CORONARY RESERVE ABNORMALITIES IN THE INFARCTED MYOCARDIUM - ASSESSMENT OF MYOCARDIAL VIABILITY IMMEDIATELY VERSUS LATE AFTER REFLOW BY CONTRAST ECHOCARDIOGRAPHY

Background The aim of this study was to determine whether myocardial c ontrast echocardiography (MCE) during exogenous vasodilation can accur ately delineate infarct size, and hence the extent of myocardial viabi lity, both immediately (15 minutes) and late (3 hours) after reperfusi on when postreflow coronary hyperemia is still present. Methods and Re sults Twenty-one open-chest anesthetized dogs underwent 3 to 6 hours o f coronary occlusion followed by reperfusion. MCE was performed 15 min utes after reflow before and during infusion of 0.2 mg . kg(-1). min(- 1) adenosine IV. In 12 dogs, infarct size was measured at this time. I n the remaining 9 dogs, reperfusion was continued for 3 hours, when MC E was repeated before and after an infusion of 0.56 mg . kg(-1). min(- 1) dipyridamole IV and infarct size was measured. In the absence of ad enosine, MCE perfusion defect at 15 minutes underestimated infarct siz es at both 15 minutes and 3 hours, whereas in the presence of adenosin e, the estimate of infarct size was more accurate. Similarly, in the a bsence of dipyridamole, although MCE perfusion defect underestimated i nfarct size (both measured 3 hours after reflow), in the presence of d ipyridamole, the estimate of infarct size was mow accurate. Conclusion s By unmasking abnormalities in flow reserve within the infarct bed, M CE in conjunction with coronary vasodilators can accurately predict in farct size both 15 minutes and 3 hours after reperfusion. Thus, MCE ca n be used for assessing the extent of myocardial viability both immedi ately and late after reperfusion when postreflow coronary hyperemia is still present.