Significance of ST segment elevations in posterior chest leads (V7 to V9) in patients with acute inferior myocardial infarction: application for thrombolytic therapy

Dressler - de Winter sign with acute inferoposterior STEMI: An ECG dilemma in artery localization

The Dressler-de Winter sign is an electrocardiogram (ECG) pattern characterized by upsloping ST-segment depression in leads V1-V6 followed by tall, hyperacute T waves, typically indicating an occlusion of the left anterior descending artery (LAD). We present a case involving an inferoposterior ST-segment elevation myocardial infarction (STEMI) with a variant of the de Winter sign, a concept of ST-segment continuum in the precordial leads. Despite initial ECG findings suggesting right coronary artery (RCA) or left circumflex artery (LCX) involvement, coronary angiography confirmed occlusion of the wrap-around LAD distal to the first septal (S1) and diagonal branch (D1) and revealed a left dominant system accompanied by a small non-dominant RCA. This case highlights the diagnostic complexity in accurately localizing the culprit artery in STEMI cases exhibiting the de Winter sign. Understanding such ECG variants is crucial for analyzing the mechanisms of acute ischemia and ensuring accurate assessment of the culprit vessel for effective revascularization.

Novel ECG changes in acute coronary syndromes. Would improvement in the recognition of 'STEMI-equivalents' affect time until reperfusion?

Current guidelines recommend that patients with non-ST elevation myocardial infarction (NSTEMI) are treated with medical management alone, or in combination with coronary angiography within 24 h. Recent research suggests that NSTEMIs show angiographic evidence of complete occlusion at rates comparable to STEMIs, suggesting a subgroup of NSTEMI patients who require urgent angiography. Novel ECG changes, termed 'STEMI-equivalents', have been described as a way of identifying this subgroup. The aim of this study was to determine whether patients with STEMI-equivalent ECG changes experience similar degrees of myocardial damage, and would thus benefit from urgent PCI. Cardiac catheterisation databases at The Wollongong Hospital were searched for STEMI, and NSTEMI patients with complete occlusion of the culprit vessel, between January 2011 and December 2013. A total of 1429 patients underwent angiography during this time period. Of these, 220 were eligible for ECG analysis. We found 10-25% of NSTEMIs with 'STEMI equivalent' ECG changes correlated with complete vessel occlusion on angiography. These patients demonstrated equivalent initial troponin readings. Recognition of STEMI-equivalents represent a chance for earlier intervention with prompt coronary angiography, as these findings are often associated with complete occlusion of the culprit vessel. These findings provide further evidence supporting the potential inclusion of STEMI-equivalents in future ACS guidelines.

Acute ST-segment elevation myocardial infarction: The prognostic importance of lead augmented vector right and leads V7-V9

Background:

Acute myocardial infarction (MI) is associated with high mortality and among survivors have high morbidity. Electrocardiogram (ECG), a cost-effective and easily available, has traditionally been used not only just for diagnosis of MI but also for culprit vessel recognition and for prognostication. However, the role of lead augmented vector right (aVR) and leads V₇–V₉ in acute MI are often neglected in clinical practice. We studied the role of lead aVR and leads V₇–V₉ in ST-elevation MI (STEMI) patients.

Methods:

A total of 209 patients presenting with STEMI were enrolled in the study. History of comorbid conditions and habits was enquired. Routine blood tests were performed. Full spectrum ECG (including V7–9) and 2D-ECHO was performed on all patients. All the patients underwent revascularization by primary percutaneous coronary intervention. The role of lead aVR, lead V7, and leads V8–9 was analyzed in anterior wall MI (AWMI) and inferior wall MI. All the patients were followed up for 1 month for outcome assessment.

Results:

Of the 209 patients, 85.1% were males and 35.8% were diabetic, 60.2% were smokers, AWMI accounted for 55.5%. Lead aVR ST deviation was noted in 75.1% of patients (elevation in 17.7% and depression in 47.1%). V7 ST elevation occurred in 27.6% and V8–9 elevation occurred in 7.5% of the study population. Total death was 11.9% in the study (including the in-hospital mortality), all these patients had lead aVR ST segment deviation (P < 0.001).

Conclusion:

Lead aVR ST deviation and Lead V7 ST deviation helps to prognosticate the STEMI patients as high risk and those with aVR ST depression had higher mortality compared to aVR ST elevation because of larger myocardial involvement.

Prognostic implications of prominent R wave in electrocardiographic leads V1 or V2 in patients with acute coronary syndrome

Although the adverse prognosis of Q-waves on electrocardiogram (ECG) has been demonstrated, the prognostic significance of prominent R wave (PRW) in V1 or V2 across a broad spectrum of acute coronary syndrome (ACS) has not been specifically studied. In the Global Registry of Acute Coronary Events (GRACE) and the Canadian ACS Registry I ECG substudies, admission ECGs were analyzed in an independent core ECG laboratory. PRW was defined as R wave >40 to 50 ms in V1 or V2, R/S ≥1 in V1, or R/S ≥1.5 in V2. Among 11,895 patients with ACS, 495 (4.2%) had PRW; they were less likely to have a history of hypertension or heart failure and had lower GRACE risk scores, but a higher incidence of ST-segment depression (all p ≤0.001). Patients with PRW had similar rates of in-hospital death (2.8% vs 4.1%, respectively, p = 0.15) but lower rates of in-hospital heart failure (8.5% vs 15.2%, respectively, p = 0.02) and 6-month mortality (4.6% vs 8.4%, respectively, p = 0.004). In multivariable analyses, PRW was not a significant independent predictor of in-hospital mortality (adjusted odds ratio = 0.99, 95% confidence interval 0.55 to 1.8) or 6-month mortality (adjusted odds ratio = 0.70, 95% confidence interval 0.43 to 1.15). Among 4,418 patients who underwent coronary angiography, those with PRW had a higher prevalence of left circumflex artery disease (62.5% vs 49.5%, respectively, p = 0.01). In conclusion, across the broad spectrum of patients with ACS, PRW provides no significant additional prognostic utility beyond comprehensive risk assessment using the GRACE risk score. PRW is more frequently associated with left circumflex artery disease.

Acute coronary syndromes: from the emergency department to the cardiac care unit

Acute coronary syndromes result in a significant burden of morbidity and mortality in the United States. This spectrum of acute coronary thrombosis (including unstable angina, non-ST-segment elevation myocardial infarction, and ST-elevation myocardial infarction) has been well studied in large clinical trials. This review details the initial management of patients presenting with possible acute coronary syndromes in the context of care from the emergency department to the cardiac care unit. The importance of a rapid and focused evaluation, risk stratification, and appropriate therapies are discussed.

Prognostic value of lead V1 ST elevation during acute inferior myocardial infarction

BACKGROUND

Lead V(1) directly faces the right ventricle and may exhibit ST elevation during an acute inferior myocardial infarction when the right ventricle is also involved. Leads V(1) and V(3) indirectly face the posterolateral left ventricle, and ST depression ("mirror-image" ST elevation) in V(1) through V(3) may reflect concomitant posterolateral infarction. The prognostic significance of V(1) ST elevation during an acute inferior myocardial infarction may therefore be dependent on V(3) ST changes.

METHODS AND RESULTS

In 7967 patients with acute inferior myocardial infarction in the Hirulog and Early Reperfusion or Occlusion-2 (HERO-2) trial, V(1) ST levels were analyzed with adjustment for lead V(3) ST level for predicting 30-day mortality. V(1) ST elevation at baseline, analyzed as a continuous variable, was associated with higher mortality. Unadjusted, each 0.5-mm-step increase in ST level above the isoelectric level was associated with approximately 25% increase in 30-day mortality; this was true whether V(3) ST depression was present or not. The odds ratio for mortality was 1.21 (95% confidence interval, 1.07 to 1.37) after adjustment for inferolateral ST elevation and clinical factors and 1.24 (95% confidence interval, 1.09 to 1.40) if also adjusted for V(3) ST level. In contrast, lead V(1) ST depression was not associated with mortality after adjustment for V(3) ST level. V(1) ST elevation >or=1 mm, analyzed dichotomously in all patients, was associated with higher mortality. The odds ratio was 1.28 (95% confidence interval, 1.01 to 1.61) unadjusted, 1.51 (95% confidence interval, 1.19 to 1.92) adjusted for V(3) ST level, and 1.35 (95% confidence interval, 1.04 to 1.76) adjusted for ECG and clinical factors. Persistence of V(1) ST elevation >or=1 mm 60 minutes after fibrinolysis was associated with higher mortality (10.8% versus 5.5%, P=0.001).

CONCLUSIONS

V(1) ST elevation identifies patients with acute inferior myocardial infarction who are at higher risk.

On the use of the inverse electrocardiogram leads

This viewpoint expresses reservations about using the inverse (or negative) aVR lead in the so-called Cabrera limb lead sequence and the implementation of inverse representations of any of the other 12 standard electrocardiographic leads. Instead, the author proposes that in patients with suspected acute coronary syndromes and a nondiagnostic electrocardiographic results, electrocardiography be repeated ("double electrocardiography"), with the V1 to V6 electrodes used to record leads V3R, V4R, V7 to V9 to the left of the spine, and V9R to the right of the spine to aid in triaging patients to the appropriate management.

Usefulness of three posterior chest leads for the detection of posterior wall acute myocardial infarction

A significant proportion of patients with myocardial infarction are missed upon initial presentation to the emergency department. The 12-lead electrocardiogram (ECG) has a low sensitivity for the detection of acute myocardial infarction, especially if the culprit lesion is in the left circumflex artery (LCA). This study was designed to evaluate the benefit of adding 3 posterior chest leads on top of the 12-lead ECG to detect ischemia resulting from LC disease, using a model of temporary balloon occlusion to produce ischemia. We studied 53 consecutive patients who underwent clinically indicated coronary interventions. At the time of coronary angiography, the balloon was inflated to produce complete occlusion of the proximal LCA. We recorded and analyzed the changes noted on the 15-lead ECG, which included 3 posterior leads in addition to the standard 12 leads. In response to acute occlusion of the LCA, the posterior chest leads showed more ST elevation than the other leads, and more patients had ST elevation in the posterior leads than in any other lead. The 15-lead ECG was able to detect>or=0.5 mm (74% vs 38%, p<0.0001) and >or=1 mm (62% vs 34%, p<0.0001) ST elevation in any 2 contiguous leads more frequently than the 12-lead ECG. In conclusion, the 15-lead ECG identified more patients with posterior myocardial wall ischemia because of temporary balloon occlusion of the LC than the 12-lead ECG. This information may enhance the detection of posterior MI in the emergency department and potentially facilitate early institution of reperfusion therapy.

Recommendations for the standardization and interpretation of the electrocardiogram: part I: the electrocardiogram and its technology a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society endorsed by the International Society for Computerized Electrocardiology

This statement examines the relation of the resting ECG to its technology. Its purpose is to foster understanding of how the modern ECG is derived and displayed and to establish standards that will improve the accuracy and usefulness of the ECG in practice. Derivation of representative waveforms and measurements based on global intervals are described. Special emphasis is placed on digital signal acquisition and computer-based signal processing, which provide automated measurements that lead to computer-generated diagnostic statements. Lead placement, recording methods, and waveform presentation are reviewed. Throughout the statement, recommendations for ECG standards are placed in context of the clinical implications of evolving ECG technology.

Recommendations for the Standardization and Interpretation of the Electrocardiogram

This statement examines the relation of the resting ECG to its technology. Its purpose is to foster understanding of how the modern ECG is derived and displayed and to establish standards that will improve the accuracy and usefulness of the ECG in practice. Derivation of representative waveforms and measurements based on global intervals are described. Special emphasis is placed on digital signal acquisition and computer-based signal processing, which provide automated measurements that lead to computer-generated diagnostic statements. Lead placement, recording methods, and waveform presentation are reviewed. Throughout the statement, recommendations for ECG standards are placed in context of the clinical implications of evolving ECG technology.

Recommendations for the standardization and interpretation of the electrocardiogram. Part I: The electrocardiogram and its technology. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society

This statement examines the relation of the resting ECG to its technology. Its purpose is to foster understanding of how the modern ECG is derived and displayed and to establish standards that will improve the accuracy and usefulness of the ECG in practice. Derivation of representative waveforms and measurements based on global intervals are described. Special emphasis is placed on digital signal acquisition and computer-based signal processing, which provide automated measurements that lead to computer-generated diagnostic statements. Lead placement, recording methods, and waveform presentation are reviewed. Throughout the statement, recommendations for ECG standards are placed in context of the clinical implications of evolving ECG technology.

Consideration of Pitfalls in and Omissions from the Current ECG Standards for Diagnosis of Myocardial Ischemia/Infarction in Patients Who Have Acute Coronary Syndromes

The ECG is the key clinical test available for the emergency determination of which patients who presenting with acute coronary syndromes indeed have acute myocardial ischemia/infarction. Because typically the etiology is thrombosis, the correct clinical decision regarding reperfusion therapy is crucial. This review follows the efforts of an AHA working group to develop new standards for clinical application of electrocardiology. The pitfalls in the current diagnostic standards regarding ischemia/infarction that have been identified by sufficiently documented studies are corrected in their report. This article focuses on the pitfalls for which new standards will emerge in future years.

Electrocardiographic Diagnosis of ST-elevation Myocardial Infarction

The ECG is an essential part of the initial evaluation of patients who have chest pain, especially in the immediate decision-making process in patients who have ST-elevation myocardial infarction. This article reviews and summarizes the current information that can be obtained from the admission ECG in patients who have ST-elevation acute myocardial infarction, with an emphasis on: (1) prediction of final infarct size, (2) estimation of prognosis, and (3) the correlations between various ECG patterns and the localization of the infarct and the underlying coronary anatomy.

How many ECG leads do we need?

The number of leads needed in clinical electrocardiography depends on the clinical problem to be solved. The standard 12-lead ECG is so well established that alternative lead systems must prove their advantage through well-conducted clinical studies to achieve clinical acceptance. Certain additional leads seem to add valuable information in specific patient groups. The use of a large number of leads (eg, in body surface potential mapping) may add clinically relevant information, but it is cumbersome and its clinical advantage is yet to be proven. Reduced lead sets emulate the 12-lead ECG reasonably well and are especially advantageous in emergency situations.

Acute coronary syndromes

Despite technologic advances in many diagnostic fields, the 12-lead ECG remains the basis for early identification and management of an acute coronary syndrome. This article reviews the use of the ECG in acute coronary syndromes.

Body surface mapping in the ED evaluation of the patient with chest pain: use of the 80-lead electrocardiogram system

Body surface mapping (BSM) is an electrocardiographic (ECG) technique that uses numerous leads on a patient's anterior and posterior chest, enabling more complete visualization of cardiac electrical activity. The rationale behind BSM is an extension of additional lead ECG. Output from BSM is displayed in a 12-lead ECG format, an 80-lead ECG format, and on color contour maps. The color contour maps can be displayed on a torso image or as a flat map.

Electrocardiographic manifestations: acute inferior wall myocardial infarction

The 12-lead electrocardiogram (EKG) is an important tool in evaluating the patient with acute myocardial infarction (MI). Patients with acute inferior wall myocardial infarction (IWMI) represent a heterogeneous group in terms of morbidity, mortality, Emergency Department (ED) management, and site of occlusion in the culprit coronary artery. The standard 12-lead EKG, right-sided chest leads and posterior chest leads, in conjunction with clinical findings often provide the necessary information for the Emergency Physician (EP) to predict complications, morbidity and mortality. IWMI patients may have associated right ventricular infarction (RVI) or lateral and posterior wall extension. Each of these entities is associated with specific hemodynamic abnormalities and increased mortality. In addition, various atrioventricular (AV) blocks are commonly associated with IWMI. This article presents several cases of IWMI with EKGs and a discussion of EKG interpretation in the setting of IWMI.

The electrocardiogram in ST elevation acute myocardial infarction: correlation with coronary anatomy and prognosis

The electrocardiogram is considered an essential part of the diagnosis and initial evaluation of patients with chest pain. This review summarises the information that can be obtained from the admission electrocardiogram in patients with ST elevation acute myocardial infarction, with emphasis on: (1) prediction of infarct size, (2) estimation of prognosis, and (3) the correlations between various electrocardiographic patterns and the localisation of the infarct and the underlying coronary anatomy.

Additional electrocardiographic leads in the ED chest pain patient: right ventricular and posterior leads

In the evaluation of the patient with chest pain, the 12-lead electro cardiogram is a less-than-(ECG) perfect indicator of acute myocardial infarction (AMI), particularly when used early in the course of the acute ischemic event; this relative insensitivity for AMI results from many different issues, including a less-than-optimal imaging of certain areas of the heart. It has been suggested that the sensitivity of the 12-lead ECG can be improved if 3 additional body surface leads are used in selected individuals. Acute posterior (PMI) and right ventricular myocardial infarctions are likely to be underdiagnosed, because the standard lead placement of the 12-lead ECG does not allow these areas to be assessed directly. Additional leads frequently used include leads V(8) and V(9), which image the posterior wall of the left ventricle, and lead V(4R), which reflects the status of the right ventricle. The standard ECG coupled with these additional leads constitutes the 15-lead ECG, the most frequently used additional lead ECG in clinical practice. The use of the additional leads might not only confirm the presence of AMI, but also provide a more accurate reflection of the true extent of myocardial damage.

Electrocardiographic algorithm for assignment of occluded vessel in acute myocardial infarction

BACKGROUND

This study was performed to elaborate an electrocardiographic (ECG) algorithm enabling assignment of an occluded coronary artery in acute myocardial infarction (AMI).

PATIENTS AND INTERVENTIONS

In 109 patients (age, 59+/-12 years) with AMI (pain onset, 3.6+/-1.7 h), coronary angiography with PTCA/stenting of the culprit lesion was performed. The diagnosis of AMI was confirmed by emergency coronary angiography and laboratory analyses. Admission ECG parameters (amplitude of R-wave, ST-segment deviation, presence of Q-wave, deflection of T-wave) in standard 12-lead ECG plus extended (V(3)R to V(6)R and V(7-9)) leads were subjected to classification and regression tree (CART) analysis.

RESULTS

Continuous CART analysis assessed ST-segment deviations in V(2) and V(5)R. AMI of the left anterior descending (LAD), right coronary artery (RCA) and left circumflex coronary artery (CX) were correctly classified in 94, 64, and 91% of cases, respectively. Dichotomised CART analysis assessed ST-segment deviations in V(2), V(5)R, and aVF. True classification rates for LAD, RCA, and CX amounted to 84, 74, and 71%, respectively.

CONCLUSIONS

Dichotomised CART analysis is a simple means of differentiation of CX from RCA occlusion during AMI.

Beyond the 12 lead: review of the use of additional leads for the early electrocardiographic diagnosis of acute myocardial infarction

Despite known limitations, the standard 12 lead ECG is the principal risk stratification device for patients presenting with chest pain to the ED. However, it has a sensitivity of less than 60% for MI. One reason for this is that the standard placement of chest leads fails to interrogate many areas of the myocardium. Various workers have addressed this problem through the use of additional leads or body surface mapping. Additional leads on the posterior and right thoracic surface have been shown to give additional information, which may be important to the emergency physician. This review demonstrates the need for additional leads in the acute setting and makes recommendations about the utility of using additional leads in the ED.

Clinical utility of ST-segment depression in lead AVR in acute myocardial infarction

The present study evaluated the prevalence and significance of ST-segment depression (STD) in lead aVR on the admission 12-lead electrocardiogram in 307 consecutive patients with an acute myocardial infarction (AMI) with ST-segment elevation. STD in aVR was present in a significantly higher proportion of patients with inferior/posterior AMIs. Within inferior/posterior AMIs those with STD in aVR had significantly more concomitant STD in V(1), V(2), V(3) and more concomitant STesegment elevation in V(5), V(6) and right precordial leads. These data suggests that STD in aVR may point to a coronary artery with a large area of supply as the culprit vessel responsible for the AMI.

Diagnosis of acute myocardial infarction in angiographically documented occluded infarct vessel : limitations of ST-segment elevation in standard and extended ECG leads

STUDY OBJECTIVES

The majority of thrombolysis studies require defined ST-segment elevations as an inclusion criterion for the diagnosis of acute myocardial infarction (AMI). However, depending on the occluded infarct vessel and the criteria applied, the ECG diagnosis of AMI can be difficult to establish. Accordingly, this study was performed to evaluate the sensitivity of ST-segment elevation of standard and extended ECG leads in a cohort of patients with angiographically confirmed diagnosis of AMI.

PATIENTS AND METHODS

In 418 patients (mean +/- SD age, 60 +/- 13 years) with AMI (pain onset, 4.8 +/- 3.0 h), coronary angiography with percutaneous transluminal coronary angioplasty/stenting of the culprit lesion was performed. The diagnosis of AMI was confirmed by emergency coronary angiography and laboratory analyses. ST-segment elevation (in two contiguous leads) of 1 mm in standard lead I through aVF and ST-segment elevations of 2 mm (or 1 mm, corresponding values presented in parentheses) in V(1) through V(6) were considered significant. In a subset of 102 AMI patients, additional right precordial leads V(3)R through V(6)R for evaluation of right ventricular infarction and additional chest leads V(7) through V(9) for evaluation of posterior infarction were recorded. ST-segment elevations of 1 mm in the right precordial leads and 1 mm or 0.5 mm in the posterior leads were considered significant.

RESULTS

Standard leads I through V(6) showed ST-segment elevation in 85% (96%) of patients with left anterior descending artery occlusion, in 46% (61%) of patients with left circumflex coronary artery (CX) occlusion, and in 85% (90%) of patients with right coronary artery occlusion. On consideration of additional ECG tracings in the subgroup of 102 patients (V(3)R through V(6)R and V(7) through V(9)), the respective numbers increased by 2 to 8% depending on different criteria for ST-segment elevation; in patients with CX occlusion, the increase amounted to 6 to 14%. There was a trend toward an extended infarct size (maximum creatine kinase [CK] values) with concomitant ST-segment elevation in additional ECG leads as assessed by maximum CK levels.

CONCLUSIONS

The sensitivity of the ECG diagnosis of AMI is only marginally increased by extended precordial chest leads. There is a trend toward an extended infarct size in those patients with concomitant ST-segment elevation in additional ECG leads.

Electrocardiographic manifestations: Acute posterior wall myocardial infarction

Posterior myocardial infarction (PMI) refers to infarction of the posterior wall of the left ventricle. Although often associated with inferior and lateral myocardial infarctions, detection of acute PMI is difficult because the standard 12-lead electrocardiogram does not adequately image the posterior wall of the left ventricle. We review the findings on 12-lead electrocardiogram with PMI, as well as discuss the utility of additional electrocardiographic leads in the diagnosis of PMI.

ELECTROCARDIOGRAPHIC DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION

The widely recognized benefits of early diagnosis and treatment of acute myocardial infarction (AMI) have only emphasized the importance of emergency physician (EP) competence in electrocardiographic interpretation. As such, the EP must be an expert in the interpretation of the electrocardiogram (ECG) in the emergency department chest pain center patient. The ECG is a powerful clinical tool used in the evaluation of patients, assisting in making the diagnosis of AMI and other syndromes, selecting appropriate therapies (including thrombolysis and primary angioplasty), securing the location of an adequate inpatient disposition, and predicting the risk of cardiovascular complications and death. This article will discuss the appropriate uses of the ECG in the patient with possible or confirmed AMI and review the typical electrocardiographic findings of AMI, diagnostically confounding patterns, mimickers of infarction, and new techniques.

Electrocardiographic diagnosis of acute myocardial infarction: Current concepts for the clinician

BACKGROUND

Over the past 2 decades, the 12-lead electrocardiogram has attained special significance for the diagnosis and triage of patients with chest pain because timely detection of myocardial injury and a rapid assessment of myocardium at risk proved pivotal to implementing effective reperfusion therapies during acute myocardial infarction. However, this wealth of information could still be underutilized by clinicians who may restrict their diagnostic quest in patients with chest pain to the more classic electrocardiographic signs.

METHODS

The medical literature on electrocardiographic manifestations of acute myocardial infarction was extensively reviewed.

RESULTS

The widespread utilization of both coronary angiography and methods to determine myocardial function and metabolism in patients with acute myocardial infarction over the last 10 years has provided the means for rigorous comparisons with electrocardiographic information. We summarize these electrocardiographic signs and patterns in terms of their relevance to the clinician to help reduce the incidence of "nondiagnostic electrocardiograms" and improve timely decision-making.

CONCLUSIONS

The electrocardiogram continues to be an invaluable tool in the initial evaluation of patients with chest pain. The plethora of data currently available on electrocardiographic changes correlating with myocardial injury allows clinicians to make faster and better decisions than ever before.

A comparison of 12- and 15-lead ECGS in ED chest pain patients: impact on diagnosis, therapy, and disposition

The objective of this study was to investigate the diagnostic and therapeutic impact of the 15-lead electrocardiogram (15ECG) on the emergency department (ED) management of chest pain (CP) patients. The design was prospective use of 15ECG with real-time physician survey and retrospective comparison to 12-lead ECG (12ECG). The study took place in a University hospital ED. Adult CP patients participated. During the 15ECG period (June 1996 to July 1996), 595 patients (92% of CP patients) had 15ECG analysis. Diagnoses of acute coronary ischemic syndromes (ACIS) were as follows: 13 acute myocardial infarction (AMI, 7 anterior [ANT], 5 inferior [INF], 1 lateral [LAT], 2 posterior [POST], 1 right ventricular [RV]) and 136 unstable angina (USA) with 47% exhibiting ECG abnormality; the 2 POST and 1 RV AMI occurred in the setting of coexisting INF AMI. The following management strategies were used: 6 fibrinolytic therapy (TT), 4 primary angioplasty (PTCA), 67 rule-out myocardial infarction (ROMI), and 144 admission to critical care unit (CCU). During the 12ECG period (June 1995 to July 1995), 599 patients were encountered. The diagnoses of ACIS were as follows: 11 AMI (5 ANT, 4 INF, 2 LAT) and 146 USA with 51% exhibiting ECG abnormality (P = NS for diagnostic comparisons to 15ECG). The following management strategies were used: 5 TT, 5 PTCA, 59 ROMI, and 137 admission to CCU (P = NS for all treatment comparisons to 15ECG). Of 15ECG cases 81% had completed real-time physician survey, showing that the diagnosis and management ACIS were not altered by the 15ECG; physicians felt, however, that the 15ECG provided a more complete anatomic picture of the ACIS. No false-positive cases of additional lead STE were noted in this investigation except in cases involving abnormal intraventricular conduction such as the bundle branch block scenario. The 15ECG provided a more complete description of myocardial injury without altering the ED diagnosis, ED-based therapy, or hospital disposition in adult CP patients. Further study is required to identify patient subset(s) which may benefit from the 15ECG.

Early diagnosis of right ventricular or posterior infarction associated with inferior wall left ventricular acute myocardial infarction

Right ventricular (RV) or posterior infarction associated with inferior wall left ventricular acute myocardial infarction (AMI) has important therapeutic and prognostic implications. However, RV and posterior chest leads in addition to the 12-lead electrocardiogram are required for accurate detection. Body surface mapping (BSM) has greater spatial sampling and may further improve inferior wall AMI classification. Consecutive patients with chest pain lasting <12 hours were assessed to identify those with AMI and > or =0.1 mV ST elevation in > or =2 contiguous inferior leads of the 12-lead electrocardiogram (bundle branch block or left ventricular hypertrophy excluded). A 12-lead electrocardiogram, RV leads (V(2)R, V(4)R), posterior chest leads (V(7), V(9)), and a BSM were recorded. From each BSM, the 12 electrodes overlying the RV region (regional RV map) and 10 electrodes overlying the posterior wall (regional posterior map) were assessed for ST elevation. Infarct size was estimated by serial cardiac enzymes. AMI occurred in 173 of 479 patients. Of the 62 patients with inferior wall AMI, ST elevation > or =0.1 mV occurred in 26 patients (42 in V(2)R or V(4)R compared with 36 patients (58%) in > or =1 electrode on the regional RV map (p = 0.0019). ST elevation > or =0.1 mV occurred in 1 patient (2%) in V(7) or V(9) compared with 17 patients (27%) in > or =1 electrode on the regional posterior map (p = 0.00003). ST elevation > or =0.05 mV occurred in 6 patients (10%) in V(7) or V(9) compared with 22 patients (36%) in > or =1 electrode on the regional posterior map (p = 0.00003). Patients with ST elevation on regional RV and/or posterior maps had a trend toward larger infarct size (mean peak creatine kinase 1,789+/-226 vs. 1,546+/-392 mmol/L; p = NS). Thus, BSM, when compared with RV or posterior chest leads, provides improved classification of patients with inferior wall AMI and RV or posterior wall involvement.

Electrocardiographic patterns in posterior chest leads (V7, V8, V9) in normal subjects

The electrocardiographic patterns in leads V7, V8, and V9 were studied in 225 young, normal men (age range 17 to 21 years). The prevalence of 0.5- to 1.0-mm ST-segment elevation in leads V7, V8, and Vg 0.08 second after the J point was 8.9%, 5.8%, and 3.1%, respectively; the ST-segment elevation was not >1.0 mm in any subject.

Improved detection of posterior myocardial wall ischemia with the 15-lead electrocardiogram

BACKGROUND

A routine 12-lead electrocardiogram is commonly obtained to evaluate for possible acute myocardial infarction during the initial screening of patients with chest discomfort. Posterior myocardial infarction is commonly missed because it is not usually visible in the standard leads. In this study, we compared the sensitivity and specificity of posterior chest leads (V(7), V(8), and V(9)) and 12-lead electrocardiography in detecting posterior injury pattern during single-vessel percutaneous transluminal coronary angioplasty.

METHODS AND RESULTS

Three posterior chest leads in addition to the routine 12-lead electrocardiogram were monitored simultaneously during single-vessel percutaneous transluminal coronary angioplasty of the right, circumflex, and left anterior descending coronary arteries in a total of 223 patients. Posterior injury patterns (95%) were detected mostly during circumflex coronary occlusion. Posterior leads were able to detect injury pattern in 49% (36 of 74) of patients, whereas the 12-lead electrocardiogram was able to detect only 32% (P <.04). When all 15 leads were used to detect all ST elevations, sensitivity increased to 57%, with a specificity of 98% for the circumflex coronary artery. If maximal ST depressions in leads V(2) to V(3) are considered to be from posterior myocardial injury, then the overall sensitivity is increased to 69%.

CONCLUSIONS

Posterior leads significantly increased the detection of posterior injury pattern compared with the standard 12-lead electrocardiogram. Using all 15 leads significantly further improved the detection of circumflex coronary-related injury pattern over the standard 12-lead electrocardiogram.

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.