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

Chest Pain in Emergency Department Patients: If the Pain is Relieved by Nitroglycerin, is it More Likely to be Cardiac Chest Pain?

Introduction:

It is often believed that chest pain relieved by nitroglycerin is indicative of coronary artery disease origin.

Objective:

To determine if relief of chest pain with nitroglycerin can be used as a diagnostic test to help differentiate cardiac chest pain and non-cardiac chest pain.

Design:

Prospective observational cohort study with a 4-week follow-up of patients enrolled.

Setting:

Academic tertiary care hospital, with 60 000 visits/year.

Inclusion criteria:

Adult patients presenting to the emergency department with active chest pain who received nitroglycerin and were admitted for chest pain.

Exclusion criteria:

Patients with acute myocardial infarction diagnosed after obtaining an ECG, patients whose chest pain could not be quantified, those for whom no cardiac work-up was done, or those who received emergent cardiac catheterization.

Results:

270 patients were enrolled. Nitroglycerin relieved chest pain in 66% of the subjects. The diagnostic sensitivity of nitroglycerin to determine cardiac chest pain was 72% (64%–80%), and the specificity was 37% (34%–41%). The positive likelihood ratio for having coronary artery disease if nitroglycerin relieved chest pain was 1.1 (0.96–1.34). Telephone follow-up at 4 weeks was performed, with a 95% follow-up rate.

Conclusions:

Relief of chest pain with nitroglycerin is not a reliable diagnostic test and does not distinguish between cardiac and non-cardiac chest pain.

Introducing a chest pain pathway in the emergency department to improve quality of care for patients with possible cardiac chest pain

Chest pain is a common reason for patients to present to an emergency department (ED). It is crucial not to miss presentations of the potentially life-threatening acute coronary syndrome (ACS), although often these people present with a non-diagnostic ECG. This makes recognition of a history consistent with ACS very important. We noted inconsistencies in assessment, with many admissions to cardiology beds who did not prove to have ACS and some erroneous discharges who subsequently did have an ACS. We introduced a history based risk tool as part of a chest pain pathway into the ED for use by medical staff assessing patients presenting with chest pain. The intervention involved a nurse from cardiology engaging with clerical, nursing, and medical staff in the ED to ensure success of this quality improvement project. The project showed a reduction in admissions to cardiology with suspected ACS from 29% to 15%, with a projected saving of £889 per patient who was prevented from being admitted. In addition, admissions became more appropriate, with an increase in the proportion of patients with a final diagnosis of ACS from 25% to 46% and a reduction in admissions with atypical chest pain from 75% to 54%.

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.

Adenosine stress cardiovascular magnetic resonance-observation unit management of patients at intermediate risk for acute coronary syndrome: a possible strategy for reducing healthcare-related costs

OPINION STATEMENT

Although clear algorithms for diagnosis and treatment of patients with chest pain at low or high risk for an acute coronary syndrome (ACS) exist, they are less well delineated for patients presenting with chest pain with an intermediate risk for ACS. In patients presenting acutely or subacutely to emergency departments (EDs) at high risk for ACS, such as those with ST segment elevation on their 12-lead electrocardiogram (ECG), immediate contrast coronary angiography is performed. On the other hand, chest pain observation units (OUs) are recommended for managing those with chest pain at low risk for an ACS event. In this setting, these OUs are associated with lower healthcare resource utilization and improved cost-effectiveness. Cost-effective diagnosis and treatment options are important goals in healthcare delivery systems. The presentation of patients at intermediate risk for ACS represents an emerging source of resource utilization for EDs. These patients often exhibit pre-existing coronary artery disease, may have sustained prior myocardial infarction, and exhibit multiple comorbidities such as diabetes and hypercholesterolemia. Importantly, however, they will not have evidence of ST elevation on their 12-lead ECG nor will they exhibit serum markers (troponin or creatinine kinase elevations) indicative of ACS. As a consequence of existing co-morbidities, their management becomes time-consuming and may require inpatient monitoring, observation, and cardiac stress testing. Cardiovascular magnetic resonance (CMR) is a powerful tool for risk stratification and prognosis determination in patients in need of stress testing at intermediate risk of ACS. For those who present with acute chest pain syndromes, the combination of CMR in an OU setting represents a potentially attractive option for reducing healthcare-related expenditures without compromising patient outcomes. Recent study results from single centers suggest that CMR-OU care may result in fewer unnecessary hospital admissions and invasive procedures in those presenting with intermediate risk ACS. Further research utilizing stress CMR testing from multiple centers in OU settings is needed to determine if this model of care improves efficiency, reduces healthcare costs, and delivers optimum care in individuals presenting to EDs with chest pain at intermediate risk of ACS.

The evolution of chest pain pathways

Patients presenting to the emergency department with chest pain require prompt identification and referral, as early treatment of patients with an acute coronary syndrome (ACS) is crucial to decrease morbidity and mortality (Steurer et al, Emerg Med J. 2010;27:896-902). Although rule-in ACS is critical and time dependant, other difficulties arise during the rule-out ACS process (Steurer et al, Emerg Med J. 2010;27:896-902). Inappropriate discharge of patients with misdiagnosed acute myocardial infarction is associated with significant morbidity and mortality. Concerns relating to inappropriate discharge result in readmission with resultant lengthy hospital stays, high costs, and contribute to overcrowding and bed block (Amsterdam et al, J Am Coll Cardiol. 2002;40:251-256; Cardiol Clin. 2005;23:503-516; Furtado et al, Emerg Med. In press; Karlson, Am J Cardiol. 1991;68:171-175; Ng et al, Am J Cardiol. 2001;88:611-617; Ramakrishna et al, Mayo Clin Proc. 2005;80:322-329; Stowers, Crit Pathw Cardiol. 2003;2:88-94). The challenge of chest pain diagnosis has led to a number of associated problems within the health care system. The growing need for improvements in consistency of patient care, resource efficiency, and quality of patient healthcare has led to the development of chest pain pathways (Erhardt et al, Eur Heart J. 2002;23:1153-1176). The development and implementation of chest pain pathways is not without difficulties. These may arise from differences in the management approaches of health practitioners, poor adherence to guidelines, and concerns for costs. New procedures such as new cardiac injury markers, stress testing, and specialized chest pain units have led to a reduction in admission rates and length of stay, reduced costs, and a reduction of inappropriate discharge of patients with ischemic heart disease.

A predictive instrument using contrast echocardiography in patients presenting to the emergency department with chest pain and without ST-segment elevation

OBJECTIVE

Risk stratification of patients presenting to the emergency department (ED) with suspected cardiac chest pain (CP) and an undifferentiated electrocardiogram (ECG) is difficult. We hypothesized that in these patients a risk score incorporating clinical, ECG, and myocardial contrast echocardiography (MCE) variables would accurately predict adverse events occurring within the next 48 hours.

METHODS

Patients with CP lasting for 30 minutes or more who did not have ST-segment elevation on the ECG, were enrolled. Regional function (RF) and myocardial perfusion (MP) were assessed by MCE. A risk model was developed in the initial 1166 patients (cohort 1) and validated in subsequent 720 patients (cohort 2). Any abnormality or ST changes on ECG (odds ratio [OR] 2.5; 95% confidence interval [CI], 1.4-4.5, P = .002, and OR 2.9, 95% CI, 1.7-4.8, P < .001, respectively), abnormal RF with normal MP (OR 3.5, 95% CI, 1.8-6.5, P < .001), and abnormal RF with abnormal MP (OR 9.6, 95% CI, 5.8-16.0, P < .001) were found to be significant multivariate predictors of nonfatal myocardial infarction or cardiac death.

RESULTS

The estimate of the probability of concordance for the risk model was 0.82 for cohort 1 and 0.83 for cohort 2. The risk score in both cohorts stratified patients into 5 distinct risk groups with event rates ranging from 0.3% to 58%.

CONCLUSION

A simple predictive instrument has been developed from clinical, ECG, and MCE findings obtained at the bedside that can accurately predict events occurring within 48 hours in patients presenting to the ED with suspected cardiac CP and an ECG that is not diagnostic for acute ischemic injury. Its application could enhance care of patients with CP in the ED. For instance, patients with a risk score of 0 could be discharged from the ED without further workup. However, this needs to be validated in a multicenter study.

Current Trends in Diagnostic Biomarkers of Acute Coronary Syndrome

The diagnosis and management of patients with acute coronary syndrome (ACS) have evolved dramatically over the past decade. Biomarkers play an important role in the diagnosis of ACS, especially in unstable angina and non-ST-segment elevation myocardial infarction. Among these, cardiac troponin and creatine kinase appear to be the most sensitive and specific markers of myocardial injury. Recent studies have revealed several novel biomarkers. Elevated levels of C-reactive protein and interleukin-6 are strong independent markers of increased mortality among patients with ACS. However, the ideal biomarkers that offer early detection, risk stratification, selection of therapy, monitoring disease progression, and treatment efficacy remain to be elucidated. This review assesses limitations and contemporary needs for biomarkers in the context of diagnosis of ACS. It also discusses the newly developing technologies for novel biomarkers or novel biomarker protein signatures discovery, and importance of point-of-care testing for future management. Key words: Cardiac troponin, Creatine kinase, NSTEMI

Emergency physician high pretest probability for acute coronary syndrome correlates with adverse cardiovascular outcomes

OBJECTIVES

The value of unstructured physician estimate of risk for disease processes, other than acute coronary syndrome (ACS), has been demonstrated. The authors sought to evaluate the predictive value of unstructured physician estimate of risk for ACS in emergency department (ED) patients without obvious initial evidence of a cardiac event.

METHODS

This was a post hoc secondary analysis of the Internet Tracking Registry for Acute Coronary Syndromes (i*trACS), a prospectively collected multicenter data registry of patients over the age of 18 years presenting to the ED with symptoms of ACS between 1999 and 2001. In this registry, following patient history, physical exam, and electrocardiogram (ECG), the unstructured treating physician estimate of risk was recorded. A 30-day follow-up and a medical record review were used to determine rates of adverse cardiac events, death, myocardial infarction (MI), or revascularization procedure. The analysis included all patients with nondiagnostic ECG changes, normal initial biomarkers, and a non-MI initial impression from the registry and excluded those without complete data or who were lost to follow-up. Data were stratified by unstructured physician risk estimate: noncardiac, low risk, high risk, or unstable angina.

RESULTS

Of 15,608 unique patients in the registry, 10,145 met inclusion/exclusion criteria. Patients were defined as having unstable angina in 6.0% of cases; high risk, 23.5% of cases; low risk, 44.2%; and noncardiac, 26.3% of cases. Adverse cardiac event rates had an inverse relationship, decreasing from 22.0% (95% confidence interval [CI] = 18.8% to 25.6%) for unstable angina, 10.2% (95% CI = 9.0% to 11.5%) for those stratified as high risk, 2.2% (95% CI = 1.8% to 2.6%) for low risk, and to 1.8% (95% CI = 1.4% to 2.4%) for noncardiac. The relative risk (RR) of an adverse cardiac event for those with an initial label of unstable angina compared to those with a low-risk designation was 10.2 (95% CI = 8.0 to 13.0). The RR of an event for those with a high-risk initial impression compared to those with a low-risk initial impression was 4.7 (95% CI = 3.8 to 5.9). The risk of an event among those with a low-risk initial impression was the same as for those with a noncardiac initial impression (RR = 0.83, 95% CI = 0.6 to 1.2).

CONCLUSIONS

In ED patients without obvious initial evidence of a cardiac event, unstructured emergency physician (EP) estimate of risk correlates with adverse cardiac outcomes.

Transferring Images via the Wireless Messaging Network Using Camera Phones Shortens the Time Required to Diagnose Acute Coronary Syndrome

BACKGROUND

Clear images can be sent via e-mail using camera phones. We examined whether camera phones are useful to transmit electrocardiogram (ECG) images.

METHODS AND RESULTS

ECG images were taken of 20 patients suspected to have acute coronary syndrome. Ten images were sent to a cardiologist by fax. The other 10 images were transmitted using a camera phone. The total time elapsed between image transmission to diagnosis by cardiologists was shorter in the camera phone group than in the fax group.

CONCLUSIONS

ECG image transmission by camera phone can be efficiently used in the diagnosis of acute coronary syndrome.

The diagnostic accuracy of 64-slice computed tomography coronary angiography compared with stress nuclear imaging in emergency department low-risk chest pain patients

STUDY OBJECTIVE

We compared the accuracy of multidetector computed tomography (CT) coronary angiography with stress nuclear imaging for the detection of an acute coronary syndrome or 30-day major adverse cardiac events in low-risk chest pain patients.

METHODS

This was a prospective study of the diagnostic accuracy of myocardial perfusion imaging and multidetector CT in low-risk chest pain patients. The target condition was an acute coronary syndrome (confirmed >70% coronary stenosis on coronary artery catheterization) or major adverse cardiac events within 30 days. Patients were low risk by Reilly/Goldman criteria and had negative serial ECGs and cardiac markers. All had both rest/stress sestamibi nuclear imaging and multidetector CT. Patients with abnormal stress nuclear imaging results (reversible perfusion defects) or multidetector CT results (stenosis >50% or calcium score >400) were considered for cardiac catheterization, and those with discordant results had a greater than 30-day reevaluation (including ECG) by a cardiologist. All were followed up for evidence of major adverse cardiac events within 30 days by review of hospital records and structured telephone interview. Primary outcomes were the accuracy of multidetector CT and myocardial perfusion imaging for the detection of an acute coronary syndrome and 30-day major adverse cardiac events.

RESULTS

Of the 92 patients, 7 (8%) were excluded because of uninterpretable multidetector CT scans. Of the remaining 85 study patients (49+/-11 years, 53% men), 7 (8%) were found to have the target condition, with all having significant coronary stenosis (88%+/-9%) and none having myocardial infarction or major adverse cardiac events during 30 days. Stress nuclear imaging results were negative in 72 (85%) patients, and multidetector CT results were negative in 73 (86%) patients. The sensitivity of stress nuclear imaging was 71% (95% confidence interval [CI] 36% to 92%), and multidetector CT was 86% (95% CI 49% to 97%), and the specificity was 90% (95% CI 81% to 95%) and 92% (95% CI 84% to 96%), respectively. The negative predictive value of stress nuclear imaging and multidetector CT was 97% (95% CI 90% to 99%) and 99% (95% CI 93% to 100%), respectively, and the positive predictive value was 38% (95% CI 18% to 64%) and 50% (95% CI 25% to 75%), respectively.

CONCLUSION

The accuracy of multidetector CT is at least as good as that of stress nuclear imaging for the detection and exclusion of an acute coronary syndrome in low-risk chest pain patients.

Chest Pain: A Clinical Assessment

Chest pain is one of the most common presentations in emergency medicine. The initial evaluation should always consider life-threatening causes such as aortic dissection, pulmonary embolism, pneumothorax, pneumomediastinum, pericarditis, and esophageal perforation. Radiographic imaging is performed in tandem with the initial clinical assessment and stabilization of the patient. Radiologic findings are key to diagnosis and management of this entity.

Acute coronary syndromes in the emergency department: diagnostic characteristics, tests, and challenges

Failure to diagnose patients who have acute coronary syndromes (ACSs)-either acute myocardial infarction (AMI) or unstable angina pectoris (UAP)-who present to the emergency department (ED) remains a serious public health issue. Better understanding of the pathophysiology of coronary artery disease has allowed the adoption of a unifying hypothesis for the cause of ACSs: the conversion of a stable atherosclerotic lesion to a plaque rupture with thrombosis. Thus, physicians have come to appreciate UAP and AMI as parts of a continuum of ACSs. This article reviews the state of the art regarding the diagnosis of ACSs in the emergency setting and suggests reasons why missed diagnosis continues to occur, albeit infrequently.

Exercise testing in chest pain units: rationale, implementation, and results

Chest pain units are now established centers for assessment of low-risk patients presenting to the emergency department with symptoms suggestive of acute coronary syndrome. Accelerated diagnostic protocols, of which treadmill testing is a key component, have been developed within these units for efficient evaluation of these patients. Studies of the last decade have established the utility of early exercise testing,which has been safe, accurate, and cost-effective in this setting. Specific diagnostic protocols vary, but most require 6 to 12 hours of observation by serial electrocardiography and cardiac injury markers to exclude infarction and high-risk unstable angina before proceeding to exercise testing. However, in the chest pain unit at UC Davis Medical Center,the approach includes "immediate" treadmill testing without a traditional process to rule out myocardial infarction. Extensive experience has validated this approach in a large, heterogeneous population. The optimal strategy for evaluating low-risk patients presenting to the emergency department with chest pain will continue to evolve based on current research and the development of new methods.

Medical Error Prevention in ED Triage for ACS: Use of Cardiac Care Decision Support and Quality Improvement Feedback

Medical errors in the care of patients who present with acute coronary syndrome (ACS)include errors in emergency department (ED) triage, such as the decision to send home a patient who presents with ACS or to hospitalize a patient who does not have ACS to the cardiac care unit (CCU), and errors in treatment, such as the failure to promptly use reperfusion therapy for patients who present with ST-elevation acute myocardial infarction(AMI). ECG-based acute cardiac ischemia time-insensitive predictive instrument(ACI-TIPI) and thrombolytic predictive instruments (TPIs), with a linked TIPI information system (TIPI-IS), provide real-time, concurrent, and retrospective decision support tools and feedback for the prevention of medical errors in the care of patients who present with ACS. In real-time, ACI-TIPI probabilities printed on the ECG header for the ED physician, provide an additional piece of information for triage decision making, and the ACI-TIPI Risk Management form reduces liability risk by prompting consideration and documentation of key clinical factors in the diagnosis of ACI. Also in real-time, the TPI increases overall coronary reperfusion therapy use. Concurrent flagging by TIPI-IS uses electronically acquired ECG and hospital data to provide concurrent alerts about potential misdiagnosis or mis-triage of patients with ACS. Retrospectively TIPI-IS-based feedback reports allow performance improvement. These examples of information technology tools integrated into ECG equipment already used in hospitals to deliver patient care demonstrate the potential to adapt other existing equipment or other patient care activities to enhance patient safety and error reduction.

Prehospital triage of acute myocardial infarction: wireless transmission of electrocardiograms to the on-call cardiologist via a handheld computer

BACKGROUND

Use of intravenous fibrinolytic agents and percutaneous coronary interventions produce the greatest benefit when they are implemented in the first 2 hours after symptom onset. Further delays in the time to treatment typically lead to reduced benefits and poorer outcomes.

METHODS

Cabarrus County Emergency Medical Service personnel complete an acute myocardial infarction case report form and assess a 12-lead electrocardiogram (ECG) to determine if ST elevation of at least 1 mV in at least 2 contiguous leads is present and then to transmit the ECG wirelessly to the emergency department (ED). The ECG is then forwarded wirelessly from the ED to the on-call cardiologist who is carrying the IPAQ handheld computer.

RESULTS

Five representative patients managed using this system during the initial year of its implementation are presented.

CONCLUSION

The examples included in this article illustrate that the system and technology can work if applied in a coordinated fashion using multiple disciplines including emergency medical service, cardiologists, ED personnel, and the hospital cardiac care team, which includes the catheterization laboratory call team, acute coronary care nurses, and clerical support staff.

Myocardial Contrast Echocardiography Versus Thrombolysis in Myocardial Infarction Score in Patients Presenting to the Emergency Department With Chest Pain and a Nondiagnostic Electrocardiogram

OBJECTIVES

We hypothesized that regional function (RF) and myocardial perfusion (MP) are superior to the Thrombolysis In Myocardial Infarction (TIMI) score for diagnosis and prognostication in patients presenting to the emergency department (ED) with chest pain (CP) and a nondiagnostic electrocardiogram.

BACKGROUND

Rapid diagnosis and prognostication is difficult in patients presenting to the ED with suspected cardiac CP.

METHODS

Contrast echocardiography was performed to assess RF and MP on 957 patients presenting to the ED with suspected cardiac CP and a nondiagnostic electrocardiogram. A modified TIMI (mTIMI) score was calculated from six immediately available variables. A full TIMI score also was derived after troponin levels were able to be accessed adequately. Follow-up was performed for early (within 24 h), intermediate (30 day), and late primary (death and myocardial infarction) or secondary (unstable angina and revascularization) events.

RESULTS

The mTIMI score was unable to discriminate between intermediate- compared to high-risk patients at any follow-up time point, whereas only 2 of 523 patients with normal RF had an early primary event. Regional function provided incremental prognostic value over mTIMI scores for predicting intermediate and late events. In patients with abnormal RF, MP further classified patients into intermediate- and high-risk groups. The full TIMI score could not improve upon these results at any follow-up time point.

CONCLUSIONS

Contrast echocardiography can rapidly and accurately provide short-, intermediate-, and long-term prognostic information in patients presenting to the ED with suspected cardiac CP even before serum cardiac markers are known. Integrating contrast echocardiography into the ED evaluation of CP may improve the risk stratification of such patients.

Acute resting myocardial perfusion imaging in patients with diabetes mellitus: results from the Emergency Room Assessment of Sestamibi for Evaluation of Chest Pain (ERASE Chest Pain) trial

BACKGROUND

Resting myocardial perfusion imaging (MPI) improves the triage of patients presenting to the emergency department (ED) with symptoms suggestive of acute cardiac ischemia (ACI). In the ED setting the presence of diabetes mellitus (DM) is a predictor of ACI and hospitalization, but the role of resting MPI in patients with DM is unknown.

METHODS AND RESULTS

A secondary data analysis of a prospective, multicenter, randomized, controlled trial of ED evaluation strategies in patients with symptoms suggestive of ACI and normal or nondiagnostic electrocardiograms was performed. In the main trial 2475 patients were randomized to receive either the usual ED evaluation strategy (n = 1260) or the usual strategy supplemented by results from resting MPI by use of single photon emission computed tomography (SPECT) technetium 99m sestamibi (n = 1215). Patients with diabetes (n = 341) were evaluated separately. Imaging results, final diagnoses, effect on triage, and prognostic value of the SPECT imaging were compared between diabetic and nondiabetic patients. Of the 341 patients with diabetes, 153 (45%) were randomized to the imaging strategy. Patients with DM had higher rates of hospitalization (66% vs 49.6%, P = .0001) and ACI (21.1% vs 12.0%, P < .001) than patients without DM. Among diabetic patients without ACI, the admission rate was 63% in the usual strategy group versus 54% in the imaging strategy group (relative risk [RR] = 0.91 [95% CI, 0.76-1.06]; P = .24). There was no difference in the magnitude of this reduced risk of admission compared with patients without DM (RR = 0.84 [95% CI, 0.77-0.92]; P = .0002 for patients without DM and P = .35 for interaction of diabetes and RR reduction).

CONCLUSIONS

Acute resting MPI with Tc-99m sestamibi is associated with improved triage decision making in symptomatic ED patients with diabetes.

Improvement in clinical outcomes in acute coronary syndromes after the implementation of a critical pathway

Although several advances have been made in the management of acute coronary syndromes, the adoption of such measures in clinical practice has been suboptimal. The implementation of critical pathways has been suggested as a strategy to improve clinical effectiveness, although its effect is still to be demonstrated. The objective was to evaluate the impact of a critical pathway on the process of care of patients admitted with acute coronary syndromes in a teaching hospital. In a prospective cohort study, patients 30 years or older admitted to the emergency department with suspected acute coronary syndromes were evaluated. Primary outcomes were major cardiovascular events, percutaneous coronary intervention, and in-hospital mortality during 1 semester before and 4 semesters after implementation of the pathway. Multivariate logistic regression analysis was used to adjust for differences between the periods studied and to identify predictors of poor prognosis. Of the 1003 patients evaluated, 150 (15%) had myocardial infarction, and 240 (24%) had unstable angina. There was no difference in clinical characteristics and risk assessment in the periods evaluated. Overall, the quality of care improved after the pathway, with a significant decrease in complication and mortality rates in the last 2 years. In multivariate analysis, patients admitted in the last semester showed fewer major cardiovascular events (odds ratio = 0.74; P = 0.02) and more percutaneous coronary intervention (odds ratio = 1.3; P = 0.03). The implementation of a critical pathway may have a positive impact on the quality of care of patients with acute coronary syndromes. Further studies are needed to evaluate better this and other initiatives aimed at maximizing clinical effectiveness.

Evaluation of patients with suspected acute coronary syndromes in the emergency department

Patients complaining of chest pain (CP) who visit the emergency department (ED) represent the second cause of consultation in this department, and 20-30% of hospital admissions for medical reasons. These patients form a somewhat heterogeneous group with many different aetiologies and degrees of severity. In this setting, the clinical objectives include the prompt identification of patients with acute coronary syndromes (ACSs), the prompt evaluation of the immediate risk (i.e., initial risk stratification) of cardiovascular complications in order to tailor the treatment for each individual patient and to make the best use of hospital resources, and the prompt identification of patients with other potentially severe diseases. The diagnosis of ACS in patients coming to the ED for CP or any equivalent angina is one of the most difficult diagnostic challenges facing physicians in the ED. The correct diagnosis and risk stratification of these patients has clinical consequences, as well as very important legal and economic implications. The only methodology with a clear clinical impact on diagnosis, risk stratification and initial management is clinical evaluation based on data obtained by questioning the patient, carrying out a physical examination, and interpreting the results of a standard 12-lead electrocardiogram (ECG). Nevertheless, its combined diagnostic efficiency for ACS is imperfect and additional strategies are emerging which include serial ECG, the detection of serum biochemical markers of myocardial necrosis, exercise testing, and radionuclide myocardial perfusion imaging.

Diagnosis of acute cardiac ischemia

A better understanding of coronary syndromes allow physicians to appreciate UAP and AMI as part of a continuum of ACI. ACI is a life-threatening condition whose identification can have major economic and therapeutic importance as far as threatening dysrhythmias and preventing or limiting myocardial infarction size. The identification of ACI continues to challenge the skill of even experienced clinicians, yet physicians continue (appropriately) to admit the overwhelming majority of patients with ACI; in the process, they admit many patients without acute ischemia [2], overestimating the likelihood of ischemia in low-risk patients because of magnified concern for this diagnosis for prognostic and therapeutic reasons. Studies of admitting practices from a decade ago have yielded useful clinical information but have shown that neither clinical symptoms nor the ECG could reliably distinguish most patients with ACI from those with other conditions. Most studies have evaluated the accuracy of various technologies for diagnosing ACI, yet only a few have evaluated the clinical impact of routine use. The prehospital 12-lead ECG has moderate sensitivity and specificity for the diagnosis of ACI. It has demonstrated a reduction of the mean time to thrombolysis by 33 minutes and short-term overall mortality in randomized trials. In the general ED setting, only the ACI-TIPI has demonstrated, in a large-scale multicenter clinical trial, a reduction in unnecessary hospitalizations without decreasing the rate of appropriate admission for patients with ACI. The Goldman chest pain protocol has good sensitivity for AMI but was not shown to result in any differences in hospitalization rate, length of stay, or estimated costs in the single clinical impact study performed. The protocol's applicability to patients with UAP has not been evaluated. Single measurement of biomarkers at presentation to the ED has poor sensitivity for AMI, although most biomarkers have high specificity. Serial measurements can greatly increase the sensitivity for AMI while maintaining their excellent specificity. Biomarkers cannot identify most patients with UAP. Finally, diagnostic technologies to evaluate ACI in selected populations, such as echocardiography, sestamibi perfusion imaging, and stress ECG, may have very good to excellent sensitivity; however, they have not been sufficiently studied.

[Chest pain in clinical practice: impact of routine troponin determination on clinical manifestations and care]

INTRODUCTION AND OBJECTIVES. To study the significance of chest pain in the clinical practice of a Spanish hospital and to evaluate the impact of routine troponin determination.

METHODS

In our institution, routine serial measurements of troponins I and T were made in the evaluation of chest pain in 2000. We compared the results obtained in 1999 for all patients who visited the emergency room for chest pain and the patients who were hospitalized. We recorded the diagnosis at discharge, duration of the hospital stay, and associated costs.

RESULTS

In 2000, 1,820 patients with chest pain visited the emergency department, which was equivalent to 1.9% of visits and 7.5 cases per 1,000 people and year: 43% of these patients were hospitalized for suspected acute coronary syndrome as compared to 49% in 1999 (-12%; p > 0.001). Among the patients admitted, 28% were discharged with a diagnosis of non-ischemic chest pain. Troponin determinations were associated with a lower probability of admission due to unstable angina (11.5 vs 16.0%; -28%; p < 0.001) and non-ischemic chest pain (12.1 vs 14.5%; -16%; p < 0.05), and an increase in diagnoses of non-Q wave acute myocardial infarction (3.4% vs 1.8%; +89%; p < 0.01). Non-ST elevation acute coronary syndrome ACS required 3,751 days of hospitalization and 1,003,420 euros of cost, and troponin determinations were associated with a reduction in hospital stays of 832 days (-18.2%) and 185,100 euros (-15.6%).

CONCLUSION

Chest pain had a high incidence, 7.5, and generates high costs in hospital admissions. The routine use of serial troponin determinations was associated with a reduction in hospital admissions due to unstable angina and non-ischemic chest pain, and costs.

Triage of patients with chest pain in the emergency department: a comparative study of physicians' decisions

PURPOSE

Little is known about physicians' triage decisions for patients with chest pain in the emergency department. We sought to understand better the variability and accuracy of physicians' triage decisions.

SUBJECTS AND METHODS

We used 20 simulated cases to compare triage decisions by 147 physicians (46 emergency medicine, 87 internal medicine, and 14 cardiology physicians) with triage decisions recommended by a previously validated prediction rule. We calculated triage sensitivity and specificity using the prediction rule to estimate the likelihood that each of the simulated patients would suffer a major complication. Triage sensitivity was defined as the proportion of all patients expected to have major complications who were triaged to the coronary care or inpatient telemetry unit.

RESULTS

Triage specificity was defined as the proportion of all patients without complications who were triaged to sites other than the coronary care or inpatient telemetry unit.Physicians' triage decisions were less sensitive (85% vs. 96%, P <0.001) and less specific (38% vs. 41%, P = 0.02) than decisions recommended by the prediction rule. Physicians overestimated patients' risk of complications and triaged more patients to inpatient monitored beds. Despite their preference for inpatient monitored beds, physicians' decisions would have resulted in four times as many major complications in patients who were not triaged to inpatient monitored beds, compared with decisions recommended by the prediction rule (2.4% vs. 0.6%, P <0.001). Although physicians' decisions were best explained by their provisional diagnoses, interphysician agreement about triage decisions (kappa = 0.34) and diagnosis (kappa = 0.31) was only fair.

CONCLUSIONS

In simulated cases, physicians' triage decisions varied widely and their predictions of patient outcomes differed markedly from that of the validated prediction rule, suggesting that use of the prediction rule in the emergency department could improve physicians' decisions and patients' outcomes.

It is safe to manage selected patients with acute coronary syndromes in unmonitored beds

This prospective, observational study evaluated the safety of the Western Hospital admission protocol for patients with suspected acute coronary syndromes. The study included all patients admitted from the Emergency Department with an admission diagnosis of unstable angina, post infarct angina, atypical chest pain, or chest pain for evaluation. Data collected included demographic data, admission diagnosis, location of admission (bed with or without cardiac monitoring), past medical history and presenting chest pain history to determine Agency for Health Care Policy (AHCPR) and Western Hospital (WH) protocol classifications, cardiac enzyme assays, electrocardiogram analysis, adverse outcomes [death, myocardial infarction (MI), dysrhythmia, acute pulmonary edema, recurrent pain], diagnosis at hospital discharge, and length of stay-(LOS). There were 508 patients with a mean age of 63.7 years enrolled in the study. Three hundred nineteen (62.8%) were admitted to beds without any cardiac monitoring. There was one unexpected death in the unmonitored group, an 85 year-old patient who suffered a presumed dysrhythmia and whom the treating physician had decided was not for resuscitation. Twelve patients suffered nonfatal MI, and none suffered pulmonary edema. All MI patients made an uneventful recovery, and none required thrombolysis. If all patients had been admitted to an area of care based on AHCPR guidelines, an additional 310 admissions to monitored beds would have been required. The results of this study suggest that selected patients with suspected acute coronary syndromes can be safely managed in beds without continuous cardiac monitoring.

[Chest pain units: state of the art of the management of patients with chest pain in the emergency department]

Chest pain is one of the most common reasons for patients coming to emergency departments. Most of these individuals end up being hospitalized due to uncertainty of the cause of their complaint. This aggressive and defensive attitude is taken by emergency physicians because some 10 to 30% of these patients actually have acute coronary syndrome. As the admission electrocardiogram and serum CK-MB level have a sensitivity of about 50% for the diagnosis of acute myocardial infarction, serial evaluation is mandatory for non-low risk patients. Inspite of this knowledge, an average of 2-3% of patients with acute myocardial infarction are erroneously released from emergency departments, what is responsible for expensive malpractice suits in the United States. Chest Pain Units were introduced in emergency practice two decades ago to improve medical care quality, reduce inappropriate hospital discharges, reduce unnecessary hospital admissions and reduce medical costs, thus making patient's assessment cost-effective. This is achieved mostly with the use of systematic diagnostic protocols by qualified and trained personnel in the emergency department setting and not in the coronary care unit.

Exercise testing in special situations: ER, preoperative and disability evaluation

In a number of medical centers, exercise testing has proven to be a safe and useful tool in the evaluation of patients presenting chest pain in an emergency room. At these centers, after a period of observation without evidence of acute myocardial infarction, exercise testing is done. If the exercise test result is normal, the patient is discharged from the emergency room, without being admitted to the hospital. Exercise testing is a well-accepted noninvasive method to evaluate at-risk patients being considered for elective noncardiac surgery. Exercise testing is frequently used to determine functional capacity during disability assessment.

Identification of chest pain patients appropriate for an emergency department observation unit

There are no perfect tests or algorithms to exclude ACI. Because acute coronary occlusion often occurs in patients with low-grade coronary stenosis, the diagnostic goal of a chest pain diagnostic protocol is not to identify patients with CAD, but rather to identify patients who may be safely discharged home without the development of complications such as MI, unstable angina, death, shock, or CHF over the next 1 to 6 months. There is an advantage to evaluating patients at the time of their symptoms. Patients who have a small plaque that is ruptured, leading to intracoronary thrombosis and ischemia, will manifest ischemia on diagnostic testing that could missed in routine outpatient testing when their plaque were stable. The diagnosis and risk stratification of acute coronary ischemia in the ED depends on a careful history and interpretation of the ECG. Multiple regression models using readily available data (e.g., history, physical examination, and ECG) provide the best tools for risk stratification. If one is deciding how to select patients for an EDOU chest pain evaluation, diagnostic tools that have previously been tested and validated in this setting are preferable. These include the Multicenter Chest Pain Study derived tools (i.e., Goldman, Lee), the ACI and ACI-TIPI tools, and sestamibi risk stratification tools. This is not to say that other tools may not play a role at individual institutions. It is probably better to select a consistent approach and evaluate its performance, rather than to allow random variation to dictate practice. The future direction probably will involve standardization of the ED chest pain population. This allows outcome and cost-effectiveness comparative research of various strategies for patients with normal or nondiagnostic ECGs and normal biomarkers. Although this approach allows more precise stratification, the risk will never be zero, meaning that there will never be a substitute for good clinical judgment and close follow-up care.

Safe discharge from the cardiac emergency room with a rapid rule-out myocardial infarction protocol using serial CK-MB(mass)

OBJECTIVE

To determine whether a new protocol, using a rapid and sensitive CK-MB(mass) assay and serial sampling, can rule out myocardial infarction in patients with chest pain and decrease their length of stay in the cardiac emergency room without increasing risk.

DESIGN

The combined incidence of cardiac death and acute myocardial infarction at 30 days, six months, and 24 months of follow up were compared between patients discharged home from the cardiac emergency room after ruling out myocardial infarction with a CK-MB(activity) assay in 1994 and those discharged home after a rapid CK-MB(mass) assay in 1996.

SETTING

Cardiac emergency room of a large university hospital.

PATIENTS

In 1994 and 1996, 230 and 423 chest pain patients, respectively, were discharged home from the cardiac emergency room with a normal CK-MB and an uneventful observation period.

RESULTS

The median length of stay in the cardiac emergency room was significantly reduced, from 16.0 hours in 1994 to 9.0 hours in 1996 (p < 0.0001). Mean event rates in patients from the 1994 and 1996 cohorts, respectively, were 0.9% (95% confidence interval (CI) -0.3% to 2.1%) v 0.7% (95% CI -0.1% to 1. 5%) at 30 days, 3.0% (95% CI 0.8% to 5.2%) v 2.8% (95% CI 1.2% to 4. 4%) at six months, and 7.0% (95% CI 3.7% to 10.3%) v 5.7% (95% CI 3. 5% to 7.9%) at 24 months. Kaplan-Meier survival analysis showed no difference in mean event-free survival at 30 days, six months, and 24 months of follow up.

CONCLUSIONS

Using a rule-out myocardial infarction protocol with a rapid and sensitive CK-MB(mass) assay and serial sampling, the length of stay of patients with chest pain in the cardiac emergency room can be reduced without compromising safety.

Validated risk stratification model accurately predicts low risk in patients with unstable angina

BACKGROUND

In the mid 1990s, two unstable angina risk prediction models were proposed but neither has been validated on separate population or compared.

OBJECTIVES

The purpose of this study was to compare patient outcome among high, medium and low risk unstable angina patients defined by the Agency for Health Care Policy and Research (AHCPR) guideline to similar risk groups defined by a validated model from our institution (RUSH).

METHODS

Four hundred sixteen patients consecutively admitted to the hospital with unstable angina between January 1, 1995, and December 31, 1997, were prospectively evaluated for risk factors. The presence of major adverse events such as myocardial infarction (MI), death and heart failure was assessed for each patient by chart review.

RESULTS

The composite end point of heart failure, MI or death occurred in 3% and 5% of the RUSH and AHCPR low risk categories, respectively, and in 8% and 10% of AHCPR and RUSH high risk categories, respectively. Recurrent ischemic events were best predicted by the RUSH model (high: 24% vs. medium: 12% and low: 10%, p = 0.029), but not by the AHCPR model (high: 14% vs. medium: 13% and low: 9%, p = 0.876). The RUSH model identified five times more low risk patients than the AHCPR model.

CONCLUSIONS

Both models identify patients with low and high event rates of MI, death or heart failure. However, the RUSH model allowed for five times more patients to be candidates for outpatient evaluation (low risk) with a similar observed event rate to the AHCPR model; also, the RUSH model more successfully predicted ischemic complications. We conclude that the RUSH model can be used clinically to identify patients for early noninvasive evaluation, thereby improving cost effectiveness of care.

Provocative testing for chest pain

Since the first Chest Pain Center (CPC) was set up in 1981 to speed up the evaluation and treatment of patients with acute myocardial infarction, the original concept has been expanded to include rapid evaluation of chest pain patients with the appropriate streamlining of care and incorporation of the latest in technology. It has also been established that among patients presenting with acute chest pain, a very low-risk group with less than 5% probability of a coronary event can be identified. The recognition of this group could prevent unnecessary admissions, affording more appropriate patient care and improved cost-effectiveness. The efficient management of these chest pain patients requires that there be reductions in: (1) delays in therapy, (2) "soft" admissions, (3) inappropriate dispositions, and (4) cost. With time, provocative testing (PT) for chest pain patients has been brought forward to the frontline. PT methods are now being studied in hundreds of emergency department (ED) patients, followed up over several months to ascertain the predictive value of both positive and negative test results. More and more CPCs are now using PT as part of their management protocol, in terms of decision-making pertaining to prognostification, treatment and disposition. This could be in the form of the ECG graded exercise test (GXT), stress echocardiography (SE) and stress single-photon emission computed tomography (SPECT) radionuclide perfusion imaging. The GXT is fairly widely used currently, SE is gaining popularity and stress radionuclide perfusion imaging will perhaps gain more acceptance as the experience with its use as well as the number of randomized controlled studies increase. As we move into the new millennium, the emergency physicians must familiarize themselves with the latest in the state-of-the-art concepts and technology to render improved, up-to-date and more cost-effective patient care.

Glycoprotein IIb/IIIa receptor inhibitor use in unstable angina/non-ST-segment elevation myocardial infarction: an appropriate-use model for the emergency department

The introduction of new platelet glycoprotein (GP) IIb/IIIa receptor inhibitors has the potential to revolutionize the treatment of certain patients with unstable angina and non-ST-segment elevation myocardial infarction (MI). Treatment with these potent platelet inhibitors has been shown to improve patient outcomes prior to percutaneous intervention (PCI), following PCI, and even in the absence of PCI. In addition, there are data from clinical studies that support a time-dependence to the beneficial effects of platelet inhibitor therapy. Patients who are treated early-for example, in the emergency department (ED)-appear to have improved outcomes over those treated later. Platelet inhibitors have been used extensively in the cardiac catheterization laboratory and in the coronary care unit (CCU). In many institutions, however, their introduction and uptake in the ED has been slow. These agents are relatively expensive and have the potential to cause major bleeding complications. This review will examine the pathophysiology of acute coronary syndromes (ACS) as it relates to the mechanism of action of GPIIb/IIIa inhibitors. The available GPIIb/IIIa inhibitors will be discussed including their indications, contraindications, doses, and mechanisms of action. Data from clinical studies supporting the use of GPIIb/IIIa inhibitors will be illustrated in the context of their applications in the ED. Finally, an algorithm for GPIIb/IIIa inhibitors in the ED will be presented.

The added diagnostic value of automated QT-dispersion measurements and automated ST-segment deviations in the electrocardiographic diagnosis of acute cardiac ischemia

The purpose of this study was to determine the added value of automated QT dispersion and ST-segment measurements to physician interpretation of 12-lead electrocardiograms (ECGs) in patients with chest pain. To date, poor reproducibility of manual measurements and lack of shown added value have limited the clinical use of QT dispersion. Twelve-lead ECGs (n = 1,161) from the Milwaukee Prehospital Chest Pain Database were independently classified by 2 physicians into 3 groups (acute myocardial infarction (AMI), acute cardiac ischemia (ACI), or nonischemic), and their consensus was obtained. QT-end and QT-peak dispersions were measured by a computerized system. The computer also identified ST-segment deviations. Sensitivity, specificity, and positive predictive values (PPVs) and negative predictive values (NPV) for AMI and ACI were evaluated independently and in combinations. For AMI, physicians' consensus classification was remarkably good (sensitivity, 48%, specificity, 99%). Independent classification by QT-end and QT-peak dispersions or ST deviations was not superior to the physicians' consensus. Optimal classification occurred by combining automated QT-end dispersion and ST deviations with physicians' consensus. This combination increased sensitivity for the diagnoses of AMI by 35% (65% vs 48%, P < .001) and ACI by 55% (62% vs 40%, P < .001) compared with physicians' consensus, while maintaining comparable specificity. This study supports a potential clinical role for automated QT dispersion when combined with other diagnostic methods for detecting AMI and ACI.

Missed diagnoses of acute cardiac ischemia in the emergency department

BACKGROUND

Discharging patients with acute myocardial infarction or unstable angina from the emergency department because of missed diagnoses can have dire consequences. We studied the incidence of, factors related to, and clinical outcomes of failure to hospitalize patients with acute cardiac ischemia.

METHODS

We analyzed clinical data from a multicenter, prospective clinical trial of all patients with chest pain or other symptoms suggesting acute cardiac ischemia who presented to the emergency departments of 10 U.S. hospitals.

RESULTS

Of 10,689 patients, 17 percent ultimately met the criteria for acute cardiac ischemia (8 percent had acute myocardial infarction and 9 percent had unstable angina), 6 percent had stable angina, 21 percent had other cardiac problems, and 55 percent had noncardiac problems. Among the 889 patients with acute myocardial infarction, 19 (2.1 percent) were mistakenly discharged from the emergency department (95 percent confidence interval, 1.1 to 3.1 percent); among the 966 patients with unstable angina, 22 (2.3 percent) were mistakenly discharged (95 percent confidence interval, 1.3 to 3.2 percent). Multivariable analysis showed that patients who presented to the emergency department with acute cardiac ischemia were more likely not to be hospitalized if they were women less than 55 years old (odds ratio for discharge, 6.7; 95 percent confidence interval, 1.4 to 32.5), were nonwhite (odds ratio, 2.2; 1.1 to 4.3), reported shortness of breath as their chief symptom (odds ratio, 2.7; 1.1 to 6.5), or had a normal or nondiagnostic electrocardiogram (odds ratio, 3.3; 1.7 to 6.3). Patients with acute infarction were more likely not to be hospitalized if they were nonwhite (odds ratio for discharge, 4.5; 95 percent confidence interval, 1.8 to 11.8) or had a normal or nondiagnostic electrocardiogram (odds ratio, 7.7; 95 percent confidence interval, 2.9 to 20.2). For the patients with acute infarction, the risk-adjusted mortality ratio for those who were not hospitalized, as compared with those who were, was 1.9 (95 percent confidence interval, 0.7 to 5.2), and for the patients with unstable angina, it was 1.7 (95 percent confidence interval, 0.2 to 17.0).

CONCLUSIONS

The percentage of patients who present to the emergency department with acute myocardial infarction or unstable angina who are not hospitalized is low, but the discharge of such patients is associated with increased mortality. Failure to hospitalize is related to race, sex, and the absence of typical features of cardiac ischemia. Continued efforts to reduce the number of missed diagnoses are warranted.

An economic analysis of an aggressive diagnostic strategy with single photon emission computed tomography myocardial perfusion imaging and early exercise stress testing in emergency department patients who present with chest pain but nondiagnostic electrocardiograms: results from a randomized trial

STUDY OBJECTIVE

Conventional emergency department testing strategies for patients with chest pain often do not provide unequivocal diagnosis of acute coronary syndromes. This study was conducted to determine whether the routine use of single photon emission computed tomography (SPECT) imaging at rest and early exercise stress testing to assess intermediate-risk patients with chest pain and no ECG evidence of acute ischemia will lead to earlier discharges, more discriminate use of coronary angiography, and an overall reduction in average costs of care with no adverse clinical outcomes.

METHODS

All patients in this study had technetium 99m tetrofosmin SPECT imaging at rest and were randomly assigned to either a conventional (results of the imaging test blinded to the physician) or perfusion imaging-guided (results of the imaging test unblinded to the physician) strategy. Patients in the conventional arm were treated at their physician's discretion. Patients in the perfusion imaging-guided arm were treated according to a predefined protocol based on SPECT imaging test results: coronary angiography after a positive scan result and exercise treadmill testing after a negative scan result. Study endpoints consisted of total in-hospital costs and length of stay. Hospital costs were calculated using hospital department-specific Medicare cost/charge ratios. Length of stay was calculated as total hospital room days billed (regular and intensive care).

RESULTS

We enrolled 46 patients, 9 with acute myocardial infarctions. Patients randomly assigned to the perfusion imaging-guided arm had $1,843 (95% confidence interval [CI] $431 to $6,171) lower median in-hospital costs and 2.0-day (95% CI 1.0 to 3.0 days) shorter median lengths of stay but similar rates of in-hospital and 30-day follow up events as patients in the conventional arm.

CONCLUSION

An ED chest pain diagnostic strategy incorporating acute resting (99m)Tc tetrofosmin SPECT imaging and early exercise stress testing may lead to reduced in-hospital costs and decreased length of stay for patients with acute chest pain and nondiagnostic ECGs.