Paula A. Johnson

Prediction of the Need for Intensive Care in Patients Who Come to Emergency Departments with Acute Chest Pain

BACKGROUND Patients who come to the emergency department with chest pain are a heterogeneous group. Some have ischemic heart disease that may lead to serious complications, whereas others have minor disorders. We performed a study to identify clinical factors that predict which patients will have complications requiring intensive care. METHODS We first studied 10,682 patients with acute chest pain at seven hospitals between 1984 and 1986 (derivation set) to identify potential clinical predictors of the development of major complications. We then validated these predictors in a separate set of 4676 patients at one hospital between 1990 and 1994 (validation set). RESULTS In the derivation set of patients, we identified the following set of clinical features, which, if present in the emergency department, were associated with an increased risk of complications: ST-segment elevation or Q waves on the electrocardiogram thought to indicate acute myocardial infarction, other electrocardiographic changes indicating myocardial ischemia, low systolic blood pressure, pulmonary rales above the bases, or an exacerbation of known ischemic heart disease. On the basis of these criteria, the patients in the validation set were stratified into four groups, with the risk of major complications in the first 12 hours ranging from 0.15 to 8 percent. After 12 hours, the probability of a major complication could be updated on the basis of whether the patient had already had a complication of major severity, a complication of intermediate severity, or a myocardial infarction (independent relative risks, 18.9, 7.7 and 4.0, respectively, as compared with patients without prior complications or myocardial infarction). CONCLUSIONS The risk of major complications in patients with acute chest pain can be estimated on the basis of the clinical presentation and new clinical observations made during the hospital course. These estimates of risk help in making rational decisions about the appropriate level of medical care for patients with acute chest pain.

Effect of Race on the Presentation and Management of Patients with Acute Chest Pain

National data indicate that the rate of decline in mortality from coronary heart disease has been more rapid in whites than in African-Americans [1-4]. Among the many possible explanations for this discrepancy is reduced access to beneficial care, including sophisticated cardiologic procedures. Wenneker and Epstein [5] showed that African-Americans were significantly less likely than whites to have cardiac procedures in Massachusetts hospitals in 1985. Maynard and colleagues [6] found that African-Americans in the Seattle-based Myocardial Infarction Triage and Intervention (MITI) Registry had significantly fewer angioplasty and coronary artery bypass grafting procedures than did whites. Goldberg and colleagues [7] analyzed national Medicare data from 1986 and showed that among persons insured by Medicare, African-Americans had a significantly lower rate of coronary artery bypass grafting procedures when compared with whites. Unfortunately, these studies lacked sufficiently detailed clinical information to determine whether these differences were a function of differing clinical characteristics or even whether the rates were higher than appropriate in whites, lower than appropriate in African-Americans, or both. For example, African-Americans have a significantly lower rate of hospital discharge with acute myocardial infarction as the primary diagnosis [8]. Although ischemic heart disease is the leading cause of death in African-Americans as well as in whites, the effect of race on clinical course and outcomes (that is, on the natural history of ischemic heart disease) in patients with chest pain has not been well studied [9]. Thus, further information is needed to understand racial differences in the rates of cardiac procedures. To address this need, we merged detailed clinical and resource utilization data on 3031 patients from two hospitals to measure the effect of race on the clinical presentation, the natural history of disease, and the resource utilization of patients coming to the emergency department because of acute chest pain. Our detailed patient-specific information permitted us to adjust for clinical characteristics and complications to understand the basis for any differences in overall procedure rates. Methods Study Design The Multicenter Chest Pain Study, a cooperative investigation of the clinical characteristics and outcomes of emergency-department patients with acute chest pain, was conducted between December 1983 and October 1986 [9-18]. All patients 30 years or older who came to one of the participating emergency departments with a chief complaint of anterior, precordial, or left lateral chest pain that could not be explained by obvious local trauma or abnormalities on a chest radiograph were eligible. The emergency-department physician, who was usually an intern or a resident, recorded clinical data at the time of presentation, including the patients age; sex; findings from the history, physical examination, and electrocardiogram; and results of cardiac enzyme assessments. The emergency-department physician or a research nurse recorded these data on a standardized data form that was part of the permanent medical record at a time when he or she had no knowledge of, and could not be biased by, the patients subsequent course. Data on race were collected prospectively in 94% of patients at the University of Cincinnati Hospital and retrospectively, by chart review, in 96% of patients at the Brigham and Womens Hospital. Patients from these two hospitals composed our study group. The term African-American is used to describe blacks residing in the continental United States who are of African descent. Each patient visit was considered an individual event. Only the first three visits for each patient during the study period were included in the analysis. Patients who experienced cardiac arrest in the emergency department were excluded from the study. During the study period, 4173 potentially eligible patient visits occurred at the two hospitals (Figure 1). A trained study nurse reviewed the charts of all admitted patients, recording data on cardiac enzyme levels, official discharge diagnoses, and dates and times of complications and procedures. Figure 1. Derivation of the study population of 3031 patients from the 4173 patients who came to the emergency department with acute chest pain. Consent was obtained from 1991 (79%) of the 2522 discharged patients. The other 531 nonconsenting, discharged patients did not differ significantly from the 1991 consenting patients in terms of gender or age. Consenting, nonadmitted patients were retained in the study only if the investigators, who were blinded to all of the patients emergency-department data, thought that the follow-up information was sufficient to place the patient into a diagnostic category, as defined below. Sixty-two percent of the consenting, nonadmitted patients included in the final study sample had a follow-up assessment of cardiac enzyme levels, and 66% had either assessment of cardiac enzyme levels or a follow-up visit. Those nonadmitted patients who did not return for follow-up evaluation were contacted by telephone to assess their clinical status. In such cases, patients considered to be at a higher risk for myocardial infarction because of a suspicious pain description, electrocardiographic abnormalities, or continuing symptoms were encouraged by telephone to return for an evaluation; if they were still unwilling to return, further follow-up was obtained by telephone and contact with the patients personal physician. Patients who returned for a follow-up visit or enzyme assessment were similar to patients who received telephone follow-up with regard to sex and age, but African-Americans were more likely than whites to have enzyme assessments, electrocardiograms, or both (71% compared with 61%, P < 0.0001). Race was identified in 1593 (97%) of the 1640 admitted patients and 1676 (94%) of the 1787 consenting, discharged patients with adequate follow-up. The 226 Hispanic and 12 Asian patients were excluded because of their small number. Therefore, the final study sample included 3031 patients: 1508 admitted patients (35% African-American, 49% male) and 1523 consenting, nonadmitted patients (55% African-American, 39% male). Data on zip-code and insurance status were available from one of the two hospitals. Household income was estimated by matching zip codes with 1980 census data on median household income in that geographic location. Diagnoses A final diagnosis of acute myocardial infarction was made in both admitted and nonadmitted patients on the basis of one of the following criteria: 1) characteristic evolution of serum enzyme levels, as defined by the detection of creatine kinase MB isoenzyme levels in more than trace amounts by the qualitative electrophoretic assay or as at least 5% of an elevated total creatine kinase level and showing a typical rise and fall by the quantitative assay; by a lactic dehydrogenase isoenzyme 1 level that was greater than the isoenzyme 2 level in the absence of hemolysis or renal infarction; or, if isoenzymes were not assayed, by serial total creatine kinase levels demonstrating a typical rise and fall, with a peak value exceeding twice the usual upper limit of normal; 2) an electrocardiogram showing development of pathologic Q waves [at least 0.04 seconds in duration] and at least a 25% decrease in the amplitude of the following R wave compared with that of the emergency-department electrocardiogram; and 3) sudden unexplained death within 72 hours of presentation. In the Chest Pain Study, the purpose of which was to define optimal management strategies for patients with acute chest pain, discharged patients with sudden death within 72 hours of admission were classified as having had an acute myocardial infarction unless contradicting data were found, because admission to an intensive or coronary care unit would have been the preferred triage strategy had this outcome been anticipated. Admitted patients who had sudden cardiac arrests and died before cardiac enzyme assessments could be done were similarly classified unless other explanations for the arrest emerged. In all of these patients, the presenting characteristics, electrocardiograms, and clinical courses were most consistent with the diagnosis of acute myocardial infarction. All patients who underwent coronary reperfusion with thrombolytic therapy showed electrocardiographic or enzymatic evidence of acute myocardial infarction before undergoing the procedure. Patients who showed creatine kinase and creatine kinase MB isoenzyme elevations after but not before an invasive procedure (for example, coronary arteriography, coronary angioplasty, or coronary artery bypass grafting) were considered not to have had infarctions, because such procedures were done at the discretion of the physicians who were caring for the patients, and acute myocardial necrosis might not have occurred if the patients had been managed conservatively. The final diagnosis of acute ischemic heart disease was made if the patient was found to have either acute myocardial infarction or unstable angina. Unstable angina was diagnosed if 1) the patients original emergency-department chest pain syndrome was either new or worse (in frequency, severity, or duration) than his or her chronic anginal syndrome; and 2) the diagnosis of angina was made by the senior clinician associated with the case. Table 1. Characteristics of the Study Sample Stratified by Race* Major complications were defined as follows: ventricular fibrillation requiring lidocaine or defibrillation, Mobitz II second-degree atrioventricular block requiring temporary or permanent pacing, new complete heart block, cardiogenic shock, or cardiac arrest. Cardiac catheterization data were collected retrospectively by chart review. Statistical Analysis Racial distribution differed by hospital, with African-Americans accoun

An Evaluation of Technologies for Identifying Acute Cardiac Ischemia in the Emergency Department: A Report from a National Heart Attack Alert Program Working Group

Abstract [Selker HP, Zalenski RJ, Antman EM, Aufderheide TP, Bernard SA, Bonow RO, Gibler WB, Hagen MD, Johnson P, Lau J, McNutt RA, Ornato J, Schwartz JS, Scott JD, Tunick PA, Weaver WD: An evaluation of technologies for identifying acute cardiac ischemia in the emergency department: A report from a National Heart Attack Alert Program Working Group. Ann Emerg Med January 1997;29:13-87.]

Prognostic value of cardiac troponin T after noncardiac surgery: 6-Month follow-up data

OBJECTIVES We sought to evaluate the prognostic significance of cardiac troponin T (TnT) serum levels after noncardiac surgery. BACKGROUND Cardiac TnT has been found to be marker for myocardial injury, but elevations of TnT are common in patients undergoing noncardiac surgery without clinical evidence of severe ischemia. METHODS We studied 772 patients who underwent major noncardiac procedures and did not have major cardiovascular complications during their inpatient course. Total serum creatine kinase (CK) and cardiac TnT were measured according to a protocol that included sampling in the recovery room and during the next 2 days. A 6-month follow-up interview was performed for 722 (94%) of the patients. RESULTS Elevated cardiac TnT and CK-MB results were detected for 92 (12%) and 211 (27%) patients, respectively. During the follow-up period, there were 19 (2.5%) major cardiac complications, including 14 cardiac deaths, 3 nonfatal myocardial infarctions and 2 admissions for unstable angina. Compared with patients with cardiac TnT values < 0.1 ng/ml, patients with elevated TnT had a relative risk for cardiac events of 5.4 (95% confidence interval: 2.2 to 13, p = 0.001), whereas CK-MB was not correlated with postdischarge cardiac events. In multivariate logistic regression analysis adjusting for preoperative clinical and CK-MB data, a cardiac TnT value > 0.1 ng/ml was in independent correlate of cardiac events (adjusted odds ratio 4.6, p < 0.05). This correlation was a function of the relation of elevated TnT levels with postoperative in-hospital congestive heart failure and new sustained arrhythmias, suggesting that elevated postoperative TnT levels detected myocardial ischemia during these clinical events. CONCLUSIONS We conclude that an abnormal TnT level in patients undergoing noncardiac surgery may be a useful marker of ischemic disease and a predictor of 6-month prognosis.

Cardiac troponin I as a predictor of major cardiac events in emergency department patients with acute chest pain

OBJECTIVES We sought to evaluate the diagnostic and prognostic value of cardiac troponin I (cTnI) in emergency department (ED) patients with chest pain. BACKGROUND Although cTnI has been shown to correlate with an increased risk for complications in patients with unstable angina, the prognostic significance of this assay in the heterogeneous population of patients who present to the ED with chest pain is unclear. METHODS cTnI and creatine kinase-MB fraction (CK-MB) mass concentration were collected serially during the first 48 h from onset of symptoms in 1,047 patients > or =30 years old admitted for acute chest pain. Sensitivity, specificity and receiver operating characteristic curves were calculated for cTnI and CK-MB collected in the first 24 h. RESULTS The sensitivity, specificity and positive predictive value of cTnI for major cardiac events were 47%, 80% and 19%, respectively. Among patients were who ruled out for myocardial infarction, cTnI was elevated in 26% who had major cardiac complications compared with 5% for CK-MB; the positive predictive value for an abnormal cTnI result was 8%. Elevated cTnI in the presence of ischemia on the electrocardiogram was associated with an adjusted odds ratio of 1.8 (95% confidence interval 1.1 to 2.9) for major cardiac events within 72 h. Among patients without a myocardial infarction or unstable angina, cTnI was not an independent correlate of complications. CONCLUSIONS In patients presenting to the ED with acute chest pain, cTnI was an independent predictor of major cardiac events, However, the positive predictive value of an abnormal assay result was not high in this heterogeneous cohort.

Triage decisions for emergency department patients with chest pain : do physicians' risk attitudes make the difference ?

OBJECTIVE: To determine whether physicians’ risk attitudes correlate with their triage decisions for emergency department patients with acute chest pain.DESIGN: Cohort.SETTING: The emergency department of a university teaching hospital.PATIENTS: Patients presenting to the emergency department with a chief complaint of acute chest pain.PHYSICIANS: All physicians who were primarily responsible for the emergency department triage of at least one patient with acute chest pain from July 1990 to July 1991.METHODS: The physicians’ risk attitudes were assessed by two methods: 1) a new, six-question risk-taking scale adapted from the Jackson Personality Index (JPI), and 2) the Stress from Uncertainty Scale (SUS).RESULTS: The physicians who had high risk-taking scores (“risk seekers”) admitted only 31% of the patients they evaluated, compared with admission rates of 44% for the medium scorers and 53% for the physicians who had low risk-taking scores (“risk avoiders”), p<0.001. After adjustment for clinical factors, the patients triaged by the risk-seeking physicians had half the odds of admission [odds ratio (OR) 0.51, 95% confidence interval (95% CI) 0.27 to 0.97], and the patients triaged by the risk-avoiding physicians had nearly twice the odds of admission (OR 1.83, 95% CI 1.10 to 3.03) of the patients triaged by the medium-risk scoring physicians. The SUS did not correlate significantly with admission rates. Of the 92 patients released home by the risk-seeking physicians, 91 (99%) were known to be alive four to six weeks afterwards and one was lost to follow-up; among the 66 patients released by the risk-avoiding physicians, 64 (97%) were known to be alive at four to six weeks, one was lost to follow-up, and one died of ischemic heart disease during a subsequent hospitalization (p=NS).CONCLUSIONS: The physicians’ risk attitudes as measured by a brief risk-taking scale correlated significantly with then-rates of admission for emergency department patients with acute chest pain. These data do not suggest that the risk-seeking physicians achieved lower admission rates by releasing more patients who needed to be in the hospital, but an adequate evaluation of the appropriateness of triage decisions of risk-seeking and risk-avoiding physicians will require further study.

Troponin T as a marker for myocardial ischemia in patients undergoing major noncardiac surgery

To assess the diagnostic performance of cardiac troponin T as a marker for myocardial injury in patients undergoing major noncardiac surgery, we prospectively collected preoperative and postoperative clinical data, including measurements for creatine kinase (CK), CK-MB, and troponin T for 1,175 patients undergoing major noncardiac surgery. Acute myocardial infarction was diagnosed in 17 patients (1.4%) by a reviewer who was blinded to troponin T data and who used CK-MB and electrocardiographic criteria to define acute myocardial infarction. Other predischarge major cardiac complications were detected for another 17 patients. Troponin T elevations (>0.1 ng/ml) occurred in 87% of patients with and in 16% of patients without myocardial infarction. Among patients without myocardial infarction, troponin T was elevated in 62% of patients with and in 15% of patients without major cardiac complications. Receiver-operating characteristic analysis indicated that troponin T had a performance for the diagnosis of acute myocardial infarction similar to CK-MB, and a significantly better correlation with other major cardiac complications in patients without definitive infarction. Future research should seek to determine the significance of troponin T elevations in patients without complications.

A critical pathway for management of patients with acute chest pain who are at low risk for myocardial ischemia : Recommendations and potential impact

Acute chest pain is a common and costly problem [1, 2]. Various strategies have been evaluated to increase the efficiency of care for persons with acute chest pain, including reducing the number of inappropriate admissions, expediting transfer from intensive care units to intermediate-care units, or disseminating practice guidelines [1, 3-6]. Such interventions have achieved only modest success [5]. Many institutions are developing innovative strategies to address this problem [7, 8], including immediate exercise treadmill testing [9, 10], early noninvasive imaging [11, 12], use of new markers for myocardial injury [13], and creation of emergency departments for chest pain [6, 14, 15]. Although some of these strategies have been evaluated [6], few data describe the expected or actual effects of most strategies on clinical outcomes or resource use. Nevertheless, short observation protocols for patients with chest pain are being implemented throughout the United States [14, 15]. Previous studies [16-18] addressed whether a patient who presents to an emergency department has unstable angina or acute myocardial infarction. An emerging paradigm instead asks whether it is safe to discharge the patient or whether it is safe for the patient to undergo an exercise treadmill test. This paradigm focuses attention on the safety of the management strategy rather than on the diagnosis because diagnosis often cannot be conclusively determined in the time frame available [19, 20]. We developed a comprehensive, evidence-based approach to management of patients with acute chest pain in the emergency department. We used published investigations to define the strategy and resolved differences or gaps in the literature by consensus of local experts. Quality management techniques were incorporated by using critical pathways to reduce variation in patient care [21-23]. Critical pathways define and manage the timing and sequence of the rate-limiting steps in the process of providing health care [21]. Management of this process includes simultaneously monitoring and giving feedback to providers of information about achievement of expected and unexpected patient outcomes. Health care providers can then adjust patient management to prevent or modify unexpected outcomes. Critical pathways are distinct from clinical guidelines and algorithms [21]. Clinical guidelines define the appropriateness of care [21], and clinical algorithms define the step-by-step procedure for providing care, usually with conditional logic (if-then statements) [22]. Neither guidelines nor algorithms use simultaneous management of the process of care delivery to monitor compliance with recommended practice and identify opportunities for improvement. The specific goals of our critical pathway were to reduce admission rates and total days of hospitalization among patients who were at low risk for complications of ischemic disease and to limit adverse outcomes. To address these goals, we developed an explicit sequence of care and recommended the daily availability of early exercise treadmill testing in low-risk patients. We retrospectively applied the criteria of the critical pathway to data from a large cohort of patients with acute chest pain to assess the potential effects of implementation of the pathway on resource use and adverse outcomes. Methods The Critical Pathway Development We developed the critical pathway on the basis of scientific evidence and the experience of local opinion leaders and physician-investigators with long-standing interest in the topic. Relevant articles from the medical literature were identified by doing a MEDLINE search for English-language articles from 1990 to 1995 using the keywords chest pain, unstable angina, and myocardial infarction combined with randomized, controlled trial (PT) and cohort study. All identified papers were reviewed for relevance. Study quality was not explicitly evaluated because existing quality scales either have not been validated [24] or do not consider the value of Bayesian analyses [25]. Relevant articles were supplemented with a national clinical practice guideline for management of unstable angina [26]. Opinion leaders included staff emergency department physicians, staff cardiologists, and a cardiologist affiliated with a large health maintenance organization. An informal nominal group process was used to reach consensus [27]. The process consisted of a series of meetings and draft documents. Team members contributed recommendations based on the medical literature, and group discussion clarified and evaluated each recommendation. Team members independently reviewed the documents between meetings to comment on the work in progress. Consensus was achieved by unanimity. Content The flow of the critical pathway is shown in Figure 1. The pathway consisted of flowsheets with instructions and preprinted orders to facilitate use. Instructions provided suggestions to the end-user (usually an emergency department physician) about what information may facilitate decision making. The preprinted orders were designed to be selected by the physician in response to the instructions. Figure 1. Critical pathway for management of patients with acute chest pain who are at low risk for myocardial ischemia. Variance tracking was incorporated into the critical pathway to monitor the length of time that patients were present in the emergency department and the disposition and clinical outcomes of patients enrolled in the pathway [28, 29]. Time goals were suggested for the performance of key elements of the care process. Failure to meet these performance standards or occurrence of other explicit events were considered key variances, which may be reviewed later in aggregate to facilitate improvement of quality of care. We recommended recording the time interval between arrival in the emergency department and completion of the following tasks: 1) obtaining an electrocardiogram, 2) deciding to perform exercise treadmill testing, 3) obtaining the results of exercise treadmill testing, and 4) deciding to admit or discharge the patient. Eligibility Four clinical categories of patients were ineligible for enrollment in the critical pathway: patients with ongoing chest pain, patients with congestive heart failure present at initial clinical examination, patients with ischemia or injury present on the initial electrocardiogram (defined as ST-segment elevation, ST-segment depression, or T-wave inversion suggestive of ischemia or infarction and not known to be old), and patients judged by physicians to be at sufficiently low risk for myocardial ischemia to be discharged. At Brigham and Womens Hospital, Boston, Massachusetts, patients with active ischemia or infarction are treated by following other protocols [30]. Patients who clearly do not have ischemic chest pain are considered for direct discharge from the emergency department, as recommended by a national consensus panel [26]. Patients with left bundle-branch block and other electrocardiographic changes who might not be candidates for exercise electrocardiography were not explicitly excluded from eligibility for the pathway; patients could undergo alternative tests, such as exercise echocardiography or nuclear medicine studies, assuming that these technologies were available. Data Clinical, demographic, and outcome data were previously collected for a prospective cohort of consenting patients 30 years of age or older from the ongoing Chest Pain Study at Brigham and Womens Hospital [5, 31, 32]. These patients presented to the emergency department with chest pain and had no history of trauma or abnormal radiologic findings between 2 July 1990 and 18 February 1994. Inclusion criteria, definition of outcomes, and verification of outcomes for that cohort study are summarized below [5, 31, 32]. Clinical data were recorded by the emergency department physician at the time of presentation or by a research nurse before he or she had any knowledge of the patients outcome. These data were recorded on a standardized form that was part of the permanent medical record. A study nurse reviewed the charts of all admitted patients to determine subsequent outcome. Reviewers who were blinded to baseline clinical data classified patients into three categories on the basis of their final discharge diagnoses [5, 33]: acute myocardial infarction, unstable angina, or other. Acute myocardial infarction was diagnosed in admitted or discharged patients on the basis of characteristic evolution of serum enzyme levels, electrocardiographic changes, or sudden unexpected death within 72 hours of presentation [16]. Acute myocardial infarction was also diagnosed in 1) patients who did not meet these criteria but received acute reperfusion therapy with intravenous thrombolytic agents or primary percutaneous angioplasty and 2) patients who had new ST-segment elevation that evolved over the next day and had total occlusion of the infarction-related artery, an echocardiographic wall-motion abnormality that corresponded to the acute electrocardiographic changes, or an elevated total creatine kinase level and a creatine kinase-MB isoenzyme level greater than 2.5% of the total creatine kinase level, with characteristic evolution. Unstable angina was diagnosed if the original chest pain that led the patient to present to the emergency department was described by the patient as similar to or worse than previous symptoms of angina or myocardial infarction or if unstable angina was diagnosed by the senior clinician associated with the case. Other cardiac diagnoses, such as congestive heart failure or arrhythmias, and noncardiac diagnoses were made by the senior clinician involved with the case. Life-threatening complications were defined as nonfatal ventricular fibrillation, new type II second-degree atrioventricular block, new complete heart block, new atrioventricular dissociation, pulmonary edema, infarction extension, c

Clinical Correlates and Prognostic Significance of Early Negative Exercise Tolerance Test in Patients With Acute Chest Pain Seen in the Hospital Emergency Department

An exercise tolerance test (ETT) is often performed to identify patients for early discharge after observation for acute chest pain, but the safety of this strategy is unproven. We prospectively studied 276 low-risk patients who underwent an ETT within 48 hours after presentation to the emergency department with acute chest pain. The ETT was considered negative if subjects achieved at least stage I of the Bruce protocol and the electrocardiogram showed no evidence of ischemia. There were no complications associated with ETT performance. The ETT was negative in 195 patients (71%); there was no identifiable subsets of patients at very low probability of an abnormal test. During the 6-month follow-up, patients with a negative ETT had fewer additional visits to the emergency department (17% vs 21%, respectively; p < 0.05) and fewer readmissions to the hospital (12% vs 17%; p < 0.01) than those with positive or inconclusive ETTs. No patient with a negative ETT died and only 4 patients with a negative ETT experienced a major cardiac event (myocardial infarction, coronary angioplasty, or bypass) within 6 months. Among these 4 patients, only 1 had an event within 4 months. In conclusion, our results suggest that ETT can be safely used to identify patients at low risk of subsequent events. Patients without a clearly negative test are at increased risk for readmission and cardiac events, and should be reevaluated either during the same admission or shortly after discharge.

An Evaluation of Technologies for Identifying Acute Cardiac Ischemia in the Emergency Department: Executive Summary of a National Heart Attack Alert Program Working Group Report ☆ ☆☆ ★

Abstract [Selker HP, Zalenski RJ, Antman EM, Aufderheide TP, Bernard SA, Bonow RO, Gibler WB, Hagen MD, Johnson P, Lau J, McNutt RA, Ornato J, Schwartz JS, Scott JD, Tunick PA, Weaver WD: An evaluation of technologies for identifying acute cardiac ischemia in the emergency department: Executive Summary of a National Heart Attack Alert Program Working Group report. Ann Emerg Med January 1997;29:1-12.]