Noninvasive assessment of reperfusion after fibrinolytic therapy for acute myocardial infarction

Assessment of reperfusion by the 12-lead electrocardiogram (ECG) or biochemical markers is limited by suboptimal sensitivity and/or specificity. Body surface mapping (BSM) improves the spatial sampling of the 12-lead ECG. Serial 12-lead ECGs and 64-lead anterior BSMs were recorded from 67 patients with acute myocardial infarction undergoing coronary angiography 90 minutes after fibrinolytic therapy. ECG-1 and BSM-1 were recorded before/shortly after therapy (median 18 minutes). ECG-2 and BSM-2 were recorded after the 90-minute angiogram (median 30 minutes). The maximum ST elevation on ECG-1 was noted and > or = 30% ST resolution on ECG-2 was taken to represent partial/complete reperfusion. Patients were randomly divided into a training set and validation set. Isointegral and isopotential ST-T variables from BSMs of training-set patients were compared with Thrombolysis In Myocardial Infarction (TIMI) trial flow using discriminant analysis to identify which variables best classified reperfusion. Reperfusion (TIMI 2/3 flow) occurred in 32 of 34 training-set patients and in 29 of 33 validation-set patients. In the training set, > or = 30% ST resolution correctly classified reperfusion with 72% sensitivity (23 of 32) and 50% specificity (1 of 2). In the validation set, > or = 30% ST resolution classified reperfusion with 59% sensitivity (17 of 29) and 50% specificity (2 of 4). In comparison, a model containing 24 BSM variables correctly classified all training-set patients, and when prospectively tested in the validation-set, correctly classified 28 of 29 patients who achieved reperfusion (97% sensitivity) and all 4 patients who failed to reperfuse (p = 0.035). In conclusion, BSM is more useful than the 12-lead ECG for noninvasive assessment of reperfusion after fibrinolytic therapy for acute myocardial infarction.     

Absence of ST elevation in ECG leads V7, V8, V9 in ischaemia of non-occlusive aetiologies

BACKGROUND AND OBJECTIVE: Occlusion of the circumflex coronary artery may present with either ST elevation typical of inferior or lateral myocardial infarction, ST depression or a normal 12-lead electrocardiogram (ECG). In patients presenting with ST depression, concomitant ST elevation in the posterior leads V7, V8 and V9 is believed to reflect ST-elevation myocardial infarction of the posterior wall. However, to be confident of this diagnosis, it is necessary to know that posterior ST depression does not occur in acute subendocardial ischaemia. METHODS AND RESULTS: We have prospectively recorded leads V7, V8 and V9 simultaneously with the standard 12-lead ECG in patients who underwent treadmill stress test. Group A consists of 35 patients who showed ischaemic praecordial ST depression in their 12-lead ECGs during treadmill stress test and subsequent angiographic documentation of significant coronary artery disease. Group B consists of 35 subjects who showed normal ECG findings during treadmill stress test. In none of the Group A or B patients was there ST elevation in leads V7, V8 or V9 either at rest or at peak exercise. ST depression was seen in 69% in V7, 31% in V8 and 11% in V9 in the Group A patients at peak exercise. CONCLUSION: ST elevation in leads V7, V8 and V9 is uncommon in patients presenting with subendocardial ischaemia. Therefore, in patients presenting with acute chest pain and ST depression in the 12-lead ECG, concomitant posterior ST elevation may be a reliable indicator of ST elevation posterior MI. This is likely due to circumflex artery occlusion and may require thrombolytic therapy.     

Improved detection of acute myocardial infarction using a diagnostic algorithm based on calculated epicardial potentials

BACKGROUND: New methods for detecting myocardial infarction in patients with suspected acute coronary syndromes are needed particularly in an era where the majority of patients with myocardial infarction present with non-diagnostic 12-lead electrocardiograms (ECG). We compared a novel epicardial diagnostic algorithm using epicardial potentials from the 80-lead body surface map with other electrocardiographic techniques in detection of myocardial infarction. METHODS: Between February 1999 and February 2001, consecutive patients (n=427) with ischemic type chest pain had an initial 12-lead ECG and body surface map recorded. Detecting myocardial infarction using an epicardial algorithm was first performed in a training set (n=213) and tested in a validation set of patients (n=214). The results from this epicardial algorithm in myocardial infarction detection were compared with the physician's interpretation of the 12-lead ECG, the body surface map algorithm (PRIME) and physician's interpretation of the body surface map. RESULTS: Myocardial infarction occurred in 205 patients (creatine kinase >or=2x upper limit of normal with creatine kinase-MB >or=7% CK). The physician's interpretation of the 12-lead ECG identified 122 with myocardial infarction (sensitivity 60%, specificity 99%), the body surface map algorithm 137 (sensitivity 67%, specificity 89%), the physician's interpretation of the body surface map 153 (sensitivity 75%, specificity 91%) and the epicardial algorithm 158 (sensitivity 77% specificity 99%). Combining the physician's interpretation of the 12-lead ECG with the epicardial algorithm increased significantly the detection of myocardial infarction (sensitivity 85%, specificity 98%, p<0.001) compared with the 12-lead ECG. CONCLUSIONS: An epicardial algorithm based on epicardial potentials increases significantly the detection of myocardial infarction particularly among those with non-diagnostic 12-lead ECG's.     

Acute myocardial infarction with isolated ST-segment elevation in posterior chest leads V7-9: "hidden" ST-segment elevations revealing acute posterior infarction.

OBJECTIVES: This study was done to determine whether electrocardiographic (ECG) isolated ST-segment elevation (ST) in posterior chest leads can establish the diagnosis of acute posterior infarction in patients with ischemic chest pain and to describe the clinical and echocardiographic characteristics of these patients. BACKGROUND: The absence of ST on the standard 12-lead ECG in many patients with acute posterior infarction hampers the early diagnosis of these infarcts and thus may result in inadequate triage and treatment. Although 4% of all acute myocardial infarction (AMI) patients reveal the presence of isolated ST in posterior chest leads, the significance of this finding has not yet been determined. METHODS: We studied 33 consecutive patients with ischemic chest pain suggestive of AMI without ST in the standard ECG who had isolated ST in posterior chest leads V7 through V9. All patients had echocardiographic imaging within 48 h of admission, and 20 patients underwent coronary angiography. RESULTS: Acute myocardial infarction was confirmed enzymatically in all patients and on discharge ECG pathologic Q-waves appeared in leads V7 through V9 in 75% of the patients. On echocardiography, posterior wall-motion abnormality was visible in 97% of the patients, and 69% had evidence of mitral regurgitation (MR), which was moderate or severe in one-third of the patients. Four patients (12%), all with significant MR, had heart failure, and one died from free-wall rupture. The circumflex coronary artery was the infarct related artery in all catheterized patients. CONCLUSIONS: Isolated ST in leads V7 through V9 identify patients with acute posterior wall myocardial infarction. Early identification of those patients is important for adequate triage and treatment of patients with ischemic chest pain without ST on standard 12-lead ECG.     

93例急性心肌梗死患者的心电图及冠脉造影分析

目的探讨急性心肌梗死患者心电图sT改变的导联与冠状动脉罪犯血管的关系。方法对93例急性心肌梗死患者心电图ST段改变与选择性冠状动脉造影结果进行对比分析。结果心电图V1-V4sT抬高伴Ⅱ、Ⅲ、aVFST段下移的罪犯血管主要为左前降支（LAD）,少数前壁心肌梗死伴下壁sT段抬高;Ⅱ、Ⅲ、aVFST抬高伴V1-V4 ST段下移的主要罪犯血管为右冠状动脉（RCA）,少部分为左回旋支（LCX）,极少部分为LAD;胸前导联T高尖与ST抬高导联不一致可排除LAD;高侧壁Ⅰ、AVLST段抬高多数罪犯血管为LCX。结论心电图ST改变的导联对急性心肌梗死罪犯血管能进行初步预测。     

Spatial distribution and prognostic significance of ST segment potential determined by body surface mapping in patients with acute inferior myocardial infarction

We investigated the mechanism and significance of ST segment changes in inferior infarction by studying 100 patients with acute inferior infarction in whom body surface maps were recorded on admission. The magnitude of the maximum ST segment elevation (denoted Vmax) and magnitude of the maximum ST segment depression (denoted Vmin), as well as the ST depression on the standard 12-lead electrocardiogram were analyzed against morbidity and mortality (at a median follow-up time of 14 months). A value obtained by subtracting Vmax from Vmin correlated (p less than .0002) with outcome. Correlations were also found between Vmin and complications, Vmin and mortality, and between increasing levels of ST depression on the 12-lead electrocardiogram and mortality. The maps were also studied by grouping the 100 ST segment map patterns into five groups by cluster analysis techniques. One group showed marked anterior negativity and had 37% mortality compared with an overall 5% mortality for the remaining groups. The limited arteriographic and autopsy data available indicated that the findings of a diseased artery or arteries corresponded with the results of mapping. The mean map patterns of the five groups showed that, in most patients with inferior infarction, the standard chest leads V1 to V6 are over a region of steep voltage gradient. Small changes in the position of the standard chest lead can cause large changes in the displayed potentials. This study indicates that patients at high risk after acute inferior infarction can be identified by surface mapping on admission to the coronary care unit.     

Comparison of value of leads from body surface maps to 12-lead electrocardiogram for diagnosis of acute myocardial infarction

We aimed to develop 12-lead electrocardiographic (ECG) models testing ST-elevation criteria with QRST variables and compare their performance with the 80-lead body surface map (BSM) in detection of acute myocardial infarction (AMI). Because the prevalence of non-ST-elevation AMI is increasing worldwide, advances in early ECG detection of AMI are urgently needed. The study population was 755 consecutive patients presenting with ischemic chest pain from January 2002 to June 2004. All patients had electrocardiography and body surface mapping performed at initial presentation. AMI occurred in 519 patients (69%, cardiac troponin T or I level > or =0.1 ng/ml). Of these 519 patients, 303 (58%) had no ST-elevation on the initial 12-lead electrocardiogram. Ten patients were classified as having an "aborted AMI" and were included in the AMI analysis. The American College of Cardiology/European Society of Cardiology criteria for ST-elevation on 12-lead electrocardiogram identified 236 patients with AMI (sensitivity 45%, specificity 92%). Additional QRST features improved sensitivity (51% to 68%) but with decreased specificity (71% to 89%), with the optimal multivariate ECG model having a c-statistic of 0.75. The optimal BSM model identified 402 patients as having AMI (sensitivity 76%, specificity 92%, c-statistic 0.84). This improvement in sensitivity over the 12-lead electrocardiogram was due mainly to detection of ST-elevation in the high right anterior, posterior, and right ventricular territories and AMI in the presence of left bundle branch block. In conclusion, QRST variables added to criteria for ST-elevation result in improvement in sensitivity of the 12-lead electrocardiogram, although with decreased specificity. The BSM is superior in detecting AMI and demonstrates the importance of electroanatomic evaluation of patients with acute coronary syndromes.     

ST segment changes in exercise body surface mapping after myocardial infarction in patients with isolated left anterior descending coronary artery disease

To investigate the clinical significance of exercise-induced ST segment elevation and ST segment depression after myocardial infarction (MI), we performed 87-lead ECG mapping after previous anterior infarction in 24 patients with isolated left anterior descending coronary artery disease before and 1.5 minutes after treadmill exercise. Thirteen patients showed ST segment elevation only, seven patients showed both ST segment elevation and depression, and four patients showed ST segment depression only. ST segment elevation most frequently occurred in the left anterior chest leads corresponding to the QS area, and ST segment depression developed in the left lower chest and left lower back leads. There was good correlation between the number of lead points showing ST segment elevation (nSTe) after exercise and the number of lead points showing QS waves (nQS) before exercise (r = 0.65). nSTe was also correlated with the asynergy index (r = 0.43). These findings suggest that ST segment elevation is mainly the result of aggravation of wall motion abnormalities of the infarcted myocardium. Body surface distribution of ST segment depression was similar to that in effort angina pectoris without MI. We conclude that exercise-induced ST segment depression in MI mainly reflects the ischemia of the surviving myocardium of small infarcts or the peripheral area of large infarcts.     

Optimizing the initial 12-lead electrocardiographic diagnosis of acute myocardial infarction.

AIMS: The optimum definition of ST elevation for diagnosis of acute myocardial infarction, with respect to both the minimum height and the minimum numbers of leads, is unknown. Furthermore, only 50% of patients with acute myocardial infarction present with ST elevation. We thus quantified the sensitivity and specificity of different ST elevation criteria for diagnosis of acute myocardial infarction, and determined whether models incorporating multiple QRST features in addition to ST elevation, could improve detection of acute myocardial infarction. METHODS AND RESULTS: The study population comprised 1190 subjects: 1041 consecutive patients presenting with chest pain (335 with acute myocardial infarction) and 149 controls without chest pain. Subjects were randomly divided into a training set (587) and a validation set (603). ECG prediction models for acute myocardial infarction incorporating different ST elevation criteria and/or additional QRST features (Q waves, ST depression, T wave inversion, bundle branch block, axes deviations, and left ventricular hypertrophy) were developed in training set patients using forward stepwise multiple logistic regression. Models were then prospectively tested in the validation set patients. The optimum ST elevation model (based on > or =1 mm ST elevation in > or = 1 inferior/lateral leads, or > or =2 mm ST elevation in > or =1 anteroseptal leads) correctly classified 83.1% of subjects (55.8% sensitivity, 94. 0% specificity). The choice of ST elevation definition had marked influence on the sensitivity (45.4-68.6%) and specificity (81.2-98. 1%) for diagnosis of acute myocardial infarction. The addition of multiple QRST variables only marginally improved overall classification but did result in high specificity (92.6-96.1%). CONCLUSION: Different definitions of 'significant' ST elevation led to marked variations in sensitivity and specificity for diagnosis of acute myocardial infarction. Multiple QRST features in addition to ST elevation only marginally improved overall classification.     

The diagnostic impact of prehospital 12-lead electrocardiography

STUDY HYPOTHESIS: It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital diagnostic accuracy is improved compared with single-lead telemetry. POPULATION: One-hundred sixty-six stable adult patients who sought paramedic evaluation for a chief complaint of nontraumatic chest pain. METHODS: One-hundred fifty-one prehospital 12-lead ECGs of diagnostic quality were obtained by paramedics on 166 adult patients presenting with nontraumatic chest pain. Paramedics and base station physicians were blinded to the information on acquired prehospital 12-lead ECGs and treated patients according to current standard of care-clinical diagnosis and single-lead telemetry. Final hospital diagnoses were classified into three groups: acute myocardial infarction (24); suspected angina or ischemia (61); and nonischemic chest pain (66). Paramedics and base station physicians' clinical diagnoses and prehospital and emergency department ECGs were similarly classified and compared. Prehospital and ED 12-lead ECGs were read retrospectively by two cardiologists. RESULTS: Paramedics achieved a high success rate (98.7%) in obtaining diagnostic quality prehospital 12-lead ECGs in 94.6% of eligible prehospital patients. For patients with acute myocardial infarction, prehospital ECG alone had significantly higher specificity than did the paramedic clinical diagnosis (99.2% vs 70.9%; P less than .001), and significantly higher positive predictive value (92.9% vs 32.7%; P less than .001). For patients with angina, combining the paramedic clinical diagnosis and the prehospital ECG significantly improved sensitivity (90.2% vs 62.3%; P less than .001) and increased negative predictive value (88.9% vs 71.3%; P less than .02) compared with paramedic clinical diagnosis alone. There was a high concordance between prehospital and ED ECG diagnosis (99.3% for acute myocardial infarction and 92.8% for angina). Furthermore, ten patients whose prehospital ECGs demonstrated ischemia and who had final hospital diagnoses of angina or acute myocardial infarction were mistriaged by paramedics and/or received no base station physician-directed therapy. CONCLUSION: It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital 12-lead ECGs have the potential to significantly increase the diagnostic accuracy in chest pain patients, approach congruity with ED 12-lead ECG diagnoses, and may allow for consideration of altering and improving prehospital and hospital-based management in this patient population.     

Prehospital identification of acute coronary syndrome/myocardial infarction in relation to ST elevation

AIM: To evaluate factors that identify patients with an acute coronary syndrome/myocardial infarction prior to hospital admission among patients with a suspected acute coronary syndrome who were transported by ambulance with and without ST elevation on the ambulance electrocardiogram (ECG). METHODS: This was a prospective observational study in the part of Stockholm that is served by South Hospital ambulance organisation and the Municipality of Goteborg. All the patients who called for an ambulance due to acute chest pain or other symptoms raising the suspicion of an acute coronary syndrome took part. Immediately after the arrival of the ambulance, a blood sample was drawn for the analysis of serum myoglobin, creatine kinase (CK) MB and troponin I. A 12-lead ECG was simultaneously recorded. Further factors that were taken into consideration were age, gender, history of cardiovascular disease, symptoms and clinical findings. RESULTS: In patients with ST elevation in prehospital ECG, the likelihood of an acute myocardial infarction increased if there were simultaneous ST depression in other leads (OR 3.94, 95% CL 1.26-12.38). For patients without an ST elevation, the likelihood of an acute myocardial infarction increased if there were: elevation of any biochemical marker OR 2.96, 95% CL 1.32-6.64; ST depression (OR 2.54, 95% CL 1.43-4.51), T-inversion (OR 2.22, 95% CL 1.10-4.48), male gender (OR 2.21, 95% CL 1.24-3.93) and increasing age (OR 1.04, 95% CL 1.01-1.06). CONCLUSION: Among patients with a suspected acute coronary syndrome, factors that increased the likelihood for an ongoing acute myocardial infarction could already be defined prior to hospital admission. For those with an ST elevation, factors were found in ECG pattern. For those without an ST elevation, such factors were found in elevation of biochemical markers, admission ECG, male gender and increasing age.     

16导联心电图ST段改变对急性心肌梗死的临床价值

目的探讨16导联心电图中ST段改变对急性心肌梗死的临床诊断价值。方法对332例急性心肌梗死患者,在原有标准12导联的基础上,增加后壁导联（V7和V8）和右胸导联（V4R和V5R）,观察附加导联中ST段改变,是否可提高心电图诊断急性心肌梗死的价值。结果12导联心电图诊断急性心肌梗死的敏感性为71.4%,特异性为86.0%;12导联＋后壁导联诊断急性心肌梗死的敏感性为79.2%,特异性为85.0%;12导联＋右胸导联诊断急性心肌梗死的敏感性为75.3%,特异性为84.5%;12导联＋后壁＋右胸导联诊断急性心肌梗死的敏感性为81.9%,特异性为83.7%。结论增加后壁和右胸导联可提高诊断急性心肌梗死的敏感性,而特异性并无显著降低。     

Right precordial and posterior electrocardiographic leads do not increase detection of ischemia in low-risk patients presenting with chest pain

BACKGROUND: A number of innovative approaches have been investigated for their value in the early detection of acute ischemia or infarction in patients presenting to the emergency department (ED) with chest pain suggestive of a cardiac origin. Prior investigations have demonstrated the utility of adding right precordial and posterior chest leads to the standard 12-lead electrocardiogram (ECG) for identifying right ventricular and posterior wall infarctions in the ED. HYPOTHESIS: To assess the utility of additional ECG leads in low-risk patients presenting to the ED with symptoms suggestive of acute coronary syndromes who are managed in a chest pain evaluation unit (CPEU). METHODS: We studied low-risk patients who presented to the ED with chest pain compatible with myocardial ischemia. Low-risk patients were identified by a normal 12-lead ECG, no arrhythmias or hemodynamic instability, and one negative serum cardiac troponin I. Patients were admitted to the CPEU where a 16-lead ECG was recorded by the addition of 2 right-sided precordial leads (V4R, V5R) and 2 posterior leads (V8, V9) to the standard 12-lead ECG. RESULTS: The 16-lead ECG system was applied to 316 consecutive patients. The study group was a middle-aged population with equal numbers of men and women and an average of 2 cardiac risk factors per patient. The 16-lead ECG demonstrated evidence of myocardial injury in only 1 patient and no evidence of ischemia in any of the 316 patients. CONCLUSION: In patients presenting to the ED with chest pain and evidence of low clinical risk by our criteria, the addition of both right-sided precordial and posterior chest leads to the standard 12-lead ECG did not provide additional information for risk stratification.     

Body surface distributions of ST segment changes after exercise in effort angina pectoris without myocardial infarction

To investigate the sites of exercise-induced ST segment changes on the body surface in effort angina pectoris without myocardial infarction, we performed 87-lead ECG mapping in 61 patients before and 1.5 and 5 minutes after treadmill exercise. ST segment depression most often occurred in the left anterior chest leads and ST segment elevation developed mainly in the right upper chest leads. There was a good correlation between the number of lead points that showed ST segment depression (nSTd) and the number of those that showed ST segment elevation (nSTe) 1.5 minutes after exercise (r = 0.92). From 1.5 to 5 minutes after exercise, changes in nSTd for individual patients correlated well with changes in nSTe (r = 0.89). It was suggested that the ST segment elevation observed in this study directly reflected the subendocardial ischemia of the left ventricle. In patients with one-vessel disease (n = 32), there was wide overlap in the sites of ST segment changes among patients with left anterior descending artery disease (n = 19), those with left circumflex artery disease (n = 6), and those with right coronary artery disease (n = 7). These findings should lead to a better understanding of exercise-induced ST segment changes for the diagnosis of coronary artery disease.     

Use of body surface electrocardiographic mapping to localize the asynergic site in previous myocardial infarction

Body surface electrocardiographic (ECG) maps of myocardial infarction were analyzed using the departure mapping technique, which represents the abnormal potential distribution out of normal ranges. Body surface ECG mapping using 87 leads was performed on 65 patients with previous myocardial infarction and on 40 normal volunteers. Potential departure maps at 10, 20, 30, 40, and 50 msec after the onset of QRS were constructed; each map indicated, if present, the area of abnormal decreased potential that is more than 2 standard deviations from the normal range (-2 SD area). In patients with myocardial infarction, the appearance time and the location of the -2 SD area were specific for the sites of left ventricular asynergy; the sensitivity and specificity were 86% and 100% for the asynergy of segment 2 (20 msec, on the upper left anterior chest), 87% and 97% for segment 3 (30 msec, on the middle anterior chest), 86% and 80% for segment 4 (20 or 30 msec, on the lower right anterior chest), and 88% and 90% for segment 5 (30, 40, or 50 msec, on the middle back), respectively. The sensitivity of these criteria was better than that of 12-lead ECG, while the specificity was comparable. In the analysis of body surface ECG mapping data, departure maps aid in depicting abnormalities and in making an accurate assessment. Body surface ECG mapping can be used to improve the diagnostic ability of ECG to detect myocardial infarction.     

ST-segment monitoring with continuous 12-lead ECG improves early risk stratification in patients with chest pain and ECG nondiagnostic of acute myocardial infarction.

OBJECTIVES: The purpose of this study was to evaluate the prognostic importance of ischemic episodes detected by ST-segment monitoring with continuous 12-lead electrocardiography (ECG) in a nonselected coronary care unit (CCU) population with chest pain and ECG nondiagnostic of acute myocardial infarction (AMI). BACKGROUND: Patients with chest pain and ECG nondiagnostic of AMI constitute a heterogeneous group concerning both diagnosis and prognosis. Continuous 12-lead ECG is a rather new method not thoroughly studied in this population. METHODS: The ST-segment monitoring with continuous 12-lead ECG was performed for 12 h in 630 consecutive patients admitted to CCU due to chest pain and a nondiagnostic ECG, i.e., no ST-segment elevations. An ST-episode was defined as a transient ST-segment depression or elevation of at least 0.10 mV. The median follow-up time was six months. RESULTS: A total of 176 ST-episodes occurred in 100 (15.9%) patients. The median duration and maximal ST-segment deviation in patients with ST-episodes were 80 min and 0.20 mV, respectively. Presence of ST-episodes predicted worse outcome concerning cardiac death and cardiac death or myocardial infarction (MI) (log-rank p < 0.001). At 30 day follow-up procedure, 10% versus 1.5% died from cardiac causes or had an MI in the group with and without ST-episodes, respectively. In a multivariate analysis, only troponin T > or = 0.10 microg/l and the presence of ST-episodes came out as independent predictors of cardiac death or MI. CONCLUSIONS: Continuous 12-lead ECG monitoring provides prognostic information on-line and considerably improves early risk stratification in patients with ECG nondiagnostic of AMI and symptoms suggestive of acute coronary syndrome.     

Frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes.

BACKGROUND: Prior investigations of transient myocardial ischaemia have focused on ST depression events. Therefore, the purpose of this analysis was to determine the frequency, characteristics, and clinical significance of transient ST segment elevation in patients with acute coronary syndromes. METHODS: A secondary analysis from two prospective studies utilizing 12-lead ST segment monitoring was used to compare ST elevation vs ST depression events. RESULTS: Of 868 patients, 177 (20%) had 574 events (242, ST elevation; 332, ST depression). Patients with ST elevation were more likely to have single vessel coronary artery disease, whereas patients with ST depression were more likely to have triple vessel coronary artery disease. ST elevation events were of shorter duration, more often associated with chest pain, and had greater ST changes than ST depression events. There was no difference in clinical outcome between patients with ST elevation vs depression; however, those with ST events were more likely to have adverse hospital outcomes (OR, 3.67) or death (OR, 2.03) than patients without ST events. After controlling for clinical prognostic factors, transient ST events observed with continuous ST monitoring predicted hospital death independently from signs of ischaemia on the initial standard 12-lead ECG. CONCLUSIONS: Transient ST elevation is nearly as prevalent as transient ST depression in patients with acute coronary syndromes. Since the vast majority of ST events are brief and otherwise clinically silent, ST segment monitoring is more efficacious in detecting ischaemic events and in predicting adverse clinical outcomes than patients' symptoms or the initial standard 12-lead ECG.     

Accuracy of 22-lead ECG analysis for diagnosis of acute myocardial infarction and coronary artery disease in the emergency department: a comparison with 12-lead ECG.

STUDY OBJECTIVES: To compare a new 22-lead ECG with the 12-lead ECG for diagnosis of acute myocardial infarction (AMI). DESIGN: Prospective study of all consenting patients presenting to the emergency department with chest pain. SETTING: Urban hospital ED. TYPE OF PARTICIPANTS: 163 patients admitted with a cardiac-related diagnosis and complete data sets of 22- and 12-lead ECG results and creatine kinase-MB analysis. INTERVENTIONS: Patient care and existing protocols were unaltered, with the exception of including the new 22-lead ECG. MEASUREMENTS AND MAIN RESULTS: Forty-one of 163 patients had an AMI as defined by creatine kinase-MB analysis. The 22-lead ECG provided a statistically significant improvement in sensitivity (83%) for AMI diagnosis over the 12-lead ECG (51%) with specificities of 76% and 99%, respectively. CONCLUSION: When combined with clinical judgment, the 22-lead ECG could provide a 97.6% sensitivity for AMI diagnosis while reducing unnecessary admissions for "rule-out MI" by 69%.     

A vector-based, 5-electrode, 12-lead monitoring ECG (EASI) is equivalent to conventional 12-lead ECG for diagnosis of acute coronary syndromes

AIMS: The conventional 12-lead electrocardiogram (cECG) derived from 10 electrodes using a cardiograph is the gold standard for diagnosing myocardial ischemia. This study tested the hypothesis that a new 5-electrode 12-lead vector-based ECG (EASI; Philips Medical Systems, formerly Hewlett Packard Co, Boeblingen, Germany) patient monitoring system is equivalent to cECG in diagnosing acute coronary syndromes (ACSs). METHODS: Electrocardiograms (EASI and cECG) were obtained in 203 patients with chest pain on admission and 4 to 8 hours later. Both types of ECGs were graded as ST-elevation myocardial infarction if at least 1 of the 2 consecutive recordings showed ST elevation more than 0.2 mV, as ACS if one or both showed ST elevation less than 0.2 mV, T-wave inversion, or ST depression. Otherwise, the ECG was graded negative. RESULTS: Final diagnosis was identical in 177 patients (87%; 95% confidence interval [CI], 82%-91%; kappa = 0.81; SE = 0.035). ST-elevation myocardial infarction was correctly identified or excluded by EASI with a specificity of 94% (95% CI, 89%-97%) and a sensitivity of 93% (95% CI, 86%-97%; using cECG as the gold standard). Of 118 patients with enzyme elevations, an almost identical number (72 [61% by EASI] and 73 [62% by cECG]) had ST elevations. Both techniques were equivalent in predicting subsequent enzyme elevation (identical, 108/143; 75% of ACS and ST-elevation myocardial infarction ECGs by EASI and cECG). Thus, both ECG methods had exactly the same specificity of 59% (95% CI, 48%-69%) and sensitivity of 91% (95% CI, 85%-96%) for detecting myocardial injury. CONCLUSION: EASI is equivalent to cECG for the diagnosis of myocardial ischemia.     

Body surface potential mapping improves detection of ST segment alteration during percutaneous coronary intervention

BACKGROUND: The 12-lead electrocardiogram underestimates ST segment alteration in acute coronary syndromes compared with multi-lead body surface mapping. We assessed whether 80-lead mapping would improve detection of ST alteration during percutaneous coronary intervention. METHODS: Simultaneous maps and 12-lead electrocardiograms were recorded pre-procedure, during balloon inflation and post-procedure from patients undergoing elective intervention to native coronary arteries. Recordings were obtained from 39 inflations (19 patients). All arteries were successfully stented. RESULTS: Mean 'lead specific' ST alteration (the difference in ST elevation/depression between pre-procedure and inflation recordings in the lead showing maximal ST alteration) was greater on the map than on electrocardiogram, both for ST elevation (0.16+/-0.02 vs. 0.06+/-0.01 mV; p<0.001) and ST depression (0.11+/-0.017 vs. -0.03+/-0.006 mV; p<0.001). During first inflations (n=19), mean lead specific ST elevation and depression on map were greater than on electrocardiogram (0.20+/-0.034 vs. 0.07+/-0.015 mV; p<0.001 and 0.11+/-0.029 vs. 0.03+/-0.009 mV; p=0.001, respectively). Mapping detected greater summated ST elevation and depression during inflation than electrocardiogram (0.04+/-0.005 vs. 0.021+/-0.003 mV; p<0.001 and 0.026+/-0.004 vs. 0.011+/-0.002 mV; p<0.001, respectively). Qualitative analysis of maps and electrocardiograms showed that 21/39 (53.8%) maps recorded during inflation met criteria for myocardial ischaemia compared with 7/39 (17.9%) electrocardiograms (p<0.001). CONCLUSION: Body surface mapping compared with the 12-lead electrocardiogram improves detection of myocardial ischaemia during intervention.