Comparison of troponin T versus creatine kinase-MB in suspected acute coronary syndromes

Limitations of creatine kinase-MB (CK-MB) have led to alternative biochemical markers, including troponin T (TnT), to detect myocardial necrosis. Limited data are available regarding the predictive value of this new marker in patients with chest pain of uncertain etiology. Therefore, we prospectively compared CK-MB and TnT in a broad population with suspected acute coronary syndromes, including those admitted to a short-stay chest pain unit. CK-MB, quantitative TnT levels, and a rapid bedside assay were performed at 0, 4, 8, and 16 hours. Adverse events, including infarction, recurrent ischemia, coronary surgery, need for catheterization and/or intervention, stroke, congestive heart failure, or death, were identified by chart review and by follow-up phone call at 6 months. Of 707 patients, 104 were excluded for creatinine >2 mg/dl or incomplete data, leaving a total cohort of 603 patients. Coronary Care Unit admissions were 18%, intermediate care admissions were 14%, telemetry admissions is 21%, and admissions to 24-hour short-stay area were 47%. TnT (at 0.1 ng/ml) and CK-MB were positive in a similar proportion of patients (20.4% and 19.7%, respectively); however, the patients identified by TnT and CK-MB were not identical. In-hospital adverse events occurred in 37.1% with no differences in positive predictive value for the markers (p = NS). If CK-MB and TnT were negative, the early adverse event rate was 27%. No cardiac marker was positive by 16 hours in 54.9% of patients with an adverse event. Six-month follow-up was obtained in 576 of the 603 patients (95.5%). One hundred fifty-five late adverse events occurred in 134 patients (23.3%) at an average of 3.3+/-2.5 months after discharge. If both markers were negative, the late event rate was 20.2% and did not increase in patients with positive CK-MB or TnT >0.2 ng/ml. However, the late event rate was substantially higher (52.9%) in those with intermediate TnT levels of 0.1 to 0.2 ng/ml (p = 0.002). Thus, TnT is a suitable alternative to CK-MB in patients with suspected acute coronary syndromes. The rapid bedside assay is comparable to quantitative TnT and may enable early diagnosis and triage. A negative cardiac marker value (TnT or CK-MB) does not necessarily confer a low risk of complication in patients presenting with acute chest pain to an emergency department.     

A comparison of cardiac troponin T and creatine kinase-MB for patient evaluation after cardiac surgery

OBJECTIVES: The aim of this study was to assess the role of serum markers of myocardial necrosis after cardiac surgery. BACKGROUND: The role of serum troponin T (TnT) and creatine kinase-MB (CK-MB) for the risk stratification of patients after cardiac surgery remains undefined. METHODS: Serum levels of TnT and CK-MB were measured from 224 patients every 8 h after cardiac surgery. The results of serum cardiac marker testing were correlated with adverse events, including new myocardial infarction (MI), cardiogenic shock or death. Univariable analysis identified factors predictive of complications, while stepwise logistic regression identified independent predictors of postoperative complications. RESULTS: Cardiac marker elevation was universal after cardiac surgery. At all time points measured, compared with those patients without complications, the TnT levels from patients with complications were more significantly elevated (all: p < 0.0005). In contrast, among identically timed specimens, the levels of CK-MB from complicated patients were less reliably discriminatory. Multivariable analysis suggested that a TnT level in the highest quintile (> or = 1.58 ng/ml) was the strongest predictor of complications, including death (post-op, odds ratio [OR] = 31.0, 95% confidence interval [CI] = 3.67 to 263.1, p = 0.002) or shock (post-op: OR = 18.9, 95% CI = 2.29 to 156.1, p = 0.006; 18 h to 24 h: OR = 30.7, 95% CI = 3.75 to 250.7, p = 0.001), as well as the composite end points of death/MI (18 h to 24 h: OR = 60.1, 95% CI = 7.34 to 492.1, p < 0.0005), shock/MI (post-op: OR = 23.3, 95% CI = 2.82 to 191.4, p = 0.003; 18 h to 24 h: OR = 37.8, 95% CI = 4.66 to 307.3, p = 0.001) or death/shock/MI (post-op: OR = 20.0, 95% CI = 2.81 to 142.0, p = 0.003; 18 h to 24 h: OR = 67.4, 95% CI = 6.96 to 652.3, p < 0.0005). In contrast, in the presence of TnT, the results of CK-MB measurement added no independent prognostic information. CONCLUSIONS: Troponin T is superior to CK-MB for the prediction of impending complications after cardiac surgical procedures.     

A proposed strategy for utilization of creatine kinase-MB and troponin I in the evaluation of acute chest pain

In recent years, cardiac troponins have attracted great interest as a marker for myocardial injury. However, there are limited data on strategies for use of creatine kinase (CK)-MB and troponin I (cTnI) in clinical practice. We sought to develop a testing strategy using prospectively collected clinical data including serial CK-MB and cTnI levels from 1,051 patients aged > or = 30 years admitted to a teaching hospital for acute chest pain. Diagnostic performance was evaluated for peak values of CK-MB and cTnI obtained during the first 24 hours for the combined end point of acute myocardial infarction and/or major cardiac events within 72 hours. The overall diagnostic accuracy was similar for both cardiac markers alone, and for the combination of cTnI and CK-MB (receiver-operating characteristic curve 0.84, 0.86, and 0.87, respectively). In the multivariate analysis, models including cardiac markers showed that both CK-MB and cTnI added information to clinical data to predict the combined end point, but cTnI added significantly less. Using recursive partitioning analysis, we developed a strategy that would restrict routine cTnI use to patients with normal CK-MB results and findings on the electrocardiogram consistent with ischemia. This strategy would divide patients with suspected myocardial ischemia into 4 groups with risks for the combined end point of 4%, 13%, 26%, and 85%. Thus, cTnI adds information to CK-MB mass and clinical data for predicting major cardiac events, but this contribution is mainly in patients with evidence of myocardial ischemia on their electrocardiograms.     

Classification and risk stratification of patients with acute chest pain using a low discriminatory level of cardiac troponin T

BACKGROUND: Cardiac troponins are the biochemical markers of choice for the evaluation of acute coronary syndromes (ACS). Using the first-generation test, most studies related adverse outcome to > 0.20 or 0.10 microg/l cardiac troponin T (cTnT) levels. With the highly sensitive and specific second- and third-generation assays, cTnT is undetectable in most healthy individuals. HYPOTHESIS: We evaluated whether a lower cTnT level, within 24 h of admission, could indicate an increased risk of future complications. METHODS: During 1998-1999, clinical data were collected in 260 patients with ACS. Cardiac troponin T was measured at arrival, and 4, 8, and 12-24 h thereafter. The maximum cTnT value was then used to assess, over a 15-month follow-up period, the cumulative risk of death or myocardial infarction (MI), as well as rates of events according to quartiles of cTnT values. RESULTS: Patients with < or = 0.03 microg/l cTnT levels had the lowest rate of adverse events and the best Kaplan-Meier event-free survival curve. Increasing cTnT levels were associated with stepwise increases in mortality rates and with a constant 10-fold increase in MI rates during follow-up. CONCLUSIONS: A low threshold cTnT elevation is recommended to assess the risk of ACS. All cTnT elevations > 0.03 microg/l predict a higher risk of MI during follow-up, whereas increasing values predict mortality in relation to the amount of elevation.     

Emergency department triage strategies for acute chest pain using creatine kinase-MB and troponin I assays: a cost-effectiveness analysis

BACKGROUND: Evaluation of acute chest pain is highly variable. OBJECTIVE: To evaluate the cost-effectiveness of strategies using cardiac markers and noninvasive tests for myocardial ischemia. DESIGN: Cost-effectiveness analysis. DATA SOURCES: Prospective data from 1066 patients with chest pain and from the published literature. TARGET POPULATION: Patients admitted with acute chest pain. TIME HORIZON: Lifetime. PERSPECTIVE: Societal. INTERVENTIONS: Creatine kinase (CK)-MB mass assay alone; CK-MB mass assay followed by cardiac troponin I assay if the CK-MB value is normal; CK-MB mass assay followed by troponin I assay if the CK-MB value is normal and electrocardiography shows ischemic changes; both CK-MB mass and troponin I assays; and troponin I assay alone. These strategies were evaluated alone or in combination with early exercise testing. OUTCOME MEASURES: Lifetime cost, life expectancy (in years), and incremental cost-effectiveness. RESULTS OF BASE-CASE ANALYSIS: For patients 55 to 64 years of age, measurement of CK-MB mass followed by exercise testing in appropriate patients was the most competitive strategy ($43000 per year of life saved). Measurement of CK-MB mass followed by troponin I measurement had an incremental cost-effectiveness ratio of $47400 per year of life saved for patients 65 to 74 years of age; it was also the most cost-effective strategy when early exercise testing could not be performed, CK-MB values were normal, and ischemic changes were seen on electrocardiography. RESULTS OF SENSITIVITY ANALYSIS: Results were influenced by age, probability of myocardial infarction, and medical costs. CONCLUSIONS: Measurement of CK-MB mass plus early exercise testing is a cost-effective initial strategy for younger patients and those with a low to moderate probability of myocardial infarction. Troponin I measurement can be a cost-effective second test in higher-risk subsets of patients if the CK-MB level is normal and early exercise testing is not an option.     

The relative utility of cardiac troponin I,creatine kinase-MBmass,and myosin light chain-1 in the long-term risk stratification of patients with chest pain

BACKGROUND: Sensitive and specific cardiac markers convey important short-term prognostic information about patients with an acute coronary syndrome. There are, however, few data assessing their value as long-term predictors. HYPOTHESIS: The aim of the current study was to assess the relative value of three such markers and clinical characteristics in determining the long-term prognosis of patients with chest pain. METHODS: Cardiac troponin I (cTnI), myosin light chain-(MLC-1), and creatine kinase-MBmass levels were obtained on admission (0 h) and at 4, 8, 16, and 24 h in 208 patients with chest pain. Eligible subjects were determined, at the time of hospital admission, to be at >7% risk of acute myocardial infarction (MI), but without new ST-segment elevation on their presenting electrocardiogram. Follow-up was performed a median of 28 (range 1-46) months later. The primary study endpoint was death or nonfatal MI, subsequent to the index admission. RESULTS: Cardiac TnI levels > or = 0.2 ng/ml (odds ratio [OR] 1.93, 95% confidence interval [CI] 1.09-3.40) and MLC-1 levels > or = 1 ng/ml (OR 3.24, 95% CI 1.83-5.73) were both significant predictors of death or MI during long-term follow-up; MLC-1 was, however, the only independent biochemical predictor (OR 2.11,95% CI 1.14-3.93). CONCLUSIONS: Both cTnl and MLC-1 predict the long-term outcome of patients with chest pain, but, in this cohort, MLC-1 proved to be a better predictor of mortality and nonfatal acute MI.     

The role of cardiac troponin t and other new biochemical markers in evaluation and risk stratification of patients with acute chest pain syndromes

Background and hypothesis: Increased serum creatinine kinase (CK) and CK-MB enzyme levels have been used for years to detect myocardial infarction (MI). However, serum myoglobin and CK-MB mass or protein levels may indicate MI earlier; cardiac troponin T is the most specific marker of myocardial injury and it can detect even minor myocardial necrosis. The diagnostic and prognostic utility of the traditional and new markers of cardiac injury in the emergency evaluation of patients with acute chest pain syndromes were therefore compared. Methods: One hundred and fifteen consecutive patients with an acute coronary syndrome, and 64 controls recruited during the same period, were examined. The time elapsed from onset of symptoms to blood collection was recorded. Cardiac markers were measured in specimens collected upon arrival (0 h), and 2 and 5–9 h, and later in cases of longer observation. The major cardiac events occurring up to 40 months after the index examination were recorded. Results: cTnT levels provided unique information: they were the most specific indicators of myocardial damage and identified unstable angina patients at high risk of future major events. Up to 6 h after the onset of chest pain, the new markers were elevated more frequently than the traditional ones and permitted earlier MI recognition. The worst prognosis (nonfatal myocardial infarction or death) was noted in subjects with chest pain at rest within 48 h before the index examination and elevated cTnT levels. Conclusions: The new markers, particularly cardiac troponin T, offer considerable advantages and they should be more widely used in the diagnosis and risk stratification of acute coronary syndromes.     

心脏肌钙蛋白T对不稳定性心绞痛危险分层的价值

目的：探讨心脏肌钙蛋白Ｔ（ｃＴｎＴ）对不稳定心绞痛（ＵＡ）危险分层的临床价值。方法：用酶联免疫法测定１１２例ＵＡ患入院即刻、第２、３日血浆ｃＴｎＴ≥０．１ｎｇ／ｍｌ或〈０．１ｎｇ／ｍｌ将患分为ｃＴｎＴ升高组和ｃＴｎＴ正常组;观察住院期间两组急性心肌梗死（ＭＡＩ）、心脏性死亡和难治性心绞痛的发生率。结果：在１１２例ＵＡ患中,ｃＴｎＴ升高４４例（３９％）,ｃＴｎＴ正常６８例（６１％）。住院期间发生ＡＭＩ１２例（１０．７％,死亡５例（４．５％）,非致死性心肌梗死及心脏性死亡１５例（１３．４％）。其中ｃＴｎＴ升高组的死亡率较ｃＴｎＴ正常组有升高趋势,但差异无显性;而ｃＴｎＴ升高组ＡＭＩ、非致死性心肌梗死及心脏性死亡的发生率显高于ｃＴｎＴ正常组（Ｐ〈０．０１）。校正年龄、性别、心绞痛分级、心电图改变等因素后,ｃ     

Timing of peak troponin T and creatine kinase-MB elevations after percutaneous coronary intervention

STUDY OBJECTIVE: The prognostic significance of elevations in creatine kinase-MB and troponin T (cTnT), which have been conventionally measured 6 to 8 h after percutaneous coronary intervention (PCI), has been established. However, the time to peak biomarker appearance in the circulation has not been defined and is the purpose of this pilot study. DESIGN: Nonrandomized, nonconsecutive patient cohort. SETTING: Clinical practice, Mayo Clinic, Rochester, MN. PATIENTS: Cohort (n = 57) undergoing elective PCI. INTERVENTIONS: cTnT and creatine kinase (CK)-MB measured at baseline, 2 h, 4 h, 8 h, and > or = 2 h (mean +/- SEM, 18 +/- 5 h) after PCI. Measurements and results: Postprocedure cTnT elevations were detected in 30 of 57 patients (53%). Of these, 4 of 30 patients (13%) had peak cTnT at 4 h (0.80 +/- 0.40 ng/mL), 5 of 30 patients (17%) had peak cTnT at 8 h (1.07 +/- 0.48 ng/mL), and 21 of 30 patients (70%) had peak cTnT at > or = 12 h (0.21 +/- 0.06 ng/mL); 22 of 30 patients received abciximab. Elevations in CK-MB occurred in 14 of 57 patients (25%). Of these, 3 of 14 patients (21%) demonstrated peak CK-MB at 2 h (18.5 +/- 7.9 ng/mL) and the remainder (11 of 14 patients, 79%) during the 12- to 20-h interval (20.2 +/- 4.4 ng/mL); 12 of 14 patients received abciximab. CONCLUSION: More cTnT than CK-MB elevations occur after PCI; however, both biomarkers demonstrate a longer time to peak value than anticipated in clinical practice. Early surveillance monitoring (< 12 h) does not detect peak biomarker levels, especially in patients with normal baseline values. If peak levels are to be used to determine prognosis, then longer time intervals should be used for post-PCI surveillance. The timing of peak elevations appears to be influenced by baselines values as well. Early elevations may reflect the conjoint effects of injury associated with the disease process and the intervention itself. These data suggest that a re-evaluation of surveillance monitoring to account for the variability reported and the influence of baseline elevations of biomarkers may improve the prognostic power of the measurements.     

Comparison between strategies using creatine kinase-MB(mass), myoglobin, and troponin T in the early detection or exclusion of acute myocardial infarction in patients with chest pain and a nondiagnostic electrocardiogram

Different strategies using creatine kinase-MB(mass), myoglobin, and troponin T were compared in 738 patients admitted because of chest pain and an electrocardiogram not diagnostic of acute myocardial infarction. We conclude that a combination of creatine kinase-MB and troponin T during the first 6 hours enables early detection or exclusion of acute myocardial infarction in this population.     

肌钙蛋白T与N端B型尿钠肽前体对急性肺栓塞患者危险分层的意义

目的探讨联合检测生化标记物肌钙蛋白T（cTnT）和N端B型尿钠肽前体（NT—proBNP）水平对急性肺栓塞（APE）患者进行危险分层及预后判断的临床意义。方法根据血浆cTnT和NT—proBNP水平将59例APE患者分为3组：1组（14例）,cTnT〈0．1ng／ml,NT—proBNP〈100pg／ml;2组（28例）,cTnT≥0．1ng／ml或NT—proBNP≥100pg／ml;3组（17例）,cTnT≥0．1ng／ml且NT-proBNP≥100pg／ml,分析cTnT和（或）NT—proBNP升高对APE患者危险分层与临床预后的关系。结果三组间动脉血PaO2、P（A—a）O2比较差异有统计学意义（P〈0．01）。进行两两比较,1、3组动脉血PaO2、P（A—a）O2分别与其他各组相比差异有统计学意义（P〈0．01）。1组、2组、3组预后不良者分别为0（0％）、7例（25．0％）、9例（52．9％）,差异有统计学意义（P〈0．01）。59例APE患者中临床不良事件发生组与无临床不良事件组比较,PaO2、cTnT、NT—proBNP水平差异均有统计学意义（P〈0．01）。结论联合检测cTnT和NT—proBNP在APE患者早期危险分层、指导临床决策及预后判断中具有重要价值。     

床边快速肌钙蛋白T测定对急性胸痛患者诊断的价值

目的评价床边快速心肌肌钙蛋白T(cTnT)检测对以急性胸痛症状住院或转科的患者诊断的价值。方法采用床边快速心肌肌钙蛋白T测定仪(CARDIACREADER)测定502例以急性胸痛症状入院或转入心内科的患者入院即刻、6h、12h的cTnT水平,同时测定患者的心肌肌钙蛋白I(cTnI)、肌酸磷酸激酶(CK)及其同功酶(CK-MB)水平。以心电图出现急性心肌梗死(AMI)的动态改变和(或)CK-MB和TnI同时升高诊断为心肌梗死,计算床边快速cTnT诊断急性心肌梗死的特异性、敏感性、阴性预测价值和阳性预测价值。结果502例急性胸痛患者,cTnT阳性160例(31.9%),cTnT阴性323例(64.3%),19例弱阳性。139例cTnT阳性患者发生AMI,7例cTnT阴性的患者发生AMI。床边快速cTnT对以急性胸痛症状住院或转科的患者诊断AMI的特异性为93.8%、敏感性为95.2%、阳性预测价值为86.9%、阴性预测价值为97.8%。结论床边快速肌钙蛋白T测定可以迅速准确地在急性胸痛患者中识别或排除AMI患者,具有重要的诊断价值。     

Comparative analysis of cardiac troponin i and creatine kinase-MB as markers of acute myocardial infarction

Background: The World Health Organization (WHO) criteria for the diagnosis of acute myocardial infarction (AMI) includes presentation of chest pain over 20 min, evolutionary changes on the electrocardiogram (ECG), and abnormal levels of cardiac enzymes. Hypothesis: A multicenter study was conducted to evaluate the efficacy of cardiac troponin I (cTnI) in detecting and ruling out AMI. Methods: The normal range for cTnI in 149 apparently healthy subjects without known history of cardiac or other diseases was 0 to 0.5 ng/ml. Cutoffs of 2.5 ng/ml for cTnI and 5.0 ng/ml for creatine kinase-MB (CK-MB) were used. Results: The diagnostic sensitivity of blood collected from 291 consecutive patients with suspicion of AMI was 95.0 and 96.4%, respectively, for samples obtained at 4–48 h after AMI onset. CK-MB was more sensitive during the early 4–8 h interval (84 vs. 74%); both had 100% sensitivity from 12–36 h. CTnI remained at 100% for 72 h, while CK-MB declined to 57%. The clinical specificity was 97.4 vs. 85.8%, respectively, on non-AMI patients with cardiac and noncardiac diseases, and those with renal disease. Conclusion: cTnI is an excellent marker for detecting and ruling out AMI, because it has better specificity and a wider diagnostic window than the accepted standard, CK-MB.