The Usefulness of Intracoronary Electrocardiography during Primary Percutaneous Coronary Intervention in Patients with Acute Myocardial Infarction

Background and Objectives：Measurements obtained using an intracoronary electrocardiogram (IC-ECG) reflect the electrical activity in various regions of the myocardium. This technique can be easily used in the catheterization laboratory during percutaneous coronary intervention (PCI) procedures. Furthermore, IC-ECG could be used to evaluate myocardial viability in patients with acute myocardial infarction (AMI). The aim of this study was to evaluate the usefulness of IC-ECG in predicting the microvascular integrity and late improvement of left ventricular (LV) function after primary PCI in patients with AMI. Subjects and Methods：A total of 78 patients (62 male, 16 female) who underwent primary PCI with stent implantation were enrolled in this study. After the implantation of the stent, IC-ECG was recorded from the tip of an insulated angioplasty guidewire before and after balloon occlusion of the infarct-related artery. The IC-ECG was obtained from the inferior and inferolateral areas in inferior wall MI, or apex and apical anterior wall regions in anterior wall MI. Significant ST segment elevation was defined as a further ST segment elevation of ≥0.2 mV at 80 msec after the J-point in comparison to the baseline value. The microvascular integrity of the myocardium was evaluated by myocardial contrast echocardiography (MCE) one day after the PCI was performed. Six months later, all of the patients were followed up by echocardiography and the wall motion score index (WMSI) and ejection fraction (EF) were measured. Results：Significant ST elevation was noted in 47 patients (Group A) after coronary occlusion. There was no significant change in the other 31 patients (Group B). MCE showed microvascular perfusion in 41 patients in group A (87%) and in four patients in group B (13%) (p<0.05). The six-month follow-up echocardiography showed that group A had a lower WMSI (1.20±0.18 vs 1.56±0.34, p<0.05) and higher EF (57.6±7 vs 47±11, p<0.05) than group B. The LV end diastolic dimension (LVEDD ) in group B was increased compared to group A (p=0.021). The LV end systolic dimension (LVESD ) was also increased in group B; however, the LVESD in group A was decreased after six months (p=0.002). Conclusion： IC-ECG during PCI is a simple and useful method for assessing the microvascular integrity of the myocardium and for predicting the long-term improvement of LV function. (Korean Circulation J 2007;37:148-153)