Relation between Perfusion of Infarcted Myocardium and Exercise-induced ST Shift in Acute Myocardial Infarction

Lim, Do Sun; Kim, Young Hoon; Kim, Byung Hoe; Kim, Mi Yang; Kim, Soo Mi; Hwang, Gyo Seung; Ahn, Jeong Cheon; Song, Woo Hyuck; Park, Chang Gyu; Seo, Hong Seog; Shim, Wan Joo; Oh, Dong Joo; Ro, Young Moo

Abstract

BACKGROUND
It has been demonstrated that within 2 weeks following acute myocardial infarction (AMI), exercise-induced ST-segment depression (STD) indicates subendocardial ischemia in the viable myocardium within infarcted or remote area from the infarction. Exercise-induced ST-segment elevation (STE) in leads with abnormal Q wave is associated with left ventricular dysfunction or aneurysm rather than transmural ischemia. We studied whether each pattern of ST-segment shift on exercise ECG during recovery phase following AMI is correlated with the perfusion status of infarcted myocardium evaluated by myocardial contrast echocardiog-raphy (MCE), regardless of findings of coronary angiography (CAG). METHOD: Study population was consisted of 25 patients with AMI (anteior wall: 11 patients, inferior wall: 14 patients, mean age=57.3+/-8.9years). Patients underwent exercise ECG and coronary angiography at 10 days post-AMI. After CAG, sonicated Hexabrix was injected into both coronory arteries alternatively and 2-D echocardiography was taken in parasternal short axis, apical 4, and 2 chamber views. To analyze the echocardiographic image semiquantitively, left ventricle was divided into 20 segments and perfusion status was graded as good, partial, and no opacification. RESULT: All patients with exercise-induced STE (n=8) in Q-leads had patent infarcted-related artery and poor collaterals on CAG, which was associated with poor or no opacification of infarcted myocardium on MCE. Patients with exercise-induced STD (n=9) frequently had closed infarct-related artery (67%), but good opacification of infarcted myocardium was shown by retrograde perfusion via collaterals, which was commonly seen in patients with multivessel disease.
CONCLUSION
In early recovery phase of acute myocardial infarction, exercise-induced ST elevation in Q leads was associated with poor perfusional status in infarcted myocardium, even with patent infarct-related artery on CAG, while exercise-induced ST depression was frequently seen in the good perfusional status despite of closed infarted-related artery, which was commonly observed in patients with multivessel disease.