Significance of reciprocal S-T segment depression in anterior precordial leads in acute inferior myocardial infarction: Concomitant left anterior descending coronary artery disease?

The reciprocal changes of S-T segment depression in the anterior precordial leads of the electrocardiogram in acute inferior myocardial infarction may be due to left anterior descending coronary artery disease and anterior wall ischemia. The electrocardiograms of 45 patients with acute inferior infarction who had subsequent cardiac catheterization (41 patients) or necropsy (4 patients) were examined to test this hypothesis.

Significant left anterior descending coronary artery disease (greater than 70 percent stenosis of luminal diameter) was observed in 31 (69 percent) of the 45 patients. The sensitivity, specificity and predictive value of S-T depression (1 mm or greater) in various anterior precordial leads singly or in combination was determined for this lesion. Left anterior descending coronary artery disease was present in 23 of 24 patients with S-T depression in one or more leads from V₁ to V₄ (predictive value 95 percent), and this index had the best combination of sensitivity (74 percent), specificity (93 percent) and predictive value in this group. Seven of 13 patients with left anterior descending coronary artery disease had S-T depression only in lead I or aVL, or both (sensitivity 100 percent, specificity 53 percent and predictive value 54 percent). S-T depression in any of leads I, aVL and V₁ to V₆ occurred in 37 patients, and 31 of these had left anterior descending coronary artery disease (sensitivity 100 percent, specificity 57 percent and predictive value 84 percent). The eight patients without anterior precordial lead S-T depression did not have left anterior descending coronary artery disease. Complications of infarction developed in 13 patients;S-T depression in at least one of leads V₁ to V₄ occurred in 12 (92 percent) of these 13 but in only 12 (38 percent) of 32 patients without complications.

Thus the predictive value of S-T depression in leads V₁ to V₄ (95 percent) for left anterior descending coronary artery disease is greater than the occurrence of the latter (69 percent) in all cases of acute inferior myocardial infarction (p < 0.05). S-T depression in these leads may be due not to reciprocal changes but rather to left anterior descending coronary artery disease with anterior wall ischemia. Such S-T depression is a sensitive marker for complications in these patients.     

Diagnostic value of exercise-induced S-T segment depression in patients with right bundle branch block

The sensitivity of submaximal exercise testing in detecting coronary artery disease in patients with right bundle branch block is not known. Thirty patients were identified who had right bundle branch block, submaximal treadmill exercise tests and selective coronary angiography. Eighteen of these patients were found to have significant coronary artery disease. Treadmill exercise testing was associated with S-T segment depression limited to leads V₁ to V₃ in three patients with coronary artery disease, whereas S-T segment depression was noted in leads V₄ to V₆ in eight patients, all of whom had multivessel coronary artery disease. Among patients without significant coronary artery disease, six had S-T segment depression limited to leads V₁ to V₃ during exercise testing.In this patient population, composed predominantly of men with symptoms of ischemic heart disease, the 12 lead submaximal treadmill exercise test had a sensitivity rate of 69 percent and a specificity rate of 45 percent in detecting coronary artery disease in the presence of right bundle branch block. The specificity of the treadmill test appears to be greater if S-T depression is recorded in leads V₄ to V₆. S-T segment depression limited to leads V₁ to V₃ often represents a false positive exercise test.     

Electrocardiographic localization of the occlusion site in left anterior descending coronary artery in acute anterior myocardial infarction

BACKGROUND: The site of occlusion of left anterior descending coronary artery is important in acute anterior myocardial infarction because, proximal occlusion is associated with less favorable outcome and prognosis. The present study attempted to evaluate the electrocardiographic correlate of the location of the site of the left anterior descending coronary artery occlusion with respect to first septal perforator and/or the first diagonal branch. METHODS AND RESULTS: The study included 50 patients with a first acute anterior myocardial infarction. The electrocardiogram with the most pronounced ST segment deviation before the start of reperfusion therapy was evaluated and correlated with the left anterior descending occlusion site as determined by coronary angiography. ST segment elevation in lead aVR, ST segment depression in lead V5 and ST segment elevation in V1>2.5 mm strongly predicted left anterior descending occlusion proximal to first septal, whereas abnormal Q wave in V4-6 was associated with occlusion distal to first septal. Abnormal Q wave in lead aVL was associated with occlusion proximal to first diagonal, whereas ST depression in lead aVL was suggestive of occlusion distal to first diagonal branch. For both first septal and first diagonal, ST segment depression > or =1 mm in inferior leads strongly predicted proximal left anterior descending artery occlusion, whereas absence of ST segment depression in inferior leads predicted occlusion distal to first septal and first diagonal. All the patients were followed during their in-hospital stay (median of 7 days), during which four patients in the proximal to first septal and first diagonal group and one patient in the distal to first septal and first diagonal group died (p < or = 0.001). CONCLUSIONS: In acute myocardial infarction electrocardiogram is useful to predict the left anterior descending occlusion site in relation to its major side branches and such localization has prognostic significance.     

急性心肌梗死对应导联ST段变化与冠状动脉病变的关系

目的 用冠状动脉造影技术研究急性心肌梗死(AMI)对应导联ST段变化与冠状动脉病变的关系。方法136例急性心肌梗死共分五组:①组,前壁梗死(V1-6)伴有Ⅱ,Ⅲ,aVF导联ST段下移。②组,下壁梗死(Ⅱ,Ⅲ,aVF)同时伴有V1-6导联ST段下移。③组,下壁梗死(Ⅱ,Ⅲ,aVF)同时伴有I,aVL导联ST段下移。④组,前壁梗死(V1-6)未伴有其它导联的ST段变化。⑤组,下壁梗死(Ⅱ,Ⅲ,aVF)未伴有其它导联的ST段变化。所有患者均进行冠状动脉造影。结果 前壁心肌梗死伴有Ⅱ,Ⅲ,aVF导联ST段下移25例中有88%为左冠状动脉前降支病变,其中90.9%为左冠状动脉近端病变。前壁心肌梗死未伴有Ⅱ,Ⅲ,aVF导联ST段下移的36例患者中有94.4%为左冠状动脉前降支病变,两者统计无显著性差异。在下壁心肌梗死伴有V1-6导联ST段下移组22例中有81.8%为右冠状动脉病变,但同时伴有前降支病变的却有77.3%,其中单支病变仅18.2%。下壁心肌梗死未伴有V1-6导联ST段下移34例有91.2%为右冠状动脉病变,但同时伴有前降支病变的仅有32.4%,其中单支病变达52.9%。两组统计分别为P<0.001和P相似文献   

The predictive value of a strongly positive stress test in patients with minimal symptoms

The ability of a strongly positive stress test to predict left main coronary artery disease in people with suspected coronary artery disease but with minimal or no angina was investigated in 40 such patients. Nine had a history of myocardial infarction but no angina. Thirty-one had mild angina or a history of mild angina. The stress electrocardiograms were analyzed according to criteria known to be associated with left main coronary artery disease in moderately or severely symptomatic patients; (1) early S-T segment changes (stage I or II of exercise), (2) 2 mm or more S-T segment depression, (3) downsloping S-T segments, (4) associated exercise-induced hypotension, (5) prolonged S-T segment changes after the test (≥8 minutes) and (6) anterior and inferior S-T segment depression. The prevalence of left main coronary artery disease was 35 percent and that of any severe coronary artery disease 75 percent. The criterion of anterior and inferior electrocardiographic changes with exercise was most predictive of left main coronary artery disease (P < 0.01 by χ²). Exercise electrocardiography is useful in the prediction of left main or other severe coronary artery disease even when performed in patients who have minimal angina or in those who are asymptomatic after myocardial infarction.     

The Value of Exercise Electrocardiography and Exercise Thallium-201 Myocardial Perfusion Scanning in Determining the Presence of Single Vessel Coronary Artery Obstruction

Summary: In 39 patients with single vessel coronary artery disease and no previous myocardial infarction, exercise thallium-207 myocardial perfusion scanning and 12 lead exercise electrocardiography (ECG) were compared to see how reliably each method identified the site of coronary artery obstruction. Significant (≥ 70% diameter) stenosis was present in the left anterior descending (LAD) coronary artery in 21 patients, in the right coronary artery (RCA) in 14 patients and in the left circumflex (LCX) in four patients. Thallium defects on the scan in the septa1 (SEPT), anteroseptal (ANT SEPT) and anterior (ANT) segments correlated (P < 0.0005) with LAD disease and defects in the inferior (INF), posteroinferior (POST INF), and posterior (POST) segments correlated (P < 0.0005) with RCA or LCX disease. Exercise induced ST segment elevation in VI and/or AVL correlated with LAD disease. The site of ischaemic ST depression did not correlate with disease in any vessel. ST segment depression in leads L2, 3, AVF (67%) and in leads V4–6 (67%) was most sensitive for detecting patients with LAD disease and ST depression in leads V4–6 was most sensitive (56%) for detecting patients with RCA or LCX disease but neither differentiated LAD from RCAILCX disease.
During exercise induced ischaemia, the site of ST segment depression on the 12 lead exercise ECG will not identify the area of ischaemia in patients with single vessel disease but thallium defects will. In contrast to ST depression, ST elevation in V1 and/or AVL may identify LAD stenosis.     

Angiographic correlates of anterior ST segment depression in acute inferior wall myocardial infarction.

This study was conducted prospectively to assess the correlation between the pattern of anterior ST segment depression on the admission electrocardiogram and the in-hospital morbidity and mortality in patients with acute inferior wall myocardial infarction. Coronary angiography was also done to assess its correlation, if any, with pattern of anterior ST segment depression. Our study cohort comprised of 165 consecutive patients with acute inferior wall myocardial infarction divided into four groups based on admission electrocardiogram. Group I (n = 33): patients with no anterior ST segment depression; group II (n = 16): patients with ST segment depression in leads V1-V3; group III (n = 71): patients with ST segment depression in leads V4-V6, I and aVF, and; group IV (n = 45): patients with ST segment depression in all anterior leads (V1-V6, I, aVL). The outcomes were analysed in terms of high grade atrioventricular block, Killip class II or higher failure, and in-hospital mortality. Coronary angiography was performed to analyse coronary anatomy. Group IV patients had increased incidence of complete heart block (37.8% vs 15.2% in the total group) (p < 0.001) and increased mortality (11.1% vs 4.2% in the total group) (p < 0.05). This group also had greater incidence of triple vessel disease (76.7%) (p < 0.001). Group II patients had greater incidence of double vessel disease (88.9%) (p < 0.05) and had no triple vessel disease. Group III patients had double vessel disease (76.5%) (p < 0.05) or triple vessel disease (23.5%) (p = NS) and no single vessel disease. Coronary angiography in group II showed greater incidence of involvement of left circumflex artery and right coronary artery while in group III there was left anterior descending artery and right coronary artery disease. We conclude that patients with anterior ST segment depression in group III and group IV categories are in high risk subset with acute inferior wall myocardial infarction.     

Transient electrocardiographic changes in patients with unstable angina: Relation to coronary arterial anatomy

The relation between the spontaneous electrocardiographic changes and coronary arterial anatomy in unstable angina pectoris was examined in 97 patients with coronary artery disease and transient electrocardiographic changes during chest pain. Sinus rhythm was maintained during pain in all patients. Heart rate increased significantly in 61 percent (mean ± standard error of the mean 72 ± 2 to 93 ± 2 beats/min, probability [p] < 0.001) and was unchanged or decreased in 39 percent of patients (73 ± 2 to 72 ± 2 beats/min; p = not significant) during pain. S-T segment changes developed in 97 percent of patients, of whom 42 percent had S-T segment elevation and 55 percent S-T depression. The magnitude of the S-T segment shift was greater in patients with triple vessel disease (2.2 ± 0.4 mm) than in those with double (1.5 ± 0.1 mm) or single (1.4 ± 0.1 mm) vessel disease (p < 0.05). In 43 patients with single vessel disease S-T segment elevation developed in 78 percent of those with right coronary artery disease and in only 9 percent of those with left circumflex disease (p < 0.02). Maximal S-T segment changes were more frequent in the inferior leads in patients with right coronary artery disease (56 percent) and in the anterior leads in patients with left anterior descending (65 percent) and circumflex (64 percent) disease (p < 0.05).Thus, patients with coronary artery disease and unstable angina maintain regular sinus rhythm during chest pain, and the heart rate usually increases but may be unchanged or decreased in a significant proportion. S-T segment elevation is common in these patients and the magnitude of the S-T segment shift is related to the extent of the underlying coronary disease. This study suggests that the type and distribution of the repolarization changes are a reflection of the location and severity of the atherosclerotic process.     

Electrocardiographic patterns of proximal left anterior descending artery occlusion in ST-elevation myocardial infarction may be modified by 3-vessel coronary artery disease

BackgroundThe electrocardiographic (ECG) pattern of ST-segment deviation in myocardial infarction is integral to the proper assessment of the location, extent, and functional significance of the infarct but may be modified by the underlying coronary artery anatomy.MethodsWe describe the ECG findings in 2 cases of proximal left anterior descending (LAD) artery occlusion in ST-elevation myocardial infarction (STEMI) associated with 3-vessel coronary artery disease.ResultsBoth patients had atypical ECG patterns of ST-segment elevation in leads V₂, I, and aVL and ST-segment depression with positive T waves suggestive of extensive subendocardial ischemia in leads II, III, aVF, and V₃ through V₆; acute proximal LAD occlusion and concomitant 3-vessel coronary artery disease were observed angiographically.ConclusionElectrocardiographic changes in proximal LAD STEMI may be modified by the presence of significant atherosclerotic disease elsewhere in the coronary vasculature. Recognition of this ECG pattern may aid the clinician in the rapid identification of high-risk STEMI.     

Detection of critical coronary lesions with treadmill exercise testing: Fact or fiction?

This study was designed to determine whether treadmill exercise testing could identify patients with critical coronary lesions. Critical lesions were defined as obstruction of the left main coronary artery or concomitant narrowing of the left anterior descending and circumflex coronary arteries proximal to any major branches. The time of onset and degree of S-T segment depression were evaluated in 25 patients with critical lesions and in 50 patients with other types of lesions. S-T segment depression of 2 mm or more was present in 82 percent of patients with left main coronary disease and in 71 percent of patients with left main coronary equivalent lesions (both P < 0.02 when compared with 36 percent of patients with other lesions). However, half of the 37 patients with this degree of S-T segment depression had noncritical lesions. Ischemic changes appearing in the first 3 minutes of exercise were seen in 63 percent of patients with left main coronary disease and 35 percent of the patients with left main coronary equivalent lesions (P < 0.001 and P < 0.002, respectively, when compared with only 6 percent of patients with other lesions). The incidence of triple vessel disease was significantly greater in patients with critical lesions (55 percent in patients with left main coronary disease and 71 percent in those with left main coronary equivalent lesions versus 10 percent in those with other lesions) (P < 0.01). S-T segment depression of 2 mm or more is not a good indicator of critical coronary lesions because it has a low level of specificity. Consideration of the time of onset of ischemic changes adds to its usefulness, but it does not permit a definitive diagnosis in individual patients.     

Predictive Value of Admission Electrocardiogram For Multivessel Disease in Acute Anterior and Anterior‐Inferior Myocardial Infarction

Background: Our aim was to investigate the correlation between admission ECG and coronary angiography findings in terms of predicting the culprit vessel responsible for the infarct or multivessel disease in acute anterior or anterior‐inferior myocardial infarction (AMI). Methods: We investigated 101 patients with a diagnosis of anterior AMI with or without ST‐segment elevation or ST‐segment depression in at least two leads in Dll, III, aVF. The patients were classified as those with vessel involvement in the left anterior descending (LAD) coronary artery and patients with multivessel disease. Vessel involvement in LAD + circumflex artery (Cx) or LAD + right coronary artery (RCA) or LAD + Cx + RCA were considered as multivessel disease. Thus, (a) anterior AMI patients with reciprocal changes in inferior leads, (b) anterior AMI patients with inferior elevations, (c) all anterior AMI patients according to the ST‐segment changes in the inferior region were analyzed according to the presence of LAD or multivesssel involvement. Results: Presence of ST‐segment depression in aVL and V6 was significantly correlated with the presence of multivessel disease in anterior AMI patients with reciprocal changes in the inferior leads (P = 0.005 and P = 0.003, respectively). No statistically significant difference between the leads were detected in terms of ST‐segment elevation in predicting vessel involvement in the two groups of anterior AMI patients with inferior elevations. When all the patients with anterior AMI were analyzed, the presence of ST‐segment depression in leads aVL, V4, V5 and V6 were significantly associated with the presence of multivessel disease (P = 0.035, P = 0.010, P = 0.011, P = 0.001, respectively). Conclusions: The presence of ST‐segment depression in anterolateral leads in the admission ECG of anterior AMI patients with reciprocal changes in inferior leads was associated with multivessel disease.     

Left ventricular dyskinesia in infarction and angina.

In 29 patients, the site and extent of coronary artery obstruction were related to the position and area of abnormally contracting segments of the left ventricle, both in patients with a history of angina without myocardial infarction (group I) and in patients with prior documented myocardial infarction (group II). The degree of coronary artery obstructive disease was estimated in the standard manner and also by a coronary artery index which considered not only the degree of obstruction but also the total length of the obstructed segment. A kinetic or dyskinetic segments were present in 22 of the 29 patients. An abnormally contracting segment was present in 12 or 18 patients without prior myocardial infarction in comparison with 10 of the 11 patients with prior infarction. Complete obstruction of a coronary vessel and resultant dyskinesia were more frequent in the right coronary artery than in either the left anterior descending or the circumflex artery. There was a significant correlation between total per cent of vessel obstruction and degree of ventricular asynergy in both groups; consideration of length of obstructed segment did not improve this correlation.     

Exercise-induced ST-segment changes in lead V1 identify the significantly narrowed coronary artery in patients with single-vessel disease: correlation with thallium-201 scintigraphy and coronary arteriography data

We investigated the correlation of exercise-induced ST-segment changes in lead V1, with the detection of the significantly narrowed vessel that induced ischemia during exercise in myocardial areas supplied by this vessel. We studied 198 patients who underwent exercise testing, thallium-201 scintigraphy, and coronary arteriography. The patients were divided into three groups. In group 1 (ST-segment elevation in lead V1), 84% had left anterior descending coronary artery disease (P<.001); in group 2 (ST-segment depression in lead V1), 76% had right coronary artery disease (P<.001); and in group 3 (no ST-segment changes in lead V1), there were no significant differences concerning the narrowed vessel. Thallium-201 scintigraphy data confirmed the existence of the reversible perfusion defect(s) in an area(s) of myocardium supplied by the respective coronary arteries (P<.001). Exercise-induced ST-segment elevation or depression in V1 may identify the obstructed vessel in patients with single-vessel disease and without prior myocardial infarction.     

Exercise electrocardiography: recognition of the ischemic response, false positive and negative patterns

The ischemic electrocardiographic response is characterized by S-T segment depression in the left ventricular leads. When this response is elicited by exercise and is accompanied by anginal discomfort, it constitutes powerful diagnostic evidence of the presence of coronary arterial obstructive disease. The amount of exercise required to elicit the response is closely related to the extent of the obstruction. S-T segment elevation provoked by exercise rarely occurs with proximal severe stenosis in the left anterior descending coronary artery or in leads exploring the region of healed myocardial infarcts. Depression of the J point may be an ischemic manifestation reversible by administration of nitroglycerin.The ischemic electrocardiographic response may be obscured by conduction defects as in bundle branch block and healed myocardial infarcts. False positive ischemic responses may be encountered in patients taking digitalis glycosides or potassium-depleting drugs, or in patients with hyperadrenergic states, pectus excavatum or short P-R Intervals.     

Role of myocardial ischemia in the genesis of stress-induced S-T segment elevation in previous anterior myocardial infarction

This study tests the hypothesis that myocardial ischemia is responsible for exercise-induced S-T segment elevation in patients with previous anterior myocardial infarction (MI). Exercise stress testing in conjunction with thallium imaging of the myocardium was performed in 28 patients with previously documented anterior MI. Thallium images were analyzed by computer for the presence of initial uptake defects and evidence of abnormal clearance of the isotope from the myocardium (that is, imaging evidence of ischemia). Total S-T segment elevation (∑ST) in precordial leads V₁ to V₆ at rest was subtracted from ∑ST at peak stress in order to quantitate the extent of S-T elevation induced by stress (ΔST). Two groups of patients were identified; 1 with stress-induced S-T elevation (Group I, ΔST ≥ 4.0 mm) and 1 without this abnormality (Group II, ΔST < 4.0 mm). Evidence of abnormal thallium washout from myocardial scan segments occurred in 12 of 15 Group I patients versus 9 of 13 Group II patients (difference not significant). In addition, abnormal tracer washout from anterolateral or septal scan segments occurred in 5 patients in each group. Likewise, abnormal thallium clearance from inferior or posterior scan segments occurred in 8 of 15 Group I patients versus 7 of 13 Group II patients (difference not significant). The patient with the greatest amount of stress-induced S-T elevation (S-T 11.5 mm) had no evidence of ischemia during the stress test. However, Group I patients did have larger anterolateral plus septal initial thallium uptake defect scores than did those of Group II (10 of 15 with defect score ≥ 350 in Group I versus 1 of 13 in Group II, p <0.002). Similarly, resting left ventricular ejection fraction ≥ 30% was present in only 4 of 15 Group I patients versus 13 of 13 in Group II (p <0.001). Finally, multiple stepwise linear regression analysis demonstrated that ΔST correlated best with the extent of initial anterolateral plus septal thallium uptake defect score (F = 17.3, p < 0.001) and to a lesser extent with resting ejection fraction (F = 5.2, p < 0.05) and change in heart rate from rest to peak stress (F = 8.1, p < 0.01; corrected multiple correlation coefficient = 0.76, p < 0.001). Thus, in patients with previous anterior MI (1) exercise-induced myocardial ischemia occurs as often with as without S-T segment elevation, (2) myocardial ischemia is not required for the production of stress-induced S-T segment elevation, and (3) stress-induced S-T elevation primarily reflects the extent of previous anterior wall damage and to a lesser extent an increase in heart rate between rest and peak stress.     

Correlation of computer-quantitated treadmill exercise electrocardiogram with arteriographic location of coronary artery disease

Graded treadmill exercise testing and coronary cinearteriographic studies were carried out on 86 patients with angina pectoris. At rest, all patients demonstrated a normal S-T segment on the modified bipolar lead V₅ recording used. The computer-quantitated S-T segment response to exercise was correlated with the location and extent of obstructive coronary artery disease. The coronary cineartertograms were reviewed by 3 physicians and stenosis of 75 percent or greater was considered significant. All patients showed at least this degree of stenosis in 1 or more major coronary arteries, and 83 of 86 exhibited 90 percent or greater stenosis in at least 1 artery. Thirty-one patients had stenosis in a single artery, 43 had stenosis in 2 arteries and 12 had significant lesions in all 3 major arteries. In 70 of the 86 (82 percent) patients, a positive S-T segment response developed during or immediately after exercise. In 12 of the 16 with a negative response, disease was limited to a single artery. In 11 of the 12 the disease was restricted to the right coronary or left circumflex arteries. Of the 12 patients with an isolated stenosis of the left anterior descending artery, 11 (92 percent) had a positive S-T segment response. Of 55 patients with 2- or 3-vessel disease, 51 (93 percent) demonstrated a positive S-T response. Graded treadmill exercise testing in 80 patients with chest pain, normal coronary art eriograms and normal left ventricular function revealed 4 (5 percent) with a false positive S-T segment response.     

246例回旋支不同节段闭塞的心电图特点

目的探讨回旋支闭塞中不同节段,不同优势型,多支病变对心电图变化的影响。方法本研究共入选246例发生急性LCX闭塞的患者（其中男187例,女59例）,根据冠脉造影结果将患者根据冠脉优势型、单支、多支、合并LAD、RCA分组,结合年龄、性别及相关危险因素,对比分析心电图改变与冠脉造影结果及临床特点的关系。结果回旋支闭塞心电图变化受不同冠脉优势型影响,Ⅱ、Ⅲ、aVF、V7~V9导联ST段抬高常见于左优势型的LCX闭塞。V1~V3导联ST段压低常见于均衡型的LCX闭塞,Ⅰ、aVL导联ST段抬高在各优势型中无特异性。在单支LCX闭塞中,V1~V3导联ST段压低常见于近段闭塞,Ⅱ、Ⅲ、aVF导联ST段抬高常见于远段闭塞,V7~V9导联ST段抬高与Ⅰ、aVL导联ST段抬高在各节段闭塞的心电图中无特异性。合并多支病变时LCX心电图变化与单纯LCX闭塞存在差异,在LCX近段闭塞中,合并多支病变的患者更易出现V7~V9导联ST段抬高,单支病变者心电图易出现V1~V3导联ST段压低,在LCX中段闭塞的患者中,单支病变与多支病变的心电图改变大致相同。在LCX远段闭塞的患者中,多支病变患者出现V1~V3导联ST段压低可能性较大。OM闭塞在单支及合并多支病变时的心电图差异无明显统计学意义。在合并LAD或RCA病变的LCX闭塞患者中,心电图改变无明显差异。结论心电图对诊断梗死相关动脉为回旋支的急性心肌梗死有重要的预测价值,结合病史及相关一般资料可对急性心肌梗死患者的预后进行评估。     

The perfusion pattern in coronary artery occlusion: comparison of exercise and adenosine.p6.

This study compared exercise to adenosine thallium-201 single photon emission computed tomography in detecting occlusion of left anterior descending or right coronary arteries in patients with no previous myocardial infarction. There were 41 patients who underwent adenosine thallium imaging (adenosine infusion at a rate of 140 micrograms/kg/min for 6 min), and 143 patients who underwent exercise thallium imaging. There were more patients with right coronary than left anterior descending coronary artery occlusion. Thus, in the adenosine group, there were 15 patients with left anterior descending artery occlusion, and 26 with right coronary artery occlusion, and in the exercise group, there were 46 patients with left anterior descending artery occlusion, and 97 patients with right coronary artery occlusion. In the adenosine group, the thallium images were abnormal in 41 patients (100%), while in the exercise group, the thallium images were abnormal in 125 patients (87%, P < 0.02) in the territories of the occluded arteries. ST segment depression was noted in 19 patients (46%) in the adenosine group, and 69 patients (48%) in the exercise group (P:NS). In patients with isolated single vessel occlusion, the size of the perfusion abnormality was 28 +/- 9% with adenosine, and 21 +/- 12% with exercise (P:NS). Thus, most patients with occlusion of the left anterior descending or right coronary artery have regional perfusion abnormality during stress; the different role of collaterals with each type of stress may explain the higher percentage of abnormal results with adenosine than exercise.     

Relation between the precordial projection of S-T segment changes after exercise and coronary angiographic findings.

The recent introduction of electrocardiographic mapping permits measurement of the precordial area and severity of exercise-induced S-T segment changes. This study was designed to compare this technique with a modified 12 lead electrocardiogram in defining the degree and site of coronary artery disease. One hundred patients, who later had diagnostic coronary arteriography, underwent an exercise test using both 16 point precordial mapping and a modified 12 lead electrocardiogram. The sensitivity of electrocardiographic mapping (96 percent) for the diagnosis of coronary artery disease was significantly greater than that of the modified 12 lead electrocardiogram (80 percent). However, the specificity of the two lead systems was similar. Typical precordial projections of S-T segment change were found when the left main stem or proximal left anterior descending coronary artery were narrowed or when there was isolated disease of the left anterior descending or right coronary artery. Widespread precordial changes were found in patients with three vessel disease. Although there was no significant difference in the sensitivity (66 percent) and specificity (100 percent) of electrocardiographic mapping and of the 12 lead system in identifying three vessel disease, there was a significant difference in sensitivity (electrocardiographic mapping 74 percent, 12 lead system 42 percent) in identifying isolated single vessel disease. In addition, information regarding the presence of left main stem or proximal left anterior descending coronary arterial narrowing was obtained only with electrocardiographic mapping. The superiority of electrocardiographic mapping over the modified 12 lead electrocardiogram has been shown, and clinical application of this technique should be useful in the management of patients presenting with chest pain.     

Comparison of S-T segment changes on exercise testing with angiographic findings in patients with prior myocardial infarction

Ninety-seven patients with a prior transmural myocardial infarction who underwent coronary angiography and treadmill stress testing were studied retrospectively to assess the reliability of the exercise electrocardiogram in detecting additional disease in patients with a prior infarction. In patients with a previous inferior wall infarction, the S-T response to the treadmill stress test had a high degree of sensitivity (87 percent) and specificity (90 percent) in detecting additional significant coronary artery disease. However, in patients with a previous anteroseptal wall Infarction, the S-T response had much less sensitivity (52 percent), but the degree of specificity remained high (90 percent). In this group a positive test suggested the presence of ischemia in the lateral or inferoposterior region of the myocardium, or both. A negative S-T response was of little value In distingulshing among groups of patients with single or multiple vessel coronary artery disease. The presence of an anterior ventricular aneurysm is most likely responsible for this low sensitivity rate because it generates an opposing force to the ischemic vector, thereby cancelling the S-T segment changes and producing a false negative treadmill stress test. The resting surface electrocardiogram proved useful in predicting a false negative exercise test. The presence of Q waves in the precordial leads extending to lead V₄ or beyond decreased the sensltivity rate of treadmill stress testing to 33 percent.