DELINEATION OF MYOCARDIAL STUNNING AND HIBERNATION BY POSITRON EMISSION TOMOGRAPHY IN ADVANCED CORONARY-ARTERY DISEASE

With positron emission tomography, the resting flow abnormalities unde rlying reversible left ventricular dysfunction in 17 patients with chr onic coronary artery disease were delineated. The level of flow in rev ersibly dysfunctional segments (i.e., those demonstrating improvement after revascularization) was markedly variable, ranging from 0.32 to 1 .25 ml/gm/min. In 20 of these segments, flow was preserved, whereas in 12 segments, flow was reduced, when compared with that in, age-matche d controls. Preservation of flow was associated with preservation of m yocardial oxygen consumption and no alterations in myocardial substrat e use. In contrast, a reduction in flow resulted in a decrease myocard ial oxygen consumption and an increase in myocardial glucose use. Thus resting reversible left ventricular dysfunction in patients with chro nic coronary artery disease can reflect a diversity of resting Row abn ormalities. Moreover, myocardial perfusion at rest is frequently withi n normal limits, suggesting that the reversible mechanical dysfunction in these patients is attributable to intermittent myocardial stunning and not hibernation.