Rates of positive cardiac troponin I and creatine kinase MB mass among patients hospitalized for suspected acute coronary syndromes

BACKGROUND: Cardiac troponin I (cTnI) is a more specific and sensitive biomarker than creatine kinase MB (CKMB) for detection of myocardial damage. We report the prevalence of positive cTnI and CKMB mass among patients hospitalized with suspected acute coronary syndrome (ACS) and the potential impact of use of different reference cutoffs, particularly those proposed by European Society of Cardiology/American College of Cardiology (ESC/ACC) consensus guidelines, on rates of diagnosis of acute myocardial infarction (AMI). METHODS: We analyzed 1719 consecutive patients with suspected ACS admitted to an urban acute care hospital over a 6-month period. Patients (> or = 18 years of age) had at least two separate sets of plasma biomarkers (cTnI and CKMB) measured more than 12-24 h after admission to determine the potential rates of AMI based on different biomarker cutoff concentrations. RESULTS: The prevalence of cTnI-positive cases ranged from 10.6%, based on a cutoff of twice the ROC curve (cTnI < or =1.2 microg/L), to 25.0%, using the ESC/ACC-recommended 99th percentile cutoff (cTnI <0.1 microg/L). The prevalence of CKMB-positive cases ranged from 10.4%, with the cutoff of twice the ROC curve (CKMB < or =10.0 microg/L) to 21.7%, with the 99th percentile cutoff (CKMB <3.9 microg/L). Use of the 10% CV cutoff (cTnI < or =0.3 microg/L and CKMB <3.9 microg/L) instead of the ROC cutoff produced a 26% increase in all cTnI-positive cases. Use of the 99th percentile reference cutoff instead of the ROC curve-derived cutoff produced an 85% increase in all cTnI-positive cases. A substantial proportion of the increase in total cTnI-positive cases was derived from cTnI-positive/CKMB-negative cases: 71 (4.1%), 73 (4.2%), 98 (5.7%), and 209 (12.2%) of cTnI-positive cases were CKMB-negative, as determined by the twice the ROC, ROC, 10% CV, and 99th percentile reference cutoffs, respectively. At the 99th percentile cutoffs, 8.8% of cases were CKMB-positive/cTnI-negative. CONCLUSIONS: Use of lower reference cutoffs for plasma biomarkers, as recommended by ESC/ACC guidelines, markedly increases the rates of cTnI-positive cases overall. A substantial proportion of the increase in total cTnI-positive cases was derived from the creation of additional cTnI-positive/CKMB-negative cases. CKMB-positive/cTnI-negative cases are likely false positive for myocardial injury.     

Effect of population selection on 99th percentile values for a high sensitivity cardiac troponin I and T assays

ObjectiveUsing objective laboratory and clinical criteria to more accurately determine the 99th percentile values for cardiac troponin I and T.Design and methodsWe measured cardiac troponin T and cardiac troponin I with high-sensitivity assays in a large cohort of apparently healthy community subjects and calculated 99th percentiles for different sexes and ages. Subjects with possible subclinical disease were eliminated based on objective laboratory criteria, eGFR and NT-proBNP, and clinical criteria, history and examination and echocardiogram.ResultsFor men and women of all ages, separately, more than 50% of subjects were excluded using these criteria, with a lesser proportion of younger subjects being excluded. In men aged < 75 years, the 99th percentile for cTnI decreased by more than 50% from 22.9 ng/L to 10.3 ng/L. In other age groups and for cTnT the decrease was smaller (%) but still considerable.ConclusionsFor establishing cardiac troponin 99th percentiles, simply using self-reporting of health is insufficient. Objective laboratory measures and clinical and echocardiographic assessments are essential to define a healthy population, especially in older persons.     

Myoglobin,creatine kinase MB isoforms and creatine kinase MB mass in early diagnosis of myocardial infarction in patients with acute chest pain

OBJECTIVES: Measurements of myoglobin and creatine kinase (CK)-MB isoforms have been suggested to be sensitive tests for the early diagnosis of myocardial infarction (MI). We have investigated the utility of myoglobin, creatine kinase (CK)-MB isoforms and creatine kinase MB mass (CK-MBm) in early diagnosis of MI using cardiac troponin T (cTnT) positivity as a reference. DESIGN AND METHODS: The study population comprised 440 patients who had had chest pain for less than 12 h. Patients were divided into cTnT negative (cTnT-) or cTnT positive (cTnT+) patients (concentration of cTnT >0.1 microg/L at two different time points during 72 h). RESULTS: At the time of admission to the emergency department receiver operating characteristics (ROC) curves of CK-MB isoforms and CK-MBm were not better than that of myoglobin. Six hours after admission CK-MB isoforms and CK-MBm provided statistically significantly larger areas under the curve (AUC) than myoglobin (p < 0.01). When ROC curves were related to the onset of chest pain (< 3 h, 3-6 h, and > 6 h) there were no significant differences between the cardiac markers studied. CONCLUSIONS: According to the present findings, CK-MB isoforms or myoglobin offer no advantage over CK-MBm as early markers of myocardial infarction.     

Correlation of antemortem serum creatine kinase, creatine kinase-MB, troponin I, and troponin T with cardiac pathology

BACKGROUND: Spurious increases in serum troponins, especially troponin T, have been reported in patients with and without acute myocardial syndromes. METHODS: We studied 78 autopsied patients without clinical myocardial infarction (MI) and correlated histologic cardiac findings with antemortem serum creatine kinase (CK), its MB isoenzyme (CK-MB), cardiac troponin I (cTnI), and cardiac troponin T (cTnT). RESULTS: There was no significant myocardial pathology in 15 patients. Cardiac pathologies were in five groups: scarring from previous MI or patchy ventricular fibrosis (n = 9), recent MI (n = 27), healing MI (n = 7), degenerative myocyte changes consistent with congestive heart failure (CHF; n = 12), and other cardiac pathologies (n = 8). The median concentrations in the five groups were not significantly different for either CK or CK-MB. Compared with the no-pathology group, only the MI group was significantly different for cTnI, and the MI and other pathology groups were significantly different for cTnT. For patients with MI, 22%, 19%, 48%, and 65% had increased CK, CK-MB, cTnI, and cTnT, respectively; for CHF and other cardiac pathologies combined, the percentages were 28%, 17%, 22%, and 50%. For patients with increased cTnI, 72% and 28% had MI and other myocardial pathologies, respectively; patients with increased cTnT had 64% and 36%, respectively. Patients without myocardial pathology had no increases in CK-MB, cTnI, or cTnT. CONCLUSIONS: All patients with increased serum CK-MB, cTnI, and cTnT had significant cardiac histologic changes. The second-generation cTnT assay appears to be a more sensitive indicator of MI and other myocardial pathologies than the cTnI assay used in this study.     

3种血清心肌标志物联合检测在急性冠状动脉综合征诊断中的应用

目的：探讨肌红蛋白（Mb）、心肌肌钙蛋白I（cTnI）、肌酸激酶同工酶 MB型（CK-MB）联合检测在急性冠状动脉综合征（ACS）诊断中的价值。方法选取85例ACS患者[其中不稳定型心绞痛（UA）25例、心肌梗死60例]作为ACS组,除ACS外的冠心病（CHD）患者68例作为CHD组,60例健康体检者作为健康组进行血清 Mb、cTnI、肌酸激酶（CK）、CK-MB检测,并进行统计学分析和评价。结果 ACS组患者血清Mb、cTnI、CK-MB水平均高于CHD组及健康组,差异有统计学意义（P＜0．05）。结论血清 Mb是ACS诊断中敏感且较特异的生化指标,Mb、cTnI、CK-MB联合检测有助于ACS早期的快速诊断和鉴别诊断,具有重要的临床意义。     

手足口病患儿联合检测肌酸激酶同工酶MB、心肌肌钙蛋白Ⅰ在合并病毒性心肌炎诊断中的价值

目的探讨手足口病患儿联合检测血清中肌酸激酶同工酶MB（CK—MB）、心肌肌钙蛋白Ⅰ（cTnI）水平对诊断合并病毒性心肌炎的价值。方法将188倒HFMD患儿分为确诊合并精毒性心肌炎组、疑似舍并病毒性心肌炎组、无合并病毒性心肌灸组。所有惠儿清晨空腹采集静脉血,检测血清中的肌酸激酶同工酶MB（CK—MB）、心肌肌钙蛋白Ⅰ（cTnI）水平,对结果进行统计分析。结果确诊合并病毒性心肌炎组与疑似合并病毒性心肌炎组血清中CK—MB、cTnI均高于无合并病毒性心肌炎组,差异有统计学意义（P〈0．05）;确诊合并病毒性心肌炎组血清中CK—MB、cTnI与疑似合并病毒性心肌炎组比较差异无统计学意义（P〉0．05）。确诊组与疑似组两项检测中的总异常率均分别高于两纽中CK—MB、cTnI单独检测异常率（P〈0．05,P〈0．05）。结论CK—MB、cTnI在HFMD中诊断合并病毒性心肌炎有重要意义;HFMD患儿同时检测血清中CK—MB、cTrI水平,可以提高合并病毒性心肌炎的捡出率。     

心肌肌钙蛋白I、肌钙蛋白T、肌酸激酶同工酶MB早期诊断 急性心肌梗死敏感性及特异性比较分析

目的 探讨心肌肌钙蛋白Ⅰ（cTnI)、 肌钙蛋白T（cTnT)、 肌酸激酶同工酶MB（CK－MB）早期诊断急性心肌梗死的临床应用价值。方法 对60例急性心肌梗死（AMI）和40例不稳定型心绞痛（UA）患者的同一血样标本检测cTnI、cTnT、CK－MB3项指标,分别进行两组间比较,并对 AMI组和UA组各指标作对比分析。结果 cTnI、cTnT早期诊断急性心肌梗死灵敏度高于CK－MB,阳性率分别为63.3%、46.7%、18.3％,P＜0.01;cTnI和cTnT无显著差别,P＞0.05;cTnI、cTnT、CK－MB特异性相当。结论 心肌肌钙蛋白I和肌钙蛋白T对于AMI的早期诊断具有较高灵敏度和较强特异性,是心肌损伤特异笥标志物,cTnI检测方便、快捷、准确,具有较好的临床价值。     

Cardiac troponin T and creatine kinase MB are not increased in exterior oblique muscle of patients with renal failure

BACKGROUND: Serum cardiac troponin T (cTnT) concentrations may be increased in patients with renal dysfunction without evidence of cardiac damage, as assessed by conventional methods. It has been suggested that these positive measurements result from the expression in skeletal muscle of fetal isoforms of cTnT, which are detected by the cTnT immunoassay. METHODS: Skeletal muscle (exterior oblique) biopsies were taken from healthy living kidney donors (n = 5) and transplant recipients (n = 19). The amounts of cTnT and creatine kinase (CK) isoenzymes in skeletal muscle of healthy controls were compared with those in patients with renal failure (Wilcoxon-Mann-Whitney test). cTnT was measured quantitatively by a second-generation assay, with a limit of detection of 1 microg/g of protein, and qualitatively by immunohistochemistry and immunoblotting. CK-MB was measured by quantitative electrophoresis. RESULTS: Minute quantities of cTnT were detected in 2 of the 5 (40%) control samples and 9 of the 19 (47%) renal failure samples, respectively, at mean concentrations of <5 microg/g of protein for both subject groups. This was <1/6000th that found in heart muscle. There was no significant difference in cTnT or CK-MB content in skeletal muscle between healthy controls and patients with renal failure. Increased serum cTnT did not predict detectable cTnT in skeletal muscle. cTnT was not detected qualitatively by immunoblotting or immunohistochemistry in any skeletal muscle samples. CONCLUSIONS: Uremia does not affect the content of cTnT or CK-MB in exterior oblique muscle, suggesting that cTnT detected in serum from patients with renal failure does not originate from skeletal muscle.