Bedside multimarker testing for risk stratification in chest pain units: The chest pain evaluation by creatine kinase-MB, myoglobin, and troponin I (CHECKMATE) study

Chest pain unit concept: rationale and diagnostic strategies

Each year in the United States, over 8 million patients present to the emergency department(ED) with complaints of chest discomfort or other symptoms consistent with possible acute coronary syndrome (ACS). While over half of these patients are typically admitted for further diagnostic evaluation, fewer than 20% are diagnosed with ACS. With hospital beds and inpatient resources scarce, these admissions can be avoided by evaluating low- to moderate-risk patients in chest pain units. This large, undifferentiated patient population represents a potential high-risk group for emergency physicians requiring a systematic approach and specific ED resources. This evaluation is required to appropriately determine if a patient is safe to be discharged home with outpatient follow-up versus requiring admission to the hospital for monitoring and further testing.

Use of biomarkers in the emergency department and chest pain unit

The use of biomarkers of cardiac injury in the emergency department (ED) and observation unit settings has several nuances that are different and, therefore, worthy of its own set of use guidelines. The markers that are used, however, are the same. The primary marker of choice continues to be cardiac troponin (Tn). Other markers that have been used because of the need in the ED for rapid triage have been myoglobin and fatty acid binding protein. In addition, some centers still prefer less sensitive and less specific markers such as creatine kinase myocardial band (CK-MB). More recently, a push has occurred to develop markers of ischemia, such as ischemia modified albumin (IMA),to determine which patients have ischemia, even in the absence of cardiac injury. As troponin assays become more sensitive and method for use becomes better understood, the use of these other markers are being relegated to lesser and lesser roles. Markers of ischemia are useful, but at present, despite some enthusiasm, are not ready for routine use. Before describing the recommendations for clinical use of biomarkers in the ED, a basic understanding of some of the science and measurement issues related to these analytes is helpful.

Point-of-Care i-STAT Cardiac Troponin I for Assessment of Patients with Symptoms Suggestive of Acute Coronary Syndrome,

Background: Few studies have investigated the role of cardiac troponin point-of-care (POC) testing for predicting adverse outcomes in acute coronary syndrome (ACS) patients. We investigated the use of a POC cTnI assay in ACS patients.

Methods: We studied consecutive patients (n = 367) presenting with symptoms suggestive of ACS who were admitted through the emergency department. We measured plasma cTnI with the i-STAT assay. Patients were risk-stratified based on cTnI concentrations defined by the predetermined 99th percentile reference limit for plasma (0.04 μg/L). Patients were followed for 60 days. We computed survival and event curves with the Kaplan–Meier method and compared risk stratification groups with the log-rank test.

Results: Acute myocardial infarction (MI) was diagnosed in 8.1% of patients. Odds ratios and 95% confidence intervals for all-cause death (ACD), MI or ACD, MI or cardiac death, and cardiac death at 60 days were all statistically significant after adjustment for age, diabetes, hypertension, and history of renal failure as follows: 2.54 (1.24–5.20), P = 0.009; 2.76 (1.37–5.58), P = 0.003; 5.98 (1.65–21.7), P = 0.008; and 2.54 (1.24–5.20), P = 0.009. Kaplan–Meier curves showed early separation between patients with increased vs. reference concentrations before 30 days for ACD, MI or ACD, and MI or cardiac death.

Conclusion: The i-STAT POC cTnI assay can be added to the list of assays for risk stratification.

Frequency and Clinical Implications of Discordant Creatine Kinase-MB and Troponin Measurements in Acute Coronary Syndromes

OBJECTIVES

We sought to evaluate the association between discordant cardiac marker results and in-hospital mortality and treatment patterns in patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS).

BACKGROUND

Creatine kinase-MB (CK-MB) and cardiac troponins (cTn) are often measured concurrently in patients with NSTE ACS. The significance of discordant CK-MB and cTn results is unknown.

METHODS

Among 29,357 ACS patients in the CRUSADE initiative who had both CK-MB and cTn measured during the first 36 hours, we examined relationships of four marker combinations (CK-MB-/cTn-, CK-MB+/cTn-, CK-MB-/cTn+, and CK-MB+/cTn+) with mortality and American College of Cardiology/American Heart Association guidelines-recommended acute care.

RESULTS

The CK-MB and cTn results were discordant in 28% of patients (CK-MB+/cTn-, 10%; CK-MB-/cTn+, 18%). In-hospital mortality was 2.7% among CK-MB-/cTn- patients; 3.0%, CK-MB+/cTn-; 4.5%, CK-MB-/cTn+; and 5.9%, CK-MB+/cTn+. After adjustment for other presenting risk factors, patients with CK-MB+/cTn- had a mortality odds ratio (OR) of 1.02 (95% confidence interval [CI] 0.75 to 1.38), those with CK-MB-/cTn+ had an OR of 1.15 (95% CI 0.86 to 1.54), and those with CK-MB+/cTn+ had an OR of 1.53 (95% CI 1.18 to 1.98). Despite variable risk, patients with CK-MB+/cTn- and CK-MB-/cTn+ were treated similarly with early antithrombotic agents and catheter-based interventions.

CONCLUSIONS

Among patients with NSTE ACS, an elevated troponin level identifies patients at increased acute risk regardless of CK-MB status, but an isolated CK-MB+ status has limited prognostic value. Recognition of these risk differences may contribute to more appropriate early use of antithrombotic therapy and invasive management for all cTn+ patients.

Elevated creatine kinase-MB with normal creatine kinase predicts worse outcomes in patients with acute coronary syndromes: results from 4 large clinical trials

BACKGROUND

The degree to which elevated creatine kinase (CK)-MB in the presence of normal CK is predictive of outcome is not well understood despite having been studied for decades. This analysis examined whether normal CK with elevated CK-MB in patients with non-ST-segment elevation acute coronary syndrome (NSTE ACS) is an independent predictor of worse outcomes. A concomitant goal was to contribute insight to the debate over how patients with NSTE ACS should be managed.

METHODS

Data for 25,960 patients from the GUSTO IIb, PARAGON A and B, and PURSUIT trials were analyzed. Of these patients, 6402 were excluded from primary analysis because of missing (unmeasured) biomarkers. Patients with complete laboratory data (n = 19,558) were grouped by CK and CK-MB results. To confirm the primary analysis results, data from patients with missing biomarkers were used in an imputation model.

RESULTS

Patients were categorized in 1 of 4 groups: normal CK + normal CK-MB; normal CK + elevated CK-MB; elevated CK + normal CK-MB; or elevated CK + elevated CK-MB. For the primary outcome, 180-day death, or myocardial infarction, Kaplan-Meier estimates were 14.9%, 20.8%, 14.5%, and 18.2%, respectively. Regardless of total CK, elevated CK-MB was associated with a 25% to 49% increased relative risk of worse outcomes. Findings from the analyses were verified by the multivariable model.

CONCLUSIONS

CK-MB remains a reliable marker for myocardial necrosis and a strong predictor of worse prognosis. All patients with ACS should have CK-MB measurement to search for cardiac ischemia. Patients with elevated CK-MB should receive aggressive management commensurate with their increased risks.

Cardiac biomarkers: a contemporary status report

The field of cardiac biomarkers has grown by leaps and bounds in the past two decades. In this review we try to summarize the explosion of emerging knowledge and address the roles of some of the biomarkers that have either proven or potential utility. We detail some of the markers of ischemia, hemodynamic markers of heart failure, inflammatory markers, and the novel and innovative approach of combining these for a multimarker strategy. At the end of this review we highlight some of the biomarker-guided approaches and strategies that might lead to better and more-effective care of patients.

The sensitivity of cardiac markers stratified by symptom duration

We compared the sensitivity of three commonly used cardiac markers between two subpopulations, those who came to the Emergency Department (ED) late (6-24 h) after their symptoms began, and those who arrived earlier (<6 h), in a prospective comparative trial. Among all adult patients who presented to our ED with symptoms suggestive of acute myocardial infarction (MI), we drew serum for myoglobin, CK-MB, and troponin I upon arrival (time 0) and 2 h later. Outcomes, including acute MI, were determined. Sensitivities for all three markers between the subpopulations who arrived fewer than 6 h from symptom onset were compared to those who arrived later (6-24 h). We enrolled 346 eligible subjects, 36% of whom described cardiac symptoms as beginning 6 or more hours earlier; 14% suffered acute MIs. For time 0, the sensitivity of all three markers for acute MI was significantly higher among those subjects with symptoms of 6 or more hours' duration as compared to those with less. For troponin I, the increase in sensitivity between these two subpopulations approached 300%. At the time of the 2-h sample, the differences in sensitivities were much less and were not statistically significant. We conclude that cardiac marker values obtained at time 0 among Emergency Department patients who arrive 6 or more hours after cardiac symptom onset provide significantly higher sensitivities as compared to those obtained in patients who arrive earlier. For troponin I, the increase in sensitivity approaches threefold.

Point-of-Care Testing and Cardiac Biomarkers: The Standard of Care and Vision for Chest Pain Centers

Point-of-care testing (POCT) is defined as testing at or near the site of patient care. POCTdecreases therapeutic turnaround time (TTAT), increases clinical efficiency, and improves medical and economic outcomes. TTAT represents the time from test ordering to patient treatment. POC technologies have become ubiquitous in the United States, and, therefore,so has the potential for speed, convenience, and satisfaction, strong advantages for physicians, nurses, and patients in chest pain centers. POCT is applied most beneficially through the collaborative teamwork of clinicians and laboratorians who use integrative strategies, performance maps, clinical algorithms, and care paths (critical pathways). For example, clinical investigators have shown that on-site integration of testing for cardiac injury markers (myoglobin, creatinine kinase myocardial band [CKMB],and cardiac troponin I [cTnI]) in accelerated diagnostic algorithms produces effective screening, less hospitalization, and substantial savings. Chest pain centers, which now total over 150 accredited in the United States, incorporate similar types of protocol-driven performance enhancements. This optimization allows chest pain centers to improve patient evaluation, treatment, survival, and discharge. This article focuses on cardiac biomarker POCT for chest pain centers and emergency medicine.

Prospects for Personalized Cardiovascular Medicine

Sequencing of the human genome has ushered in prospects for individualizing cardiovascular health care. There is growing evidence that the practice of cardiovascular medicine might soon have a new toolbox to predict and treat disease more effectively. The Human Genome Project has spawned several important "omic" technologies that allow "whole genome" interrogation of sequence variation (re-sequencing, genotyping, comparative genome hybridization), transcription (expression profiling, tissue arrays), proteins (gas or liquid chromatography and tandem mass spectroscopy [MS]), and metabolites (MS or nuclear magnetic resonance profiling); deoxyribonucleic acid, ribonucleic acid, protein, and metabolic approaches all provide more exacting detail of cardiovascular disease mechanisms and, in some cases, are redefining its taxonomy. Pharmacogenomic approaches are emerging across broad classes of cardiovascular therapeutics to assist practitioners in making more precise decisions about which drugs to give to which patients to optimize the benefit-to-risk ratio. Molecular imaging is developing chemical and biological probes that can sense molecular pathway mechanisms that will allow us to monitor health and disease. Together, these tools will enable a paradigm shift from genetic medicine--on the basis of the study of individual inherited characteristics, most often single genes--to genomic medicine, which by its nature is comprehensive and focuses on the functions and interactions of multiple genes and gene products, among themselves and with their environment. The information gained from such analyses, in combination with clinical data, is now allowing us to assess individual risks and guide clinical management and decision-making, all of which form the basis for cardiovascular genomic medicine.

Pretest probability assessment derived from attribute matching

Background

Pretest probability (PTP) assessment plays a central role in diagnosis. This report compares a novel attribute-matching method to generate a PTP for acute coronary syndrome (ACS). We compare the new method with a validated logistic regression equation (LRE).

Methods

Eight clinical variables (attributes) were chosen by classification and regression tree analysis of a prospectively collected reference database of 14,796 emergency department (ED) patients evaluated for possible ACS. For attribute matching, a computer program identifies patients within the database who have the exact profile defined by clinician input of the eight attributes. The novel method was compared with the LRE for ability to produce PTP estimation <2% in a validation set of 8,120 patients evaluated for possible ACS and did not have ST segment elevation on ECG. 1,061 patients were excluded prior to validation analysis because of ST-segment elevation (713), missing data (77) or being lost to follow-up (271).

Results

In the validation set, attribute matching produced 267 unique PTP estimates [median PTP value 6%, 1^st–3^rd quartile 1–10%] compared with the LRE, which produced 96 unique PTP estimates [median 24%, 1^st–3^rd quartile 10–30%]. The areas under the receiver operating characteristic curves were 0.74 (95% CI 0.65 to 0.82) for the attribute matching curve and 0.68 (95% CI 0.62 to 0.77) for LRE.

The attribute matching system categorized 1,670 (24%, 95% CI = 23–25%) patients as having a PTP < 2.0%; 28 developed ACS (1.7% 95% CI = 1.1–2.4%). The LRE categorized 244 (4%, 95% CI = 3–4%) with PTP < 2.0%; four developed ACS (1.6%, 95% CI = 0.4–4.1%).

Conclusion

Attribute matching estimated a very low PTP for ACS in a significantly larger proportion of ED patients compared with a validated LRE.

Combining different biochemical markers of myocardial ischemia does not improve risk stratification in chest pain patients compared to troponin I alone

OBJECTIVE

Early evaluation of patients with chest pain is important not only for the detection of acute myocardial infarction (AMI) but also for identification of patients at high risk for future cardiac events. A multimarker strategy applying results of early measurements of different biochemical markers of cardiac necrosis in combination may improve risk prediction in chest pain patients.

METHODS

Rapid measurements of troponin I (TnI), creatine kinase MB and myoglobin were performed in 191 consecutive patients with chest pain and a non-diagnostic electrocardiogram for AMI. The prognostic value of these markers and different multimarker strategies was evaluated and compared.

RESULTS

Ten (5.2%) patients died during follow-up, which for eight (4.2%) patients was due to cardiac causes. Myocardial reinfarctions occurred in 17 (6.8%) patients. TnI was most predictive for cardiac mortality (TnI>or=0.1 microg/l, 10.7% event rate compared with TnI<0.1 microg/l, 0%, P<0.001) and myocardial reinfarction (14.9% compared with 1.7%, P<0.001). The other markers and multimarker strategies had a lower capacity for predicting adverse events apart from myoglobin and the combination of TnI or myoglobin regarding the endpoint of total mortality.

CONCLUSION

The combinations of different markers were prognostically non-superior compared to TnI, which thus, should be preferred as a biochemical marker for risk stratification in patients with chest pain.

New Risk Score for Patients With Acute Chest Pain, Non-ST-Segment Deviation, and Normal Troponin Concentrations

OBJECTIVES

The purpose of this research was to develop a risk score for patients with chest pain, non-ST-segment deviation electrocardiogram (ECG), and normal troponin levels.

BACKGROUND

Prognosis assessment in this population remains a challenge.

METHODS

A total of 646 consecutive patients were evaluated by clinical history (risk factors and chest pain score according to pain characteristics), ECG, and early exercise testing. ST-segment deviation and troponin elevation were exclusion criteria. The primary end point was mortality or myocardial infarction at one year. The secondary end point was mortality, myocardial infarction, or urgent revascularization at 14 days (similar to the Thrombolysis In Myocardial Infarction [TIMI] risk score).

RESULTS

Primary and secondary end point rates were 6.7% and 5.4%. A risk score was constructed using the variables related to the primary end point: chest pain score > or =10 points (hazard ratio [HR] = 2.5; 1 point), > or =2 pain episodes in last 24 h (HR = 2.2; 1 point), age > or =67 years (HR = 2.3; 1 point), insulin-dependent diabetes mellitus (HR = 4.2; 2 points), and prior percutaneous transluminal coronary angioplasty (HR = 2.2; 1 point). Patients were classified into five categories of risk (p = 0.0001): 0 points, 0% event rate; 1 point, 3.1%; 2 points, 5.4%; 3 points, 17.6%; > or =4 points, 29.6%. The accuracy of the score was greater than that of the TIMI risk score for the primary (C index of 0.78 vs. 0.66, p = 0.0002) and secondary (C index of 0.70 vs. 0.66, p = 0.1) end points.

CONCLUSIONS

Patients presenting with chest pain despite no ST-segment deviation or troponin elevation show a non-negligible rate of events at one year. A risk score derived from this specific population allows more accurate stratification than when using the TIMI risk score.

Risk stratification of patients with acute chest pain and normal troponin concentrations

OBJECTIVE

To investigate the outcome of patients with acute chest pain and normal troponin concentrations.

DESIGN

Prospective cohort design.

SETTING

Single centre study in a teaching hospital in Spain.

PATIENTS

609 consecutive patients with chest pain evaluated in the emergency department by clinical history (risk factors and a chest pain score according to pain characteristics), ECG, and early (< 24 hours) exercise testing for low risk patients with physical capacity (n = 283, 46%). All had normal troponin concentrations after serial determination.

MAIN OUTCOME MEASURES

Myocardial infarction or cardiac death during six months of follow up.

RESULTS

29 events were detected (4.8%). No patient with a negative early exercise test (n = 161) had events versus the 6.9% event rate in the remaining patients (p = 0.0001). Four independent predictors were found: chest pain score > or = 11 points (odds ratio (OR) 2.4, 95% confidence interval (CI) 1.1 to 5.5, p = 0.04), diabetes mellitus (OR 2.3, 95% CI 1.1 to 4.7, p = 0.03), previous coronary surgery (OR 3.1, 95% CI 1.3 to 7.6, p = 0.01), and ST segment depression (OR 2.8, 95% CI 1.3 to 6.3, p = 0.003). A risk score proved useful for patient stratification according to the presence of 0-1 (2.7% event rate), 2 (10.2%, p = 0.008), and 3-4 predictors (29.2%, p = 0.0001).

CONCLUSIONS

A negative troponin result does not assure a good prognosis for patients coming to the emergency room with chest pain. Early exercise testing and clinical data should be carefully evaluated for risk stratification.

Plasmonic technology: novel approach to ultrasensitive immunoassays

At the Center for Fluorescence Spectroscopy, we have taken advantage of the favorable properties of surface plasmon-coupled emission (SPCE) to improve fluorescence-based immunoassays. SPCE occurs when excited fluorophores near conducting metallic structures efficiently couple to surface plasmons. These surface plasmons, appearing as free electron oscillations in the metallic layer, produce electromagnetic radiation that preserves the spectral properties of fluorophores but is highly polarized and directional. SPCE immunoassays provide several advantages over other fluorescence-based methods. This review explains new approaches to fluorescence immunoassays, including our own use of SPCE for simultaneous detection of more than one fluorescent marker and performance of immunoassays in the presence of an optically dense medium, such as whole blood.

Patients With Prolonged Ischemic Chest Pain and Presumed-New Left Bundle Branch Block Have Heterogeneous Outcomes Depending on the Presence of ST-Segment Changes

OBJECTIVES

The purpose of this research was to examine the prognostic value of ST-segment changes (concordant ST-segment elevation and/or precordial V1 to V3 ST-segment depression) during presumed-new left bundle branch block (LBBB) in patients receiving fibrinolytic therapy.

BACKGROUND

These patients are often considered high-risk, but their outcome is not well-defined.

METHODS

The Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial compared bivalirudin with heparin in patients receiving streptokinase for ST-segment elevation or presumed-new LBBB. Each patient with LBBB was matched with a control (with normal intraventricular conduction) for age, gender, pulse rate, systolic blood pressure, Killip class, and region.

RESULTS

A total of 300 patients had LBBB (92 with and 208 without ST-segment changes) and 15,340 had normal conduction. Acute myocardial infarction (AMI) occurred in 80.7% of LBBB patients and 88.7% of controls (p = 0.006). ST-segment changes were specific (96.6%) but not sensitive (37.8%) for enzymatic diagnosis of AMI. Mortality at 30 days was similar in LBBB patients with ST-segment changes (21.7%) and controls (25.0%, p = 0.563), but lower in LBBB patients without ST-segment changes than in controls (13.5% vs. 21.6%, p = 0.022). In the whole HERO-2 cohort, the LBBB patients with ST-segment changes had higher mortality than patients with normal conduction (odds ratio [OR] 1.37, 95% confidence interval [CI] 0.78 to 2.42). The LBBB patients without ST-segment changes had lower mortality than patients with normal conduction (OR 0.52, 95% CI 0.33 to 0.80).

CONCLUSIONS

ST-segment changes during LBBB are specific for the diagnosis of AMI and predict 30-day mortality; LBBB patients without ST-segment changes have lower adjusted 30-day mortality than those with normal conduction. Trials are required to determine the best treatment for high-risk and low-risk patients with LBBB.

Myoglobin immunoassay based on metal particle-enhanced fluorescence

Enhanced fluorescence on silver island films (SIFs) is utilized to develop a sandwich-format immunoassay for the cardiac marker myoglobin (Myo). Myoglobin was first captured on surfaces coated with anti-Myo antibodies; the surface was then incubated with fluorescently labeled anti-Myo antibodies. The system was examined on glass surfaces and on SIFs. We observed the enhancement of the signal from SIFs in the range of 10-15-fold if compared to the signal from the glass substrate not modified with a SIF. A kinetic immunoassay for Myo on SIF-modified surface results in a decreased background signal. The initial results show that it is possible to detect Myoglobin concentrations below 50 ng/mL, which is lower than clinical cut-off for Myoglobin in healthy patients. We suggest the use of SIF-modified substrates for increasing the sensitivity of surface assays with fluorescence detection.

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.

The effect of cardiac troponin testing on clinical care in a veterans population: a randomized controlled trial

BACKGROUND

Cardiac troponin is more accurate than creatine kinase (CK) testing for detecting myocardial injury in patients with acute coronary syndromes (ACS), but its effects on clinical care compared with CK testing alone is open to question.

OBJECTIVE

To test the effects of troponin I on medical decisions for patients undergoing cardiac enzyme testing.

DESIGN

Randomized, controlled trial.

SETTING

Urban academic Veterans Affairs medical center.

PATIENTS

Three hundred ninety-two patients presenting to the emergency department (ED) and outpatient settings with symptoms and/or electrocardiograms suggestive but not diagnostic of ACS.

INTERVENTION

Random assignment to linked CK-troponin I (CKTnI) testing or CK testing alone.

MEASUREMENTS

ED discharge and cardiac catheterization incidence (primary); ED medication use, inpatient noninvasive testing, revascularization procedures, discharge medications, and 8-week ED visits, hospitalizations, and procedures (secondary).

RESULTS

Groups were similar in all variables except history of heart failure (CK 26.8% vs CKTnI 17.0%). ACS comprised 12.2% of the cohort. ED discharge incidence was greater in the CKTnI arm (18% vs 9.6%; relative risk [RR], 1.83; 95% CI, 1.08 to 3.31; P=.02; number needed to test=12.6; 95% CI, 4.5 to 130). Troponin testing had no significant effect on catheterization incidence (18.2% vs 14.5%; RR, 1.19; 95% CI, 0.72 to 1.92; P>.20) or other outcomes except follow-up echocardiography (13.4% vs 7.4%; RR, 2.24; 95% CI, 1.11 to 4.69; P=.02).

CONCLUSIONS

In a veterans population undergoing cardiac enzyme testing, CKTnI testing led to more ED discharges than CK testing alone but had no effect on inpatient care and was associated with more echocardiograms in a follow-up period.

Using biomarkers to assess risk and consider treatment strategies in non-ST-segment elevation acute coronary syndromes

Since the first biomarker of myocardial necrosis was described in 1954, cardiac-specific biomarkers have been increasingly identified. This, coupled with dramatic evolution in assay technology and resultant highly sensitive assays, has rendered a remarkable transformation in the medical use of biomarkers. Initially used to aid in diagnosis of myocardial infarction, newer biomarkers of inflammation, plaque instability, and ischemia may complement biomarkers of necrosis by providing tools to diagnose impending myocardial necrosis before irreversible damage occurs, and offering additional information for risk stratification. Importantly, biomarkers of different processes may be combined to enhance risk stratification above that of any single marker.

Risk stratification in non-ST elevation acute coronary syndromes: predictive power of troponin I, C-reactive protein, fibrinogen and homocysteine

INTRODUCTION

In acute coronary syndromes, myocardial damage markers and acute-phase reactants predict adverse cardiac events. The aim of this study was to define the fitted prognostic value of the most widely used variables of necrosis and inflammation as well as of homocysteine.

METHODS AND RESULTS

Troponin I, high-sensitivity C-reactive protein, fibrinogen and homocysteine were measured in 515 consecutive patients admitted to our institution for non-ST elevation acute coronary syndrome. The risk for major events (death or nonfatal myocardial infarction) through 6 months of follow-up was analysed. In the univariate analysis, all markers were related to major events (p<0.01 in all cases). In a multivariate model fitting for baseline characteristics and electrocardiographic changes, the only biomarkers related to major events were C-reactive protein >11 mg/l (2.1 [1.2-3.8] p=0.007) and troponin I >3 ng/ml (1.9 [1.1-3.4] p=0.03). Moreover, the rate of major events was significantly higher (p<0.0001) only when both C-reactive protein and troponin I were increased (31.4% vs. 9.3% if any or both markers were normal).

CONCLUSION

In non-ST elevation acute coronary syndromes elevated levels of troponin I, C-reactive protein, fibrinogen and homocysteine are strongly related to the risk of major events. The prognostic value of troponin I and C-reactive protein is independent and additive with respect to each other.

Evaluation and management of the acutely dyspneic patient: the role of biomarkers

The etiology of dyspnea can often be difficult to rapidly and accurately determine and can delay timely and appropriate therapies. The current literature reveals important diagnostic, prognostic, and therapeutic implications of several currently used biomarkers: sensitive d -dimer, myoglobin, creatine kinase-MB, cardiac troponins, and b-type natriuretic peptide. These biomarkers were found to have a high sensitivity and negative predictive value for rapidly ruling out potential serious etiologies of dyspnea, namely, pulmonary embolism (PE), acute myocardial infarction (AMI), and congestive heart failure (CHF). In the setting of a low to moderate pretest probability of PE, a negative sensitive d -dimer can rule out a PE with 97% accuracy. After 10 hours from the onset of symptoms, normal levels of myoglobin, creatine kinase-MB, and cardiac troponin I can rule out an AMI with greater than 96% accuracy. A b-type natriuretic peptide level less than 80 pg/mL can confidently rule out decompensated CHF with greater than 99% accuracy. However, no literature was found analyzing the use of these biomarkers in combination. A dyspnea biomarker panel could rapidly and accurately assist a clinician to rule out PE, AMI, and CHF. If a PE, AMI, or CHF is determined to be the cause of dyspnea, a biomarker panel could help risk stratify and help determine initial therapies. Subsequent clinical research is needed to corroborate this postulation.

Laboratory diagnosis of acute myocardial injury

Considerable effort by clinicians and scientists focuses on the utility of biomarkers to prevent, diagnose and manage adverse cardiac events as well as provide information on a specific patient's underlying pathology. Although troponins I and T (TnI and TnT) are cardiac specific markers that yield diagnostic and prognostic value in patients with myocardial injury, troponins cannot be utilized in all clinical settings. Troponins have limited utility for the diagnosis of early ischemia and preoperative myocardial infarction. Troponin T also lacks specificity in patients with renal failure. New markers, such as ischemia modified albumin (IMA) and CD40 ligand, and new technologies, such as proteomics, are under investigation to advance our knowledge of heart disease.

Risk stratification after hospitalization for decompensated heart failure

BACKGROUND

Decompensated heart failure (HF) is among the most common indications for hospitalization in the United States, but little is known about features on admission that predict adverse events. We used data from the Outcomes of a Prospective Trial of Intravenous Milrinone for Exacerbations of Chronic Heart Failure (OPTIME-CHF) study to develop a model that would predict outcomes in patients with decompensated HF.

METHODS AND RESULTS

OPTIME-CHF randomized 949 patients hospitalized with decompensated HF for 48 to 72 hours of infusion of either milrinone or placebo. We used multivariable modeling to evaluate variables on admission that would be predictive of 60-day mortality or the composite of death or rehospitalization at 60 days. Variables at presentation that predicted death at 60 days were increased age, lower systolic blood pressure, New York Heart Association class IV symptoms, elevated blood urea nitrogen (BUN), and decreased sodium. Predictors of the composite of death or rehospitalization within 60 days were the number of HF hospitalizations in the preceding 12 months, elevated BUN, lower systolic blood pressure, decreased hemoglobin, and a history of percutaneous coronary intervention (PCI). The discriminatory power of the model was substantial for the mortality model (c-index .77) but less for the composite endpoint (c-index .69).

CONCLUSIONS

Risk stratification of patients with decompensated HF may be accomplished using easily assessed clinical variables. Further research into the validity of this model in independent samples will potentially aid in the development of risk stratification strategies.

New cut-off values of cardiac markers for risk stratification of angina pectoris

BACKGROUND

The aim of this present prospective study was to investigate the accuracy of cardiac markers for the prediction of subsequent cardiac events (cardiac death, acute myocardial infarction and recurrent ischemia requiring coronary revascularization).

METHODS

Fibrinogen, cardiac troponin T, troponin I, creatine phosphokinase myocardial fraction, C-reactive protein and myoglobin at baseline and after 6 h were measured on 154 patients (109 male, 63+/-11 years) with chest pain. Receiver operator characteristic analyses were performed to determine cut-off points of cardiac markers in prediction of adverse events.

RESULTS

The following cut-off values for prediction of cardiac events were calculated: troponin I at baseline 0.3 ng/ml (predictive accuracy=0.870), troponin I at 6 h 0.50 ng/ml (p.a.=0.909); troponin T at baseline 0.05 ng/ml (p.a.=0.643), troponin T at 6 h 0.05 ng/ml (p.a.=0.612), creatine phosphokinase myocardial fraction at baseline 2.0 ng/ml (p.a.=0.721), creatine phosphokinase myocardial fraction at 6 h 2.5 ng/ml (p.a.=0.734), myoglobin at baseline 23 ng/ml (p.a.=0.623), myoglobin at 6 h 26 ng/ml (p.a.=0.617), C-reactive protein at baseline 0.31 mg/dl (p.a.=0.662), C-reactive protein at 6 h 0.55 mg/dl (p.a.=0.682), and fibrinogen at baseline 360 mg/dl (p.a.=0.701). The combination of baseline troponin I with different parameters resulted in a higher sensitivity of up to 98%, with a similar predictive accuracy, but a lower specificity. Additive measurements of cardiac troponin I at 6 h to baseline cardiac troponin T and I proved to be the best combination for prediction of subsequent cardiac events.

CONCLUSIONS

Changes in cut-off levels of cardiac markers and inflammatory parameters results in a high accuracy of risk stratification in patients with chest pains. Combination of these measurements might further help in the identification of patients who would benefit from early coronary revascularization.

Multimarker risk strategy for predicting 1-month and 1-year major events in non-ST-elevation acute coronary syndromes

BACKGROUND

The aim of this study was to define the utility of the combined measurement of troponin I, myoglobin, C-reactive protein, fibrinogen, and homocysteine to predict risk in non-ST elevation acute coronary syndromes.

METHODS

Troponin I, myoglobin, high-sensitivity C-reactive protein, fibrinogen, and homocysteine were measured in 557 consecutive patients admitted to our institution for non-ST elevation acute coronary syndrome. The risk for major events (death or nonfatal myocardial infarction) at first month and at first year follow-up was analyzed.

RESULTS

In a multivariate model adjusting for baseline characteristics and electrocardiographic changes, the only biomarkers related to major events at first month were C-reactive protein (P = .007) and myoglobin (P = .02), and at first year troponin I (P = .02), C-reactive protein (P = .03), and homocysteine (P = .04). The rate of major events depending on the number (0-5) of elevated biomarkers were at first month: 4.1%, 3.7%, 5.7%, 6.1%, 6.5%, and 30.8% (P < .0001), and at first year: 8.2%, 11.1%, 12.3%, 16.2%, 23.7%, and 50% (P < .0001). A simple score including the number of elevated biomarkers showed an adjusted risk of major events of 1.6 [1.3-1.9] at first month and of 1.4 [1.2-1.7] at first year.

CONCLUSIONS

Markers of myocardial damage, inflammation, and homocysteine analyzed separately provide prognostic information. The number of elevated biomarkers is an independent risk predictor of major events.

Abnormal Ankle Brachial Indices may Predict Cardiovascular Disease Among Diabetic Patients Without Known Heart Disease

BACKGROUND

Cardiovascular disease remains the primary cause of diabetes-associated morbidity and mortality. Previous studies have failed to provide accurate, inexpensive, screening techniques to detect cardiovascular disease in diabetics. Ankle brachial indices (ABI) testing may be an effective screening technique for diabetics.

METHODS AND RESULTS

The aim of this 100-subject clinical study was to determine cardiovascular disease prevalence, via perfusion stress testing, in diabetic patients having abnormal ABI (<0.90) and without known heart disease who were referred to the South Carolina Heart Center, Columbia, SC for nuclear perfusion stress testing. Study data were analyzed using frequency and descriptive statistics and 2-sample T-testing. Mean subject age was 62+/-11 years, ABI 0.76+/-13, and ejection fraction 60+/-12%. Perfusion stress testing detected 49 abnormal electrocardiograms, 36 subjects with coronary ischemia, 20 with diminished left ventricular function, and 26 subjects having significant thinning of the myocardium. There were 71 subjects who tested positive for at least one form of cardiovascular disease. The sole predictive variable reaching significance for the presence of cardiovascular disease was an ABI score <0.90 (p< or =0.0001).

CONCLUSION

Cardiovascular disease may be predicted among diabetic patients via ABI scores and confirmed by nuclear perfusion testing.

Ischemia-modified albumin improves the usefulness of standard cardiac biomarkers for the diagnosis of myocardial ischemia in the emergency department setting

We studied the role of ischemia-modified albumin (IMA) with standard biomarkers (myoglobin, creatine kinase-MB [CK-MB], troponin I [TnI]) in assessment of 200 patients with suspected myocardial ischemia admitted to the emergency department. Every case was reviewed by a cardiologist. A clinical diagnosis of ischemia was assigned and correlated with biomarker test results. Of the patients, 25 (13.0%) had myocardial ischemia. Receiver operating characteristic curves demonstrated IMA as highly sensitive but somewhat poorly specific for the presence of ischemia (area under curve, 0.63; P = .01). With a cut point of 90 U/mL, the Albumin Cobalt Binding Test had 80% sensitivity and 31% specificity for diagnosing ischemia and a negative predictive value of 92%. IMA was positive in 4 of 5 patients with electrocardiographic (ECG) evidence of ischemia and 16 of 20 patients with coronary ischemia but negative ECG. Among the same patients, the myoglobin-CK-MB-TnI triad had a sensitivity of 57%. The combination of IMA-myoglobin-CK-MB-TnI increased the sensitivity for detecting ischemia to 97%, with a negative predictive value of 92%. IMA is highly sensitive and has a high negative predictive value, which might improve the usefulness of standard biomarkers of myocardial ischemia.

Quantitative T-wave analysis predicts 1 year prognosis and benefit from early invasive treatment in the FRISC II study population

AIMS

To investigate the prognostic value of T-wave abnormalities in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS), and whether such ECG changes may predict benefit from an early coronary angiography. Although ST-segment changes are considered the most important ECG feature in NSTE-ACS, T-wave abnormalities are the most common ECG finding. We hypothesize that a new quantitative approach to T-wave analysis could improve the prognostic value of this ECG abnormality.

METHODS AND RESULTS

Quantitative T-wave analysis was performed on the admission ECG in 1609 patients with NSTE-ACS. Nine different categories of T-wave abnormality were analysed for their prognostic value concerning clinical outcome in patients not randomized to early coronary angiography. Also, the presence of one category (i.e. T-wave abnormality in > or =6 leads) was analysed for its predictive value concerning benefit from early coronary angiography. The combined study endpoint was death or myocardial infarction at 1 year follow-up. Patients with > or =6 leads with abnormal T-waves and concomitant ST-segment depression had a higher risk when not receiving early coronary angiography (24 vs. 12%, respectively; P=0.003), but could be brought to the same level of risk as the remaining patients with this treatment. For non-invasively treated patients five different categories of T-wave abnormality were significantly associated with an adverse outcome.

CONCLUSION

New quantitative T-wave analysis of the admission ECG gives additional predictive information concerning clinical outcome and identifies patients who benefit from early coronary angiography.

Myoglobin immunoassay utilizing directional surface plasmon-coupled emission

We described an immunoassay for the cardiac marker myoglobin on a thin silver mirror surface using surface plasmon-coupled emission (SPCE). SPCE occurs for fluorophores in proximity (within approximately 200 nm) of a thin metal film (in our case, silver) and results in a highly directional radiation through a glass substrate at a well-defined angle from the normal axis. We used the effect of SPCE to develop a myoglobin immunoassay on the silver mirror surface deposited on a glass substrate. Binding of the labeled anti-myoglobin antibodies led to the enhanced fluorescence emission at a specific angle of 72 degrees . The directional and enhanced directional fluorescence emission enables detection of myoglobin over a wide range of concentrations from subnormal to the elevated level of this cardiac marker. Utilizing SPCE allowed us also to demonstrate significant background suppression (from serum or whole blood) in the myoglobin immunoassay. We expect SPCE to become a powerful technique for performing immunoassays for many biomarkers in surface-bound assays.

A change in serum myoglobin to detect acute myocardial infarction in patients with normal troponin I levels

We sought to determine the sensitivity of a change in myoglobin for acute myocardial infarction (AMI) in patients who had normal levels of troponin I at presentation. Myoglobin increases as soon as 1 to 2 hours after symptom onset in AMI. The change in myoglobin may help identify AMI in patients with normal cardiac levels of troponin I on admission. A total of 817 consecutive patients who were examined in the emergency department for possible AMI were studied. In patients whose electrocardiograms were nondiagnostic, we measured levels of myoglobin and cardiac troponin I at presentation, at 90 minutes, and at 3 and 9 hours. Patients whose initial levels of myoglobin (<200 ng/ml) and cardiac troponin I (<0.4 ng/ml) were normal underwent receiver-operating characteristic curve analysis to determine the best cutpoint for a myoglobin increase from 0 to 90 minutes. Overall, 75 patients (9%) were diagnosed with AMI, including 27 patients with normal cardiac levels of troponin I at presentation. An increase of 20 ng/ml of myoglobin from 0 to 90 minutes provided maximal diagnostic utility in patients who did not have increased levels of myoglobin or cardiac troponin I at presentation. In the absence of an increased level of cardiac troponin I or myoglobin at presentation in the emergency department, a change >or=20 ng/ml of myoglobin at 90 minutes produced 83.3% sensitivity, 88.6% specificity, and 99.5% negative predictive value for AMI. The combined sensitivity of levels of cardiac troponin I and myoglobin and a change >or=20 ng/ml of myoglobin over 90 minutes was 97.3%. In emergency department patients with normal cardiac levels of troponin I at presentation, a change in myoglobin provides a highly accurate diagnosis of AMI within 90 minutes.

Delta creatine kinase–MB outperforms myoglobin at two hours during the emergency department identification and exclusion of troponin positive non–ST-segment elevation acute coronary syndromes

STUDY OBJECTIVE

Limited information is available about the diagnostic performance of creatine kinase (CK)-MB and myoglobin levels during the early evaluation of chest pain patients using cardiac troponins as the criterion standard for diagnosing acute myocardial infarction. In this study, we compare the sensitivity and specificity of the baseline, 2-hour absolute, and 2-hour delta values of myoglobin and CK-MB mass assay for detection of acute myocardial infarction using cardiac troponin I (troponin) as the sole marker of myocardial necrosis.

METHODS

A prospective observational study was conducted of 975 chest pain patients with a baseline troponin level of 1.0 ng/mL or less (Abbott Axsym Assay) and an initial ECG nondiagnostic for injury. CK-MB, myoglobin, and troponin levels were all measured on the Abbott Axsym immunoassay. Acute myocardial infarction was diagnosed if there was at least 20 minutes of chest pain and any one of the following criteria within 24 hours of ED presentation: a serial increase in troponin to more than 1.0 ng/mL, new Q-wave formation in 2 contiguous leads, or patient death by cardiac or unknown cause. The optimal values of CK-MB and myoglobin were chosen at the most accurate value on the receiver operating characteristic (ROC) curve (ie, value with lowest false-negative and false-positive rate) of the 2-hour absolute and 2-hour delta value for predicting acute myocardial infarction.

RESULTS

Acute myocardial infarction was diagnosed in 44 (4.5%) of the 975 study patients. ROC curve analysis revealed no statistically significant differences in areas for myoglobin and CK-MB values at baseline and 2 hours for determination of acute myocardial infarction. However, the ROC curve area of the delta CK-MB level significantly outperformed the ROC curve area of the delta myoglobin level for early identification of acute myocardial infarction (0.97 versus 0.81; 95% confidence interval [CI] for difference between areas 0.09 to 0.24). At the most accurate cutoff value, a 2-hour delta CK-MB level more than 0.7 ng/mL had a sensitivity of 93.2% (95% CI 81.3% to 98.5%), a specificity of 94.4% (95% CI 92.7% to 95.8%), a positive likelihood ratio of 16.7, and a negative likelihood ratio of 0.07.

CONCLUSION

A 2-hour delta CK-MB level outperforms myoglobin level in the early identification and exclusion of acute myocardial infarction in non-ST-segment elevation chest pain patients. This finding suggests that myoglobin may no longer be the optimal early marker of acute myocardial infarction when troponins are used as the criterion standard.

[Independent role of C reactive protein to predict major events at one-month and at one-year in acute coronary syndrome without ST elevation]

BACKGROUND AND OBJECTIVE

We intended to determine whether C-reactive protein (CRP) provides independent prognostic information after a non-ST elevation acute coronary syndrome.

PATIENTS AND METHOD

We prospectively studied 630 consecutive patients admitted with a diagnosis of non-ST elevation acute coronary syndrome. Cut-off values were: troponin I > 1 ng/ml (n = 354; 56%) and CRP > 11 mg/l (n = 273; 43%).

RESULTS

Within a one-year follow-up period, 56 (9%) cardiac deaths, 85 (13%) myocardial infarctions (MI) and 127 (20%) first major events were detected. Patients with increased CRP showed higher rates of death at one-month (8% vs 1%), death at one-year (15% vs 4%), myocardial infarction at one-month (8% vs 4%), myocardial infarction at one-year (19% vs 9%), major events at one-month (15% vs 5%) and major events at one-year (30% vs 13%). In the multivariate analysis, once adjusted for baseline and electrocardiogram data and for myocardial damage markers, CRP was an independent predictor of death at one-month (odds ratio [OR] 4.6) and death at one-year (OR = 2.7), major events at one-month (OR = 1.8) and major events at one-year (OR = 1.8). Troponin I predicted MI at one-month (OR = 2.5) and MI at one-year (OR = 2.2).

CONCLUSIONS

CRP provided independent information to predict major events in non-ST elevation acute coronary syndromes. Troponin I was a more powerful predictor of MI than PCR. The analysis of CRP and myocardial damage markers in the short-term and long-term risk stratification seems worthy.

[Prognostic markers of non-ST elevation acute coronary syndromes]

OBJECTIVES

We analyzed whether the study of systolic function by echocardiography adds independent information to that afforded by biochemical markers in predicting six-month major events after non-ST elevation acute coronary syndrome.

PATIENTS AND METHOD

Baseline clinical and electrocardiographic data as well as serum concentrations of troponin, myoglobin, C-reactive protein, fibrinogen and homocysteine were recorded prospectively in 515 consecutive patients admitted because of non-ST elevation acute coronary syndrome. Ejection fraction (echocardiogram) was determined in 248 cases (48%). Predictors of cardiac death or infarction within the following six months were analyzed.

RESULTS

In the 248 patients in whom ejection fraction was analyzed, 38 major events were recorded. Increased biochemical markers were related to major events (p < 0.05 for all markers). In the final multivariate model, which included clinical, electrocardiographic, serological and systolic function data, ejection fraction was the most powerful predictor of six-month major events: age > 70 years (p = 0,04), insulin-dependent diabetes (p = 0.03), C-reactive protein > 11 mg/l (p = 0.004) and ejection fraction < 50% (p < 0.0001); C-statistic = 0.80.

CONCLUSIONS

Apart from the clinical and biochemical profile, analysis of systolic function is advisable for correct risk stratification of patients with non-ST elevation acute coronary syndrome.

Risk stratification in patients with unstable angina and non-ST-elevation myocardial infarction

Risk stratification in acute coronary syndromes is important both for prognosis and for treatment. Consistently, using any of a variety of clinical predictors of risk, patients at highest risk for poor outcomes derive the greatest benefit from aggressive therapy with early coronary angiography, glycoprotein IIb/IIIa antagonists, or low molecular weight heparins. By contrast, patients at low risk may be managed conservatively without long-term impact on their risk of death or myocardial infarction. Several clinical and laboratory parameters have been identified as independent, powerful predictors of poor outcome, helping to distinguish high-risk from low-risk patients. Although not a substitute for astute clinical judgment, risk prediction scores may help clinicians to synthesize the relevant clinical data at presentation into an overall assessment of risk, allowing for cost-effective utilization of therapies that add significant expense and morbidity. With the ever-expanding range of pharmacologic and interventional therapies that impact the treatment of patients with unstable angina and non-ST-elevation myocardial infarction (NSTEMI), risk stratification will become increasingly important in targeting therapies to those who are likely to achieve the most benefit. In this review, we first consider the identifiable components of risk in patients presenting with unstable angina or NSTEMI and then evaluate the emerging information regarding differential response to treatment based on the presence of these risk factors.

The significance of troponin T and CK-MB release in coronary artery bypass surgery

Measurement of cardiac markers is an index of care standard in the assessment and diagnosis of cardiovascualr disease. Two of the major cardiac markers are Creatine Kinase isoenzyme CK-MB and Troponin T, which are extensively used in the diagnosis of heart disease. The release of Troponin T and creatine kinase isoenzyme (CK-MB) was investigated in 50 coronary artery bypass surgery patients. Measurement of plasma samples was carried out at five different time points, namely before surgery, 1,6,12,24 hours after surgery. The results indicated that CK-MB level were increased by a factor more than four times compared with the upper limit of baseline (befor surgery). Troponin T concentration showed more than six fold over the upper limit of baseline (before surgert) at 1,6,12,24 hours after surgery. In order to assess the significance of the length of the surgical procedure on the release of Troponin T and CK-MB, the surgery patient were divided into two groups according to the length of the surgical procedure: group I was selected on the basis that the surgical procedure they underwent lasted above 90 minutes and group II with a surgical procedure below 90 minutes. Both Troponin T and CK-MB showed a significant increase in-group I compared to group II. To investigate the likelihood that this effect is party due to myocardial infarction during surgery, the patients were divided into two groups: Group A with some sings of myocardial infarction on Q wave of ECG and group B without any change. The results showed approximately a two-fold increase of these markers in-group A compared to group B. Since these markers reach into blood following damage to myocardial their increase in patients with time course surgery of more than 90 minutes and those with a probability of MI during operation, indicating that these patient fall into a high risk group of repeat (MI) after surgery.

Prognostic significance of an elevated creatine kinase in the absence of an elevated troponin I during an acute coronary syndrome

In patients with troponin-negative acute coronary syndromes, creatine kinase (CK)-MB elevation predicts a significantly higher risk of death and major acute cardiac events compared with CK-MB negative patients. This risk is accentuated in troponin-negative, CK-MB positive patients who do not demonstrate ST elevation by electrocardiogram.

Development of a displacement immunoassay for human heart-type fatty acid-binding protein in plasma: the basic conditions

To risk-stratify patients with chest pain who are admitted to emergency rooms and for whom initial evaluation is not conclusive, the use of cardiac markers has become a standard procedure. A recently introduced early plasma marker for acute myocardial infarction (AMI) is the 14.5-kDa cytoplasmic heart-type fatty acid-binding protein (FABP). To fully exploit its early release from injured myocardium, a rapid method for repeated measurements or continuous monitoring of FABP in plasma is desirable. Such an on-line method could be an immunosensor based on displacement. The aim of the present study was to further investigate the principles underlying the displacement assay of FABP, both in buffer and in plasma. Batches of sepharose-bound FABP were loaded with an antibody-horseradish peroxidase (HRP) conjugate (anti-FABP). Continuous measurement of FABP was mimicked by repeated addition of FABP containing solutions followed by several washing steps. In the presence of free FABP the antibody-HRP complex dissociated and was subsequently quantified. Significant displacement in the presence of free FABP was observed in both buffer and human plasma. Anti-FABP could be intermittently displaced in the same batch, for at least 9 h, and the displacement was concentration-dependent. These results show the feasibility of a sensor based on the displacement principle to be used for the diagnosis of AMI in emergency medicine.

The prognostic significance of serial myoglobin, troponin I, and creatine kinase-MB measurements in patients evaluated in the emergency department for acute coronary syndrome

STUDY OBJECTIVE

We sought to determine the value of serial measurements of myoglobin, cardiac troponin I (cTnI), and creatine kinase-MB (CK-MB) to predict 30-day adverse events in patients evaluated in the emergency department (ED) for possible acute coronary syndrome.

METHODS

Serum myoglobin, cTnI, and CK-MB levels were measured at presentation, 90 minutes, 3 hours, and 9 hours in patients evaluated in the ED for possible acute coronary syndrome. In 764 consecutive patients, the ability of each individual marker and combination of markers to predict a 30-day adverse event (death or myocardial infarction) over time was calculated.

RESULTS

There were 109 (14%) patients with an adverse event at 30 days (84 myocardial infarctions and 43 deaths). The sensitivities of initial measurements of myoglobin, cTnI, and CK-MB for identifying adverse events were 60%, 47%, and 52%, respectively. The combined sensitivity of myoglobin and cTnI measurements during a 9-hour period was 94%; specificity was 50%. Measurement of CK-MB did not improve sensitivity.

CONCLUSION

The measurement of both myoglobin and cTnI during a 9-hour period was the most predictive of subsequent adverse events in patients evaluated in the ED for possible acute coronary syndrome.

Status report: Development of emergency medicine research since the Macy Report

In Williamsburg, VA, April 17 to 20, 1994, the Josiah Macy, Jr. Foundation sponsored a conference entitled "The Role of Emergency Medicine in the Future of American Medical Care," a report on which was published in Annals in 1995. This report promulgated recommendations for the development and enhancement of academic departments of emergency medicine and a conference to develop an agenda for research in emergency medicine. The American College of Emergency Physicians' Research Committee, along with several ad hoc members, presents updates in several of the areas addressed by the Macy Report and subsequent conferences, as a status report for the development of emergency medicine research as a whole, as of late 2002.