectively studied 20 patients with greater than or equal to 50% diameter stenosis documented by quantitative coronary angiogra phy in at least one vessel. A same-day rest/exercise sestamibi myocard ial function and perfusion study was performed within 24 hours before percutaneous transluminal coronary angioplasty. At 1 minute after ball oon inflation, while the vessel was occluded, sestamibi was injected, and a myocardial perfusion and function study was performed. Perfusion defect size was greater during occlusion (28+/-3%) than during exerci se (13+/-2%) (P<.01). Ejection fraction was greater during exercise (5 3+/-3%) compared with values measured during occlusion (41+/-2%) (P<.0 1). Conclusions Physiological abnormalities induced by coronary occlus ion are greater than those that occur during exercise, thereby indicat ing that stress-induced ischemia may not reflect the total potential m yocardium in jeopardy from a stenotic lesion, if sudden occlusion occu rs.