The impact of the ESC/ACC redefinition of myocardial infarction and new sensitive troponin assays on the frequency of acute myocardial infarction

High-Sensitivity Troponin: A Review on Characteristics, Assessment, and Clinical Implications

The use of high-sensitivity cardiac troponin (hs-cTn) assays has become part of the daily practice in most of the laboratories worldwide in the initial evaluation of the typical chest pain. Due to their early surge, the use of hs-cTn may reduce the time needed to recognise myocardial infarctions (MI), which is vital for the patients presenting in the emergency departments for chest pain. The latest European Society of Cardiology Guidelines did not only recognise their central role in the diagnosis algorithm but also recommended their use for rapid rule-in/rule-out of MI. High-sensitivity cardiac troponins are also powerful prognostic markers for long-term events and mortality, not only in a wide spectrum of other cardiovascular diseases (CVD) but also in several non-CVD pathologies. Moreover, these biomarkers became a powerful tool in special populations, such as paediatric patients and, most recently, COVID-19 patients. Although highly investigated, the assessment and interpretation of the hs-cTn changes are still challenging in the patients with basal elevation such as CKD or critically ill patients. Moreover, there are still various analytical characteristics not completely understood, such as circadian or sex variability, with major clinical implications. In this context, the present review focuses on summarizing the most recent research in the current use of hs-cTn, with a main consideration for its role in the diagnosis of MI but also its prognostic value. We have also carefully selected the most important studies regarding the challenges faced by clinicians from different specialties in the correct interpretation of this biomarker. Moreover, future perspectives have been proposed and analysed, as more research and cross-disciplinary collaboration are necessary to improve their performance.

Impact of high-sensitivity cardiac troponin implementation on emergency department length of stay, testing, admissions, and diagnoses

OBJECTIVE

While high-sensitivity (hs) troponin (cTn) has been associated with shorter emergency department (ED) length of stay (LOS) and decreased hospital admissions outside the United States (US), concerns have been raised that it will have opposite effects in the US. In this study, we aimed to compare ED LOS, admissions, and acute coronary syndrome (ACS) diagnoses before and after the implementation of hs-cTn.

METHODS

We conducted a single-institution, retrospective study of two temporally matched six-month study periods before and after the implementation of hs-cTn. We included consecutive adults presenting with chest pain. The primary outcome was ED LOS, which was log transformed and analyzed using multiple linear regression. Binary secondary outcomes of admissions, cardiac testing, cardiology consultation, and ACS diagnoses were analyzed using multiple logistic regression.

RESULTS

We studied 1589 visits before and 1616 visits after implementation of hs-cTn. Median age and sex ratios were similar between study periods. Median ED LOS was longer in the post-implementation period [post: 384 (interquartile range, IQR 260-577) minutes; pre: 374 (IQR 250-564) minutes; adjusted geometric mean ratio 1.05; 95% confidence interval, CI 1.01-1.10)]. Admissions were lower in the post-implementation period [post: 24% (385/1616) vs. pre: 28% (447/1589); adjusted odds ratio, aOR 0.75 (95% CI 0.64-0.88)]. Cardiac risk stratification testing [pre: 9% (142/1589) vs post: 9% (144/1616); aOR 0.95 (95% CI 0.74-1.22)], cardiology consultation [pre: 13% (208/1589) vs post: 13% (207/1616); aOR 0.91 (95% CI 0.73-1.12)], and ACS diagnoses [pre: 7% (116/1589) vs post: 7% (120/1616); aOR 0.94 (95% CI 0.72-1.24)] were similar between the two study periods.

CONCLUSION

In this single-center study, transition to hs-cTn was associated with an increased ED LOS, decreased admissions, and no substantial change in cardiac risk stratification testing, cardiology consultation, or ACS diagnoses.

A diagnostic accuracy study validating cardiovascular ICD-9-CM codes in healthcare administrative databases. The Umbria Data-Value Project

BACKGROUND

Administrative healthcare databases are useful and inexpensive tools that can provide a comprehensive assessment of the burden of diseases in terms of major outcomes, such as mortality, hospital readmissions, and use of healthcare resources. However, a crucial issue is the reliability of information gathered. The aim of this study was to validate ICD-9 codes for several major cardiovascular conditions, i.e., acute myocardial infarction (AMI), atrial fibrillation/flutter (AF), and heart failure (HF), in order to use them for epidemiological, outcome, and health services research.

METHODS

Data from the centralised administrative database of the Umbria Region (890,000 residents, located in Central Italy) were considered. Patients with a first hospital discharge for AMI, AF/flutter, and HF, between 2012 and 2014, were identified using ICD-9-CM codes in primary position. A sample of cases and non-cases was randomly selected, and the corresponding medical charts reviewed by specifically trained investigators. For each disease, case ascertainment was based on all clinical, laboratory, and instrumental examinations available in medical charts. Sensitivity, specificity, and predictive values with 95% confidence intervals (CIs), were calculated.

RESULTS

We reviewed 458 medical charts, 128 for AMI, 127 for AF/flutter, 127 for HF, and 76 of non-cases for each condition. Diagnostic accuracy measures of the original discharge diagnosis were as follows. AMI: sensitivity 98% (95% CI, 94-100%), specificity 91% (95% CI, 83-97%), positive predictive value (PPV) 95% (95% CI, 89-98%), negative predictive value (NPV) 97% (95% CI, 91-100%). AF/flutter: sensitivity 95% (95% CI, 90-98%), specificity 95% (95% CI, 87-99%), PPV 97% (95% CI, 92-99%), NPV 92% (95% CI, 84-97%). HF: sensitivity 96% (95% CI, 91-99%), specificity 90% (95% CI, 81-96%), PPV 94% (95% CI, 88-97%), NPV 93% (95% CI, 85-98%).

CONCLUSION

The case ascertainment for AMI, AF and flutter, and HF, showed a high level of accuracy (≥ 90%). The healthcare administrative database of the Umbria Region can be confidently used for epidemiological, outcome, and health services research.

Clinical significance and correlation of microRNA-21 expression and the neutrophil-lymphocyte ratio in patients with acute myocardial infarction

OBJECTIVES

To explore the clinical significance and correlation of microRNA-21 (miR-21) and the neutrophil-lymphocyte ratio (NLR) in patients with acute myocardial infarction (AMI).

METHODS

The observation group contained 184 patients, while the control group contained 150 patients. The expression of miR-21 in the serum of each group was detected by qRT-PCR.

RESULTS

A total of 184 patients and their family members were followed-up for 30 days, among which 35 patients died and 149 patients survived, resulting in a survival rate of 80.97%. According to univariate analysis, there were significant differences in age, cardiac troponin (cTn), heart rate, Killip grade, percutaneous coronary intervention (PCI) operation rate, miR-21 and NLR. In the receiver operating characteristic (ROC) analysis, the area under the curve (AUC) values of miR-21 and NLR for the diagnosis of AMI were 0.909 and 0.868, respectively, and the area under the combined detection curve was 0.960. In the Kaplan-Meier survival analysis, the survival of patients with high miR-21 expression and NLR was significantly higher than that of patients with low miR-21 expression and NLR (p=0.027; p=0.001). The correlation showed that miR-21 expression in serum was positively correlated with the NLR in the observation group (r=0.528, p<0.05). cTn, heart rate, Killip classification, PCI operation rate, miR-21, NLR are independent risk factors for AMI.

CONCLUSION

miR-21 and NLR play a role in the diagnosis of AMI and can be used as predictors for the survival of AMI.

Fisetin, a plant flavonoid ameliorates doxorubicin-induced cardiotoxicity in experimental rats: the decisive role of caspase-3, COX-II, cTn-I, iNOs and TNF-α

Doxorubicin (DOX) is a widely used anthracycline antibiotic for the management of carcinoma. However, it is associated with cardiotoxicity. Fisetin is a plant flavonoid reported to have anti-inflammatory and antiapoptotic potential. To evaluate the cardioprotective potential of fisetin in DOX-induced cardiotoxicity in experimental rats. Sprague-Dawley rats were pre-treated with either fisetin (10, 20 and 40 mg/kg) or sitagliptin (10 mg/kg, p.o.) for 7 days. Cardiac toxicity was induced in rats (except the normal group) by doxorubicin (15 mg/kg i.p.) on 8th day. Various behavioral, biochemical, molecular and histological parameters were assessed in cardiac tissue. DOX-induced alterations in electrocardiographic, hemodynamic and left ventricular function were significantly (p < 0.05) inhibited by fisetin (20 and 40 mg/kg) treatment. Fisetin significantly decrease (p < 0.05) DOX-induced elevated serum CK-MB, LDH, AST, ALT and ALP levels. DOX-induced elevated cardiac oxido-nitrosative (SOD, GSH, MDA and NO) was significantly inhibited (p < 0.05) by fisetin. Up-regulated cardiac caspase-3, COX-II, cTn-I, iNOs, TNF-α, and IL-1β mRNA, as well as protein expressions were significantly decreased (p < 0.05) by fisetin treatment. It also significantly (p < 0.05) attenuated DOX-induced histopathological alterations in cardiac tissue. In conclusion, the fisetin exerts its cardioprotective potential against DOX-induced toxicity via inhibition of multiple pathways including oxidative stress (SOD, GSH, MDA and NO), inflammation (COX-II, TNF-α, and IL-1β), and apoptosis (Caspase-3). Therefore, fisetin can be considered as a potential cardioprotective agent during the management of carcinoma using doxorubicin anthracyclines.

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.

Heart Disease Mortality in the Life Span Study, 1950-2008

Based on the findings from the Radiation Effects Research Foundation's studies of the cohort of Japanese atomic bomb survivors, it has been reported that total-body irradiation at 0.5-1.0 Gy could be responsible for increased rates of mortality from broad-based categories of cardiovascular disease (CVD), i.e., stroke and heart disease. However, CVD consists of various subtypes that have potentially different radiation dose responses, as well as subtype-specific risks that have not been fully evaluated. Potential problems with changes in the coding rules for the International Classification of Diseases (ICD) and the underlying causes and trends in CVD mortality in Japan also need to be considered. The goal of this study was to clarify the radiation risk of subtype-specific heart disease over different time periods. Radiation dose response was examined for mortality from several heart disease subtypes in 86,600 members of the Life Span Study (LSS) cohort during 1950-2008. These subtypes included ischemic heart disease (IHD), valvular heart disease (VHD), hypertensive organ damage (HOD) and heart failure (HF). Individual radiation doses ranged between 0 and 4 Gy. In addition to analyses for the total period, we examined specific periods, 1950-1968, 1969-1980, 1981-1994 and 1995-2008, corresponding to major developments in medical technologies and ICD code revisions. We observed significant positive associations between radiation dose and mortality from heart disease overall in 1950-2008 [excess relative risk or ERR/Gy (95% CI) = 0.14 (0.06, 0.22)]. Subtype-specific ERRs also positively increased with dose: 0.45 (0.13, 0.85) for VHD, 0.36 (0.10, 0.68) for HOD and 0.21 (0.07, 0.37) for HF, respectively. No significant departure from linearity was shown for the dose-response model. Although there was no evidence for a threshold in a model function, the lowest dose ranges with a statistically significant dose response were 0-0.7 Gy for heart disease overall and VHD, 0-1.5 Gy for HOD and 0-0.4 Gy for HF. No significant association between radiation exposure and IHD was observed in any model, although a quadratic model fit the best. The risk of HOD and rheumatic VHD increased significantly in the earliest periods [ERR/Gy = 0.59 (0.07, 1.32) and 1.34 (0.24, 3.16), respectively]. The risk of nonrheumatic VHD increased with calendar time and was significant in the latest period [ERR/Gy = 0.75 (0.02, 1.92)]. The risk of IHD, especially for myocardial infarction, tended to be elevated in the most recent period after 2001, where cautious interpretation is needed due to the uncertain validity of death diagnosis. Radiation risks of heart disease mortality in the LSS appeared to vary substantially among subtypes, indicating possible differences in radiation-induced pathogenesis. Trends in CVD rates in Japan during the long observation period may also impact risk analyses.

Increase in waist circumference over 6 years predicts subsequent cardiovascular disease and total mortality in nordic women

OBJECTIVE

Despite solid evidence of an association between centralized body fatness and subsequent disease risk, little is known about the consequences of changes in body fat distribution. Recently it was shown that large hip circumference (HC), measured once, was protective against total and cardiovascular disease (CVD) mortality in women but that gain or loss in HC was unrelated to these outcomes. This study examines whether a 6-year change in waist circumference (WC) predicts mortality and CVD in the same study sample.

METHODS

Baseline WC and 6-year change in WC as predictors of mortality and CVD were analyzed in 2,492 women from the Danish MONICA study and the Prospective Population Study of Women in Gothenburg, Sweden.

RESULTS

Increase in WC was significantly associated with increased subsequent mortality and CVD adjusting for BMI and other covariates, with some evidence of a J-shaped association. Associations between increase in WC and outcomes were restricted to women with normal weight at baseline and to ever-smokers.

CONCLUSIONS

In contrast to changes in HC which did not predict mortality and CVD, a 6-year increase in WC is strongly predictive, particularly among initially lean women and ever-smokers. This implies the importance of developing strategies to prevent central fat deposition.

Effectiveness of practices for improving the diagnostic accuracy of Non ST Elevation Myocardial Infarction in the Emergency Department: A Laboratory Medicine Best Practices™ systematic review

OBJECTIVES

This article is a systematic review of the effectiveness of four practices (assay selection, decision point cardiac troponin (cTn) threshold selection, serial testing, and point of care testing) for improving the diagnostic accuracy Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) in the Emergency Department.

DESIGN AND METHODS

The CDC-funded Laboratory Medicine Best Practices (LMBP) Initiative systematic review method for quality improvement practices was used.

RESULTS

The current ACC/AHA guidelines recommend using cardiac troponin assays with a 99th percentile upper reference limit (URL) diagnostic threshold to diagnose NSTEMI. The evidence in this systematic review indicates that contemporary sensitive cTn assays meet the assay profile requirements (sensitivity, specificity, PPV, and NPV) to more accurately diagnose NSTEMI than alternate tests. Additional biomarkers did not increase diagnostic effectiveness of cTn assays. Sensitivity, specificity, and NPV were consistently high and low PPV improved with serial sampling. Evidence for use of point of care cTn testing was insufficient to make recommendation, though some evidence suggests that use may result in reduction to patient length of stay and costs.

CONCLUSIONS

Based on the review of and the LMBP(TM) A-6 Method criteria, we recommend the use of cardiac troponin assays without additional biomarkers using the 99th percentile URL as the clinical diagnostic threshold for the diagnosis of NSTEMI. We recommend serial sampling with one sample at presentation and at least one additional second sample taken at least 6h later to identify a rise or fall in the troponin level. No recommendation is made either for or against the use of point of care tests.

DISCLAIMER

The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention/the Agency for Toxic Substances and Disease Registry (CDC/ATSDR).

Noise versus signal: the clinical implications of an increasingly sensitive troponin assay for patients with suspected acute coronary syndrome

OBJECTIVES

To evaluate the clinical impact of a troponin assay switch in suspected acute coronary syndromes (ACS).

METHODS

Retrospective analysis of ACS cases in the 3 months before and after changing to a contemporary, higher sensitivity troponin assay. Admitting diagnosis, proportion with a positive result, initial treatment and testing, coronary artery intervention, inhospital events, and final discharge diagnosis were compared by assay group.

RESULTS

Seven hundred seventy patients were included: 319 (41.4%) preassay and 451 (58.6%) postassay. Preassay change, non-ST segment elevation myocardial infarction at admission (43.0% vs. 70.5%; diff [95% confidence interval (CI)] = -27.5 [-34.2, -20.6]) was diagnosed less often, and a positive troponin was less common (33.2% vs. 72.3%; diff [95% CI] = -39.1 [-45.4, -32.2]). However, anticoagulation (53.3% vs. 42.4%; diff [95% CI] = 10.9 [3.8, 18.0]) and cardiac catheterization use were more frequent (53.9% vs. 41.9%; diff [95% CI] = 12.0 [19.0, 48.5]). There was no difference in coronary intervention (41.9% vs. 40.7%; diff [95% CI] = 1.2 [-9.0, 11.2]) by assay period. Inhospital event were rare (unstable ventricular arrhythmia = 1.2%, cardiac arrest = 3.4%, death = 4.4%) with no difference between groups. A non-ACS diagnosis at discharge was more common in the postassay group (31.6% vs. 46.5%; diff [95% CI] = 14.9 [7.9, 21.6]).

CONCLUSIONS

Although non-ST segment elevation myocardial infarction diagnosis at admission and a positive troponin were more frequent postassay change, rates of anticoagulation and cardiac catheterization were lower and a non-ACS diagnosis at discharge was more common. These data suggest an evolving understanding and clinical impact of contemporary troponin assays when used in real-world settings.

Validity of myocardial infarction diagnoses in administrative databases: a systematic review

BACKGROUND

Though administrative databases are increasingly being used for research related to myocardial infarction (MI), the validity of MI diagnoses in these databases has never been synthesized on a large scale.

OBJECTIVE

To conduct the first systematic review of studies reporting on the validity of diagnostic codes for identifying MI in administrative data.

METHODS

MEDLINE and EMBASE were searched (inception to November 2010) for studies: (a) Using administrative data to identify MI; or (b) Evaluating the validity of MI codes in administrative data; and (c) Reporting validation statistics (sensitivity, specificity, positive predictive value (PPV), negative predictive value, or Kappa scores) for MI, or data sufficient for their calculation. Additonal articles were located by handsearch (up to February 2011) of original papers. Data were extracted by two independent reviewers; article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

Thirty studies published from 1984-2010 were included; most assessed codes from the International Classification of Diseases (ICD)-9th revision. Sensitivity and specificity of hospitalization data for identifying MI in most [≥50%] studies was ≥86%, and PPV in most studies was ≥93%. The PPV was higher in the more-recent studies, and lower when criteria that do not incorporate cardiac troponin levels (such as the MONICA) were employed as the gold standard. MI as a cause-of-death on death certificates also demonstrated lower accuracy, with maximum PPV of 60% (for definite MI).

CONCLUSIONS

Hospitalization data has higher validity and hence can be used to identify MI, but the accuracy of MI as a cause-of-death on death certificates is suboptimal, and more studies are needed on the validity of ICD-10 codes. When using administrative data for research purposes, authors should recognize these factors and avoid using vital statistics data if hospitalization data is not available to confirm deaths from MI.

Identification of acute myocardial infarction from electronic healthcare records using different disease coding systems: a validation study in three European countries

OBJECTIVE

To evaluate positive predictive value (PPV) of different disease codes and free text in identifying acute myocardial infarction (AMI) from electronic healthcare records (EHRs).

DESIGN

Validation study of cases of AMI identified from general practitioner records and hospital discharge diagnoses using free text and codes from the International Classification of Primary Care (ICPC), International Classification of Diseases 9th revision-clinical modification (ICD9-CM) and ICD-10th revision (ICD-10).

SETTING

Population-based databases comprising routinely collected data from primary care in Italy and the Netherlands and from secondary care in Denmark from 1996 to 2009.

PARTICIPANTS

A total of 4 034 232 individuals with 22 428 883 person-years of follow-up contributed to the data, from which 42 774 potential AMI cases were identified. A random sample of 800 cases was subsequently obtained for validation.

MAIN OUTCOME MEASURES

PPVs were calculated overall and for each code/free text. 'Best-case scenario' and 'worst-case scenario' PPVs were calculated, the latter taking into account non-retrievable/non-assessable cases. We further assessed the effects of AMI misclassification on estimates of risk during drug exposure.

RESULTS

Records of 748 cases (93.5% of sample) were retrieved. ICD-10 codes had a 'best-case scenario' PPV of 100% while ICD9-CM codes had a PPV of 96.6% (95% CI 93.2% to 99.9%). ICPC codes had a 'best-case scenario' PPV of 75% (95% CI 67.4% to 82.6%) and free text had PPV ranging from 20% to 60%. Corresponding PPVs in the 'worst-case scenario' all decreased. Use of codes with lower PPV generally resulted in small changes in AMI risk during drug exposure, but codes with higher PPV resulted in attenuation of risk for positive associations.

CONCLUSIONS

ICD9-CM and ICD-10 codes have good PPV in identifying AMI from EHRs; strategies are necessary to further optimise utility of ICPC codes and free-text search. Use of specific AMI disease codes in estimation of risk during drug exposure may lead to small but significant changes and at the expense of decreased precision.

Delta troponin for the early diagnosis of AMI in emergency patients with chest pain

OBJECTIVES

In patients presenting to the Emergency Department (ED) with potential acute myocardial infarction (AMI), elevated cardiac troponin (cTn) levels are indicative of myocardial necrosis. We assessed the accuracy of 'delta cTn' at 2h or 6h compared to the cTn concentration above the 99th percentile reference value for AMI in a prospective study of adult patients presenting to ED with symptoms suggestive of possible acute coronary syndrome.

METHODS

Blood was sampled for cardiac troponin I (cTnI) on presentation, and at 2h and 6h following presentation using a sensitive assay (Beckman AccuTnI). All clinical endpoints were adjudicated by a cardiologist who was blinded to the 2h cTn assay result.

RESULTS

Of the 874 patients, 70 (8%) were diagnosed with an AMI during their index presentation. The area under the ROC curve for diagnosing AMI at 2h was 0.89 [95%CI, 0.84-0.95] for absolute delta cTn versus 0.79 [95%CI 0.73-0.85] for the relative change. Specificity and PPV at 2h were optimized using a delta cTnI ≥ 0.03 μg/L (95.8% [95%CI 94.1-97.0] and 61.4% [95%CI 50.9-70.9] respectively). Sensitivity and NPV for AMI were optimized using the 99th percentile with the addition of a delta of<0.03 μg/L (97.1% [95%CI 90.2-99.2] and 99.7% [95%CI 99-99.9] respectively).

CONCLUSIONS

An algorithm incorporating cTnI concentration and delta cTn values with a sensitive troponin assay allows accurate diagnosis of AMI within 2h from presentation and earlier rule-out of AMI in the majority of patients.

Harmonization process for the identification of medical events in eight European healthcare databases: the experience from the EU-ADR project

OBJECTIVE

Data from electronic healthcare records (EHR) can be used to monitor drug safety, but in order to compare and pool data from different EHR databases, the extraction of potential adverse events must be harmonized. In this paper, we describe the procedure used for harmonizing the extraction from eight European EHR databases of five events of interest deemed to be important in pharmacovigilance: acute myocardial infarction (AMI); acute renal failure (ARF); anaphylactic shock (AS); bullous eruption (BE); and rhabdomyolysis (RHABD).

DESIGN

The participating databases comprise general practitioners' medical records and claims for hospitalization and other healthcare services. Clinical information is collected using four different disease terminologies and free text in two different languages. The Unified Medical Language System was used to identify concepts and corresponding codes in each terminology. A common database model was used to share and pool data and verify the semantic basis of the event extraction queries. Feedback from the database holders was obtained at various stages to refine the extraction queries.

MEASUREMENTS

Standardized and age specific incidence rates (IRs) were calculated to facilitate benchmarking and harmonization of event data extraction across the databases. This was an iterative process.

RESULTS

The study population comprised overall 19 647 445 individuals with a follow-up of 59 929 690 person-years (PYs). Age adjusted IRs for the five events of interest across the databases were as follows: (1) AMI: 60-148/100 000 PYs; (2) ARF: 3-49/100 000 PYs; (3) AS: 2-12/100 000 PYs; (4) BE: 2-17/100 000 PYs; and (5) RHABD: 0.1-8/100 000 PYs.

CONCLUSIONS

The iterative harmonization process enabled a more homogeneous identification of events across differently structured databases using different coding based algorithms. This workflow can facilitate transparent and reproducible event extractions and understanding of differences between databases.

Point-of-care testing during medical emergency team activations: a pilot study

OBJECTIVE

To estimate the prognostic value of point-of-care measurement of biomarkers related to dyspnea in patients receiving a medical emergency team (MET) review.

DESIGN

Prospective observational study.

SETTING

University affiliated hospital.

PATIENTS

Cohort of 95 patients receiving MET review over a six month period.

METHODS

We used a commercial multi-biomarker panel for shortness-of-breath (SOB panel) (Biosite Triage Profiler, Biosite Incorporated®), 9975 Summers Ridge Road, San Diego, CA 92121, USA) including Brain natriuretic peptide (BNP), D-dimer, myoglobin (Myo), creatine kinase MB isoenzyme (CK-MB) and troponin I (Tn-I). We recorded information about demographics, MET review triggers, and MET procedures and patient outcome.

RESULTS

Mean age was 70.5 (±15) years, 38 (41%) patients had a history of chronic heart failure (CHF) and 67 (70%) chronic kidney disease (CKD). At MET activation, 42 (44%) patients were dyspneic. The multi-biomarker panel was positive for at least one marker in 48 (51%) cases. BNP and D-dimer had a sensitivity of 0.79 and 0.93 for ICU admission with a negative predictive value (NPV) of 0.89 and 0.92 respectively. Thirty-five (37%) patients died. BNP was positive in 85% of such cases with sensitivity and NPV of 0.86 and 0.82, respectively. D-dimer was positive in 77% of non-survivors with a sensitivity and NPV of 0.94 and 0.88, respectively. BNP (area under the curve of receiver operating characteristic curve--AUC-ROC: 0.638) and D-dimer (AUC-ROC: 0.574) achieved poor discrimination of subsequent death. Similar findings applied to ICU admission. The combination of normal BNP and D-dimer levels completely ruled out ICU admission or death. The cardiac part of the panel was not useful in predicting ICU admission or mortality.

CONCLUSIONS

Although, BNP and D-dimer are poor discriminants of ICU admission and hospital mortality, normal BNP and D-dimer levels practically exclude subsequent need for ICU admission and hospital mortality.

Recurrent low-level troponin I elevation is a worse prognostic indicator than occasional injury pattern in patients hospitalized with heart failure

BACKGROUND

Elevated troponin at baseline is associated with higher mortality in heart failure (HF) patients, but the prognostic role of recurrently elevated troponin is not well described.

METHODS AND RESULTS

We performed chart reviews of 196 HF patients without acute coronary syndrome, with at least three Troponin I (TnI) measurements on different admissions. For the analyses, three sets of TnI values closest to baseline, one year and two years were selected for each patient. Based on the three sets of TnI, the lowest value of TnI (minimum), the highest value of TnI (maximum), median value of TnI and delta TnI (3rd TnI-baseline TnI) were derived for each patient. The study population of 196 patients had 632 person-year follow-up, consisted predominantly of elderly (68 ± 10 years) male patients (99%) with mean ejection fraction of 26 ± 13%. Using multivariate Cox proportional hazards model only minimum TnI, but not the maximum, median or delta of TnI values, was significantly associated with mortality (HR: 13.7, 95% CI: 3.7 to 50.8, p<0.001). As a categorical variable, minimum TnI value of >0.04ng/ml was also independently associated with mortality (p=0.01, HR=1.6, 95% CI: 1.1 to 2.3).

CONCLUSIONS

In HF patients without acute coronary syndrome, the persistence of TnI elevation, even at low levels, is associated with a worse survival than sporadic TnI elevations of higher magnitude or any single elevation in TnI; and a recurrent elevation of TnI >0.04ng/ml portends a poor prognosis.

High-Sensitivity Cardiac Troponin I Measurement for Risk Stratification in a Stable High-Risk Population

BACKGROUND

Past investigations regarding the utility of high-sensitivity cardiac troponin I (cTnI) assays have been focused primarily on the acute coronary syndrome setting. We assessed whether such assays can predict future ischemic cardiovascular events in a stable high-risk population.

METHODS

We quantified serum cTnI using an investigational high-sensitivity assay (hs-cTnI IUO, Beckman Coulter) in 2572 participants from the Heart Outcomes Prevention Evaluation (HOPE) study. The derived ROC curve cutoff and the 99th percentile for the hs-cTnI assay were assessed by Kaplan–Meier and Cox analyses for the primary outcome [composite of myocardial infarction (MI), stroke, and cardiovascular death] at 4.5 years of follow-up. We also assessed individual outcomes (MI, stroke, cardiovascular death) and the combined outcome (MI/cardiovascular death) by regression analyses to determine hazard ratios (HRs) and c statistics in models that included established risk factors, C-reactive protein, and N-terminal pro-B–type natriuretic peptide (NT-proBNP).

RESULTS

Participants with hs-cTnI &gt;6 ng/L (ROC cutoff) were at higher risk for the primary outcome (HR 1.38, 95% CI 1.09–1.76; P = 0.008, adjusted models). For the individual outcomes, participants with hs-cTnI above the 99th percentile (≥10 ng/L) had higher risk for cardiovascular death (HR 2.15, 95% CI 1.32–3.52; P = 0.002) and MI (HR 1.49, 95% CI 1.05–2.10; P = 0.025) but not stroke (HR 1.38, 95% CI 0.76–2.47; P = 0.288, adjusted models). Addition of hs-cTnI to an established risk model with NT-proBNP also yielded a higher c statistic for the combined outcome of MI/cardiovascular death.

CONCLUSIONS

The investigational Beckman Coulter hs-cTnI assay provides prognostic information for future MI and cardiovascular death in a stable high-risk population.

A practical assessment of the short-term in vitro stability of troponin I at the 99th percentile

Background

Serial troponin measurement is important for the diagnosis of myocardial infarction. As troponin concentrations approach the cut-off for detectable myocardial necrosis, smaller changes in troponin as a result of decreased in vitro stability may be sufficient to generate changes of apparent clinical significance. This is particularly relevant regarding retrospective ‘add-on’ testing on samples several hours after venepuncture. We investigated the stability of troponin I (cTnI) at values close to the 99th percentile limit.

Methods

Serum samples with baseline cTnI concentrations in the range 0.04–0.15 μg/L were analysed routinely using the Siemens TnI-Ultra assay. Follow-up analysis was carried out at 6, 9, 12, 24 and 48 h post-venepuncture after storage at room temperature and in the cold room.

Results

There was a significant decrease in cTnI concentration after 6 h post-venepuncture compared with baseline levels ( P < 0.001). The maximum percentage change was −17.1% observed after 48 h storage at room temperature. Of samples with baseline cTnI concentration 0.040 μg/L, 80% had a cTnI concentration below 0.040 μg/L on re-analysis after 6 h.

Conclusions

Requests for retrospective addition of troponin measurement on samples several hours after venepuncture is commonplace in many laboratories. Analysis of samples drawn >6 h previously may produce values below the cut-off for myocardial necrosis (0.040 μg/L) that would have been detectable if measured earlier as a result of decreased in vitro stability. Significant percentage decreases in cTnI concentration following storage may also have implications in lowering the threshold for an apparently clinically significant change to occur.

Identification of myocardial injury in the emergency setting

Within the past decade, the use of biomarkers to detect myocardial injury in the emergency department (ED) has been given increasing prominence as evident by the numerous studies and guidelines documenting their use. This review details the scope of the clinical problem, the history of changes in the definition of myocardial infarction (MI) and the new approaches, as well as suggestions for using laboratory biomarkers in the early detection of MI in the ED.

High-Sensitivity Cardiac Troponin T for Early Prediction of Evolving Non–ST-Segment Elevation Myocardial Infarction in Patients with Suspected Acute Coronary Syndrome and Negative Troponin Results on Admission

Background: We sought to determine the diagnostic performance of the new high-sensitivity cardiac troponin T (hs-cTnT) assay for early detection of non–ST-segment myocardial infarction (NSTEMI) in patients with acute coronary syndrome.

Methods: We enrolled patients with retrospectively confirmed unstable angina or NSTEMI and an initially negative cTnT concentration and compared the performance of baseline concentrations and serial changes in concentration within 3 and 6 h. Percentage change criteria included ≥20% δ change and ROC-optimized value.

Results: Based on the standard fourth-generation cTnT result of ≥0.03 μg/L, an evolving NSTEMI was diagnosed in 26 patients, and 31 patients were classified as having unstable angina. With the use of the hs-cTnT assay at the 99th-percentile cutoff, the percentage of NSTEMI cases detected increased gradually from 61.5% on presentation to 100% within 6 h, and the overall number of MI diagnoses increased by 34.6% (35 vs 26 cases). A δ change ≥20% or ≥ROC-optimized value of &gt;117% within 3 h or ≥243% within 6 h yielded a specificity of 100% at sensitivities between 69% and 76%. The standard cTnT at the 99th percentile was less sensitive than hs-cTnT for early diagnosis of MI on presentation, and follow-up samples obtained within the initial 3 h demonstrated very low specificity of cTnT compared with hs-cTnT.

Conclusions: The high-sensitivity cTnT assay increases the number of NSTEMI diagnoses and enables earlier detection of evolving NSTEMI. A doubling of the hs-cTnT concentration within 3 h in the presence of a second concentration ≥99th percentile is associated with a positive predictive value of 100% and a negative predictive value of 88%.

The role of postmortem cardiac markers in the diagnosis of acute myocardial infarction

Sudden cardiac deaths because of acute myocardial infarction (MI) constitute a significant percentage of the caseload for death investigators, coroners, and forensic pathologists. Clinicians use cardiac markers, highly sensitive and specific for myocardial damage, to screen living patients for acute MI; however, to this point, the utility of these markers in the autopsy setting has not been fully established. The current study included 10 decedents, five who died of acute MI, and five subjects who died of noncardiac disease. Samples of pericardial fluid and blood from multiple sites were tested for creatine kinase, creatinine kinase MB, and troponin-I. Three main conclusions were drawn: the levels of cardiac markers from all patients are significantly higher than the reference range for living patients, there are significant differences in cardiac marker levels between samples from different anatomic locations, and only three cardiac marker/anatomic site combinations were significantly different between the control and study groups.

Troponins and high-sensitivity troponins as markers of necrosis in CAD and heart failure

For years, cardiac troponins (cTn) have been regarded as the preferred biomarkers for the diagnosis of myocardial infarction and for the risk stratification of patients with acute coronary syndromes, as well as for the selection of patients who need an early invasive strategy, and for the guidance of adjunctive pharmacological therapy. In addition, measurement of cTn has been found useful for detection of myocardial necrosis in conditions unrelated to myocardial ischemia including acute pulmonary embolism, myocarditis, heart failure, sepsis, and end-stage renal disease. In these conditions, an unfavorable prognosis is unequivocally associated with detectable concentrations of cTn.A major limitation of most currently available cTn assays is the lack of adequate precision, i.e., to measure cTn concentrations at the 99th percentile value with a coefficient of variation < 10%. As a consequence, many manufacturers have developed more sensitive cTn assays that now comply with precision criteria required by the Joint European Society of Cardiology/ American College of Cardiology/American Heart Association/World Heart Federation Task Force for the Redefinition of Acute Myocardial Infarction.Using assays with higher analytic sensitivity more patients will be seen in clinical practice with the high-sensitivity cardiac troponin T (TnThs) above the 99th percentile discriminator. The causes of these elevations may be due to acute, subacute and chronic cardiac disease such as heart failure or cardiomyopathies.

Short- and long-term risk stratification using a next-generation, high-sensitivity research cardiac troponin I (hs-cTnI) assay in an emergency department chest pain population

BACKGROUND

The next-generation, high-sensitivity cardiac troponin assays can measure quantifiable concentrations of cTn in a majority of individuals, but there are few studies assessing these assays for risk stratification. The present study was undertaken to determine if a research hs-cTnI assay can be useful for predicting death/myocardial infarction (MI), both short- and long-term, in an emergency department acute coronary syndrome (ACS) population.

METHODS

In a cohort of 383 subjects, originally recruited in 1996, presenting to the emergency department with symptoms suggestive of ACS, the heparin plasma obtained at initial presentation was thawed and measured in 2007 with a research hs-cTnI assay. AccuTnI (Beckman Coulter) measurements were made on these same samples in 2003. The population was divided into 4 groups by hs-cTnI: <5.00, 5.00-9.99, 10.00-40.00, and >40.00 ng/L. Kaplan-Meier, Cox proportional hazards, ROC curves, and logistic regression analyses were used to identify which hs-cTnI concentrations were predictive of death/MI within 10 years after presentation.

RESULTS

There were significant differences between the hs-cTnI groups for the probability of death/MI up to 10 years after presentation (P < 0.05). At 6 months, patients with hs-cTnI > or =10.00 ng/L were at higher risk for death/MI (hazard ratio >3.7; P < 0.05) compared with those having hs-cTnI <5.00 ng/L. ROC curve analysis for death/MI at 30 days with the hs-cTnI assay had an area under the curve of 0.74 (95% CI 0.65-0.82), with logistic models yielding an optimal assay threshold of 12.68 ng/L.

CONCLUSIONS

This research hs-cTnI assay appears useful for risk stratification for death/MI in an ACS population.

PAPP-A as a marker of increased long-term risk in patients with chest pain

OBJECTIVES

Long-term risk stratification in patients presenting with acute coronary syndromes (ACS) is possible by measuring cardiac troponin (cTn). The present study examined whether PAPP-A measured in an emergency department (ED) chest pain population in association with conventional and novel high sensitivity cTn (hs-cTnI) assays can predict long-term mortality.

METHODS

In 320 patients with cTn measurements the earliest heparinized plasma PAPP-A concentration after presentation was used for risk stratification for death by Kaplan-Meier and Cox analyses. Subgroup analyses using the earliest PAPP-A concentrations were also performed in a cohort of subjects with presentation cTnI < or = 99th percentile but with significantly changing cardiac troponin concentrations as measured by the AccuTnI assay and the hs-cTnI assay (n=45 and 120 subjects, respectively).

RESULTS

Subjects with PAPP-A concentrations in the highest tertile were at higher risk for death (HR > 2.00; p < or = 0.05 at 2 years) even after adjusting for cTnI at presentation. In the cohort with cTnI < or = 99th percentile but with changing hs-cTnI concentrations, subjects in the top PAPP-A tertile had a higher probability for death (p=0.02).

CONCLUSION

Early measurement of PAPP-A may identify chest pain patients at higher risk for long-term death. Additional prospective ACS studies are required to fully elucidate PAPP-A's role.

Role of monitoring changes in sensitive cardiac troponin I assay results for early diagnosis of myocardial infarction and prediction of risk of adverse events

BACKGROUND

We sought to determine the diagnostic accuracy of the cardiac troponin I (cTnI) VITROS(R) Troponin I-ES assay for early detection of acute myocardial infarction (AMI) and for risk prediction of adverse events in patients with symptoms of acute coronary syndrome (ACS).

METHODS

cTnI was measured on admission and approximately 6 h postadmission in 381 patients. The 99th percentile cTnI concentration (0.034 microg/L) and change [delta (delta)] between admission and follow-up concentrations were evaluated in diagnostic sensitivity and specificity calculations. Risk of cardiac event or death within 60 days was evaluated by Cox proportional hazards regression.

RESULTS

AMI occurred in 52 patients. Diagnostic sensitivities (95% CI) of admission and follow-up cTnIs for AMI were 69% (55%-81%) and 94% (84%-99%), respectively. The corresponding specificities (95% CI) were 78% (73%-82%) and 81% (77%-85%), and ROC curve areas were 0.82 vs 0.96 (P < 0.001). Deltas between admission and follow-up cTnI >30% had a sensitivity of 75% (95% CI 61%-86%) and a specificity of 91% (95% CI 87%-94%). During follow-up, 1 cardiac death, 2 noncardiac deaths, 52 AMIs, 6 coronary artery bypass grafts, and 43 percutanous coronary interventions occurred in 62 patients. A delta cTnI >30%, when added to either initial cTnI >0.034 microg/L or follow-up cTnI >0.034 microg/L, improved risk stratification for cardiac event or death (P < 0.001).

CONCLUSIONS

Admission cTnI measured by the VITROS ES assay is a sensitive biomarker for detection of AMI. Utilizing >30% cTnI delta in addition to either the baseline or follow-up concentration improved both specificity and risk assessment in patients presenting with symptoms of ACS.

Analytic and Clinical Utility of a Next-Generation, Highly Sensitive Cardiac Troponin I Assay for Early Detection of Myocardial Injury

Background: Improvements in cardiac troponin (cTn) assays have increased the rapidity with which clinicians can identify patients with changing cTn concentrations (rise or fall) indicative of acute myocardial injury. The aim of the present study was to characterize a new, high-sensitivity cTnI (hs-cTnI) assay and examine whether increased sensitivity can result in still earlier detection of evolving injury.

Methods: We determined the limit of detection, precision profiles, and preliminary estimates of the 99th percentile for the Beckman Coulter hs-cTnI assay in 125 healthy individuals (age &lt;55 years, 54% male). We compared AccuTnI® and hs-cTnI to assess whether change criteria for early concentration changes (i.e., ≥3SD for low concentrations and 20% difference for concentrations &gt;0.10 μg/L) were exceeded in the first 2 specimens (median time between specimens, 1 h; 25th–75th percentile, 1–3 h) from subjects with symptoms suggestive of cardiac ischemia (n = 290).

Results: The limit of detection for the hs-cTnI assay was 2.06 ng/L, and the 20% CV and 10% CV concentrations were 2.95 and 8.66 ng/L, respectively. The preliminary 99th percentile estimates in lithium heparin, serum, and EDTA plasma were 9.20, 8.00, and 8.60 ng/L, respectively. In 108 patients with myocardial injury based on the peak AccuTnI concentration, applying the change criteria on the 2 earliest specimens identified 81% (95% CI 73%–88%) of patients using the hs-cTnI assay compared to 62% (53%–71%) using the AccuTnI assay (P &lt; 0.001).

Conclusions: Although more extensive validation studies are required, this Beckman Coulter hs-cTnI assay appears to detect patients with evolving myocardial injury earlier.

The value of biochemical markers for risk stratification prior to hospital admission in acute chest pain

We describe the use of biochemical markers in the pre-hospital setting with regard to diagnostic accuracy for the detection of an acute myocardial infarction (AMI) and for prognosis in connection with acute chest pain. The sensitivity has been reported to be limited; blood sampling occurs very early and often prior to the release of biochemical markers into the circulation. The specificity was in some studies also limited, but this is more difficult to explain. New biochemical markers like human heart fatty acid binding protein (H-FACB) have shown improved diagnostic accuracy, in the pre-hospital setting, in one small pilot study compared with traditional biochemical markers like troponins, creatine kinase (CK-MB) and myoglobin. However, in a recent small study, the sensitivity for troponin I (when a low decision limit for myocardial damage was used), when analysed prior to hospital admission, was reported to be very high. The latter data need to be confirmed in larger studies and various biochemical markers reflecting various pathophysiological aspects of the disease need to be tested before the analysis of any marker can be recommended for use in the pre-hospital setting of a suspected AMI.

Assessment of the multiple-biomarker approach for diagnosis of myocardial infarction in patients presenting with symptoms suggestive of acute coronary syndrome

BACKGROUND

Cardiac troponin is the preferred biomarker for detecting acute myocardial injury and infarction (MI). We studied whether multiple biomarkers of numerous pathophysiological pathways would increase the diagnostic accuracy for detecting MI.

METHODS

Seven biomarkers [myeloperoxidase, soluble CD40 ligand, placental growth factor, matrix metalloproteinase 9 (MMP-9), high-sensitivity C-reactive protein (hsCRP), cardiac troponin I (cTnI), N-terminal pro-B-type natriuretic peptide] and estimated glomerular filtration rate were measured in 457 patients presenting on admission with symptoms suggestive of acute coronary syndrome. Twenty-five patients (5.4%) received MI diagnoses. Clinical sensitivities and specificities were evaluated from 99th-percentile reference values. Forward and backward stepwise logistic regression modeling techniques were used to identify biomarkers that were independently predictive of MI.

RESULTS

Biomarker sensitivities ranged from 20% to 96%, and specificities ranged from 19% to 89%. MMP-9 had the highest sensitivity, but its specificity was 19%. cTnI demonstrated a sensitivity of 72% (95% CI, 51%-88%) and a specificity of 89% (95% CI, 85%-92%). In multivariate models, cTnI (P < 0.001) and either hsCRP (P = 0.009) or MMP-9 (P = 0.03) were independently predictive of MI. Addition of hsCRP or MMP-9 increased the specificity to 95% (95% CI, 92%-97%) or 91% (95% CI, 88%-94%), respectively, but reduced the sensitivity to 56% (95% CI, 35%-76%) and 68% (95% CI, 47%-85%) relative to cTnI alone.

CONCLUSIONS

Our findings indicate that the most clinically accurate biomarker for the early diagnosis of MI is the use of cTnI alone, rather than a multiple-biomarker approach, when an analytically robust cardiac troponin assay based on the 99th percentile is used.

The new and old definitions of acute myocardial infarction: a data-based comparison

PURPOSE

To measure the agreement between the newer European Society of Cardiology-American College of Cardiology (ESC-ACC) definition of acute myocardial infarction (AMI) and the traditional definition established by the World Health Organization (WHO).

BASIC PROCEDURES

All adult ED patients admitted to our institution with at least one abnormally elevated cardiac biomarker were determined to have had an AMI by either or both definitions. The degree of agreement and the frequency of the reasons for disagreement between these 2 definitions were measured.

MAIN FINDINGS

A final study population consisted of 339 patients; 196 (58%) had an AMI by one or both definitions. Among them, 126 (64%; 95% confidence interval [CI], 57-71) were discordant for these 2 definitions: 104 (53%; 95% CI, 46-60) met only the ESC-ACC, whereas 22 (11%; 95% CI, 6-16) met only the WHO definition. Among those who met only the ESC-ACC definition, 37 (36%; 95% CI, 27-45) met none of the 3 traditional WHO criteria.

PRINCIPAL CONCLUSIONS

More patients are discordant than concordant for the 2 standard definitions of AMI. Among them, a large majority meet only the new ESC-ACC definition.

Is a pattern of increasing biomarker concentrations important for long-term risk stratification in acute coronary syndrome patients presenting early after the onset of symptoms?

BACKGROUND

Guidelines for treatment of acute coronary syndrome (ACS) recommend observing a rise or fall in cardiac troponin (cTn) concentrations for assessing acute injury. It is unknown whether a rising pattern presages a more adverse long-term prognosis than elevations that do not change. The present study assessed whether a rising pattern of cardiac biomarkers was more prognostic than simple elevations.

METHODS

We measured N-terminal pro-brain natriuretic peptide (NT-proBNP) (Roche), cTnT (Roche) and cTnI (Beckman Coulter) in 212 ACS patients. These biomarkers were measured in coincident EDTA and heparin plasma samples available from at least 2 different time points, an early first specimen obtained a median of 2 hours after onset of symptoms, interquartile range (IQR) 2-4 hours, and a later second specimen obtained at 9 hours, IQR 9-9 hours. The cTn concentration in the second specimen was used to classify myocardial necrosis (cTnI >0.04 ug/L; cTnT >0.01 ug/L). Outcomes [death, myocardial infarction (MI), heart failure (HF)] were obtained >8 years after the initial presentation. For patients with myocardial necrosis and a cTn concentration ratio (second/first measured concentrations) > or =1.00, the concentration ratios and the absolute concentrations in the second specimen were used to assess prognosis after 4 years.

RESULTS

In myocardial necrosis, the relative change (cTn2/cTn1) was greater for cTnI than for cTnT (P <0.01), whereas the relative change in NT-proBNP was the same regardless of which troponin was used to classify necrosis (P = 0.71). The concentration ratio for cTnI, cTnT, and NT-proBNP was not useful for risk stratification (i.e., death/MI/HF; P > or =0.15).

CONCLUSIONS

A rise in cardiac troponin or NT-proBNP concentration in ACS patients presenting early after onset of pain is not helpful for long-term prognosis.

A study to derive a clinical decision rule for triage of emergency department patients with chest pain: design and methodology

BACKGROUND

Chest pain is the second most common chief complaint in North American emergency departments. Data from the U.S. suggest that 2.1% of patients with acute myocardial infarction and 2.3% of patients with unstable angina are misdiagnosed, with slightly higher rates reported in a recent Canadian study (4.6% and 6.4%, respectively). Information obtained from the history, 12-lead ECG, and a single set of cardiac enzymes is unable to identify patients who are safe for early discharge with sufficient sensitivity. The 2007 ACC/AHA guidelines for UA/NSTEMI do not identify patients at low risk for adverse cardiac events who can be safely discharged without provocative testing. As a result large numbers of low risk patients are triaged to chest pain observation units and undergo provocative testing, at significant cost to the healthcare system. Clinical decision rules use clinical findings (history, physical exam, test results) to suggest a diagnostic or therapeutic course of action. Currently no methodologically robust clinical decision rule identifies patients safe for early discharge.

METHODS/DESIGN

The goal of this study is to derive a clinical decision rule which will allow emergency physicians to accurately identify patients with chest pain who are safe for early discharge. The study will utilize a prospective cohort design. Standardized clinical variables will be collected on all patients at least 25 years of age complaining of chest pain prior to provocative testing. Variables strongly associated with the composite outcome acute myocardial infarction, revascularization, or death will be further analyzed with multivariable analysis to derive the clinical rule. Specific aims are to: i) apply standardized clinical assessments to patients with chest pain, incorporating results of early cardiac testing; ii) determine the inter-observer reliability of the clinical information; iii) determine the statistical association between the clinical findings and the composite outcome; and iv) use multivariable analysis to derive a highly sensitive clinical decision rule to guide triage decisions.

DISCUSSION

The study will derive a highly sensitive clinical decision rule to identify low risk patients safe for early discharge. This will improve patient care, lower healthcare costs, and enhance flow in our busy and overcrowded emergency departments.

Risk Stratification for Heart Failure and Death in an Acute Coronary Syndrome Population Using Inflammatory Cytokines and N-Terminal Pro-Brain Natriuretic Peptide

Background: Inflammation in acute coronary syndrome (ACS) can identify those at greater long-term risks for heart failure (HF) and death. The present study assessed the performance of interleukin (IL)-6, IL-8, and monocyte chemoattractant protein-1 (MCP-1) (cytokines involved in the activation and recruitment of leukocytes) in addition to known biomarkers [e.g., N-terminal pro-brain natriuretic peptide (NT-proBNP)] for predicting HF and death in an ACS population.

Methods: In a cohort of 216 ACS patients, NT-proBNP (Elecsys®; Roche) and IL-6, IL-8, and MCP-1 (evidence investigator™; Randox) were measured in serial specimens collected early after symptom onset (n = 723). We collected at least 2 specimens from each participant: an early specimen (median 2 h; interquartile range 2–4 h) and a later specimen (9 h; 9–9 h), and used the later specimens’ biomarker concentrations for risk stratification.

Results: An increase in both IL-6 and NT-proBNP was observed but not for IL-8 or MCP-1 early after pain onset. Kaplan–Meier analysis demonstrated that individuals with increased NT-proBNP (&gt;183 ng/L) or cytokines (IL-6 &gt; 6.4 ng/L; above upper limit of normal for IL-8 or MCP-1) had a greater probability of death or HF in the following 8 years (P &lt;0.05). In a Cox proportional hazard model adjusted for both CRP and troponin I, increased IL-6, MCP-1, and NT-proBNP remained significant risk factors. Combining all 3 biomarkers resulted in a higher likelihood ratio for death or HF than models restricted to any 2 of these biomarkers.

Conclusion: IL-6, MCP-1, and NT-proBNP are independent predictors of long-term risk of death or HF, highlighting the importance of identifying leukocyte activation and recruitment in ACS patients.