Dydfunction of microvasculature was frequently observed despite of successful revascularization with alteration of coronary flow dynamics flow dynamics in acute myocardial infarction (AMI). Reduction of coronary vasodilatory reserve was found in poorly perfused infarcted myocardium. The objectives of this study was to evaluate the vasodilatory reserve in infarcted myocardium and determind its relationship to perfusion status of myocardium in early recovery phase of acute myocardial infarction.

The study subjects consisted of 14 patients with anterior AMI and 6 controls with atypical chest pain and have normal coronary artery. The coronary flow pattern was assessed using intracoronary Doppler wire and vasodilatory reserve was measured after injection of 18µg of adenosine to infarct-related artery after successful revascularization by percutaneous angioplasty at average 11days post-AMI. After measurement of coronary blood flow pattern, myocardial perfusion status was evaluated by myocardial contrast echocardiography(MCE). Perfusion status by MCE was analysed semiquantitatively and compared to various parameters of coronary flow and vasodilatory reserve of infarct-related artery.

After successful revascularization, perfusion defect by MCE was observed in 50%(n=7) of patients. The vasodilatory reserve was lower in patients with perfusion defect by MCE than those of patients without perfusion defect(p<0.05) and contol(p<0.05). There was no difference in coronary flow reserve between patients with no perfusion defect and controls(p=0.54). Coronary flow reserve was more than 2.0 in patients with no perfusion defect and was below 2.0 in patients with perfusion defect except one patient. Coronay flow reserve correlated well with the degrees of contrast opacification of left anterior descending artery territory(r=0.80, p=0.005). The increments of peak diastolic velocity after adenosine was correlated with coronary flow reserve better than that of systolic peak velocity(r=0.63, p=0.016 vs r=0.3, p=0.29).

These data showed a good correlation of coronary flow reserve with the degree of myocardial perfusion in patients of reperfused acute myocardial infarction. The increments of peak diastolic velocity was important to maintain the coronary flow than that of systolic peak velocity. This suggests that the measurement of vasodilatory reserve by intracoronary Doppler wire is a good method to assess the perfusion status of infarcted myocardium in early recovery phase of AMI.