Application Of Changes Of ST/T In Electrocardiogram In Acute Coronary Syndrome

Objectives: We sought to investigate the value of changes of ST/T inelectrocardiogram (ECG) in diagnose the coronary artery disease in acute coronarysyndrome (ACS) by comparing and analyzing the result of coronary angiography(CAG) and the change of ECG.Methods: We retrospectively studied the 310 patients who were diagnosed ofACS and admitted to the department of cardiology of our hospital from May 2004 toDecember 2006. All patients underwent CAG and electrocardiographic examination.The stenosis≥50％was considered significantly. ST-segment elevation≥0.10mv(ST-segment elevation≥0.30mv in leads V1-V3), ST depression≥0.05mv and/or theamplitude of T wave≥0.1 mv in leads with dominant R wave in two continous leadsexcept lead AVR were considered significantly. The elevation in lead AVR≥0.05mvwas considered significantly. The result of CAG and the change of ECG wererecorded, compared and analyzed. For comparison of measurement data,Independent-Sample t test or One-Way ANOVA were used.For comparison ofnumeration data, the chi-square test or the Fisher exact test were used. Pearson'slinear correlation or logistic regression analysis were used for the examination ofcorrelation. A probability value＜0.05 was considered statistically significant.Results: 1. Compared to the group without coronary artery stenosis≥50％, it wasstatistically significant of the change of ST, ST/T, ST-T in ECG for the group withcoronary artery stenosis≥50％(P＜0.01), with the sensitivities of 79.49％, 86.32％,22.22％and the specificities of 82.89％, 53.95％, 94.74％, respectively. But there wasno significant differences in the change oft wave (P＞0.05). The areas of ST, T, ST/T,ST-T under the ROC curve were 0.812,0.474,0.585,0.299 respectively. It was moreprone to have the change of ST, ST/T and ST-T in the group with single-vessel,double-vessel, three-vessel, left main coronary artery disease as well as the group with the proximal, the distal, the proximal+the distal stenosis than the group withoutstenosis≥50％(P＜0.05). But there was no statistically significant between the groupof different number and different site of coronary artery disease (P＞0.05). The groupwith stenosis≥50％,≥70％,≥90％were more prone to have the change of ST andST/T (P＜0.05). As the degree of the stenosis aggravated, the sensitivity of ECGincreased (79.49％VS 84.04％VS 89.50％, 86.32％VS 89.20％VS 92.27％), but thespecificity decreased (82.89％VS 79.38％VS 71.32％, 53.95％VS 51.55 VS45.74％). The positive rate of CAG with ST- segment elevation was 99％, andobviously higher than the group with ST-segment depression (82％) and the groupwithout ST-segment change (43％).2. In non-ST-segment elevation acute coronary syndrome (NSTEACS), theaccuracies of ST, T, ST/T, ST-T were not high, the areas under the ROC curve were0.311, 0.447, 0.381, 0.378, respectively. Patients with three-vessel disease had ahigher prevalence of ST-segment elevation in lead AVR and a higher prevalence ofST-segment depression≥0.20mv (P＜0.01). Multivariate logistic regression analysisshowed that ST-segment elevation in lead AVR was related to three-vessel disease(P＜0.05), the sensitivity, specificity, positive predictive value, negative predictivevalue and accuracy was 48.57％, 85.51％, 62.96％, 76.62％and 73.08％, respectively.3. ST-segment elevation acute myocardial infarction(1) In acute anterior wall myocardial infarction, there were no significantdifferences in the degree of ST-segment deviation in leadsⅠand V1 toV6(P＞0.05), but the degree of ST-segrnent depression in leadsⅡ,Ⅲ, AVF wasobviously lower in the proximal left anterior descending artery (LAD) occlusion thanthe distal one (-0.08±0.08mv VS -0.02±0.05mv, -0.10±0.13mv VS -0.02±0.05mv,-0.11±0.12mv VS -0.01±0.04mv, P＜0.05), and the elevation in leads AVR and AVLwas higher in the proximal LAD occlusion (0.04±0.05my VS 0.00±0.05my, 0.07±0.10my VS 0.01±0.07mv, P＜0.05). The sensitivities to predict the proximal LADlesion were 58.82％, 58.82％, 64.71％, 58.82％and 52.94％respectively, whilespecificities were 73.08％, 73.08％, 69.23％, 84.62％and 76.92％respectively. (2) There were no significant differences in the degree of ST-segment deviationin leadsⅡ, AVF and V1 to V4 between the right coronary artery (RCA) group andthe left circumflex branch (LCX) group in patients with acute inferior wallmyocardial infarction (P＞0.05 ). If the infarct-related artery (IRA) was RCA, it had ahigher prevalence of ST-segment depression in leads I and AVL (46/53 VS 6/12,47/53 VS 2/12, P＜0.01), ST-segment depression in lead AVL exceeding leadⅠ(33/53VS 3/12, P＜0.05), ST-segment elevation in leadⅢexceeding leadⅡ(48/53 VS 4/12,P＜0.01) and without significant ST-segment depression in lead AVR (37/53 VS 3/12,P＜0.01) than LCX group, the sensitivities to predict the RCA lesion were 86.79％,88.68％, 62.26％, 90.57％and 69.81％respectively, whereas the specificities were50.00％, 83.33％, 75.00％, 66.67％and 75.00％respectively.It was more probably tobe LCX as the culprit artery if it appeared to be ST-segment elevation in leads V5 orV6 (6/12 VS 9/53, P＜0.05) and ST-segment depression in lead AVR (9/12 VS 16/53,P＜0.01), with the sensitivities of 50.00％, 75.00％respectively and the specificities of83.02％, 69.81％respectively.In acute inferior wall myocardial infarction, the incidence of three-vessel diseasein groups with maximal precordial ST-segment depression in leads V4-V6, noprecordial ST-segment depression and maximal precordial ST-segment depression inleads V1-V3 were 67％, 31％and 19％, whereas the LAD stenosis were 89％, 63％,52％. The incedence of three-vessel disease and LAD stenosis were higher in groupwith maximal precordial ST-segment depression in leads V4-V6 than the other twogroups (P＜0.05).(3) Left ventricutar dysfunction to be over killip 2 occurred more frequently inacute anterior wall myocardial infarction than acute inferor wall myocardialinfarction(7/35 VS 3/51, P＜0.05), and the LVEF was also lower than acute inferorwall myocardial infarction (52.09％±9.30±VS 56.36％±5.88％, P＜0.05). In acuteanterior wall myocardial infarction, the group with ST-segment elevation in lead AVRhad a lower LVEF than the group with no ST-segment deviation in lead AVR and thegroup with ST-segment depression in lead AVR (46.22％±7.41％VS 55.00％± 8.83％VS 51.71％±7.48％, P＜0.05). there were no differences among groups withST-segment elevation, no ST-segment deviation and ST-segment depression in leadAVR in acute inferior wall myocardial infarction (P＞0.05).Conclusions: 1. It has some value of ECG to identify coronary artery disease.ST-segment elevation in lead AVR in NSTEACS is useful to identify three-vesseldisease.2. In acute anterior wall myocardial infarction, ST-segment depression in leadsⅡ,Ⅲ,AVF and ST-segrnent elevation in leads AVL, AVR suggest to be the proximalLAD occlusion. In acute inferior wall myocardial infarction, ST-segment depressionin leads I and AVL, ST-segment depression in lead AVL exceeding leadⅠ,ST-segment elevation in leadⅢexceeding leadⅡand without significant ST-segmentdepression in lead AVR suggest the IRA is RCA, while ST-segment elevation in leadsV5 or V6 and ST-segment depression in lead AVR can be helpful to identify the LCXlesion.Maximal precordial ST-segment depression in leads V4-V6 in acute inferior wallmyocardial infarction is suggestive of three-vessel disease involving the LADdisease.