Accuracy of biomarkers to diagnose acute cardiac ischemia in the emergency department: a meta-analysis

Improvement of Emergency Department Chest Pain Evaluation Using Hs-cTnT and a Risk Stratification Pathway

BACKGROUND

Chest pain is among the most common reasons for presentation to the emergency department (ED) worldwide. Additional studies on most cost-effective ways of differentiating serious vs. benign causes of chest pain are needed.

OBJECTIVES

Our study aimed to evaluate the effectiveness of a novel risk stratification pathway utilizing 5th generation high-sensitivity cardiac troponin T assay (Hs-cTnT) and HEART score (History, Electrocardiogram, Age, Risk factors, Troponin) in assessing nontraumatic chest pain patients in reducing ED resource utilization.

METHODS

A retrospective chart review was performed 6 months prior to and after the implementation of a novel risk stratification pathway that combined hs-cTnT with HEART score to guide evaluation of adult patients presenting with nontraumatic chest pain at a large academic quaternary care ED. Primary outcome was ED length of stay (LOS); secondary outcomes included cardiology consult rates, admission rates, number of ED boarders, and number of eloped patients.

RESULTS

A total of 1707 patients and 1529 patients were included pre- and postimplementation, respectively. Median overall ED LOS decreased from 317 to 286 min, an absolute reduction of 31 min (95% confidence interval 22-41 min), after pathway implementation (p < 0.001). Furthermore, cardiology consult rate decreased from 26.9% to 16.0% (p < 0.0001), rate of admission decreased from 30.1% to 22.7% (p < 0.0001), and number of ED boarders as a proportion of all nontraumatic chest pain patients decreased from 25.13% preimplementation to 18.63% postimplementation (p < 0.0001).

CONCLUSIONS

Implementation of our novel chest pain pathway improved numerous ED throughput metrics in the evaluation of nontraumatic chest pain patients.

Methods and Advances in the Design, Testing and Development of In Vitro Diagnostic Instruments

With the continuous improvement of medical testing and instrumentation engineering technologies, the design, testing and development methods of in vitro diagnostic instruments are developing rapidly. In vitro diagnostic instruments are also gradually developing into a class of typical high-end medical equipment. The design of in vitro diagnostic instruments involves a variety of medical diagnostic methods and biochemical, physical and other related technologies, and its development process involves complex system engineering. This paper systematically organizes and summarizes the design, testing and development methods of in vitro diagnostic instruments and their development in recent years, focusing on summarizing the related technologies and core aspects of the R&D process, and analyzes the development trend of the in vitro diagnostic instrument market.

Myocardial infarction risk is increased by periodontal pathobionts: a cross-sectional study

To establish the role of periodontal pathobionts as a risk factor for myocardial infarction, we examined the contribution of five periodontal pathobionts and their virulence genes' expressions to myocardial injury (Troponin-I) and coronary artery disease burden (SYNTAX-I scores) using hierarchical linear regression. Pathobiont loads in subgingival-plaques and intra-coronary-thrombi were compared. Troponin-I release increased with one 16S rRNA gene copy/ng DNA of Porphyromonas gingivalis (β = 6.8 × 10^-6, 95% CI = 1.1 × 10^-7-2.1 × 10^-5), one-fold increased expressions of fimA (β = 14.3, 95% CI = 1.5-27.1), bioF-3 (β = 7.8, 95% CI = 1.1-12.3), prtH (β = 1107.8, 95% CI = 235.6-2451.3), prtP (β = 6772.8, 95% CI = 2418.7-11,126.9), ltxA (β = 1811.8, 95% CI = 217.1-3840.8), cdtB (β = 568.3, 95% CI = 113.4-1250.1), all p < 0.05. SYNTAX-I score increased with one 16S rRNA gene copy/ng DNA of Porphyromonas gingivalis (β = 3.8 × 10^-9, 95% CI = 3.6 × 10^-10-1.8 × 10^-8), one-fold increased expressions of fimA (β = 1.2, 95% CI = 1.1-2.1), bioF-3 (β = 1.1, 95% CI = 1-5.2), prtP (β = 3, 95% CI = 1.3-4.6), ltxA (β = 1.5, 95% CI = 1.2-2.5), all p < 0.05. Within-subject Porphyromonas gingivalis and Tannerella forsythia from intra-coronary-thrombi and subgingival-plaques correlated (rho = 0.6, p < 0.05). Higher pathobiont load and/or upregulated virulence are risk factors for myocardial infarction.Trial registration: ClinicalTrials.gov Identifier: NCT04719026.

Imaging of Heart Type Fatty Acid Binding Protein Under Acute Reperfusion Ischemia Using Radio-labeled Antibody in Rat Heart Model

Purpose: Heart-type fatty acid binding protein (H-FABP) is primary transporter of free fatty acid and plays an important role in myocardial metabolism, which is characterized by high specificity and rapid appearance under ischemic condition. The objective of this study was to clarify the usefulness of imaging study of targeting H-FABP appearance using radio-labeled antibody, and correlation with myocardial fatty acid metabolism and perfusion in acute reperfusion ischemia. Method: Wistar rats were allotted to sham-operated control group (sham; n=4), ischemia non-reperfused group (IG; n=5), and ischemia-reperfusion group (RG; n=5). Ligation of left coronary artery (LCA) was performed for IG and RG. 20 min of ischemia was followed by 60min of reperfusion for RG. ¹²⁵I labeled anti H-FABP antibody (anti H-FABP), BMIPP and ^99mTc-sestamibi (MIBI) was injected intravenously. Multi-tracer digital autoradiogram was performed using µ-imager^®. The ratio of radioactivity in LCA related (culprit) area to the inferior (remote) area (target uptake ratio=TUR) was generated. Results: In sham group, no visually detectable accumulation was observed for the anti H-FABP image, and TUR_MIBI and TUR_BMIPP were equivalent to 1. In IG, TUR_MIBI and TUR_BMIPP were remarkably low (0.12±0.01, 0.24±0.07). In RG, TUR_MIBI was significantly lower (0.20±0.03, p<0.05 vs. other groups). However, TUR_BMIPP was significantly higher (2.78±1.28, p<0.05) compared to the sham and IG, whereas anti H-FABP showed markedly higher ratio in the reperfused area compared to the sham and IG (3.43±0.73 vs. 0.31±0.13 and 1.09±0.07 for IG and sham; p<0.05, and <0.01, respectively). Conclusion: Anti H-FABP accumulated specifically in reperfused area under acute ischemia, and it accorded to the area where fatty acid metabolism was activated. This study has shown the future potential for clinical application in vivo imaging of acute coronary syndrome.

Role of Creatine Kinase in the Troponin Era: A Systematic Review

Introduction

The diagnosis of non-ST-elevated myocardial infarction (NSTEMI) depends on a combination of history, electrocardiogram, and cardiac biomarkers. The most sensitive and specific biomarkers for cardiac injury are the troponin assays. Many hospitals continue to automatically order less sensitive and less specific biomarkers such as creatine kinase (CK) alongside cardiac troponin (cTn) for workup of patients with chest pain. The objective of this systematic review was to identify whether CK testing is useful in the workup of patients with NSTEMI symptoms.

Methods

We undertook a systematic review to ascertain whether CK ordered as part of the workup for NSTEMI was useful in screening patients with cardiac chest pain. The MEDLINE, Embase, and Cochrane databases were searched from January 1995–September 2020. Additional papers were added after consultation with experts. We screened a total of 2,865 papers, of which eight were included in the final analysis. These papers all compared CK and cTn for NSTEMI diagnosis.

Results

In each of the eight papers included in the analysis, cTn showed a greater sensitivity and specificity than CK in the diagnosis of NSTEMI. Furthermore, none of the articles published reliable evidence that CK is useful in NSTEMI diagnosis when troponin was negative.

Conclusion

There is no evidence to continue to use CK as part of the workup of NSTEMI acute coronary syndrome in undifferentiated chest pain patients. We conclude that CK should not be used to screen patients presenting to the emergency department with chest pain.

State of the Art-High-Sensitivity Troponins in Acute Coronary Syndromes

In cases of suspected acute coronary syndrome (ACS), rapid and accurate diagnosis is essential to establish effective evidence-based medical treatment. Patients' history, clinical examination, 12-lead electrocardiogram, and cardiac biomarkers are cornerstones in initial management. Since high-sensitivity cardiac troponins were established, they have markedly expedited and revolutionized rule-in and rule-out pathways of patients with ACS and changed our everyday clinical practice. Thus, they have become an indispensable tool in daily routine in emergency units. This review focuses on historical and contemporary standards in laboratory biomarkers of myocardial injury and discusses their implication in the context of the updated universal definition of myocardial infarction.

Performance of the modified HEART score in an Asian population

INTRODUCTION

Chest pain is the most common potentially life-threatening presentation to the emergency department (ED). Furthermore, the identification of acute coronary syndrome (ACS) including its risk stratification and subsequent disposition can be challenging. The original HEART score was derived as a predictive tool to risk stratify patients presenting with undifferentiated chest pain (CP) and aid physician decision-making. However, it utilized conventional troponins as its cardiac biomarker component. Our study aims to assess the utility of the modified HEART score with highly sensitive troponins in an Asian setting with mixed ethnicity to determine if it corroborates the findings of another recent Chinese study by Chun-Peng et al. (Journal of Geriatric Cardiology 13:64-69, 2016).

METHODS

Clinical data from 413 patients presenting to the ED for evaluation of chest pain were analyzed. The predictive value of the modified HEART score for determining major adverse cardiac events (MACE) was then evaluated.

RESULTS

A total of 49 patients (11.9%) had a MACE: 31 patients (7.5%) underwent PCI and 1 patient (0.2%) underwent CABG. There were 17 (4.1%) deaths. Three risk groups were elucidated based on MACE. In the low-risk group (0-2), there were 72 patients (17.4%), with a MACE rate of 1.4%. In the intermediate-risk group (3-5), there were 233 patients (56.4%), with a MACE rate of 5.2%. In the high-risk group (6-10), there were 108 patients (26.2%), with a MACE rate of 33.3%.

CONCLUSION

The modified HEART score is an effective risk stratification tool in an ethnically diverse Asian population. Furthermore, it identifies low-risk patients who are candidates for early discharge from a local emergency department.

High-Risk Chief Complaints I: Chest Pain-The Big Three (an Update)

Nontraumatic chest pain is a frequent concern of emergency department patients, with causes that range from benign to immediately life threatening. Identifying those patients who require immediate/urgent intervention remains challenging and is a high-risk area for emergency medicine physicians where incorrect or delayed diagnosis may lead to significant morbidity and mortality. This article focuses on the 3 most prevalent diagnoses associated with adverse outcomes in patients presenting with nontraumatic chest pain, acute coronary syndrome, thoracic aortic dissection, and pulmonary embolism. Important aspects of clinical evaluation, diagnostic testing, treatment, and disposition and other less common causes of lethal chest pain are also discussed.

Observational study to determine the optimal dose of daptomycin based on pharmacokinetic/pharmacodynamic analysis

High doses of daptomycin (DAP) (>6 mg/kg/day) have been preliminarily recommended in recent practical guidelines for methicillin-resistant Staphylococcus aureus infection, to achieve better clinical effects. While such doses can elevate the plasma trough concentration (Cmin) of DAP, there is an associated risk of creatine phosphokinase (CPK) elevation warranting further investigation. In the current study relationships between DAP Cmin and CPK elevation were investigated, and optimal DAP doses were determined. Plasma DAP concentrations were measured in 20 patients. Logistic regression analysis was performed to assess relationships between DAP Cmin and CPK elevation, then a population pharmacokinetic model of DAP was developed. To determine an optimal DAP dose a Monte Carlo simulation (MCS) was performed to minimize the risk of CPK elevation and maximize the probability of successful treatment. In logistic regression analysis DAP Cmin was significantly associated with CPK elevation (odds ratio 1.21, p = 0.048). With respect to dose-dependent increases in the probability of CPK elevation and exposure to DAP, MCS estimated an optimal DAP dose of 4-6 mg/kg/day, corresponding to a minimum inhibitory concentration (MIC) of ≤0.5 μg/mL. For an MIC of 1 μg/mL, MCS estimated an optimal DAP dose of 10 mg/kg/day. However, the probability of CPK elevation associated with high doses of DAP was higher than that associated with the approved doses. In cases where high doses of DAP are administered, close CPK monitoring is required and therapeutic drug monitoring of DAP may be desirable.

The Value of Point-Of-Care Fatty Acid Binding Protein in Patients with Chest Pain in Determining Myocardial Infarction in the Emergency Setting

Introduction

Detecting patients in the early hours of acute myocardial infarction is still a challenge for emergency physicians. Fatty acid binding protein (FABP) was thought to be released into the intravascular space earlier than cardiac troponins. The aim of this study was to determine the diagnostic value of point-of-care FABP test either in diagnosing or excluding myocardial infarction during the initial admission of patients presenting with typical chest pain to the emergency department.

Methods

This study was performed in a tertiary care emergency department. Patients with typical chest pain were included into the study. Point-of-care FABP was studied during the initial admission and two hours after admission. Patients were diagnosed as myocardial infarction or not ultimately by ECG and troponin levels.

Results

A total of 224 patients were included into the study, 73 of them (32.6%) were diagnosed as acute myocardial infarction. FABP had a sensitivity and specificity of 41.0% (95%CI 29.7 to 53.2) and 100% (95%CI 97.6 to 100) and myoglobin had a sensitivity and specificity of 57.5% (95%CI 45.4 to 69.0) and 90.7% (95%CI 85.0 to 95.0) during the initial admission. Cardiac troponin T had a sensitivity of 45.2% (95%CI 33.7 to 57.2) and specificity of 100% (95%CI 97.0 to 100) during the initial admission. Two hours after admission, FABP had a sensitivity of 56.0% (95%CI 40.0 to 71.0) and specificity of 99.0% (95%CI 96.4 to 100) respectively.

Conclusions

Point-of-care FABP is good at diagnosing acute myocardial infarction in patients presenting with chest pain. However, FABP was found to be not better than either myoglobin or cardiac troponin T in excluding acute myocardial infarction in patients presenting with chest pain.

Cardiovascular Complications of Cancer Therapy: Best Practices in Diagnosis, Prevention, and Management: Part 1

Modern cancer therapy has successfully cured many cancers and converted a terminal illness into a chronic disease. Because cancer patients often have coexisting heart diseases, expert advice from cardiologists will improve clinical outcome. In addition, cancer therapy can also cause myocardial damage, induce endothelial dysfunction, and alter cardiac conduction. Thus, it is important for practicing cardiologists to be knowledgeable about the diagnosis, prevention, and management of the cardiovascular complications of cancer therapy. In this first part of a 2-part review, we will review cancer therapy-induced cardiomyopathy and ischemia. This review is based on a MEDLINE search of published data, published clinical guidelines, and best practices in major cancer centers. With the number of cancer survivors expanding quickly, the time has come for cardiologists to work closely with cancer specialists to prevent and treat cancer therapy-induced cardiovascular complications.

Cardiac biomarkers of acute coronary syndrome: from history to high-sensitivity cardiac troponin

The role of cardiac troponins as diagnostic biomarkers of myocardial injury in the context of acute coronary syndrome (ACS) is well established. Since the initial 1st-generation assays, 5th-generation high-sensitivity cardiac troponin (hs-cTn) assays have been developed, and are now widely used. However, its clinical adoption preceded guidelines and even best practice evidence. This review summarizes the history of cardiac biomarkers with particular emphasis on hs-cTn. We aim to provide insights into using hs-cTn as a quantitative marker of cardiomyocyte injury to help in the differential diagnosis of coronary versus non-coronary cardiac diseases. We also review the recent evidence and guidelines of using hs-cTn in suspected ACS.

Evaluation of Cardiac Toxicity Biomarkers in Rats from Different Laboratories

There is a great need for improved diagnostic and prognostic accuracy of potential cardiac toxicity in drug development. This study reports the evaluation of several commercially available biomarker kits by 3 institutions (SRI, Eli Lilly, and Pfizer) for the discrimination between myocardial degeneration/necrosis and cardiac hypertrophy as well as the assessment of the interlaboratory and interplatform variation in results. Serum concentrations of natriuretic peptides (N-terminal pro-atrial natriuretic peptide [NT-proANP] and N-terminal pro-brain natriuretic peptide [NT-proBNP]), cardiac and skeletal troponins (cTnI, cTnT, and sTnI), myosin light chain 3 (Myl3), and fatty acid binding protein 3 (FABP3) were assessed in rats treated with minoxidil (MNX) and isoproterenol (ISO). MNX caused increased heart-to-body weight ratios and prominent elevations in NT-proANP and NT-proBNP concentrations detected at 24-hr postdose without elevation in troponins, Myl3, or FABP3 and with no abnormal histopathological findings. ISO caused ventricular leukocyte infiltration, myocyte fibrosis, and necrosis with increased concentrations of the natriuretic peptides, cardiac troponins, and Myl3. These results reinforce the advantages of a multimarker strategy in elucidating the underlying cause of cardiac insult and detecting myocardial tissue damage at 24-hr posttreatment. The interlaboratory and interplatform comparison analyses also showed that the data obtained from different laboratories and platforms are highly correlated and reproducible, making these biomarkers widely applicable in preclinical studies.

Role of copeptin in dual-cardiac marker strategy for patients with chest pain presented to ED

OBJECTIVE

The objective of the study is to evaluate the role of copeptin in the diagnosis of acute coronary syndrome (ACS) and its role in dual-cardiac marker diagnostic strategy with troponin.

DESIGN

A prospective cohort study was carried out from May 2012 to October 2012.

SETTING

The study was conducted at the emergency department (ED) of a public hospital in a cluster of Hong Kong.

METHODS

Patients aged at least 18 years presented with chest pain to ED who have intermediate or high likelihood of ACS were included. All patients had blood taken in the ED for copeptin and troponin I. The adjudicated diagnoses of ACS were made by 2 independent physicians based on the universal definition. Diagnostic characteristics were calculated. Receiver operating characteristic curves were created. Areas under the curves were compared for copeptin, troponin I, and dual-marker strategy with copeptin and troponin I.

RESULTS

A total of 637 patients were recruited. Seventy-eight had been diagnosed to be ACS. The negative predictive value of copeptin for ACS was 0.881 (0.849-0.907) compared with troponin I, 0.937 (0.913-0.956). The areas under the receiver operating characteristic curves of copeptin, troponin I, and dual-marker strategy were 0.68, 0.859, and 0.880, respectively.

CONCLUSIONS

Addition of copeptin to troponin does not have significant improvement of the diagnostic accuracy of ACS in patients presented with chest pain.

Diagnostic accuracy of a new cardiac electrical biomarker for detection of electrocardiogram changes suggestive of acute myocardial ischemic injury

OBJECTIVE

A new cardiac "electrical" biomarker (CEB) for detection of 12-lead electrocardiogram (ECG) changes indicative of acute myocardial ischemic injury has been identified. Objective was to test CEB diagnostic accuracy.

METHODS

This is a blinded, observational retrospective case-control, noninferiority study. A total of 508 ECGs obtained from archived digital databases were interpreted by cardiologist and emergency physician (EP) blinded reference standards for presence of acute myocardial ischemic injury. CEB was constructed from three ECG cardiac monitoring leads using nonlinear modeling. Comparative active controls included ST voltage changes (J-point, ST area under curve) and a computerized ECG interpretive algorithm (ECGI). Training set of 141 ECGs identified CEB cutoffs by receiver-operating-characteristic (ROC) analysis. Test set of 367 ECGs was analyzed for validation. Poor-quality ECGs were excluded. Sensitivity, specificity, and negative and positive predictive values were calculated with 95% confidence intervals. Adjudication was performed by consensus.

RESULTS

CEB demonstrated noninferiority to all active controls by hypothesis testing. CEB adjudication demonstrated 85.3-94.4% sensitivity, 92.5-93.0% specificity, 93.8-98.6% negative predictive value, and 74.6-83.5% positive predictive value. CEB was superior against all active controls in EP analysis, and against ST area under curve and ECGI by cardiologist.

CONCLUSION

CEB detects acute myocardial ischemic injury with high diagnostic accuracy. CEB is instantly constructed from three ECG leads on the cardiac monitor and displayed instantly allowing immediate cost-effective identification of patients with acute ischemic injury during cardiac rhythm monitoring.

Variation of a test's sensitivity and specificity with disease prevalence

BACKGROUND

Anecdotal evidence suggests that the sensitivity and specificity of a diagnostic test may vary with disease prevalence. Our objective was to investigate the associations between disease prevalence and test sensitivity and specificity using studies of diagnostic accuracy.

METHODS

We used data from 23 meta-analyses, each of which included 10-39 studies (416 total). The median prevalence per review ranged from 1% to 77%. We evaluated the effects of prevalence on sensitivity and specificity using a bivariate random-effects model for each meta-analysis, with prevalence as a covariate. We estimated the overall effect of prevalence by pooling the effects using the inverse variance method.

RESULTS

Within a given review, a change in prevalence from the lowest to highest value resulted in a corresponding change in sensitivity or specificity from 0 to 40 percentage points. This effect was statistically significant (p < 0.05) for either sensitivity or specificity in 8 meta-analyses (35%). Overall, specificity tended to be lower with higher disease prevalence; there was no such systematic effect for sensitivity.

INTERPRETATION

The sensitivity and specificity of a test often vary with disease prevalence; this effect is likely to be the result of mechanisms, such as patient spectrum, that affect prevalence, sensitivity and specificity. Because it may be difficult to identify such mechanisms, clinicians should use prevalence as a guide when selecting studies that most closely match their situation.

Triage of patients presenting with chest pain to the emergency department: implementation of coronary CT angiography in a large urban health care system

OBJECTIVE

There is growing evidence supporting the use of coronary CT angiography (CTA) to triage patients in the emergency department (ED) with acute chest pain and low risk of acute coronary syndrome (ACS). We hypothesized that coronary CTA can guide early management and safely discharge patients by introducing a dedicated patient management protocol.

SUBJECTS AND METHODS

We conducted a prospective cohort study in three EDs of a large health care system (> 1300 beds). Five hundred twenty-nine patients (mean age, 52.1 years; 56% women) with chest pain, negative cardiac enzyme results, normal or nondiagnostic ECG findings, and a thrombolysis in myocardial infarction (TIMI) risk score of 2 or less were admitted and underwent CTA. A new dedicated chest pain triage protocol (levels 1-5) was implemented. On the basis of CTA findings, patients were stratified into one of the following four groups: 0, low (negative CTA findings); 1, mild (1-49% stenosis); 2, moderate (50-69% stenosis); or 3, severe (≥ 70% stenosis) risk of ACS. Outcome measures included major adverse cardiac events (MACEs) during the first 30 days after CTA, downstream testing results, and length of stay (LOS). LOS was compared before and after implementation of our chest pain triage protocol.

RESULTS

Three hundred seventeen patients (59.9%) with negative CTA findings and 151 (28.5%) with mild stenosis were discharged from the ED with a very low downstream testing rate and a very low MACE rate (negative predictive value = 99.8%). Twenty-five patients (4.7%) had moderate stenosis (n = 17 undergoing further testing). Thirty-six patients (6.8%) had stenosis of 70% or greater by CTA (n = 34 positive by invasive angiography or SPECT-myocardial perfusion imaging). The sensitivity of CTA was 94%. The rate of MACEs in patients with stenosis of 70% or greater (8.3%) was significantly higher (p < 0.001) than in patients with negative CTA findings (0%) or those with mild stenosis (0.2%). A 51% decrease in LOS-from 28.8 to 14.0 hours--was noted after implementation of the dedicated chest pain protocol (p < 0.001).

CONCLUSION

Chest pain patients with negative or mild nonobstructive CTA findings can be safely discharged from the ED without further testing. Implementation of a dedicated chest pain triage protocol is critical for the success of a coronary CTA program.

Cardiogoniometry as a diagnostic tool in patients with acute coronary syndromes: results of the CGM@ACS trial

BACKGROUND

Cardiogoniometry (CGM) is a novel electrocardiac method utilising computer-assisted three-dimensional information on cardiac potentials.

OBJECTIVE

To investigate the potential of CGM in discriminating non-ST-segment elevation acute coronary syndrome (NSTE-ACS) and relevant coronary stenosis upon hospital admission by prospectively comparing its sensitivity, specificity and accuracy against those of a single troponin test and a 12-lead ECG performed on admission

DESIGN

A multicenter prospective observational trial.

SETTING

Eight interventional cardiac centres in Germany.

PATIENTS

A cohort of 216 patients (mean age 67 years, 34.7 % female) who presented with acute chest pain or dyspnoea without ST-segment elevation and were scheduled for coronary angiography within 72 h of admission.

INTERVENTION

Pre-angiography screening by CGM, troponin test, 12-lead ECG MAIN OUTCOME MEASURES: ECG, troponin and CGM on admission compared with final diagnosis of NSTE-ACS or relevant diameter stenosis ≥70 % verified by an independent review board and an angiographic core laboratory.

RESULTS

NSTE-ACS was finally confirmed in 162 cases, whereas the remaining 54 cases without proof of NSTE-ACS served as controls. Diagnostic sensitivity for NSTE-ACS was 28, 50 and 69 % and specificity 78, 96 and 54 % for first ECG, serial troponin and first CGM, respectively. Accuracy was 40, 62 and 65 %. The sensitivity of the tests to detect relevant coronary stenosis (n = 126) was 32, 53 and 74 %, respectively. The sensitivity of CGM to detect NSTE-ACS (65 %) or relevant stenosis (71 %) was high even in patients with normal troponin and ECG.

CONCLUSIONS

CGM can detect NSTE-ACS at first medical contact. CGM in conjunction with traditional markers, 12-lead ECG and troponin may effectively aid early decision making in patients presenting with acute chest pain.

A translational study of urine miRNAs in acute myocardial infarction

The currently used biomarkers for acute myocardial infarction (AMI) are blood creatinine phosphokinase-muscle band (CPK-MB), troponin-T (TnT), and troponin I (TnI). However, no good biomarkers are identified in urine after AMI, because these blood protein biomarkers are difficult to be filtered into urine. In this study, the role of urine microRNAs in the diagnosis of AMI and the mechanism involved were determined. We found that urine miR-1 was quickly increased in rats after AMI with peak at 24h after AMI, in which an over 50-fold increase was demonstrated. At 7 days after AMI, the urine miR-1 level was returned to the basal level. No miR-208 was found in normal urine. In urine from rats with AMI, miR-208 was easily detected. To determine the mechanism involved, we determined the levels of heart-released miR-1 in the liver, spleen and kidney after AMI in rats and found that the kidney was an important metabolic organ. To determine the renal elimination of blood miRNAs, we isolated serum exosomes from rats after AMI and injected these exosomes into the circulating blood of normal rats. We found that the urine miR-1 was significantly increased in exosome-injected animals. Moreover, PKH67-labeled exosomes injected into circulating blood could enter into the kidney tissues and cells, as well as urine. Furthermore, the levels of urine miR-1 were significantly increased in patients with AMI. The results suggest that urine miRNAs such as miR-1 could be novel urine biomarkers for AMI.

Chapter 8: meta-analysis of test performance when there is a "gold standard"

Synthesizing information on test performance metrics such as sensitivity, specificity, predictive values and likelihood ratios is often an important part of a systematic review of a medical test. Because many metrics of test performance are of interest, the meta-analysis of medical tests is more complex than the meta-analysis of interventions or associations. Sometimes, a helpful way to summarize medical test studies is to provide a "summary point", a summary sensitivity and a summary specificity. Other times, when the sensitivity or specificity estimates vary widely or when the test threshold varies, it is more helpful to synthesize data using a "summary line" that describes how the average sensitivity changes with the average specificity. Choosing the most helpful summary is subjective, and in some cases both summaries provide meaningful and complementary information. Because sensitivity and specificity are not independent across studies, the meta-analysis of medical tests is fundamentaly a multivariate problem, and should be addressed with multivariate methods. More complex analyses are needed if studies report results at multiple thresholds for positive tests. At the same time, quantitative analyses are used to explore and explain any observed dissimilarity (heterogeneity) in the results of the examined studies. This can be performed in the context of proper (multivariate) meta-regressions.

Biomarkers in acute myocardial injury

Acute coronary syndrome (ACS) is a significant cause of morbidity and mortality worldwide. The proper diagnosis of ACS requires reliable and accurate biomarker assays to detect evidence of myocardial necrosis. Currently, troponin is the gold standard biomarker for myocardial injury and is used commonly in conjunction with creatine kinase-MB (CK-MB) and myoglobin to enable a more rapid diagnosis of ACS. A new generation of highly sensitive troponin assays with improved accuracy in the early detection of ACS is now available, but the correct interpretation of assay results will require a careful consideration of assay characteristics and the clinical setting prior to incorporation into routine practice. B-type natriuretic peptides, copeptin, ischemia-modified albumin, heart-type fatty-acid-binding protein, myeloperoxidase, C-reactive protein, choline, placental growth factor, and growth-differentiation factor-15 make up a promising group of other biomarkers that have shown the ability to improve prognosis and diagnosis of ACS compared with traditional markers.

Evaluation of the diagnostic indices and clinical utility of qualitative cardiodetect® test kit in diagnosis of ami within 12 hours of onset of chest pain in the emergency department

Introduction

Cardiac biomarkers may be invaluable in establishing the diagnosis of acute myocardial infarction (AMI) in the ED setting.

Objective

To assess the diagnostic indices of the Cardio Detect assay and the quantitative cardiac troponin T test, in diagnosing AMI in the ED, according to the time of onset of chest pain.

Methodology

A total of 80 eligible patients presenting with ischemic type chest pain with duration of symptoms within the last 36 h were enrolled. All patients were tested for H-FABP and troponin T at presentation to the ED. A repeated Cardio Detect test was performed 1 h after the initial negative result, and a repeated troponin T test was also performed 8-12 h after an initial negative result. The diagnostic indices [sensitivity, specificity, positive predictive value, negative predictive value, receiver operating curve (ROC)] were analyzed for Cardio Detect and Troponin T (individually and in combination) and also for the repeat Cardio Detect test. Data entry and analysis were performed using SPSS version 12.0 and Analyze-it software.

Results

The Cardio Detect test was more sensitive and had a higher NPV than the troponin T (TnT) test during the first 12 h of onset of chest pain. The repeat Cardio Detect had better sensitivity and NPV than the initial Cardio Detect. The sensitivity and NPV of the combination test (Cardio Detect and troponin T) were also superior to each test performed individually.

Conclusion

The Cardio Detect test is more sensitive and has a better NPV than the troponin T test during the first 12 h of AMI. It may be used to rule out myocardial infarction during the early phase of ischemic chest pain.

Cardiac CT in the emergency department: convincing evidence, but cautious implementation

In clinical practice, assessment of chest pain patients presenting to the emergency department is difficult and the work-up can be lengthy and costly. There is growing evidence supporting the use of coronary computed tomography angiography (CTA) in early assessment of patients presenting with acute chest pain to the emergency department. CTA appears to be a faster and more accurate way to diagnosis or rule out coronary stenosis, leading to reduced hospital admissions, decreased time in the ED and lower costs. The focus of this article is to review the current literature of the use of Coronary CTA and "triple rule out" protocols in the emergency department setting and to provide a chest pain algorithm, showing how Coronary CTA can be implemented effectively in clinical practice. Potential pitfalls and requirements for implementation will also be discussed.

Elevated Soluble fms-Like Tyrosine Kinase-1 Levels in Acute Coronary Occlusion

Objective—

Early recognition of an acute coronary occlusion (ACO) improves clinical outcomes. Soluble fms-like tyrosine kinase-1 (sFLT1) is an endothelium-derived protein induced by hypoxia. We tested whether sFLT1 levels are elevated in ACO.

Methods and Results—

Serum sFLT1 levels were measured by enzyme-linked immunosorbent assay in patients with ST-segment elevations and angiographically confirmed ACO, unstable angina/non ST-segment elevation myocardial infarction, and 2 control groups. To further explore sFLT1 release, a mouse model of ACO and in vitro human coronary artery endothelial cell injury were used. sFLT1 levels were increased in ACO compared with unstable angina/non-ST-elevation myocardial infarction, catheterized controls, or healthy volunteers (200.7±15.5 versus 70.7±44.0 versus 10.2±4.0 versus 11.7±1.7 pg/mL respectively, P <0.001 versus ACO). At presentation, all ACO patients had elevated sFLT1 levels (>15 pg/mL, 99th percentile in controls), whereas 57% had levels of the MB isoform of creatine kinase levels >10 ng/mL ( P <0.01) and 85% had ultrasensitive troponin I levels >0.05 ng/mL ( P <0.05). Within 60 minutes after symptom onset, sFLT1 was more sensitive than the MB isoform of creatine kinase or ultrasensitive troponin I for ACO (100% versus 20% versus 20% respectively; P ≤0.01 for each). Within 60 minutes of ACO in mice, sFLT1 levels were elevated. Hypoxia and thrombin increased sFLT1 levels within 15 minutes in human coronary artery endothelial cells.

Conclusion—

sFLT1 levels may be an early indicator of endothelial hypoxia in ACO.

Novel markers, a payer's perspective: commissioning a new service

Diagnostic technologies assist clinicians and care givers in making decisions about the care of individual patients. The demands for an evidence-based approach to practice, is proving to be challenging in the field of laboratory medicine as: (i) there has been little formal requirement to demonstrate evidence of effectiveness prior to the introduction of new tests, (ii) generating evidence of effectiveness of tests depends, in most cases, on complementary actions being accomplished e.g. making the correct decision on receipt of the result, and taking the right action, (iii) the principles of evidence-based laboratory medicine highlight the fact that diagnostic tests have the potential to solve a wide range of problems, in a number of clinical settings, with the potential to generate a varied range of benefits (outcomes), and (iv) outcomes invariably accrue to parts of the health economy outside of the laboratory, which can prove challenging for health service managers. Commissioning a new service involves (a) assessing the local health care needs - and the expected outcomes, (b) specifying the services required-including the resources, and transformational change required, (c) securing the services required - and the implementation strategy to be employed, and (d) monitoring against the contract issued, as well as evaluating the outcomes against the expectations. In this way the purchaser can ensure that diagnostic services are meeting clinical needs, and are being used appropriately to generate the best outcome for the patient and the exchequer, thereby meeting clinical and fiscal governance requirements.

The utility of troponin measurement to detect myocardial infarction: review of the current findings

Myocardial infarction (MI) is defined by the presence of myocardial necrosis in combination with clinical evidence of myocardial ischemia. Cardiac troponins are regulatory proteins within the myocardium that are released into the circulation when damage to the myocyte has occurred. Therefore, serum troponin is an exquisitely sensitive marker of myocardial injury and is necessary for establishing the diagnosis of MI. High-sensitivity troponin assays are improving the diagnostic accuracy and rapid detection of myocardial infarction. The early identification of MI is vital for the institution of anti-thrombotic therapy to limit myocardial damage and preserve cardiac function. Troponin has both diagnostic and prognostic significance in the setting of acute coronary syndrome (ACS). Increased troponin levels in the absence of ACS should prompt an evaluation for an alternative, non-thrombotic mechanism of troponin elevation and direct management at the underlying cause. This review describes the role of troponin in the evaluation of patients with suspected myocardial infarction.

High-risk chief complaints I: chest pain--the big three

Chest pain is one of the most frequently seen chief complaints in patients presenting to emergency departments, and is considered to be a "high-risk" chief complaint. The differential diagnosis for chest pain is broad, and potential causes range from the benign to the immediately life-threatening. Although many (if not most) emergency department patients with chest pain do not have an immediately life-threatening condition, correct diagnoses can be difficult to make, incorrect diagnoses may lead to catastrophic therapies, and failure to make a timely diagnosis may contribute to significant morbidity and mortality. Several atraumatic "high-risk" causes of chest pain are discussed in this article, including myocardial infarction and ischemia, thoracic aortic dissection, and pulmonary embolism. Also included are brief discussions of tension pneumothorax, esophageal perforation, and cardiac tamponade.

Comparison of usefulness of heart-type fatty acid binding protein versus cardiac troponin T for diagnosis of acute myocardial infarction

We aimed to assess the additive diagnostic value of measuring the serum levels of soluble human heart-type fatty acid binding protein (H-FABP) in the early diagnosis of acute myocardial infarction (AMI) in unselected patients with chest pain. A total of 97 consecutive patients with acute ischemic-type chest pain were prospectively enrolled and classified according to the American Heart Association/American College of Cardiology guidelines. The test characteristics of H-FABP and cardiac troponin T serum levels at admission revealed a greater sensitivity of H-FABP in the first 4 hours of symptoms (86% vs 42%, p <0.05). Combining H-FABP and cardiac troponin T also improved the sensitivity in the detection of AMI (97% vs 71%, p <0.05) but demonstrated a greater misclassification rate (25% vs 9%, p <0.05). The specificity of H-FABP was poor (65%, 95% confidence interval 58% to 71%). Receiver operating characteristics revealed a poor performance of H-FABP in patients with non-ST-elevation myocardial infarction. Classification tree analysis demonstrated that an H-FABP-related improvement in the early definite rule-out of AMI (reduction of false-negative rate from 11% to 3%) was at the expense of an increase in the false-positive rate to 5%. In conclusion, measurement of H-FABP, in addition to cardiac troponin T, serum levels within the first 4 hours of symptoms improves the sensitivity and negative predictive value for the detection of AMI at the cost of test accuracy and precision, especially in patients with non-ST-elevation myocardial infarction.

Clinical usefulness of measuring red blood cell distribution width on admission in patients with acute coronary syndromes

BACKGROUND

Conventional cardiac markers used for the biochemical diagnosis of acute coronary syndromes (ACS) have a high specificity but low sensitivity within 2-4 h of symptoms onset. The red blood cell distribution width (RDW), reflecting the size variability of circulating red blood cells, has been shown to be independently associated with an increased risk of major cardiovascular events. We assessed whether there is an association between RDW at admission and cardiac troponin T (cTnT) elevation in patients with chest pain.

METHODS

We analyzed RDW values in 2304 adult patients, who were consecutively admitted over a 1-year period to the local emergency department for chest pain suggestive of ACS. In all patients, a baseline blood sample was collected for routine haematological testing, whereas cTnT was measured at baseline and after 4, 6, and 12 h.

RESULTS

A total of 456 patients (19.8% of total) had ACS. These patients, all having cTnT> or =0.03 microg/L up to 12 h from admission other than ischaemic electrocardiographic changes, had higher RDW than non-ACS patients [median 15.1%, (5th-95th percentiles) 13.2%-19.0% vs. 13.5%, 12.9%-17.1%, p<0.001]. On admission, the sensitivity and specificity of cTnT were 94% (25 false negative results) and 100%, respectively. The diagnostic accuracy of RDW, as calculated by the receiver operating characteristic curve analysis, was 0.705 (p<0.001). At the cut-off value of 14%, the clinical sensitivity and specificity of RDW on admission were 79% and 50%, respectively. In 21 out of 25 patients classified as false negative for cTnT on admission, the RDW was >14%. Accordingly, the diagnostic sensitivity of the two combined measurements on admission was 99%.

CONCLUSIONS

As RDW is widely available to clinicians as a part of the complete blood count, and therefore incurs no additional costs, it might be considered with other conventional cardiac markers for the risk stratification of ACS patients admitted to emergency departments.

Cardiac magnetic resonance with T2-weighted imaging improves detection of patients with acute coronary syndrome in the emergency department

BACKGROUND

Cardiac magnetic resonance (CMR) imaging permits early triage of patients presenting to the emergency department with acute chest pain but has been limited by the inability to differentiate new from old myocardial infarction. Our objective was to evaluate a CMR protocol that includes T2-weighted imaging and assessment of left ventricular wall thickness in detecting patients with acute coronary syndrome in the emergency department.

METHODS AND RESULTS

In this prospective cohort observational study, we enrolled patients presenting to the emergency department with acute chest pain, negative cardiac biomarkers, and no ECG changes indicative of acute ischemia. The CMR protocol consisted of T2-weighted imaging, first-pass perfusion, cine function, delayed-enhancement magnetic resonance imaging, and assessment of left ventricular wall thickness. The clinical outcome (acute coronary syndrome) was defined by review of clinical charts by a consensus panel that used American Heart Association/American College of Cardiology guidelines. Among 62 patients, 13 developed acute coronary syndrome during the index hospitalization. The mean CMR time was 32+/-8 minutes. The new CMR protocol (with the addition of T2-weighted and left ventricular wall thickness) increased the specificity, positive predictive value, and overall accuracy from 84% to 96%, 55% to 85%, and 84% to 93%, respectively, compared with the conventional CMR protocol (cine, perfusion, and delayed-enhancement magnetic resonance imaging). Moreover, in a logistic regression analysis that contained information on clinical risk assessment (c-statistic=0.695) and traditional cardiac risk factors (c-statistic=0.771), the new CMR protocol significantly improved the c-statistic to 0.958 (P<0.0001).

CONCLUSIONS

The present study indicates that a new CMR protocol improves the detection of patients with acute coronary syndrome in the emergency department and adds significant value over clinical assessment and traditional cardiac risk factors.

Usefulness of 201TlCl/ 123I-BMIPP dual-myocardial SPECT for patients with non-ST segment elevation myocardial infarction

OBJECTIVE

Earlier studies suggested that elevated cardiac troponin T (cTnT) might be useful for detecting less severe types of myocardial injury (i.e., non-ST segment elevation myocardial infarction). The objective of this study is to elucidate the usefulness of (201)thallous chloride ((201)TlCl) and (123)I-betamethyl-p-iodophenyl-pentadecanoic acid ((123)I-BMIPP) dual-single-photon emission computed tomography (SPECT) imaging for patients with myocardial infarction (MI) without ST segment elevation.

METHODS

Consecutive 86 patients (56 men and 30 women; mean age 66 +/- 12 years) clinically diagnosed with acute myocardial infarction (AMI) were divided into two groups according to serum creatine kinase MB (CK-MB) and cTnT levels. Group A consisted of 53 patients with increased serum CK-MB and cTnT levels, and Group B, 33 patients with increased serum cTnT without increased serum CK-MB. All patients underwent (201)TlCl and (123)I-BMIPP dual-SPECT about 8 days following the onset. The left ventricular myocardium was divided into 20 segments on each SPECT image, and tracer accumulation in those segments was scored on a five-point scoring system. The total defect scores (TDS) were calculated by summing the scores for all 20 segments, and compared between groups A and B. Group B patients were subdivided into two groups according to the TDS on (123)I-BMIPP images as groups B(S) (severe; TDS > or = 8) and B(M) (mild; TDS < or = 7), and we compared the prognosis over a period of 2 years from the onset between the three groups.

RESULTS

The TDS of group A derived from (201)TlCl and (123)I-BMIPP images was significantly higher than those of group B (14.5 +/- 10.8 vs. 1.5 +/- 2.4 and 20.8 +/- 13.3 vs. 9.1 +/- 6.2, respectively; P < 0.0001). The sensitivities of (201)TlCl and (123)I-BMIPP images were 94.3% (50/53) and 96.2% (51/53) to detect the culprit coronary lesions in group A (no significant difference). In contrast, the sensitivity of (123)I-BMIPP images (72.7%, 24/33) was higher than that of (201)TlCl images (27.3%, 9/33) in group B (P < 0.05). At 2 years of follow-up, the incidence of hard cardiac events in groups A, B(S), and B(M) was 24.5%, 27.8%, and 6.7%, respectively. The rate of group BS, as well as that of group A, was significantly higher than that of group B(M) (P < 0.05).

CONCLUSIONS

Of those with a clinical diagnosis of AMI accompanied by increased cTnT, the CK-MB negative patients accounted for 38% (33/86) of all patients as having non-ST segment elevation myocardial infarction such as NTMI. For such patients, (123)I-BMIPP imaging is useful not only for the detection of the culprit lesions but also for the prediction of the prognosis.

Evaluation of acute coronary syndromes by cardiac magnetic resonance imaging

The use of cardiovascular magnetic resonance (CMR) imaging for the evaluation of patients with acute chest pain and acute coronary syndromes has great potential. The strength of CMR relies on its ability to provide information on anatomy, physiology, and function in a single scanning session in a noninvasive manner without the need for iodinated contrast, radiation, or the need to undergo invasive procedures. Specifically, with regard to imaging patients with acute chest pain and/or myocardial infarction (MI), CMR has the ability to qualitatively and quantitatively evaluate global and regional right and left ventricular systolic functions, myocardial edema, myocardial perfusion, and myocardial infarct size and transmurality/viability. This review will focus on CMR imaging for the following applications: (1) imaging for the evaluation of ventricular function and infarct size in patients with acute chest pain and/or acute MI, (2) for triage and prognosis of patients presenting to the emergency department with acute chest pain, (3) for evaluating patients after sustaining an acute MI, and (4) for stem cell research.

New methods for improved evaluation of patients with suspected acute coronary syndrome in the emergency department

This paper aims to identify and review new and unproven emergency department (ED) methods for improved evaluation in cases of suspected acute coronary syndrome (ACS). Systematic news coverage through PubMed from 2000 to 2006 identified papers on new methods for ED assessment of patients with suspected ACS. Articles found described decision support models, new ECG methods, new biomarkers and point-of-care testing, cardiac imaging, immediate exercise tests and the chest pain unit concept. None of these new methods is likely to be the perfect solution, and the best strategy today is therefore a combination of modern methods, where the optimal protocol depends on local resources and expertise. With a suitable combination of new methods, it is likely that more patients can be managed as outpatients, that length of stay can be shortened for those admitted, and that some patients with ACS can get earlier treatment.

Human heart-type fatty-acid-binding protein as a point-of-care test in the early diagnosis of acute myocardial infarction

BACKGROUND

At very early stages of acute myocardial infarction (AMI), highly sensitive biomarkers are still lacking.

AIM

To evaluate the utility of human heart-type fatty acid-binding protein (h-FABP) for early diagnosis of AMI.

DESIGN

Prospective diagnostic study.

METHODS

Consecutive patients presenting to the emergency department with chest pain or dyspnoea within 24 h of symptom onset were included. At presentation, the h-FABP test result was compared to the standard diagnostic work-up, including repeated ECG and troponin T measurements. Sensitivity analysis was performed for inconclusive tests.

RESULTS

We enrolled 280 patients presenting to hospital with a median symptom onset of 3 h (IQR 2-6 h): 109 (39%) had AMI. At presentation, h-FABP had a sensitivity of 69% (95%CI 59-77) and specificity of 74% (95%CI 66-80); 45 tests were false-positive and 34 were false-negative. Omitting inconclusive tests increased sensitivity and specificity only slightly. AMI was identified significantly earlier by h-FABP than by troponin T (24 vs. 8 patients, p=0.005).

DISCUSSION

Although h-FABP can help to detect myocardial damage at an early stage in patients with chest pain or dyspnoea, it appears unsuitable as a stand-alone test for ruling out AMI.

A comprehensive view of sex-specific issues related to cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality in women. In fact, CVD is responsible for a third of all deaths of women worldwide and half of all deaths of women over 50 years of age in developing countries. The prevalence of CVD risk factor precursors is increasing in children. Retrospective analyses suggest that there are some clinically relevant differences between women and men in terms of prevalence, presentation, management and outcomes of the disease, but little is known about why CVD affects women and men differently. For instance, women with diabetes have a significantly higher CVD mortality rate than men with diabetes. Similarly, women with atrial fibrillation are at greater risk of stroke than men with atrial fibrillation. Historically, women have been underrepresented in clinical trials. The lack of good trial evidence concerning sex-specific outcomes has led to assumptions about CVD treatment in women, which in turn may have resulted in inadequate diagnoses and suboptimal management, greatly affecting outcomes. This knowledge gap may also explain why cardiovascular health in women is not improving as fast as that of men. Over the last decades, mortality rates in men have steadily declined, while those in women remained stable. It is also becoming increasingly evident that gender differences in cultural, behavioural, psychosocial and socioeconomic status are responsible, to various degrees, for the observed differences between women and men. However, the interaction between sex-and gender-related factors and CVD outcomes in women remains largely unknown.

Pharmacologic Support of the Failing Heart

Cardiovascular failure in critically ill patients carries a high mortality. Identification and treatment of the underlying etiology simultaneously with prompt therapy are indicated to avoid the consequences of prolonged shock. Physicians should assess patients using all available clinical, radiologic, and laboratory data to avoid the pitfalls associated with use of single measures of regional or global perfusion. Continued evidence of inadequate perfusion despite fluid resuscitation warrants consideration of placement of a pulmonary artery catheter or pharmacologic support of the cardiovascular system. Finally, the dynamic nature of physiology in critically ill patients requires constant patient reassessment and flexibility in treatment to tailor therapy individually as the pathologic state evolves.

The Internet Tracking Registry of Acute Coronary Syndromes (i*trACS): A Multicenter Registry of Patients With Suspicion of Acute Coronary Syndromes Reported Using the Standardized Reporting Guidelines for Emergency Department Chest Pain Studies

STUDY OBJECTIVE

Observational studies of well-described patient populations presenting to emergency departments (EDs) with suspicion of acute coronary syndrome are necessary to understand the relationships between patients' signs and symptoms, cardiac risk profile, test results, practice patterns, and outcomes. We describe the methods for data collection and the ED population enrolled in a multicenter registry of patients with chest pain.

METHODS

Patients older than 18 years, presenting to one of 8 EDs in the United States or 1 ED in Singapore, and with possible acute coronary syndrome were enrolled in the Internet Tracking Registry of Acute Coronary Syndromes between June 1999 and August 2001. Prospective data, including presenting signs and symptoms, ECG findings, and the ED physician's initial impression of risk, were systematically collected. Medical record review or daily follow-up was used to obtain cardiac biomarker results, invasive and noninvasive testing, treatments, procedures, and inhospital outcomes. Thirty-day outcomes were determined by telephone follow-up and medical record review.

RESULTS

The registry includes 15,608 patients, with 17,713 visits. Chest pain was the chief complaint in 71% of visits. The ECG was diagnostic of ischemia or infarction in 10.1% and positive cardiac biomarkers were observed in 10% of visits. Forty-three percent of patients were sent home directly from the ED. Of admitted patients, 5% died by 30 days, and 3% had documented coronary artery disease or had undergone percutaneous coronary intervention or coronary artery bypass grafting within 30 days. For patients discharged directly from the ED, 0.4% died or had a documented myocardial infarction within 30 days. Coronary artery bypass graft surgery, percutaneous coronary intervention, or a diagnosis of coronary artery disease was found in 0.5% of discharged patients.

CONCLUSION

A unique description of undifferentiated ED chest pain patients with suspected acute coronary syndrome is provided. The data set can be used to generate and explore hypotheses to improve understanding of the complex relationships between presentation, treatment, testing, intervention and outcomes.

Multimarker panel to rule out acute coronary syndromes in low-risk patients

OBJECTIVES

To test novel markers of acute coronary syndrome (ACS), monocyte chemoattractant protein-1 (MCP), myeloperoxidase (MPO), C-reactive protein (CRP), and brain natriuretic peptide (BNP) in low-risk emergency department (ED) patients who were evaluated for ACS in a chest pain unit (CPU).

METHODS

A convenience sample of 414 patients underwent CPU evaluation, including provocative testing, and were followed prospectively for 45 days for ACS, which was defined as death, myocardial infarction (MI), revascularization, or >60% coronary artery stenosis prompting new medical treatment, adjudicated by three blinded reviewers. Published diagnostic thresholds were used to calculate diagnostic indices for each marker and for the multimarker panel.

RESULTS

The prevalence of ACS was 7 in 414 (1.7%; 95% CI = 0.7% to 3.5%). Only MCP demonstrated a negative likelihood ratio [LR(-)] of less than 0.5, with a sensitivity of 85% (95% CI = 42% to 99%), specificity of 72% (95% CI = 67% to 76%), and LR(-) of 0.20 (95% CI = 0.04 to 0.71). For MPO, CRP, and BNP, LR(-) was 0.89 (95% CI = 0.26 to 2.05), 0.79 (95% CI = 0.40 to 1.01), and 0.90 (95% CI = 0.51 to 1.03), respectively. The sensitivity, specificity, and LR(-) of an abnormal multimarker panel were 86% (95% CI = 42% to 100%), 17% (95% CI = 13% to 21%), and 0.84 (95% CI = 0.15 to 3.12), respectively.

CONCLUSIONS

The prevalence of ACS was very low but was similar to reports from other CPUs. BNP and CRP had high specificities, but had limited sensitivities, whereas MPO had a low specificity. Only MCP had a low LR(-) and should be studied further. The combined multimarker panel had an unexpectedly low sensitivity and specificity, yielding an LR(-) of 0.84, suggesting that the panel would not be an efficient screening test to decrease unnecessary CPU testing.

Use of methodological search filters to identify diagnostic accuracy studies can lead to the omission of relevant studies

OBJECTIVE

To determine the usefulness of methodological filters in search strategies for diagnostic studies in systematic reviews.

STUDY DESIGN AND SETTING

We made an inventory of existing methodological search filters for diagnostic accuracy studies and applied them in PubMed to a reference set derived from 27 published systematic reviews in a broad range of clinical fields. Outcome measures were the fraction of not identified relevant studies and the reduction in the number of studies to read.

RESULTS

We tested 12 search filters. Of the studies included in the systematic reviews, 2%-28% did not pass the sensitive search filters, 4%-24% did not pass the accurate filters, and 39%-42% did not pass the specific filters. Decrease in number-needed-to-read when a search filter was used in a search strategy for a diagnostic systematic review varied from 0% to 77%.

CONCLUSION

The use of methodological filters to identify diagnostic accuracy studies can lead to omission of a considerable number of relevant studies that would otherwise be included. When preparing a systematic review, it may be preferable to avoid using methodological filters.

Chest Pain: A Clinical Assessment

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

Evidence of bias and variation in diagnostic accuracy studies

BACKGROUND

Studies with methodologic shortcomings can overestimate the accuracy of a medical test. We sought to determine and compare the direction and magnitude of the effects of a number of potential sources of bias and variation in studies on estimates of diagnostic accuracy.

METHODS

We identified meta-analyses of the diagnostic accuracy of tests through an electronic search of the databases MEDLINE, EMBASE, DARE and MEDION (1999-2002). We included meta-analyses with at least 10 primary studies without preselection based on design features. Pairs of reviewers independently extracted study characteristics and original data from the primary studies. We used a multivariable meta-epidemiologic regression model to investigate the direction and strength of the association between 15 study features on estimates of diagnostic accuracy.

RESULTS

We selected 31 meta-analyses with 487 primary studies of test evaluations. Only 1 study had no design deficiencies. The quality of reporting was poor in most of the studies. We found significantly higher estimates of diagnostic accuracy in studies with nonconsecutive inclusion of patients (relative diagnostic odds ratio [RDOR] 1.5, 95% confidence interval [CI] 1.0-2.1) and retrospective data collection (RDOR 1.6, 95% CI 1.1-2.2). The estimates were highest in studies that had severe cases and healthy controls (RDOR 4.9, 95% CI 0.6-37.3). Studies that selected patients based on whether they had been referred for the index test, rather than on clinical symptoms, produced significantly lower estimates of diagnostic accuracy (RDOR 0.5, 95% CI 0.3-0.9). The variance between meta-analyses of the effect of design features was large to moderate for type of design (cohort v. case-control), the use of composite reference standards and the use of differential verification; the variance was close to zero for the other design features.

INTERPRETATION

Shortcomings in study design can affect estimates of diagnostic accuracy, but the magnitude of the effect may vary from one situation to another. Design features and clinical characteristics of patient groups should be carefully considered by researchers when designing new studies and by readers when appraising the results of such studies. Unfortunately, incomplete reporting hampers the evaluation of potential sources of bias in diagnostic accuracy studies.