ST depression only on the initial 12-lead ECG: early diagnosis of acute myocardial infarction.

AIMS: To compare the diagnostic ability of the 12-lead ECG with body surface mapping for early detection of acute myocardial infarction in patients presenting with ST depression only on the 12-lead ECG. METHODS AND RESULTS: Fifty-four consecutive patients with chest pain <24 h and ST depression were recruited. A 12-lead ECG and 80-lead body surface map were recorded at presentation from which univariate and multivariate prediction models of acute myocardial infarction were developed. Patients were randomly divided into a training-set and a validation-set. Acute myocardial infarction occurred in 16/30 training-set and 8/24 validation-set patients. Univariate prediction of acute myocardial infarction by the 12-lead ECG, based on the depth or numbers of leads with ST depression, was not improved by assessment of ST elevation outside the conventional 12 leads using body surface mapping. The optimum multivariate 12-lead ECG model developed in training-set patients (six ST depression variables) had poor sensitivity (38%) although good specificity (81%) for acute myocardial infarction when tested prospectively in validation-set patients. In contrast, the optimum body surface mapping model developed in training-set patients (three isointegral or isopotential variables) achieved high sensitivity (88%) whilst maintaining good specificity (75%) for acute myocardial infarction when tested prospectively in validation-set patients. CONCLUSION: Body surface mapping, when compared with the 12-lead ECG, may improve the early diagnosis of acute myocardial infarction in patients presenting with chest pain and ST depression only on the 12-lead ECG.     

Accuracy of the EASI 12-lead electrocardiogram compared to the standard 12-lead electrocardiogram for diagnosing multiple cardiac abnormalities

This study was performed to compare a derived 12-lead electrocardiogram (ECG) using a simple 5-electrode lead configuration (EASI 12-lead) with the standard ECG for multiple cardiac diagnoses. Accurate diagnosis of arrhythmias and ischemia often require analysis of multiple (ideally, 12) ECG leads; however, continuous 12-lead monitoring is impractical in hospital settings. EASI and standard ECGs were compared in 540 patients, 426 of whom also had continuous 12-lead ST segment monitoring with both lead methods. Independent standards relative to a correct diagnosis were used whenever possible, for example, echocardiographic data for chamber enlargement-hypertrophy, and troponin levels for acute infarction. Percent agreement between the 2 methods were: cardiac rhythm, 100%; chamber enlargement-hypertrophy, 84%–99%; right and left bundle branch block, 95% and 97%, respectively; left anterior and posterior fascicular block, 97% and 99%, respectively; prior anterior and inferior infarction, 95% and 92%, respectively. There was very little variation between the 2 lead methods in cardiac interval measurements; however, there was more variation in P, QRS, and T-wave axes. Of the 426 patients with ST monitoring, 138 patients had a total of 238 ST events (26, acute infarction; 62, angioplasty-induced ischemia; 150, spontaneous transient ischemia). There was 100% agreement between the 2 methods for acute infarction, 95% agreement for angioplastyinduced ischemia, and 89% agreement for transient ischemia. EASI and standard 12-lead ECGs are comparable for multiple cardiac diagnoses; however, serial ECG changes (eg, T-wave changes) should be assessed using one consistent 12-lead method.     

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。     

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。     

Comparison of EASI-derived 12-lead electrocardiograms versus paramedic-acquired 12-lead electrocardiograms using Mason-Likar limb lead configuration in patients with chest pain

INTRODUCTION: Monitoring or serial 12-lead electrocardiogram (ECG) recordings are the accepted requirement for prehospital data acquisition in patients with chest pain. The purpose of this study was to determine whether waveforms and clinical triage decision are similar in EASI-derived ECGs and paramedic-acquired 12-lead ECGs using Mason-Likar limb lead configuration when compared with standard 12-lead ECGs (stdECG). METHOD: Twenty patients with chest pain had a prehospital 12-lead ECG recorded in the ambulance, and paramedic-applied electrodes retained in place at hospital arrival. An ECG technician applied standard precordial and EASI electrodes in their correct positions. Twelve-lead ECGs were obtained from the paramedic-applied electrodes, using their Mason-Likar limb lead configuration, and derived from the EASI leads for comparison with the stdECG. Three computer-measured QRS-T waveform parameters were considered, and differences in waveform measurement between EASI and stdECG (EASIDeltastdECG) versus differences in waveform measurements between paramedic Mason-Likar and stdECG (PMLDeltastdECG) were calculated. Two physicians determined whether the EASI-derived or the paramedic Mason-Likar ECG contained information that would change their clinical triage decision from that indicated by the stdECG. RESULTS: EASIDeltastdECG and PMLDeltastdECG were identical in 28%, whereas EASIDeltastdECG was more than PMLDeltastdECG in 35%, and PMLDeltastdECG was accurate (both time) than EASIDeltastdECG in 37% (P = .62). The physicians were more likely to change the level of patient care based on the EASI-derived ECGs compared with the paramedic ECGs; however, this difference was not statistically significant (P = .27), but this may only be caused by the small study population. CONCLUSIONS: There are similar differences from stdECG waveforms in EASI-derived ECGs and those acquired via paramedic-applied precordial electrodes using Mason-Likar limb lead configuration. Either method can be used as a substitute for monitoring, but neither should be considered equivalent to the stdECG for diagnostic purposes.     

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.     

The combination of a continuous 12-lead ECG and troponin T; a valuable tool for risk stratification during the first 6 hours in patients with chest pain and a non-diagnostic ECG.

AIMS: The aim was to examine the early prognostic value of a combination of a continuous 12-lead ECG and troponin T in patients with chest pain and an ECG non-diagnostic for acute myocardial infarction. METHODS AND RESULTS: ST monitoring was performed and samples for analysis of troponin T were collected from admission for 12 h from 598 patients. After 6 h, the peak value of troponin T in 27% was > or = 0.10 microg.l(- 1), while 15% had had ST episodes, defined as transient ST deviations of at least 0.1 mV. Both a troponin T > or = 0.10 microg. l(-1) and ST episodes predicted worsening outcome. After 30 days, there were 6.8% and 1.4% (P<0.01) cardiac deaths or myocardial infarctions in the group with and without troponin T > or = 0.10 microg.l(-1), respectively. The corresponding event rates in patients with and without ST episodes were 10% and 1.6% (P<0.001). In a multivariate analysis both troponin T and ST episodes were independent predictors of cardiac death or myocardial infarction. When ST monitoring and troponin T status were combined, patients could be divided into low-, intermediate-, and high-risk groups. CONCLUSIONS: A combination of continuous 12-lead monitoring and troponin T seems to be a valuable tool for risk stratification during the first 6 h in this population.     

Initial presenting electrocardiogram as determinant for hospital admission in patients presenting to the emergency department with chest pain: a pilot investigation

BACKGROUND: Evaluation of chest pain accounts for millions of costly Emergency Department (ED) visits and hospital admissions annually. Of these, approximately 10-20% are myocardial infarctions (MI). HYPOTHESIS: Patients with chest pain whose initial electrocardiogram (ECG) is normal do not require hospital admission for evaluation and management of a possible myocardial infarction. METHODS: The medical records of a consecutive cohort of 250 patients who presented to the ED with chest pain and were admitted by the ED physician to a cardiology inpatient service of an academic tertiary care medical center were reviewed. Reasons for admission to hospital was to rule out an acute coronary syndrome, specifically, myocardial infarction. The initial ECG of each patient was evaluated for abnormalities and compared with the final diagnosis. RESULTS: Of the 75 patients presenting with normal ECGs (normal, upright T waves and isoelectric ST segments), 1 (1.3%) was subsequently diagnosed with a myocardial infarction by Troponin I elevation alone. Of the 55 patients presenting with abnormal ECGs but no clear evidence of ischemia [i.e., left bundle branch block (LBBB), right bundle branch block (RBBB), left anterior hemiblock (LAH)], 2 (3.6%) were diagnosed with MI. Of the 48 patients presenting with abnormal ECGs questionable for ischemia (nonspecific ST and T wave changes that were not clearly ST segment elevation or depression), 7 (14.6%) were diagnosed with an MI. Of the 72 patients who presented with abnormal ECGs showing ischemia (acute ST segment elevation and/or depression), 39 (54.2%) were shown to have evidence for MI. SUMMARY: Patients who presented with normal ECGs (category 1) were extremely low risk for acute myocardial infarction. Patients with abnormal ECGs but no evidence of definite ischemia (category 2) had a relatively low incidence of MI. Patients with abnormal ECGs questionable for ischemia (category 3) had an intermediate risk of acute myocardial infarction. The majority of patients with abnormal ECGs demonstrating ischemia (category 4) were subsequently shown to evolve an acute myocardial infarction. CONCLUSIONS: Patients with chest pain and initial ECGs with ST segment abnormalities suggestive or diagnostic for ischemia, should be admitted to the hospital for further evaluation and management. Patients with ECGs that do not display acute ST segment changes are at a lower risk for acute myocardial infarction than those with acute ST segment changes and should be admitted on the basis of cardiac risk profile. (i.e., age, gender, hypertension, diabetes, smoking, known coronary artery disease, etc.) Patients with normal ECGs (category 1) are at extremely low risk, and it may be acceptable to consider further evaluation on an outpatient basis.     

Assessment of a widely applicable torso ECG in acute coronary syndrome

IntroductionThe time from symptom onset to arrival at healthcare facility, and door to reperfusion time in treatment of acute coronary syndrome (ACS) can be improved significantly if the patient or the relatives can record a 12-lead ECG at home and transmit it to the physician for prompt interpretation. To make this widely applicable, the 12-lead ECG recording device has to be simple and user friendly. In this regard, torso ECG (T-ECG) electrode positions that are less cumbersome than the conventional ECG (C-ECG) electrode positions are an alternative worthy of consideration.Objectiveand setting: To study the utility of T-ECG versus C-ECG in ACS patients.Designand intervention: We proposed torso electrode positions in which upper limb electrodes were placed in the respective deltopectoral grooves below the lateral end of the clavicle; the right lower limb electrode was placed 2 finger breadths above the umbilicus and the left lower limb electrode, 2 finger breadths to the left of the umbilicus. We then studied the ECGs recorded, to ascertain whether T-ECGs miss or over-diagnose ACS changes. Twelve lead ECGs were recorded by both techniques (C-ECG & T-ECG) in 1361 patientsfrom the coronary care unit & out-patient department of a tertiary care hospital. A total of 1526 sets of ECGs (each set consisting of one C-ECG and one T -ECG) were read by two trained cardiologists independently and in a blinded fashion. There were 457 ECG sets from 342 patients with ACS. Of these, 116 ECG sets from 112 patients of anterior infarction who had changes restricted to precordial leads were excluded. Finally, 341 ECG sets from 230 patients with ACS and 324 sets of patients diagnosed to be normal on C-ECG were considered for the purpose of this study.Main resultsAll 341 ECG sets from the 230 patients of ACS diagnosed by C-ECG were correctly diagnosed by T-ECG (100% sensitivity) and all 324 normal ECGs on C-ECG were also identified as normal on T-ECG (100% specificity). Of the ACS ECGs, ST elevation was seen in 234 ECGs and ST depressions 154 ECGs. The localizations of ST elevation and ST depression were also accurately diagnosed by the T-ECG.ConclusionThe ECG recorded by our novel proposed torso electrode positions is comparable to a conventional ECG for the diagnosis of ACS.     

High-frequency electrocardiogram as a supplement to standard 12-lead ischemia monitoring during reperfusion therapy of acute inferior myocardial infarction

Background

Resolution of ST-segment elevation in the electrocardiogram (ECG) is used as a reperfusion sign during thrombolytic therapy in acute myocardial infarction. Analysis of high-frequency QRS components (HF-QRS) might provide additional information. The study compares changes in HF-QRS (150-250 Hz) to ST-segment changes in the standard ECG during thrombolytic therapy.

Methods

Twelve patients receiving intravenous thrombolytic therapy were included. A continuous 12-lead ECG recording was acquired for 4 hours.

Results

After 1 hour of therapy, 3 patients showed ST-elevation resolution as well as an increase in HF-QRS. These changes in ST and HF-QRS occurred simultaneously. No other patient showed significant changes in ST or HF-QRS after 1 hour. After 2 and 4 hours, there was less concordance between the standard and high-frequency ECGs.

Conclusions

In patients with early ST-elevation resolution, the standard and high-frequency ECGs show similar results. Later changes are more disparate and may provide different clinical information.     

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.     

Detection of acute ischemia from the EASI-derived 12-lead electrocardiogram and from the 12-lead electrocardiogram acquired in clinical practice

ST-segment measurements in the standard 12-lead electrocardiogram (ECG) of patients with acute coronary syndromes are crucial for these patients' management. Our objective was to determine whether the 12-lead ECG derived from the 3-lead EASI system can attain a level of diagnostic performance similar to that of the Mason-Likar (ML) 12-lead ECG acquired in clinical practice (CP) by paramedics and emergency department technicians. Using 120-lead body surface potential maps recorded before and during balloon inflation angioplasty from 88 patients (divided into “responders” and “nonresponders”), and electrode placement data from 60 applications of precordial leads in CP, we generated for the “nonischemic” and “ischemic” states of each patient the following lead sets: the ML 12-lead ECG, the EASI-derived 12-lead ECG, and 60 sets of 12-lead CP ECGs. We extracted ST deviations at J + 60 milliseconds, summed them for all 12 leads of each lead set to obtain ΣST, and, by using the bootstrap method, determined the mean sensitivity and specificity for recognizing the “ischemic” state at various thresholds of ΣST. Results were displayed as receiver operating characteristics, and the area under these curves (AUC) ± SE was used as the measure of diagnostic performance. AUC ± SE for all patients were ML ECG, 0.66 ± 0.03; EASI ECG, 0.64 ± 0.03; and CP ECG, 0.67 ± 0.03. Corresponding results for responders only were 0.81 ± 0.04 for ML ECG, 0.78 ± 0.04 for EASI ECG, and 0.81 ± 0.04 for CP ECG. The differences between the AUCs for the different lead sets were not significant (P > .05). Thus, the EASI-derived 12-lead ECG is as good for detecting acute ischemia as is the 12-lead ECG acquired in CP.     

The 24-lead ECG display for enhanced recognition of STEMI-equivalent patterns in the 12-lead ECG

In a patient with chest pain and suspected acute coronary syndrome, the electrocardiogram (ECG) is the only readily available diagnostic tool. It is important to maximize its usefulness to detect acute myocardial ischemia that may evolve to myocardial infarction unless the patient is treated expediently with reperfusion therapy. Since diagnostic guidelines have usually included only ST-elevation myocardial infarction (STEMI) as the entity that should be diagnosed and treated urgently, a patient with coronary occlusion represented on ECG as ST depression is likely not to be considered a candidate for receiving immediate coronary angiography and coronary intervention. ECG criteria for STEMI detection require that ST elevation meet predetermined millivolt thresholds and appear in at least two spatially contiguous ECG leads. The typical ECG reader recognizes only three contiguous pairs: aVL and I; II and aVF; aVF and III. However, viewing the “orderly sequenced” 12-lead ECG display, two more contiguous pairs become obvious in the frontal plane: + I and − aVR; − aVR and + II. The 24-lead ECG is a display of the standard 12-lead ECG as both the classical positive leads and their negative (inverted) counterparts. Leads + V1, + V2, + V3, + V4, + V5, and + V6 and their inverted counterparts are used to generate a “clock-face display” for the transverse plane. Similarly, + aVL, + I, − aVR, + II, + aVF, + III in the frontal plane and their inverted counterparts are used to generate a clock-face display for the frontal plane. Optimum results, 78% sensitivity and 93% specificity, were obtained using the following 19 ECG leads: frontal plane: + aVR, − III, + aVL, + I, − aVR, + II, + aVF, + III, − aVL; transverse plane: + V1, + V2, + V3, + V4, + V5, + V6, − V1, − V2, − V3.     

Change in ST segment elevation 60 minutes after thrombolytic initiation predicts clinical outcome as accurately as later electrocardiographic changes

Objective—To compare prospectively the prognostic accuracy of a 50% decrease in ST segment elevation on standard 12-lead electrocardiograms (ECGs) recorded at 60, 90, and 180 minutes after thrombolysis initiation in acute myocardial infarction.
Design—Consecutive sample prospective cohort study.
Setting—A single coronary care unit in the north of England.
Patients—190 consecutive patients receiving thrombolysis for first acute myocardial infarction.
Interventions—Thrombolysis at baseline.
Main outcome measures—Cardiac mortality and left ventricular size and function assessed 36 days later.
Results—Failure of ST segment elevation to resolve by 50% in the single lead of maximum ST elevation or the sum ST elevation of all infarct related ECG leads at each of the times studied was associated with a significantly higher mortality, larger left ventricular volume, and lower ejection fraction. There was some variation according to infarct site with only the 60 minute ECG predicting mortality after inferior myocardial infarction and only in anterior myocardial infarction was persistent ST elevation associated with worse left ventricular function. The analysis of the lead of maximum ST elevation at 60 minutes from thrombolysis performed as well as later ECGs in receiver operating characteristic curves for predicting clinical outcome.
Conclusion—The standard 12-lead ECG at 60 minutes predicts clinical outcome as accurately as later ECGs after thrombolysis for first acute myocardial infarction.

Keywords: myocardial infarction;  thrombolysis;  ST segment elevation     

心电图在诊断急性心肌梗死相关动脉中的价值

目的分析急性心肌梗死患者不同梗死部位心电图表现及梗死相关动脉的分布特点,评价心电图诊断梗死相关动脉的价值。方法对132例急性心肌梗死患者心电图和冠状动脉造影资料进行回顾性比较分析。结果心电图显示心肌梗死发生率以心脏下壁、前间壁和广泛前壁最高,分别为31例(23.5%)、26例(19.7%)和22例(16.7%);造影显示梗死相关动脉的发生率分别为左主干(LM)3例(2.3%)、前降支(LAD)73例(55.3%)、回旋支(LCX)18例(13.6%)、右冠状动脉(RCA)38例(28.8%);前壁心肌梗死(55例)的梗死相关动脉多为LAD(51例,92.7%),下壁心肌梗死(31例)的梗死相关动脉多为RCA(22例,71.0%)或LCX(7例,22.6%),且与冠状动脉优势类型密切相关,前壁梗死合并aVR、aVL导联ST段抬高对诊断LAD近段闭塞的特异性较高,分别为86.7%和90.0%。结论急性心肌梗死心电图表现与梗死相关动脉存在明显相关性,有较高的临床诊断价值。     

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.     

Comparison of ST depression recorded by Holter monitors and 12-lead ECGs during coronary angiography and exercise testing

Data from previous studies are debatable regarding whether Holter monitors are a reliable electrocardiographic indicator of ischemia, for which the 12-lead electrocardiogram (ECG) is the standard. Simultaneous 12-lead and Holter ECGs were performed on 30 patients with typical angina pectoris during coronary angiography or exercise testing. ST depression recorded by both methods was directly compared, using the 12-lead ECG as the reference. The Holter tapes were also scanned by two automated ST analysis programs and the results were compared to 12-lead ECGs. Only 66 of the 178 12-lead ECG ST depression events were also present on the Holter recordings (37.1% Holter sensitivity). ST depression was underestimated by the Holter recordings compared to the 12-lead ECGs (p < 0.0001). The majority (67.0%) of ST depression events identified by one computer program were false positive events. The degree of ST depression was overestimated compared to 12-lead ECGs by the second program (p = 0.0033). Holter-detected ST depression may not be a reliable ECG indicator of myocardial ischemia.     

Comparison of waveforms in conventional 12-lead ECGs and those derived from EASI leads in children

To investigate the possibility of simplifying electrocardiogram (ECG) recording in children, we compared waveforms in conventional 12-lead ECGs to those derived from EASI leads in 221 children of various ages. The conventional 12-lead ECGs and the ECGs using EASI electrode positions were collected simultaneously. We developed and determined the value of age-specific transformation coefficients for use in deriving 12-lead ECGs from the signals recorded at the EASI sites. We compared the results of using age-specific coefficients to the results of using adult coefficients and studied the "goodness-of-fit" between the conventional and the derived 12-lead ECGs. The age-specific coefficients performed slightly better than the adult coefficients, and good agreement was usually attained between the conventional 12-lead ECG and the EASI-derived 12-lead ECG. Our conclusion is that EASI leads in children have the same high levels of "goodness-of-fit" to replicate conventional 12-lead ECG waveforms, as reported earlier in adults.     

心电图在急性心肌梗死超急性期诊断中的应用

目的：探讨心电图诊断急性心肌梗死（心梗）超急性期的临床价值。方法选择2013年1月至2015年1月经我院确诊的90例急性心梗超急性期患者,根据发病时间将其随机分为 A、B、C 三组,分别有患者55例、18例和17例,发病时间分别为≤2 h、2～6 h 及6～8 h。对三组患者行24 h 心电监测,详细记录各组心电图 Q 波、ST 段和 T 波的变化情况,并统计分析阳性改变率。结果经24 h 心电监测发现,所有患者的心电图阳性改变主要是 Q 波、ST 段及 T 波的改变。其中,ST 段及 T 波的改变诊断急性心梗超急性期的敏感性和特异性、阳性预测值与阴性预测值均高于 Q 波改变。三组的心电图阳性改变发生率依次为81．82％、38．89％和17．65％,A 组均显著高于 B、C 组（P ＜0．05）。A 组患者中,ST 段抬高型心梗者的心电图诊断阳性率显著高于非 ST 段抬高型心梗者（34．09％ vs．18．18％,P ＜0．05）。结论对急性心梗超急性期患者,尤其是发病2 h 内的患者进行24 h 心电监护,对准确判断病情和及时施治非常关键。T 波宽大、高耸及 ST 段抬高可作为急性心梗超急性期的特征性心电图表现,为临床诊断和治疗提供参考依据。     

The 12-lead ECG in peripartum cardiomyopathy

Background

The value of the 12-lead electrocardiogram (ECG) to provide prognostic information in the deadly and disabling syndrome peripartum cardiomyopathy (PPCM) is unknown.

Aims

To determine the prevalence of major and minor ECG abnormalities in PPCM patients at the time of diagnosis, and to establish whether there are ECG correlates of persistent left ventricular dysfunction and/or clinical stability at six months of follow up, where available.

Methods

Twelve-lead ECGs were performed at the point of diagnosis on 78 consecutive women presenting with PPCM to two tertiary centres in South Africa and 44 cases (56%) at the six-month follow up. Blinded Minnesota coding identified major ECG abnormalities and minor ECG changes.

Results

The cohort mainly comprised young women of black African ancestry (90%) [mean age 29 ± 7 years and median body mass index 24.3 (IQR: 22.7–27.5) kg/m²]. The majority of cases (n = 70; 90%) presented in sinus rhythm (mean heart rate 100 ± 21 beats/min). At baseline, at least one ECG abnormality/variant was detected in 96% of cases. Major ECG abnormalities and minor changes were detected in 49% (95% CI: 37–60%) and 62% (95% CI: 51–74%) of cases, respectively; the most common being T-wave changes (59%), p-wave abnormality (29%) and QRS-axis deviation (25%).Of the 44 cases (56%) reviewed at six months, normalisation of the 12-lead ECG occurred in 25%; the most labile ECG features being heart rate (mean reduction of 27 beats/min; p < 0.001) and abnormal QRS axis (36 vs 14%; p = 0.014). On an adjusted basis, major T-wave abnormalities on the baseline 12-lead ECG were associated with lower left ventricular ejection fraction (LVEF) at baseline (average of –9%, 95% CI: –1 to –16; p = 0.03) and at six months (–12%; 95% CI: –4 to –24; p = 0.006). Similarly, baseline ST-segment elevation was also associated with lower LVEF at six months (–25%; 95% CI: –0.7 to –50; p = 0.04).

Conclusions

In this unique study, we found that almost all women suffering from PPCM had an ‘abnormal’ 12-lead ECG. Pending more definitive studies, the ECG appears to be a useful adjunctive tool in both screening and prognostication in resource-poor settings.