Early prediction of acute myocardial infarction from clinical history, examination and electrocardiogram in the emergency room

Intervention in the timeliness of two ECG types for emergency department patients with chest pain: randomized controlled trial (Preprint)

Background

In the emergency department (ED), the result obtained using the 12-lead electrocardiography (ECG) is the basis for diagnosing and treating patients with chest pain. It was found that performing ECG at the appropriate time could improve treatment outcomes. Hence, a wearable ECG device with a timer can ensure that the findings are continuously recorded.

Objective

We aimed to compare the time accuracy of a single-patch 12-lead ECG (SP-ECG) with that of conventional ECG (C-ECG). We hypothesized that SP-ECG would result in better time accuracy.

Methods

Adult patients who visited the emergency room with chest pain but were not in shock were randomly assigned to one of the following 2 groups: the SP-ECG group or the C-ECG group. The final analysis included 33 (92%) of the 36 patients recruited. The primary outcome was the comparison of the time taken by the 2 groups to record the ECG. The average ages of the participants in the SP-ECG and C-ECG groups were 63.7 (SD 18.4) and 58.1 (SD 12.4) years, respectively.

Results

With a power of 0.95 and effect sizes of 0.05 and 1.36, the minimum number of samples was calculated. The minimum sample size for each SP-ECG and C-ECG group is 15.36 participants, assuming a 20% dropout rate. As a result, 36 patients with chest pain participated, and 33 of them were analyzed. The timeliness of SP-ECG and C-ECG for the first follow-up ECG was 87.5% and 47.0%, respectively (P=.74). It was 75.0% and 35.2% at the second follow-up, respectively (P=.71).

Conclusions

Continuous ECG monitoring with minimal interference from other examinations is feasible and essential in complex ED situations. However, the precision of SP-ECG has not yet been proved. Nevertheless, the application of SP-ECG is expected to improve overcrowding and human resource shortages in EDs, though more research is needed.

Trial Registration

ClinicalTrials.gov NCT04114760; https://clinicaltrials.gov/ct2/show/NCT04114760

The Feasibility of Arrhythmias Detection from A Capacitive ECG Measurement Using Convolutional Neural Network

Capacitive ECG (cECG) can measure the cardiac electrical signal via capacitive coupling between electrodes and skin. This unconstrained measurement is suitable for personal heart monitoring; however, the instability in the quality of the signal hinders a further use of the signal. To use the cECG for heart monitoring, an adapted framework that could automatically classify the signal into clear cECG, arrhythmias and noise signal is a prerequisite. In view of this problem, the conventional quality estimation method using predefined features based on R-peak detection is not suitable for this unconstrained measurement of cECG. In this study, we examine the feasibility of arrhythmias detection from the cECG measurement using a convolutional neural network (CNN) model. The malignant ventricular tachycardia (VT) and ventricular fibrillation (VF) do not have the Q-R-S waveforms and therefore may be easily classified as the noise. Hence, in this study, we used the cECG signals that have 3 classes in quality (C1: clear signal; C2: blurry signal with significant R peak and N: noise) and the arrhythmias signals (VT, VF, and atrial fibrillation) from open databases to train the classification model. 13 subjects were recruited in an experiment for the cECG data collection in the Nara Institute of Science and Technology. As a result, the CNN model could recognize C1 and AF signal with over 0.98 recalls and precisions; whereas the recall and precision of VT and VF are lower scores and the lower scores were caused mainly by the similarity between VT and VF. Given the results of the CNN model, this CNN-based framework can accurately label the C1, AF, and malignant ventricular arrhythmias (VT and VF) signals. Further stratification of the C2, VT, and VF will further enhance the use of the cECG measurement.

The low accuracy of the non-ST-elevation myocardial infarction electrocardiograph criteria of the fourth universal definition of myocardial infarction

Background:

The electrocardiograph has been integral to the diagnosis of acute coronary syndromes since the mid-20th Century and is an important initial investigation that chest pain patients undergo on presentation to the Emergency Department. The Fourth Universal Definition of Myocardial Infarction recommends using dichotomous cut-offs to identify ischaemic electrocardiographs.

Objectives:

We aimed to summarise the existing knowledge to inform emergency clinicians about the diagnostic accuracy of the new guidelines.

Methods:

We performed a systematic review and a narrative analysis due to the heterogeneity of the studies.

Results:

We were able to obtain diagnostic characteristics for 10 papers. The ST-depression criteria were highly specific but poorly sensitive in five papers, with a specificity of 97.2%–99.3% and a sensitivity of 16.6%–20.0%. The remaining papers reported a higher sensitivity of 25.7%–58.6% but a lower specificity of 86.0%–91.2%. T wave inversion demonstrated poor specificity; the papers that looked at 0.1 mV T wave inversion demonstrated a sensitivity of 26.9%–46.8% and a specificity of 68.6%–86.4%.

Conclusion:

The heterogeneous evidence database demonstrates that the Fourth universal definition’s diagnostic performance varies wildly. Apart from two outlying papers, ST-depression has suboptimal sensitivity but high specificity. T wave inversion appears to be more sensitive yet less specific.

A Novel CNN-Based Framework for Classification of Signal Quality and Sleep Position from a Capacitive ECG Measurement

The further exploration of the capacitive ECG (cECG) is hindered by frequent fluctuations in signal quality from body movement and changes in sleep position. The processing framework must be fundamentally adapted to make full use of this signal. Therefore, we propose a new signal-processing framework that determines the signal quality for short signal segments (2 and 4 seconds) using a multi-class classification model (qua_model) based on a convolutional neural network (CNN). We built another independent deep CNN classifier (pos_model) to classify the sleep position. In the validation, 12 subjects were recruited for a 30-minute experiment, which required the subjects to lie on a bed in different sleeping positions. The short segments, classified as clear (C1 class) by the qua_model, were used to determine sleep positions with the pos_model. In 10-fold cross-validation, the qua_model for signals of 4-second length could recognize the signal of the C1 class at a 0.99 precision and a 0.99 recall; the pos_model could recognize the supine sleep position, the left, and right lateral sleep positions at a 0.99 averaged precision and a 0.99 averaged recall. Given the amount of data accumulated per night and the instability in the signal quality, this fully automatic processing framework is indispensable for a personal healthcare system. Therefore, this study could serve as an important step for cECG technique trying to explore the cECG for unconstrained heart monitoring.

Non-cardiac Chest Pain: A Review for the Consultation-Liaison Psychiatrist

BACKGROUND

Patients presenting with chest pain to general practice or emergency providers represent a unique challenge, as the differential is broad and varies widely in acuity. Importantly, most cases of chest pain in both acute and general practice settings are ultimately found to be non-cardiac in origin, and a substantial proportion of patients experiencing non-cardiac chest pain (NCCP) suffer significant disability. In light of emerging evidence that mental health providers can serve a key role in the care of patients with NCCP, knowledge of the differential diagnosis, psychiatric co-morbidities, and therapeutic techniques for NCCP would be of great use to both consultation-liaison (C-L) psychiatrists and other mental health providers.

METHODS

We reviewed prior published work on (1) the appropriate medical workup of the acute presentation of chest pain, (2) the relevant medical and psychiatric differential diagnosis for chest pain determined to be non-cardiac in origin, (3) the management of related conditions in psychosomatic medicine, and (4) management strategies for patients with NCCP.

RESULTS

We identified key differential diagnostic and therapeutic considerations for psychosomatic medicine providers in 3 different clinical contexts: acute care in the emergency department, inpatient C-L psychiatry, and outpatient C-L psychiatry. We also identified several gaps in the literature surrounding the short-term and long-term management of NCCP in patients with psychiatric etiologies or co-morbid psychiatric conditions.

CONCLUSIONS

Though some approaches to the care of patients with NCCP have been developed, more work is needed to determine the most effective management techniques for this unique and high-morbidity population.

Feasibility and Safety of Evaluating Patients with Prior Coronary Artery Disease Using an Accelerated Diagnostic Algorithm in a Chest Pain Unit

An accelerated diagnostic protocol for evaluating low-risk patients with acute chest pain in a cardiologist-based chest pain unit (CPU) is widely employed today. However, limited data exist regarding the feasibility of such an algorithm for patients with a history of prior coronary artery disease (CAD). The aim of the current study was to assess the feasibility and safety of evaluating patients with a history of prior CAD using an accelerated diagnostic protocol. We evaluated 1,220 consecutive patients presenting with acute chest pain and hospitalized in our CPU. Patients were stratified according to whether they had a history of prior CAD or not. The primary composite outcome was defined as a composite of readmission due to chest pain, acute coronary syndrome, coronary revascularization, or death during a 60-day follow-up period. Overall, 268 (22%) patients had a history of prior CAD. Non-invasive evaluation was performed in 1,112 (91%) patients. While patients with a history of prior CAD had more comorbidities, the two study groups were similar regarding hospitalization rates (9% vs. 13%, p = 0.08), coronary angiography (13% vs. 11%, p = 0.41), and revascularization (6.5% vs. 5.7%, p = 0.8) performed during CPU evaluation. At 60-days the primary endpoint was observed in 12 (1.6%) and 6 (3.2%) patients without and with a history of prior CAD, respectively (p = 0.836). No mortalities were recorded. To conclude, Patients with a history of prior CAD can be expeditiously and safely evaluated using an accelerated diagnostic protocol in a CPU with outcomes not differing from patients without such a history.

Characteristics of and outcomes for elderly patients with acute myocardial infarction: differences between females and males

Objectives

This study analyzed age-adjusted sex differences among acute myocardial infarction (AMI) patients aged 75 years and above with regard to 7-year mortality (primary end point) and the frequency of angiograms and admission to the coronary care unit (CCU) as well as 1-year mortality (secondary end points).

Methods

A retrospective cohort study comprised 1,414 AMI patients (748 females and 666 males) aged at least 75 years, who were admitted to Sahlgrenska University Hospital in Gothenburg, Sweden, during two periods (2001/2002 and 2007). All comparisons between female and male patients were age adjusted.

Results

Females were older and their previous history included fewer AMIs, coronary artery bypass grafting procedures, and renal diseases, but more frequent incidence of hypertension. On the contrary, males had higher age-adjusted 7-year mortality in relation to females (hazard ratio [HR] 1.16 with corresponding 95% confidence interval [95% CI 1.03, 1.31], P=0.02). Admission to the CCU was more frequent among males than females (odds ratio [OR] 1.38 [95% CI 1.11, 1.72], P=0.004). There was a nonsignificant trend toward more coronary angiographies performed among males (OR 1.34 [95% CI 1.00, 1.79], P=0.05), as well as a nonsignificant trend toward higher 1-year mortality (HR 1.18 [95% CI 0.99, 1.39], P=0.06).

Conclusion

In an AMI population aged 75 years and above, males had higher age-adjusted 7-year mortality and higher rate of admission to the CCU than females. One-year mortality did not differ significantly between the sexes, nor did the frequency of performed coronary angiograms.

Diagnostic values of chest pain history, ECG, troponin and clinical gestalt in patients with chest pain and potential acute coronary syndrome assessed in the emergency department

In the assessment of chest pain patients with suspected acute coronary syndrome (ACS) in the emergency department (ED), physicians rely on global diagnostic impressions (‘gestalt’). The aim of this study was to determine the diagnostic value of the ED physician’s overall assessment of ACS likelihood, and the values of the main diagnostic modalities underlying this assessment, namely the chest pain history, the ECG and the initial troponin result. 1,151 consecutive ED chest pain patients were prospectively included. The ED physician’s interpretation of the chest pain history, the ECG, and the global likelihood of ACS were recorded on special forms. The discharge diagnoses were retrieved from the medical records. A chart review was carried out to determine whether patients with a non-ACS diagnosis at the index visit had ACS or suffered cardiac death within 30 days. The gestalt was better than its components both at ruling in (“Obvious ACS”, LR 29) and at ruling out (“No Suspicion of ACS”, LR 0.01) ACS. In the “Strong suspicion of ACS” group, 60% of the patients did not have ACS. A positive TnT (LR 24.9) and an ischemic ECG (LR 8.3) were strong predictors of ACS and seemed superior to pain history for ruling in ACS. In patients with a normal TnT and non-ischemic ECG, chest pain history typical of AMI was not a significant predictor of AMI (LR 1.9) while pain history typical of unstable angina (UA) was a moderate predictor of UA (LR 4.7). Clinical gestalt was better than its components both at ruling in and at ruling out ACS, but overestimated the likelihood of ACS when cases were assessed as strong suspicion of ACS. Among the components of the gestalt, TnT and ECG were superior to the chest pain history for ruling in ACS, while pain history was superior for ruling out ACS.

ECG signs of acute myocardial ischemia in the prehospital setting of a suspected acute coronary syndrome and its association with outcomes

AIMS

The aims of this study were (a) to determine the prehospital prevalence of electrocardiographic (ECG) signs of acute myocardial ischemia in patients with suspected acute coronary syndrome and (b) to describe the relationships between the various ECG patterns and the diagnosis of acute myocardial infarction (AMI) and outcomes.

METHODS

Prospective cohort study using data from an interventional trial in acute chest pain patients transported by the emergency medical services. These patients were classified into 3 groups: patients with ECG showing signs of acute myocardial ischemia, patients with ECG showing other abnormal changes (bundle-branch block, pacemaker rhythm, Q-wave or T-wave inversion) and patients without significant pathologic findings. All P values are age-adjusted.

RESULTS

Among 1546 patients, 312 (20%) had ECG signs of acute myocardial ischemia. Of them, 57% had a final diagnosis of AMI versus 26% of those with other abnormal ECGs and 12% of those with ECG without significant pathologic findings (P<.0001). In all, 53% of all AMI cases involved patients without ECG signs of acute myocardial ischemia. Although ECG signs of acute myocardial ischemia predicted heart failure and ventricular tachyarrhythmias both prior to and after hospital admission, there was no significant difference in 30-day mortality between the 3 patient groups (4.3%, 3.7%, and 1.2%, respectively, P=.11).

CONCLUSION

Among patients with a clinical suspicion of AMI in the prehospital setting, the prevalence of ECG signs suggesting AMI was low, as was the ability to identify AMI patients using ECG findings only. We therefore need better instruments in the prehospital triage of patients with acute chest pain.

Behavioral changes following experimentally-induced acute myocardial infarction in rats

Rats with experimentally-induced acute myocardial infarction (AMI) have proven to be a clinically relevant model for visceral pain. As there are no behavioral data available on rats in the postinfarction period, we aimed to identify specific pain-related behavioral changes following AMI to increase the validity of the model. AMI was induced by left coronary artery ligation and pain-related behavior was analyzed using the open field test (OFT) and elevated plus maze (EPM). Morphine was applied following AMI induction to differentiate pain-related changes from those related to nonspecific global changes in responsiveness. AMI was histologically confirmed. Hypolocomotion was consistently evident in all behavioral tests for both the infarcted group and sham group. In the OFT, both AMI and sham rats exhibited less exploratory behavior and less activity. A similar pattern of behavior was observed in EPM, where both surgical groups showed fewer entries to the open arms and spent less time in the open arms. The sham group with an intact pericardium showed the same pattern of activity as control rats. The reduction in activity and rearing observed following AMI was successfully reversed following morphine injection. This effect was abolished after naloxone application allowing us to attribute observed changes specifically to pain.This study demonstrates that pain-related behavior in the acute postinfarction period is generally characterized by reduced mobility and explorative behavior. Our results showed that cardiac ischemia as a consequence of experimentally-induced infarction is a less important source of pain behavior than manipulation of the pericardium.

Implementation of a chest pain management service improves patient care and reduces length of stay

OBJECTIVE

Chest pain is one of the most common complaints in patients presenting to an emergency department. Delays in management due to a lack of readily available objective tests to risk stratify patients with possible acute coronary syndromes can lead to an unnecessarily lengthy admission placing pressure on hospital beds or inappropriate discharge. The need for a co-ordinated system of clinical management based on enhanced communication between departments, timely and appropriate triage, clinical investigation, diagnosis, and treatment was identified.

METHODS

An evidence-based Chest Pain Management Service and clinical pathway were developed and implemented, including the introduction of after-hours exercise stress testing.

RESULTS

Between November 2005 and March 2013, 5662 patients were managed according to a Chest Pain Management pathway resulting in a reduction of 5181 admission nights by more timely identification of patients at low risk who could then be discharged. In addition, 1360 days were avoided in high-risk patients who received earlier diagnosis and treatment.

CONCLUSIONS

The creation of a Chest Pain Management pathway and the extended exercise stress testing service resulted in earlier discharge for low-risk patients; and timely treatment for patients with positive and equivocal exercise stress test results. This service demonstrated a significant saving in overnight admissions.

Diagnostic time course, treatment, and in-hospital outcomes for patients with ST-segment elevation myocardial infarction presenting with nondiagnostic initial electrocardiogram: a report from the American Heart Association Mission: Lifeline program

BACKGROUND

Prior studies indicate that a subset of patients diagnosed as having ST-segment elevation myocardial infarction (STEMI) will have an initial non-diagnostic electrocardiogram (ECG) during evaluation. However, the timing of diagnostic ECG changes in this group is unknown. Our primary aim was to describe the timing of ECG diagnosis of STEMI in patients whose initial ECG was non-diagnostic. Secondarily, we sought to compare the delivery of American College of Cardiology/American Heart Association guidelines-based care and in-hospital outcomes in this group compared with patients diagnosed as having STEMI on initial ECG.

METHODS

We analyzed data from 41,560 patients diagnosed as having STEMI included in the National Cardiovascular Data Registry ACTION Registry-GWTG from January 2007 to December 2010. We divided this study population into 2 groups: those diagnosed on initial ECG (N = 36,994) and those with an initial non-diagnostic ECG that were diagnosed on a follow-up ECG (N = 4,566).

RESULTS

In general, baseline characteristics and clinical presentations were similar between the 2 groups. For patients with an initial non-diagnostic ECG, 72.4% (n = 3,305) had an ECG diagnostic for STEMI within 90 minutes of their initial ECG. There did not appear to be significant differences in the administration of guideline-recommended treatments for STEMI, in-hospital major bleeding (P = .926), or death (P = .475) between these groups.

CONCLUSIONS

In a national sample of patients diagnosed as having STEMI, 11.0% had an initial non-diagnostic ECG. Of those patients, 72.4% had a follow-up diagnostic ECG within 90 minutes of their initial ECG. There did not appear to be clinically meaningful differences in guidelines-based treatment or major inhospital outcomes between patients diagnosed as having STEMI on an initial ECG and those diagnosed on a follow-up ECG.

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.

Early Diagnosis of Acute Myocardial Infarction by Bedside Multimarker Test at an Emergency Department in Hong Kong

Introduction

Cardiac biomarker measurement can aid diagnosis of acute myocardial infarction. The present study evaluates the efficacy and efficiency of point-of-care multimarkers measurement of myoglobin, creatine kinase (CK-MB) and troponin in identifying patients with acute myocardial infarction.

Method

We prospectively enrolled consecutive patients (N=105) in the emergency department who were being evaluated for possible acute myocardial infarction. Point-of-care testing (POCT) of myoglobin, CK-MB and troponin I (TnI) was performed in all patients. Central laboratory measurement of troponin I was also performed simultaneously. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and receiver operating characteristic (ROC) curve were evaluated.

Result

The specificity and positive likelihood ratio of TnI (POCT) and TnI (laboratory) were 98%, 13.0 and 98%, 21.8 respectively. The areas under curve of the ROC curve of TnI (POCT) and TnI (laboratory) were 0.692 and 0.725 respectively.

Conclusion

A high positive likelihood ratio for acute myocardial infarction through point-of-care testing can help timely diagnosis and just-in-time appropriate management for patients presenting with chest pain.

Pre-hospital ECG for acute coronary syndrome in urban India: a cost-effectiveness analysis

Background

Patients with acute coronary syndrome (ACS) in India have increased pre-hospital delay and low rates of thrombolytic reperfusion. Use of ECG could reduce pre-hospital delay among patients who first present to a general practitioner (GP). We assessed whether performing ECG on patients with acute chest pain would improve long-term outcomes and be cost-effective.

Methods

We created a Markov model of urban Indian patients presenting to a GP with acute chest pain to compare a GP's performing an ECG versus not performing one. Variables describing the accuracy of a GP's referral decision in chest pain and ACS, ACS treatment patterns, the effectiveness of thrombolytic reperfusion, and costs were derived from Indian data where available and other developed world studies. The model was used to estimate the incremental cost-effectiveness ratio (ICER) of the intervention in 2007 US dollars per quality adjusted life years (QALY) gained.

Results

Under baseline assumptions, the ECG strategy cost an additional $12.65 per QALY gained compared to no ECG. Sensitivity analyses around the cost of the ECG, cost of thrombolytic, and referral accuracy of the GP yielded ICERs for the ECG strategy ranging between cost-saving and $1124/QALY. All results indicated the intervention is cost-effective under current World Health Organization recommendations.

Conclusions

While direct presentation to the hospital with acute chest pain is preferable, in urban Indian patients presenting first to a GP, an ECG performed by the GP is a cost-effective strategy to reduce disability and mortality. This strategy should be clinically studied and considered until improved emergency transport services are available.

A triage algorithm for the rapid clinical assessment and management of emergency department patients presenting with chest pain

This article describes an algorithm for the rapid clinical assessment and evidence-based managemant of patients presenting to the Emergency Department (ED) with chest pain. While broadly applicable, it is specifically designed for use in an ED-based chest pain unit, and incorporates time-sensitive pathways for patients with acute coronary syndromes as well as observation protocols for patients in which the etiology of chest pain is less clear.

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.

Negative predictive value and potential cost savings of acute nuclear myocardial perfusion imaging in low risk patients with suspected acute coronary syndrome: a prospective single blinded study

BACKGROUND

Previous studies from the USA have shown that acute nuclear myocardial perfusion imaging (MPI) in low risk emergency department (ED) patients with suspected acute coronary syndrome (ACS) can be of clinical value. The aim of this study was to evaluate the utility and hospital economics of acute MPI in Swedish ED patients with suspected ACS.

METHODS

We included 40 patients (mean age 55 +/- 2 years, 50% women) who were admitted from the ED at Lund University Hospital for chest pain suspicious of ACS, and who had a normal or non-ischemic ECG and no previous myocardial infarction. All patients underwent MPI from the ED, and the results were analyzed only after patient discharge. The current diagnostic practice of admitting the included patients for observation and further evaluation was compared to a theoretical "MPI strategy", where patients with a normal MPI test would have been discharged home from the ED.

RESULTS

Twenty-seven patients had normal MPI results, and none of them had ACS. MPI thus had a negative predictive value for ACS of 100%. With the MPI strategy, 2/3 of the patients would thus have been discharged from the ED, resulting in a reduction of total hospital cost by some 270 EUR and of bed occupancy by 0.8 days per investigated patient.

CONCLUSION

Our findings in a Swedish ED support the results of larger American trials that acute MPI has the potential to safely reduce the number of admissions and decrease overall costs for low-risk ED patients with suspected ACS.

A prospective study of an algorithm using cardiac troponin I and myoglobin as adjuncts in the diagnosis of acute myocardial infarction and intermediate coronary syndromes in a veteran's hospital

BACKGROUND

Accurate and cost-effective evaluation of acute chest pain has been problematic for years. The high prevalence of missed myocardial infarctions (MI) has led to conservative triage behavior on the part of physicians, leading to expensive admissions to coronary care units. New algorithms are sorely needed for more rapid and accurate triage of patients with chest pain to appropriate treatment settings.

HYPOTHESIS

We sought to test an algorithm for rapid diagnosis of MI and acute coronary syndromes using cardiac troponin I (cTnI) and myoglobin as adjuncts to creatine kinase (CK)-MB. We hypothesized our algorithm would be both sensitive and specific at early time points, and would allow safe stratification of patients not ruling in by conventional CK-MB criteria.

METHODS

This was a 6-month prospective study of 505 consecutive patients who presented with chest pain at a university-affiliated veteran's hospital. The percentage of MIs at various time points was identified using combinations of markers. Safety outcomes were assessed by follow-up of patients discharged home. Cost savings analysis was assessed by surveying the physicians as to whether the use of the algorithm affected their disposition of patients. Forty-nine patients ruled in for MI. Using the combination of cTnI, 2-h doubling of myoglobin, and CK-MB, 37 (76%) ruled in at the time of presentation, 43 (88%) at 2 h, and 100% by 6 h.

RESULTS

Cardiac troponin I plus a 2-h myoglobin was as accurate as the combination of all three markers and performed better than CK-MB in detecting patients presenting late and as a predictor for complications when CK-MB was normal. Of the 456 patients with normal markers after 6 h, only 140 were sent to the coronary care unit (CCU), and 176 were sent home. A 3-month follow-up showed minimal adverse events. One-half of physicians completing a survey stated the use of markers changed their disposition of patients, leading to an estimated 6-month cost savings of a half-million dollars.

CONCLUSIONS

We developed an algorithm using troponin I and myoglobin as adjuncts to usual CK-MB levels that allowed for rapid and accurate assessment of patients with acute MI. It also afforded physicians important input into their decision making as to how best to triage patients presenting with chest pain. Their comfort in sending home certain subgroups of patients who otherwise would have been admitted to the CCU was rewarded with a good short-term prognosis and a large cost savings to the hospital.

Myoglobin and troponin I elevation predict 5-year mortality in patients with undifferentiated chest pain in the emergency department

BACKGROUND

The long-term prognostic significance of elevated cardiac markers in an undifferentiated patient population with chest pain is unknown.

METHODS

Serum troponin I (cTnI), creatine kinase-MB (CK-MB), and myoglobin were measured at presentation in 951 consecutive patients evaluated in the emergency department for possible acute coronary syndrome, and all-cause mortality was measured over 5 years.

RESULTS

Final diagnoses included myocardial infarction in 70 (7.4%), unstable angina in 78 (8.2%), stable angina in 26 (2.7%), heart failure in 135 (14.2%), syncope in 61 (6.4%), arrhythmia in 62 (6.5%), and noncardiac diagnoses in 519 (54.6%). Our study population had a mean (+/-SD) age of 63 (+/-16), 434 (46%) were male, 774 (81%) were African American, 408 (43%) had known coronary artery disease, 647 (68%) had hypertension, 244 (26%) had diabetes mellitus, and 237 (25%) had a serum creatinine>or=1.5 mg/dL. At 5 years, there were 349 (36.7%) deaths. In a multivariate model with adjustment for baseline covariates, an elevated cTnI>or=1.0 ng/mL (hazard ratio [HR] 1.7, 95% CI 1.3-2.3) and myoglobin>or=200 ng/mL (HR 1.6, 95% CI 1.2-2.1), but not CK-MB>or=9.0 ng/mL (HR 0.9, 95% CI 0.6-1.3), remained independent predictors of all-cause mortality. Patients with both elevated cTnI and myoglobin had a particularly high mortality rate.

CONCLUSION

Among patients evaluated in the emergency department for possible acute coronary syndromes, myoglobin and cTnI at presentation are powerful, independent predictors of long-term (5-year) prognosis.

In search of the best method to predict acute coronary syndrome using only the electrocardiogram from the emergency department

INTRODUCTION

The aim of this study was to compare different methods to predict acute coronary syndrome (ACS) using only data from a single electrocardiogram (ECG) in the emergency department (ED).

METHOD

We compared the ACS prediction abilities of classical ECG criteria, human expert ECG interpretation, a logistic regression model and an artificial neural network ensemble (ANN). The ED ECG and discharge diagnoses were retrieved for 861 patient visits to the ED for chest pain. Cross-validation was used to estimate the generalization performance of the logistic regression and the ANN model.

RESULTS

The logistic regression model had the overall best performance in predicting ACS with an area under the receiver operating characteristic curve of 0.88. The sensitivities of logistic regression, ANN, expert physicians, and classical ECG criteria were 95%, 95%, 82%, and 75%, respectively, and the specificities were 54%, 44%, 63%, and 69%.

CONCLUSION

Our logistic regression model was the best overall method to predict ACS, followed by our ANN. Decision support models have the potential to improve even experienced ECG readers' ability to predict ACS in the ED.

Predictive value of T-wave abnormalities at the time of emergency department presentation in patients with potential acute coronary syndromes

OBJECTIVES

T-wave abnormalities on electrocardiograms (ECGs) are common, but their ability to predict 30-day cardiovascular outcomes at the time of emergency department (ED) presentation is unknown. The authors determined the association between T-wave abnormalities on the presenting ECG and cardiovascular outcomes within 30 days of presentation in patients with potential acute coronary syndromes (ACSs).

METHODS

This was a secondary analysis of a prospective cohort study of ED patients that presented with a potential ACS. Patients were excluded if they had a prior myocardial infarction, ST-segment elevation or depressions, right or left bundle branch block, or Q-waves on the initial ECG. Data included demographics, medical and cardiac history, and ECG findings including the presence or absence of T-wave flattening, inversions of 1-5 mm, and inversions >5 mm. Investigators followed the hospital course for admitted patients, and 30-day follow-up was performed on all patients. The main outcome was a composite of death, acute myocardial infarction, revascularization, coronary stenosis greater than 50%, or a stress test with reversible ischemia.

RESULTS

Of 8,298 patient visits, 5,582 met criteria for inclusion: 4,166 (74.6%) had no T-wave abnormalities, 721 (12.9%) had T-wave flattening in two or more leads, 659 (11.8%) had T-wave inversions of 1-5 mm, and 36 (0.64%) had T-wave inversions >5 mm. The composite endpoint was more common in patients with T-wave flattening (8.2% vs. 5.7%; p = 0.0001; relative risk [RR] = 1.4; 95% confidence interval [CI] = 1.1 to 1.9), T-wave inversions 1-5 mm (13.2% vs. 5.7%; p = 0.0001; RR = 2.4; 95% CI = 1.8 to 3.1), and T-wave inversions >5 mm (19.4% vs. 5.7%; p = 0.0001; RR = 3.4; 95% CI = 1.7 to 6.1), or any T-wave abnormality (10.8% vs. 5.7%; p = 0.0001; RR = 1.9; 95% CI = 1.6 to 2.3), even after adjustment for initial troponin. This association also existed in the subset of patients without known coronary artery disease.

CONCLUSIONS

In patients with potential ACS presenting to the ED, T-wave abnormalities are associated with higher rates of 30-day cardiovascular events.

Comparison of early dobutamine stress echocardiography and exercise electrocardiographic testing for management of patients presenting to the emergency department with chest pain

This study compared the cost-effectiveness of dobutamine-atropine stress echocardiography (DASE) and electrocardiographic exercise testing (EET) implemented in emergency department accelerated diagnostic protocols for the early stratification of low-risk patients presenting with acute chest pain (ACP). One hundred ninety-nine patients with ACP, nondiagnostic electrocardiographic results, and negative biomarker results were randomized to DASE (n = 110) or EET (n = 89) <6 hours after emergency department presentation. Patients with negative risk assessment results were immediately discharged and followed for 2 months. Ninety patients (82%) in the DASE arm and 78 (88%) in the EET arm were discharged after the diagnosis of nonischemic ACP. The mean lengths of stay in the hospital were 23 +/- 12 and 31 +/- 23 hours in the DASE and EET arms, respectively (p = 0.01). No 2-month follow-up events occurred in DASE patients, and the event rate was significantly higher in EET patients (0% vs 11%, p = 0.004). The DASE strategy showed lower costs compared with the EET strategy at 1-month ($1,026 +/- $250 vs $1,329 +/- $1,288, p = 0.03) and 2-month ($1,029 +/- 253 vs $1,684 +/- $2,149, p = 0.005) follow-up. In conclusion, early DASE in emergency department triage of low-risk patients with ACP is safe and reduces costs of care compared to EET.

The role of cardiovascular imaging techniques in the assessment of patients with acute chest pain

Chest pain is the most common presenting symptom of coronary artery disease. The assessment and appropriate management of patients with acute chest pain and non-diagnostic electrocardiograms (ECGs) remain a continuing clinical problem, with major logistic and financial implications for health-care providers. Cardiovascular imaging is at the forefront of health care, experiencing rapid changes over the recent years, particularly with the use of advanced medical technologies. Imaging techniques like acute rest myocardial perfusion imaging (MPI), echocardiography, electron beam computed tomography (CT), cardiac magnetic resonance imaging (MRI) and multi-detector CT (MDCT) have been used recently in the evaluation and triage of patients with chest pain in addition to the conventional investigations such as ECGs and cardiac biomarkers in the chest pain units. The annual potential cost savings, by incorporating the routine use of acute rest MPI in patients with low-to-moderate risk and non-diagnostic ECGs are substantial. The high negative predictive value of a normal resting MPI in patients with chest pain for myocardial infarction and future cardiac events is well established. Echocardiography is also considered to be useful but the technique is operator dependent and at present there is insufficient data to support its use. Cardiac MRI is expensive and time consuming and there is insufficient diagnostic and prognostic data to make it suitable for chest pain patients at present. There has been increasing interest in MDCT recently, especially with the advent of 64-slice CT but the sensitivity and specificity in chest pain patients are no better than MPI so far.

Modified Thrombolysis in Myocardial Infarction (TIMI) risk score to risk stratify patients in the emergency department with possible acute coronary syndrome

OBJECTIVE

To assess the prognostic utility of the Thrombolysis in Myocardial Infarction (TIMI) risk score in patients in the emergency department (ED) evaluated for possible acute coronary syndrome (ACS).

BACKGROUND

The ability of the TIMI risk score to risk stratify patients at initial presentation in the ED with chest pain of unclear etiology is uncertain.

METHODS

We investigated the prognostic utility of the TIMI risk score in 947 consecutive patients evaluated in the ED for possible ACS. A multivariate analysis was done to evaluate the independent predictive power of the individual components of the TIMI risk score to predict an adverse event at 30 days (all-cause death, myocardial infarction, and coronary revascularization).

RESULTS

There were 151 (16%) patients diagnosed with ACS. At 30 days there were 48 (5%) deaths, 84 (9%) myocardial infarctions, and 49 (5%) coronary revascularization procedures. The mean TIMI risk score was significantly higher in patients with an adverse event compared with those without (2.6 +/- 1.3 vs. 1.7 +/- 1.2, P < 0.0001). Four of the 7 TIMI risk factors (age > or = 65 years, ST segment deviation > or = 0.5 mm elevated troponin I, and coronary stenosis > or = 50%) were independently associated with adverse events. A simplified TIMI risk score was computed and was found to have similar prognostic ability as the 7 variable TIMI risk score.

CONCLUSION

A modified TIMI risk score may simplify risk stratification of ED patients with undifferentiated chest pain.

Prognostic implications of myocardial necrosis triad markers' concentration measured at admission in patients with suspected acute coronary syndrome

The aim of the study was to analyze the prognostic implications of 3 myocardial necrosis markers measured at admission in short-term observation of patients with suspected acute coronary syndrome. The study group consisted of 336 consecutive patients whose concentration of cardiac troponin I, creatine kinase-MB fraction, and myoglobin were measured at admission. All patients referred due to chest pain and suspected acute coronary syndrome and were followed up for 30 days. The patients who died had statistically higher concentration of cardiac troponin I (8.7 +/- 17.2 vs 0.9 +/- 3.2 ng/mL; P = .0006), myoglobin (215.2 +/- 181.5 vs 109.7 +/- 151.5 ng/mL; P = .003), and creatine kinase-MB (21.9 +/- 30.7 vs 8.8 +/- 25.9 ng/mL; P = .005), compared to patients who stayed alive. There was statistically significant increase in 30-day all-cause mortality with increasing numbers of positive markers-0.6% for patients with nonpositive marker, 3.4% for patients with 1 positive marker, and 11.5% for patients with at least 2 positive markers (P = .001 for trend).

Prognostic value of symptoms during a normal or nonspecific electrocardiogram in emergency department patients with potential acute coronary syndrome

OBJECTIVES

Emergency department (ED) patients with symptoms concerning for acute coronary syndrome (ACS) and a normal electrocardiogram (ECG) are at risk for adverse cardiovascular events. The authors hypothesized that patients with a normal or nonspecific ECG during symptoms have a lower risk for ACS than do those who are asymptomatic.

METHODS

This was a prospective cohort study of ED patients with potential ACS. Outcomes were acute myocardial infarction (AMI), ACS, and 30-day cardiovascular events (death, AMI, revascularization). Fisher's exact test, t-tests, and logistic regression were used for data analysis.

RESULTS

Of 2,593 patient visits, 2,007 patients had normal or nonspecific ECG findings. There were 1,196 who had symptoms during ECG, whereas 811 did not. Patients with symptoms at ECG acquisition were younger (49.9 vs. 55.2 years; p < 0.001) and were more likely to be black (70% vs. 64%; p = 0.002), female (63% vs. 58%; p = 0.03), and to have used cocaine (5% vs. 2%; p = 0.004). They were less likely to have hypertension (49% vs. 58%; p < 0.001), and diabetes (22% vs. 17%; p = 0.002). Patients with and without symptoms were equally likely to have AMI (both 2.8%; p > 0.99), ACS (10.1% vs. 11.5%; p = 0.34), and 30-day adverse outcomes (both 5.3%; p > 0.99). After adjustment for baseline cardiovascular-risk factors, odds ratios for patients with symptoms at the time of ECG acquisition were not significantly different for any of the outcomes: AMI (1.1; 95% confidence interval [CI] = 0.6 to 1.9); ACS (1.1; 95% CI = 0.8 to 1.4); or 30-day events (1.2; 95% CI = 0.8 to 1.9).

CONCLUSIONS

Patients who are symptomatic during acquisition of a normal or nonspecific ECG have rates of adverse cardiovascular events similar to those of patients without symptoms. Clinicians should not rely on the absence of ECG abnormalities during symptoms to help exclude ACS.

Comparison between neural networks and multiple logistic regression to predict acute coronary syndrome in the emergency room

OBJECTIVE

Patients with suspicion of acute coronary syndrome (ACS) are difficult to diagnose and they represent a very heterogeneous group. Some require immediate treatment while others, with only minor disorders, may be sent home. Detecting ACS patients using a machine learning approach would be advantageous in many situations.

METHODS AND MATERIALS

Artificial neural network (ANN) ensembles and logistic regression models were trained on data from 634 patients presenting an emergency department with chest pain. Only data immediately available at patient presentation were used, including electrocardiogram (ECG) data. The models were analyzed using receiver operating characteristics (ROC) curve analysis, calibration assessments, inter- and intra-method variations. Effective odds ratios for the ANN ensembles were compared with the odds ratios obtained from the logistic model.

RESULTS

The ANN ensemble approach together with ECG data preprocessed using principal component analysis resulted in an area under the ROC curve of 80%. At the sensitivity of 95% the specificity was 41%, corresponding to a negative predictive value of 97%, given the ACS prevalence of 21%. Adding clinical data available at presentation did not improve the ANN ensemble performance. Using the area under the ROC curve and model calibration as measures of performance we found an advantage using the ANN ensemble models compared to the logistic regression models.

CONCLUSION

Clinically, a prediction model of the present type, combined with the judgment of trained emergency department personnel, could be useful for the early discharge of chest pain patients in populations with a low prevalence of ACS.

A simple statistical model for prediction of acute coronary syndrome in chest pain patients in the emergency department

BACKGROUND

Several models for prediction of acute coronary syndrome (ACS) among chest pain patients in the emergency department (ED) have been presented, but many models predict only the likelihood of acute myocardial infarction, or include a large number of variables, which make them less than optimal for implementation at a busy ED. We report here a simple statistical model for ACS prediction that could be used in routine care at a busy ED.

METHODS

Multivariable analysis and logistic regression were used on data from 634 ED visits for chest pain. Only data immediately available at patient presentation were used. To make ACS prediction stable and the model useful for personnel inexperienced in electrocardiogram (ECG) reading, simple ECG data suitable for computerized reading were included.

RESULTS

Besides ECG, eight variables were found to be important for ACS prediction, and included in the model: age, chest discomfort at presentation, symptom duration and previous hypertension, angina pectoris, AMI, congestive heart failure or PCI/CABG. At an ACS prevalence of 21% and a set sensitivity of 95%, the negative predictive value of the model was 96%.

CONCLUSION

The present prediction model, combined with the clinical judgment of ED personnel, could be useful for the early discharge of chest pain patients in populations with a low prevalence of ACS.

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.

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.

Cardiac markers in the low-risk chest pain patient

With the arrival of point-of-care cardiac marker determination, emergency physicians may be able to arrive at the diagnosis of cardiac ischemia faster than ever before. However, these tests must be used with care, as a lack of understanding about when and how they should be obtained is important both for good patient care and to avoid medicolegal pitfalls. This report reviews risk stratification of patients who present with chest pain, provides an overview of cardiac markers and literature supporting their use, and concludes with a practice guideline for the utilization of cardiac markers in the emergency department.

Cardiac markers in acute coronary syndrome

Over the last several years there has been a dramatic increase in the number of serum cardiac markers that may aid the diagnosis, prognosis, triage and treatment of patients with acute coronary syndrome. These markers help identify the degree of platelet activation, ischemia, inflammation, left ventricular dysfunction and myocardial necrosis encountered in acute coronary syndrome. The future challenge will be to determine which markers, or combination of markers, will be most effective in identifying and treating these patients.

Usefulness of rapid quantitative measurement of myoglobin and troponin T in early diagnosis of acute myocardial infarction

BACKGROUND

New equipment, the Cardiac Reader(TM), which can measure blood concentrations of troponin T (T) and myoglobin (M) in only 15 min at the bedside was evaluated for early diagnosis of acute myocardial infarction (AMI).

METHODS AND RESULTS

A total of 34 consecutive patients with AMI who came to hospital within 24 h after onset were studied. Blood samples were collected from the patients at admission and 6, 12, 24, 48 h after onset to qualitatively and quantitatively measure T, M and creatine kinase-MB fraction. There were 20 patients with positive results by qualitative troponin T test and 29 with positive results by quantitative test. Of the patients who visited hospital within 3 h of onset, 17% were positive by the qualitative test and 67% cases had positive results in the quantitative test. The patients were divided into 2 groups according to the flow grade in the infarct-related coronary artery. In the TIMI 0-1 group (n=28), serum myoglobin concentrations were higher than in the TIMI 3-4 group (n=6) at admission and at their peak.

CONCLUSION

The rapid quantitative test of T and M is useful for early diagnosis of AMI and as an indicator of its severity, which can be evaluated from the myoglobin concentration in the hyper-acute phase.

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

AIM

To evaluate factors that identify patients with an acute coronary syndrome/myocardial infarction prior to hospital admission among patients with a suspected acute coronary syndrome who were transported by ambulance with and without ST elevation on the ambulance electrocardiogram (ECG).

METHODS

This was a prospective observational study in the part of Stockholm that is served by South Hospital ambulance organisation and the Municipality of Goteborg. All the patients who called for an ambulance due to acute chest pain or other symptoms raising the suspicion of an acute coronary syndrome took part. Immediately after the arrival of the ambulance, a blood sample was drawn for the analysis of serum myoglobin, creatine kinase (CK) MB and troponin I. A 12-lead ECG was simultaneously recorded. Further factors that were taken into consideration were age, gender, history of cardiovascular disease, symptoms and clinical findings.

RESULTS

In patients with ST elevation in prehospital ECG, the likelihood of an acute myocardial infarction increased if there were simultaneous ST depression in other leads (OR 3.94, 95% CL 1.26-12.38). For patients without an ST elevation, the likelihood of an acute myocardial infarction increased if there were: elevation of any biochemical marker OR 2.96, 95% CL 1.32-6.64; ST depression (OR 2.54, 95% CL 1.43-4.51), T-inversion (OR 2.22, 95% CL 1.10-4.48), male gender (OR 2.21, 95% CL 1.24-3.93) and increasing age (OR 1.04, 95% CL 1.01-1.06).

CONCLUSION

Among patients with a suspected acute coronary syndrome, factors that increased the likelihood for an ongoing acute myocardial infarction could already be defined prior to hospital admission. For those with an ST elevation, factors were found in ECG pattern. For those without an ST elevation, such factors were found in elevation of biochemical markers, admission ECG, male gender and increasing age.

Clinical features in the emergency department can identify patients with suspected acute coronary syndromes who are safe for care in unmonitored hospital beds

BACKGROUND

Standard practice for patients requiring hospital admission with suspected acute coronary syndromes (ACS) is admission to a monitored cardiology bed. The Western Hospital Chest Pain Protocol was developed to identify a subset of these patients who could be safely managed in an unmonitored bed.

AIM

The objective of this prospective study of chest pain patients classified as 'high' or 'intermediate' risk by the Agency for Health Care Policy and Research/National Health and Medical Research Council guidelines was to further evaluate the safety of this protocol.

METHODS

This study was a prospective, observational, cohort study investigating the outcomes of patients admitted to hospital with suspected ACS. The primary outcome of interest was death or life-threatening arrhythmia within 24 h of hospital admission.

RESULTS

If the Western Hospital Chest Pain Protocol had been strictly applied, there would have been one death in the group assigned to unmonitored beds (1/750; 0.13%, 95% confidence interval 0.01-0.85%) and no other life-threatening arrhythmias.

CONCLUSION

There is a subgroup of patients with suspected ACS who require hospital admission who can, based on clinical and biochemical features in the emergency department, be safely assigned to unmonitored beds.

Ischemia Modified Albumin for the assessment of patients presenting to the emergency department with acute chest pain but normal or non-diagnostic 12-lead electrocardiograms and negative cardiac troponin T

BACKGROUND

The diagnosis of myocardial ischemia in patients with acute chest pain at rest but non-diagnostic electrocardiograms (ECG) is problematic. Ischemia Modified Albumin (IMA) is a new biochemical marker of ischemia, which may be useful to characterise acute coronary syndrome (ACS) patients.

METHODS

We studied 131 patients (mean age 58.5 years; 95 male) presenting to the emergency department with symptoms suggestive of ACS but with normal or non-diagnostic ECGs. Cardiac troponin T (cTnT) and IMA were measured within 3 h of last chest pain episode. Based on hospital diagnostic test results, patients were classified as having ACS or non-ischemic chest pain (NICP), by two independent cardiologists unaware of IMA results.

RESULTS

Mean IMA levels (U/ml) were higher in patients with ACS (98.3+/-11) compared to patients with NICP (85.5+/-15); p<0.0001. IMA levels >93.5 U/ml demonstrated a sensitivity and specificity of 75% for the diagnosis of ACS; area under the receiver operator characteristic curve 0.78 (95% CI: 0.70-0.85). If we applied the manufacturer cutoff point of 85 U/ml, the sensitivity of IMA increased to 90.6% with a specificity of 49.3% (negative predictive value=84.6%). In combination with cTnT (6-12 h) (>0.05 ng/ml), the sensitivity increased to 92.2%. After multivariate analysis, IMA levels >85 U/ml (odds ratio=14.6 [95% CI 4.4-48.4]; p<0.0001), age and prior myocardial infarction were independent predictors of ACS.

CONCLUSION

IMA may be a useful biomarker for the identification of ACS in patients presenting with typical acute chest pain but normal or non-diagnostic ECGs.

Circulating endothelial cell count as a diagnostic marker for non-ST-elevation acute coronary syndromes

BACKGROUND

Shedding of endothelial cells from damaged endothelium into the blood occurs in a variety of vascular disorders. The purpose of this study was to evaluate the utility of circulating endothelial cell (CEC) count as a diagnostic marker of non-ST-elevation acute coronary syndromes (ACSs).

METHODS AND RESULTS

CEC counts were determined immediately (H0), 4 hours (H4), and 8 hours (H8) after admission in 60 patients with documented non-ST-elevation ACS and 40 control patients with no evidence of coronary artery disease. A total of 32 patients in the ACS group had elevated CEC counts (>3 cells/mL) in relation to early admission and single-episode chest pain. Patients from the control group had normal CEC counts. The interval between the chest pain episode and elevation was significantly shorter for CEC than troponin I. No correlation was found between the 2 markers. Interestingly, a subgroup of ACS patients with initially normal troponin I levels had high CEC counts, thus allowing early diagnosis in 30% more cases. At H0, the mean area under the receiver operating characteristic curve was significantly higher with the CEC count than with the troponin I level. At H4 and H8, the combined use of CEC and troponin was significantly better as a marker of ACS than CEC alone or troponin I alone.

CONCLUSIONS

This study demonstrates that CEC count can be used as an early, specific, independent diagnostic marker for non-ST-elevation ACS. A combined strategy using CEC count and troponin I level could provide an effective diagnostic tool.

Bedside diagnosis of coronary artery disease: a systematic review

PURPOSE

To assess the accuracy of bedside findings for diagnosing coronary artery disease and acute myocardial infarction.

METHODS

A MEDLINE search was performed to retrieve articles published from January 1966 to January 2003 that were relevant to the bedside diagnosis of coronary disease in adults.

RESULTS

In patients with stable, intermittent chest pain, the most useful bedside predictors for a diagnosis of coronary disease were found to be the presence of typical angina (likelihood ratio [LR]=5.8; 95% confidence interval [CI]: 4.2 to 7.8), serum cholesterol level >300 mg/dL (LR=4.0; 95% CI: 2.5 to 6.3), history of prior myocardial infarction (LR=3.8; 95% CI: 2.1 to 6.8), and age >70 years (LR=2.6; 95% CI: 1.8 to 4.0). Nonanginal chest pain (LR=0.1; 95% CI: 0.1 to 0.2), pain duration >30 minutes (LR=0.1; 95% CI: 0.0 to 0.9), and intermittent dysphagia (LR=0.2; 95% CI: 0.1 to 0.8) argued against a diagnosis of coronary disease. In patients with acute chest pain, the most important bedside predictors for a diagnosis of myocardial infarction were new ST elevation (LR=22; 95% CI: 16 to 30), new Q waves (LR=22; 95% CI: 7.6 to 62), and new ST depression (LR=4.5; 95% CI: 3.6 to 5.6). A normal electrocardiogram (LR=0.2; 95% CI: 0.1 to 0.3), chest wall tenderness (LR=0.3; 95% CI: 0.2 to 0.4), and pain that was pleuritic (LR=0.2; 95% CI: 0.2 to 0.3), sharp (LR=0.3; 95% CI: 0.2 to 0.5), or positional (LR=0.3; 95% CI: 0.2 to 0.5) argued against the diagnosis of myocardial infarction.

CONCLUSION

The accuracy of bedside predictors depends on the clinical setting. In the evaluation of stable, intermittent chest pain, a patient's description of pain was found to be the most important predictor of underlying coronary disease. In the evaluation of acute chest pain, the electrocardiogram was the most useful bedside predictor for a diagnosis of myocardial infarction. Aside from the extremes in cholesterol values, the analysis of traditional risk factors changed the probability of coronary disease or myocardial infarction very little or not at all.

The future of cardiac markers in the emergency department

The development of new cardiac marker strategies has the potential of improving the treatment and triage of patients in the emergency department with possible acute coronary syndrome. Although there has been a proliferation of new cardiac markers, at present rigorous studies demonstrating the incremental utility of many of these are lacking.