Simultaneous assessment of myocardial perfusion and left ventricular function during transient coronary occlusion

Abstract

Objectives. We used technetium-99m sestamibi imaging to evaluate the magnitude of changes in left ventricular function and perfusion and to investigate their interdependence during transient coronary occlusion.Background. Transient coronary occlusion during coronary angioplasty provides a unique opportunity for examining the effects of acute myocardial ischemia on left ventricular function and perfusion.Methods. Thirty-five patients with normal left ventricular function underwent first-pass radionuclide angiography with technetium-99m sestamibi using a multicrystal gamma camera during balloon occlusion of a coronary artery. Single-photon tomography was performed 2.1 ± 1.7 h later. Subsequently, all scans were repeated at rest.Results. The mean size ± SD of the perfusion defect during coronary occlusion was 23 ± 18%, with significantly larger defects observed for occlusions of the left anterior descending coronary artery (39 ± 20%) than for occlusions of the left circumflex (15 ± 11%) or right (15 ± 9%) coronary artery (p < 0.05). The mean change in ejection fraction from recovery to occlusion was −17 ± 17% and was significantly larger for left anterior descending (−26 ± 21%) and left circumflex (−15 ± 11%) than for right (−8 ± 10%) coronary artery occlusions (p < 0.05). For the entire group, ejection fraction during occlusion correlated significantly with perfusion defect size ( r= 0.63, p = 0.0004), whereas the extent of ischemic myocardium correlated with the decrease in ejection fraction (r = 0.69, p = 0.0001). The defects present during occlusion reversed within a few hours.Conclusions. Changes in left ventricular function and perfusion develop pari passu during coronary occlusion and are more severe when the left anterior descending artery is occluded. Although a significant correlation exists between the extent of the perfusion defect and the severity of the decrease in ejection fraction, there is a substantial individual variation with respect to changes in both myocardial perfusion and ventricular function during acute coronary occlusion.