Early Diagnostic Efficiency of Cardiac Troponin I and Troponin T for Acute Myocardial Infarction

Objective : To compare the early diagnostic efficiency of the cardiac troponin I (cTn-I) level with that of the cardiac troponin T (cTn-T) level, as well as the creatine kinase (CK), CK-MB, and myoglobin levels, for acute myocardial infarction (AMI) in patients without an initially diagnostic ECG presenting to the ED within 24 hours of the onset of their symptoms. Methods : A prospective, observational, cohort study was performed involving chest pain patients admitted to a large urban community hospital. Participants were consecutive consenting ED chest pain patients ≥30 years of age. Exclusions included duration of symptoms >24 hours, inability to complete data collection, receipt of CPR, and ST-segment elevation on the initial ECG. Measurements included levels of cTn-I, cTn-T, CK, CK-MB, and myoglobin at the time of presentation and 1, 2, 6, and 12–24 hours after presentation as well as presenting ECG and clinical follow-up. Confirmation of the diagnosis of AMI was based on World Health Organization criteria. Results : Of the 177 patients included in the study, 27 (15%) were diagnosed as having AMIs. The sensitivities of all 5 biochemical markers for AMI were poor at the time of ED presentation (3.7–33.3%) but rose significantly over the study period. The sensitivity of cTn-T was significantly better than that of cTn-I over the initial 2 hours, but both markers' sensitivities were low (<60%) during this time frame. The cTn-I was significantly more specific for AMI than was the cTn-T, but not significantly better than CK-MB or myoglobin. Likelihood ratio analysis showed that the biochemical markers with the highest positive likelihood ratios for AMI during the first 2 hours following ED presentation were myoglobin and CK-MB. From 6 through 24 hours, the positive likelihood ratios for cTn-I, CK-MB, and myoglobin were superior to those of CK and cTn-T. Conclusions : cTn-I, CK-MB, and myoglobin are significantly more specific for AMI than are CK and cTn-T. Myoglobin is the biochemical marker having the highest combination of sensitivity, specificity, and negative predictive value for AMI within 2 hours of ED presentation. Neither cTn-I nor cTn-T offers significant advantages over myoglobin and CK-MB in the early (≤2 hours) initial screening for AMI. The cardiac troponins are of benefit in identifying AMI ≤6 hours after presentation.     

Prospective Assessment of Presenting Serum Markers for Cardiac Risk Stratification

Objective: To quantify the association of initial ED serum cardiac markers with the risk for life-threatening events (LEs) or need for lifesaving interventions (Lis) or administration of IV nitroglycerin.
Methods: A prospective, observational study was performed using a cohort of hemodynamically stable, hospitalized patients (age > 25 years) presenting with nontraumatic chest discomfort. Patients with ST-segment elevation on their initial ECGs were excluded. Presenting serum samples were assayed for serum myoglobin and creatine kinase-MB isomer (CK-MB) using the Opus and Stratus systems. Target cases were defined as patients having LEs (e.g., cardiogenic shock, ventricular fibrillation, cardiac arrest), requiring Lis (e.g., intubation, cardioversion, pacing, reperfusion therapy), or needing IV nitroglycerin within 48 hours. Manufacturer's thresholds defined abnormal marker levels. Abnormal ECGs were defined using the Brush criteria.
Results: Of the 178 eligible patients, 44 (25%) were target cases . Most (55%) target cases had blood drawn for assays within four hours of chest discomfort onset. The relative risk and sensitivity of the serum markers and the ECG for target cases follow:
Of the seven patients with an LE/LI, six had blood drawn four hours or less after symptom onset; two LE/LI patients had abnormal myoglobin levels' no LE/LI patient had an abnormal CK-MB level.
Conclusions: Isolated serum myoglobin and CK-MB levels obtained at patient ED presentation were not strongly associated with the 48-hour risk for LEs, Lis, or the use of IV nitroglycerin. Future studies of risk stratification should address the merits of serial serum marker measurements that extend up to 12 hours beyond patient symptom onset.     

Serum markers in the emergency department diagnosis of acute myocardial infarction

No currently used cardiac-specific serum marker meets all the criteria for an "ideal" marker of AMI. No test is both highly sensitive and highly specific for acute infarction within 6 hours following the onset of chest pain, the timeframe of interest to most emergency physicians in making diagnostic and therapeutic decisions. Patients presenting to the ED with chest pain or other symptoms suggestive of acute cardiac ischemia therefore cannot make a diagnosis of AMI excluded on the basis of a single cardiac marker value obtained within a few hours after symptom onset. The total CK level is far too insensitive and nonspecific a test to be used to diagnose AMI. It retains its value, however, as a screening test, and serum of patients with abnormal total CK values should undergo a CK-MBmass assay. Elevation in CK-MB is a vital component of ultimate diagnosis of AMI, but levels of this marker are normal in one fourth to one half of patients with AMI at the time of ED presentation. The test is highly specific, however, and an abnormal value (particularly when it exceeds 5% of the total CK value) at any time in a patient with chest pain is highly suggestive of an AMI. There have been several improvements of CK-MB assay timing and subform quantification that appear highly useful for emergency physicians. Rapid serial CK-MB assessment greatly increases the diagnostic value of the assay in a timeframe suitable for ED purposes but unfortunately still misses about 10% of patients ultimately diagnosed with acute MI. Assays of CK-MB subforms have very high sensitivity, and, although unreliable within 4 hours of symptom onset, have excellent diagnostic value at 6 or more hours after chest pain begins. Automated test assays recently have become available and could prove applicable to ED settings. The cardiac troponins are highly useful as markers of acute coronary syndromes, rather than specifically of AMI, and abnormal values at any time following chest pain onset are highly predictive of an adverse cardiac event. The ED applicability of the troponins is severely limited, however, because values remain normal in most patients with acute cardiac events as long as 6 hours following symptom onset. Myoglobin appeared promising as a marker of early cardiac ischemia but appears to be only marginally more sensitive than CK-MB assays early after symptom onset and less sensitive than CK-MB at 8 hours or more after chest pain starts. Rapid serial myoglobin assessment, however, appears highly useful as an early marker of AMI. The marker has a very narrow diagnostic window. The clinician is left with several tests that are highly effective in correctly identifying patients with AMI (or at high risk for AMI), but none that can dependably exclude patients with acute coronary syndromes soon after chest pain onset. A prudent strategy when assessing ED patients with chest pain and nondiagnostic ECGs is to order CK-MB and troponin values on presentation in the hope of making an early diagnosis of AMI or unstable coronary syndrome. Although it is recognized that normal values obtained within 6 hours of symptom onset do not exclude an acute coronary syndrome, patients at low clinical risk and having normal cardiac marker tests could be provisionally admitted to low-acuity hospital settings or ED observation. After 6 to 8 hours of symptom duration has elapsed, the cardiac-specific markers are highly effective in diagnosing AMI, and such values obtained can be used more appropriately to make final disposition decisions. At no time should results of serum marker tests outweigh ECG findings or clinical assessment of the patient's risk and stability.     

Comparison of the temporal release pattern of copeptin with conventional biomarkers in acute myocardial infarction

Background

Early detection of acute myocardial infarction (AMI) using cardiac biomarkers of myocardial necrosis remains limited since these biomarkers do not rise within the first hours from onset of AMI. We aimed to compare the temporal release pattern of the C-terminal portion of provasopressin (copeptin) with conventional cardiac biomarkers, including creatine kinase isoenzyme (CK-MB), cardiac troponin T (cTnT), and high-sensitivity cTnT (hs-cTnT), in patients with ST-elevation AMI.

Methods

We included 145 patients undergoing successful primary percutaneous coronary intervention (PCI) for a first ST-elevation AMI presenting within 12?h of symptom onset. Blood samples were taken on admission and at four time points within the first 24?h after PCI.

Results

In contrast to all other markers, copeptin levels were already elevated on admission and were higher with a shorter time from symptom onset to reperfusion and lower systolic blood pressure. Copeptin levels peaked immediately after symptom onset at a maximum of 249?pmol/L and normalized within 10?h. In contrast, CK-MB, cTnT, and hs-cTnT peaked after 14?h from symptom onset at a maximum of 275?U/L, 5.75???g/L, and 4.16???g/L, respectively, and decreased more gradually.

Conclusions

Copeptin has a distinct release pattern in patients with ST-elevation AMI, peaking within the first hour after symptom onset before conventional cardiac biomarkers and falling to normal ranges within the first day. Further studies are required to determine the exact role of copeptin in AMI suspects presenting within the first hours after symptom onset.     

Human heart-type cytoplasmic fatty acid-binding protein (H-FABP) for the diagnosis of acute myocardial infarction. Clinical evaluation of H-FABP in comparison with myoglobin and creatine kinase isoenzyme MB.

Heart-type fatty acid-binding protein (H-FABP) is a low molecular weight cytoplasmic protein and present abundantly in the myocardium. When the myocardium is injured, as in the case of myocardial infarction, low molecular weight cytoplasmic proteins including H-FABP are released into the circulation and H-FABP is detectable in a blood sample. We have already developed a direct sandwich-ELISA for quantification of human H-FABP using two distinct types of monoclonal antibodies specific for human H-FABP. In this study we investigated the clinical validity of H-FABP as a biochemical diagnostic marker in the early phase of acute myocardial infarction (AMI). To evaluate the diagnostic usefulness of H-FABP in the early phase of AMI, blood samples were obtained from the following patients within 12 hours after the appearance of symptoms, and serum levels of H-FABP were compared with those of conventional diagnostic markers, such as myoglobin and creatine kinase isoenzyme MB (CK-MB). Blood samples were collected from patients with confirmed AMI (n=140), patients with chest pain who were afterwards not classified as AMI by normal CK-MB levels (non-AMI) (n=49) and normal healthy volunteers (n=75). The serum concentration of H-FABP was quantified with our direct sandwich-ELISA. The concentration of myoglobin mass was measured with a commercial RIA kit. The serum CK-MB activity was determined with an immuno-inhibition assay kit. The overall sensitivity of H-FABP, within 12 hours after the appearance of symptoms, was 92.9%, while it was 88.6% with myoglobin and 18.6% with CK-MB. The overall specificity of H-FABP was 67.3%, while it was 57.1% with myoglobin and 98.0% with CK-MB. The diagnostic efficacy rates with these markers were 86.2% (H-FABP), 80.4% (myoglobin) and 39.2% (CK-MB), respectively. The diagnostic validity of H-FABP was further assessed by receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) of H-FABP was 0.921, which was significantly greater than with myoglobin (AUC: 0.843) and CK-MB (AUC: 0.654). These parameters, such as sensitivity, specificity, diagnostic efficacy and diagnostic accuracy, obtained for patients with chest pain within 3 hours and/or 6 hours after the onset of symptoms were almost the same as those for patients within 12 hours after symptoms. H-FABP is more sensitive than both myoglobin and CK-MB, more specific than myoglobin for detecting AMI within 12 hours after the onset of symptoms, and shows the highest values for both diagnostic efficacy and ROC curve analysis. Thus, H-FABP has great potential as an excellent biochemical cardiac marker for the diagnosis of AMI in the early phase.     

AMI患者早期CK同工酶亚型的高压电泳图谱分析

目的探讨CK同工酶亚型在AMI胸痛发作后24h内的变化规律,为AMI患者的早期诊断提供依据。方法采用REP全自动高压电泳仪检测AMI胸痛发作后不同时间以及对照组的CK-MM1、CK-MM2、CK-MM3、CK-MB1、CK-MB2等指标并进行荧光扫描,同时在Olympus2700全自动生化分析仪上测定CK、CK-MB的总活性,对所得数据进行恰当的统计分析。结果在AMI患者胸痛发作24h内,CK同工酶亚型有一特殊的变化规律:4~6h内,CK-MB2、CK-MM3开始升高,8~12h达高峰,92%的病人CK-MB2/CK-MB1>1.5,同时91%的病人CK-MM3/CK-MM1>0.5。结论CK同工酶亚型CK-MM3/CK-MM1、CK-MB2/CK-MB1的检测可作为AMI早期诊断的指标。     

Impact of Community Intervention to Reduce Patient Delay Time on Use of Reperfusion Therapy for Acute Myocardial Infarction Rapid Early Action for Coronary Treatment (REACT) Trial

BACKGROUND: Reperfusion therapy for acute myocardial infarction (AMI) is a time-dependent intervention that can reduce infarct-related morbidity and mortality. Out-of-hospital patient delay from symptom onset until emergency department (ED) presentation may reduce the expected benefit of reperfusion therapy. OBJECTIVE: To determine the impact of a community educational intervention to reduce patient delay time on the use of reperfusion therapy for AMI. METHODS: This was a randomized, controlled community-based trial to enhance patient recognition of AMI symptoms and encourage early ED presentation with resultant increased reperfusion therapy rates for AMI. The study took place in 44 hospitals in 20 pair-matched communities in five U.S. geographic regions. Eligible study subjects were non-institutionalized patients without chest injury (aged > or =30 years) who were admitted to participating hospitals and who received a hospital discharge diagnosis of AMI (ICD 410); n = 4,885. For outcome assessment, patients were excluded if they were without survival data (n = 402), enrolled in thrombolytic trials (n = 61), receiving reperfusion therapy >12 hours after ED arrival (n = 628), or missing symptom onset or reperfusion times (n = 781). The applied intervention was an educational program targeting community organizations and the general public, high-risk patients, and health professionals in target communities. The primary outcome was a change in the proportion of AMI patients receiving early reperfusion therapy (i.e., within one hour of ED arrival or within six hours of symptom onset). Trends in reperfusion therapy rates were determined after adjustment for patient demographics, presenting blood pressure, cardiac history, and insurance status. Four-month baseline was compared with the 18-month intervention period. RESULTS: Of 3,013 selected AMI patients, 40% received reperfusion therapy. Eighteen percent received therapy within one hour of ED arrival (46% of treated patients), and 32% within six hours of symptom onset (80% of treated patients). No significant difference in the trends in reperfusion therapy rates was attributable to the intervention, although increases in early reperfusion therapy rates were noted during the first six months of the intervention. A significant association of early reperfusion therapy use with ambulance use was identified. CONCLUSIONS: Community-wide educational efforts to enhance patient response to AMI symptoms may not translate into sustained changes in reperfusion practices. However, an increased odds for early reperfusion therapy use during the initiation of the intervention and the association of early therapy with ambulance use suggest that reperfusion therapy rates can be enhanced.     

Serial Myoglobin Levels for Patients with Possible Myocardial Infarction

Objectives: To determine the sensitivity and specificity of a new myoglobin assay for acute myocardial infarction (AMI), considering both the total amount of serum myoglobin and its percentage change over 2 hours.
Methods: A prospective, observational test performance study for the recognition of AMI was done using serial myoglobin assays of 42 admitted chest pain patients at a large, urban teaching hospital ED. Myoglobin testing was performed at presentation (time 0) and at 1 and 2 hours after arrival. A myoglobin level >100 g/L (ng/mL) or a change >50% from baseline (increase or decrease) any time during the 2–hour period was considered positive. Patients and their physicians were blinded to the myoglobin results. The managing clinician's final diagnosis of the presenting event was used as the diagnostic criterion standard.
Results: The sensitivity of the myoglobin technique for detection of AMI in the first hours in the ED was 13/14 (93%; 95% CI: 66–100%). The 1 patient who had a false-negative test had evidence of AMI on the ECG and an initially abnormal creatine kinase-MB (CK-MB) assay. The specificity was 22/28 (79%; 59–92%). However, of the 6 patients who had "false-positive" myoglobin tests, all had serious illness: significant cardiac disease (n = 4), in-hospital death (n = 1), or deep venous thrombosis (n = 1).
Conclusion: Myoglobin level determinations are sensitive tests to detect AMI during the first 2 hours of a patient's stay in the ED and may complement current clinical tools.     

快速检测心肌脂肪酸结合蛋白诊断早期急性心肌梗死

目的 探讨快速检测血浆心肌脂肪酸结合蛋白（H-FABP）在诊断早期急性心肌梗死（AMI）中的价值.方法 比较H-FABP、cTnI、CK-MB和MYO四种物质定量检测诊断发病6 h内AMI的敏感性、特异性和准确性;比较H-FABP快速检测试剂条定性检测结果与ELISA定量检测结果.结果 H-FABP诊断发病3 h和6 h内AMI的敏感性显著高于cTnI和CK-MB,特异性相比,差异无显著性,诊断准确性显著高于cTnI、CK-MB和MYO.试剂条定性检测结果与ELISA比较符合率达96.9%.结论 H-FABP定性检测试剂条可用于早期AMI筛选诊断.     

The additive value of copeptin for early diagnosis and prognosis of acute coronary syndromes

BackgroundOne promising biomarker that has received substantial interest for the evaluation of suspected acute coronary syndromes (ACS) is copeptin. Therefore, our goal was to assess the additive value of copeptin for early diagnosis and prognosis of Non-ST segment acute coronary syndromes (NSTE-ACS).MethodsThe study included ninety patients with suspected ACS. Patients with typical ischemic chest pain within six hours of symptom onset and without ST-segment elevation on electrocardiograph (ECG) were included. In addition to cardiac troponin I (cTnI), copeptin was assayed from venous blood samples obtained on admission, followed by serial troponin measurements six and twelve hours later. One year follow-up was performed for any major adverse cardiac events (MACEs) including cardiac death, re-infarction, re- hospitalization for ischemic events, heart failure, stroke and target lesion revascularization (TLR).ResultsOf seventy nine patients included in the final analysis, Forty (50.6%) were diagnosed as unstable angina (UA), while thirty nine (49.4%) had a non-ST elevation myocardial infarction (NSTEMI). Copeptin level on admission was significantly higher among NSTEMI patients than those with UA. With regard to the correlation analyses, copeptin was positively correlated with each of, Global Registry of Acute Coronary Events (GRACE), Thrombolysis In Myocardial Infarction (TIMI) and synergy between percutaneous coronary intervention with taxus and cardiac surgery (SYNTAX) scores. The sensitivity and negative predictive value (NPV) of the combination of admission copeptin and cTn-I were 100% and 100%, respectively, versus 57% and 70%, respectively, with admission of cTn-I alone. The area under curve (AUC) of the combination of copeptin and cTn-I was (0.975, p < 0.001) and was significantly higher than the AUC of cTn-I alone (0.888, p < 0.001). Admission copeptin was an independent predictor for MACEs by multiple regression analysis (OR: 0.01, 95% CI: 0.0–0.8, P = 0.04). High values of copeptin had the highest rate of MACEs and coronary revascularization during one year of follow up.ConclusionThe combination of copeptin and conventional troponin I aids in early rule out of NSTEMI virtually independent of chest pain onset (CPO) with high NPV in patients presenting within three hours from chest pain onset with excellent prognostic value for risk stratification and prediction of MACEs.     

Evaluation of a Bedside Whole-blood Rapid Troponin T Assay in the Emergency Department

Objective : To evaluate the performance of a new bedside whole-blood rapid assay for cardiac troponin T (cTnT) in patients presenting to the ED with symptoms consistent with acute coronary ischemia. Methods : A prospective, observational trial was performed in 8 participating medical centers. Serial blood samples were obtained on presentation to the ED and 3 and 6 hours later. The cTnT whole-blood rapid assays were performed immediately at the site. Treating physicians and patients were blinded to the results of the rapid assays. Serum samples were analyzed at the core laboratory for serum cTnT, creatine kinase (CK)-MB, and myoglobin. The sensitivity of the rapid assay for detecting acute myocardial infarction (AMI) was compared with the sensitivities of serum cTnT, CK-MB, and myoglobin assays. Results : Of 721 patients, 102 were diagnosed as having AMI. The median elapsed time from symptom onset to ED arrival was 3 hours. The sensitivities of the rapid assay for detecting AMI were 19.6%, 59.0%, and 69.7% at 0, 3, and 6 hours, respectively. The sensitivities of the serum cTnT assay (p-values for comparison with the rapid assay for cTnT) were 25.0% (p = 0.18), 69.6% (p = 0.04), and 79.8% (p = 0.02) at 0, 3, and 6 hours, respectively. The CK-MB and myoglobin sensitivities were 21.9%, 64.5%, and 81.0%; and 43.8%, 77.4%, and 71.4%, respectively. There were 7 patients with AMI who had negative rapid assay readings and positive serum cTnT levels; 4 of these patients were enrolled at the same site. Twenty patients not diagnosed as having AMI had at least one positive rapid assay. Fourteen of these 20 patients had a diagnosis of clinically relevant cardiac disease. Conclusions : The sensitivity of this whole-blood rapid cTnT assay for detecting AMI is comparable to that of current serum assays and offers the advantage of providing rapid bedside results. Discrepancies between serum and whole-blood assays for cTnT noted in this study may indicate the need for further education for the test reader prior to patient use.     

Release kinetics of serum cardiac troponin i in ischemic myocardial injury

Objectives: The study was undertaken to evaluate the release kinetics of cardiac troponin I (c-cTn-I) in ischemic myocardial injury.

Design and Methods: The reference range for cTn-I was established by determination of cTn-I in sera and plasma obtained from 622 healthy volunteers (Group 1). cTn-I was compared to: (a) Creatine kinase (CK) MB mass and myoglobin in 12 patients with severe skeletal muscle damage (Group 2); (b) CK-MB activity in 48 patients with myocardial infarction (MI) receiving intravenous thrombolysis (Group 3) (in this group, an additional 43 patients with MI were analyzed separately to characterize cTn-I patterns in thrombolyzed and nonthrombolyzed populations); and in 44 patients with unstable angina (Group 4).

Results: In Groups 1 and 2, no positive results (0.1 μg/L) were obtained. In Group 3, the time-courses of cTn-I were mostly monophasic in form. A pathologic increase occurred earlier in cTn-I than in CK-MB activity (p = 0.0002); the period with increased cTn-I was longer (p = 0.001), the overall sensitivity of cTn-I (93.9%) was higher than that of CK-MB activity (p = 0.00001). cTn-I was more sensitive at admission (p = 0.0004). In additional patients, the cTn-I peak occurred and cTn-I disappeared significantly later in nonthrombolyzed than in the thrombolyzed group. In Group 4, positive tests results were detected in 45% of patients for cTn-I, 16% for CK-MB activity, and 32% for CK-MB mass.

Conclusions: The cTn-I assay appears to be ideally suited for the detection of ischemic myocardial injury in complex clinical situations because of its high specificity; cTn-I indicates myocardial tissue damage in patients with unstable angina and is superior to CK-MB activity and mass in this respect.     

Cardiac multi-marker strategy for effective diagnosis of acute myocardial infarction

BackgroundHeart-type fatty acid-binding protein (H-FABP) is a heart-specific and highly sensitive biomarker for early diagnosis of acute myocardial infarction (AMI). We investigated the effectiveness of H-FABP for diagnosis of AMI in patients with different ethnic background and different time from symptom onset.MethodsVenous blood was withdrawn from consecutive patients with acute chest pain admitted to the First Affiliated Hospital of Xinjiang Medical University. The blood samples were used for measurement of creatine kinase MB (CK-MB) and cardiac troponin I (cTnI) using Beckman Coulter DC-800 analyzer, and detection of H-FABP using a one-step bedside immunotest.ResultsTwo hundred and eighty-nine patients admitted within 12 h after the onset of symptoms were recruited in the study. The H-FABP immunotest was found to have higher diagnostic accuracy than cTnI and CK-MB in patients admitted within 3 h. The combination of H-FABP and cTnI was found to have the highest diagnostic accuracy (91%) among different cardiac markers and the other combinations. It gave the highest sensitivity [96% (95% CI: 91–98%)] and a comparable specificity [84% (95% CI: 76–89%)] to cTnI alone.ConclusionA cardiac panel consisting of H-FABP and troponin is recommended.     

The Prognostic Significance of Troponin I and Troponin T

Abstract. Objectives : To determine and compare the prognostic abilities of early, single-sample measurements of cardiac troponin I (cTn-I), cardiac troponin T (cTn-T), creatine kinase-MB (CK-MB) among ED patients with possible myocardial ischemia. Methods : Prospective collection of clinical and serologic data using an identity-unlinked technique from patients with possible myocardial ischemia at 2 urban EDs. Outcome data concerning the occurrence of adverse events (AEs) during the 14 days after enrollment were used to calculate and compare the relative risks (RRs) and predictive values (with 95% confidence intervals) of the 3 markers for predicting AEs. Results : Among the 401 study patients, 105 AEs occurred in 67 patients. cTn-I, cTn-T, and CK-MB were all significantly predictive of AEs, with RRs of 3.87 (2.39, 6.26), 3.03 (1.92, 4.79), and 6.45 (4.74, 8.77), respectively. For prediction of AEs, sensitivity for each of the 3 markers was low (cTn-I = 15.38, cTn-T = 24.62, CK-MB = 15.38), while specificity was high (cTn-I = 97.62, cTn-T = 93.15, CK-MB = 99.70). No significant difference in predictive ability was found between cTn-I and cTn-T. However, a positive CK-MB result was a stronger predictor of AEs than either cTn-I (p = 0.01) or cTn-T (p = 0.001). Conclusions : No significant difference in predictive abilities was found between cTn-I and cTn-T. However, routine testing for both CK-MB and either of the troponins may optimize early identification of high-risk patients so they may be targeted for a higher level of care and consideration of more aggressive therapies.     

脂肪酸结合蛋白在急性心肌梗死早期诊断中的临床意义

目的探讨脂肪酸结合蛋白(H-FABP)在AMI早期诊断中(尤其是3h内)的应用价值。方法对30例AMI患者于入院即刻采静脉血测定cTNT、cTNI、CK-MB、MYO和H-FABP浓度,并同时检测50名健康体检者作对照。结果在发病后3h内入院的AMI患者中,五种标志物的敏感性顺序由高到低为H-FABP>MYO>CK-MB>cTNT=cTNI。发病后3～6h入院的AMI患者中,五种标志物的敏感性顺序由高到低为H-FABP>MYO>CK-MB>cTNT>cTNI。对检测AMI的五种标志物的敏感性进行比较,H-FABP要优于MYO、CK-MB、cTNT和cTNI(P<0.05或P<0.01)。结论血清H-FABP较MYO、CK-MB、cTNT、cTNI对早期(尤其是3h内)AMI具有更好的诊断价值。     

Clinical Characteristics of Diabetic vs Nondiabetic Patients Who "Rule-in" for Acute Myocardial Infarction

OBJECTIVE: To compare the clinical characteristics of diabetic vs nondiabetic patients who present to the ED with acute myocardial infarction (AMI). METHODS: This was a prospective, observational study at a suburban, university hospital ED of patients presenting to the ED during study hours between December 1993 and October 1996 with typical and atypical symptoms consistent with cardiac ischemia. Diabetic and nondiabetic patients with AMI were compared. Demographic, historical, and clinical data were recorded by trained research assistants using a standardized, closed-question, data collection instrument. Final discharge diagnosis of AMI was assigned by WHO criteria. Continuous variables were analyzed by t-tests. Clinical variables were analyzed by chi-square tests. All tests were two-tailed with alpha preset at 0.05. RESULTS: There were 216 patients with AMI during the study period; 51 of these patients (24%) were diabetic. For diabetic vs nondiabetic patients with AMI, there was no significant difference in age (64.0 +/- 13 vs 60.0 +/- 14 years, p = 0.13), female gender (37% vs 26%, p = 0.13), and time to presentation from symptom onset (192 +/- 238 vs 251 +/- 456 minutes, p = 0.41). Hypertension was the only cardiac risk factor significantly more prevalent in diabetic vs nondiabetic patients with AMI (77% vs 50%, OR = 1.54, 95% CI = 1.24 to 1.91, p = 0.001), though elevated cholesterol (48% vs 33%, OR = 1.47, 95% CI = 1.02 to 2.12, p = 0.06) tended to be more prevalent in the diabetic group. There was no statistically significant difference between the two groups in terms of the frequency of chest pain (OR = 1.04, 95% CI = 0.95 to 1.14, p = 0.30), associated symptoms, and diagnostic ECGs (OR = 1.16, 95% CI = 0.76 to 1.79, p = 0.53). CONCLUSION: Diabetic patients with AMI may have similar symptoms upon presentation as do nondiabetic patients with AMI. Of the cardiac risk factors, hypertension is more prevalent in diabetic vs nondiabetic patients with AMI.     

床旁心肌标志物联合测定对急性心肌梗死诊断的临床应用价值

目的：探讨快速床旁心肌钙蛋白 I（cTnI）、肌红蛋白（MYO）及肌酸激酶同工酶（CK-MB）水平联合测定在急性心肌梗死（AMI）诊断的临床应用价值。方法收集冠状动脉综合征病例74例为患病组,健康体检者40例为健康对照组。不同时间用床旁快速免疫定量法测定 cTnI、MYO、CK-MB 水平,比较诊断 AMI 的敏感性和特异性,确定联合检测和独立检测的最佳时间具有不同的诊断价值。结果 AMI 组发病有症状2～12 h cTnI、MYO、CK-MB 阳性率均显著高于不稳定型心绞痛（UAP）组及健康对照组。差异有统计学意义（P ＜0．01）。在发病有症状后6～12 h 采集标本分析,cTnI、MYO、CK-MB 联合检测诊断 AMI,有较高的敏感性和特异性,在发病有症状后的12～24 h 采集标本联合检测 cTnI、CK-MB 诊断 AMI。可达到最佳敏感性和特异性。在发病有症状后24～72 h 采集标本分析,cTnI 诊断的敏感性和特异性分别是100．0％和100．0％。结论床旁 cTnI、MYO、CK-MB 联合检测能够方便、快速诊断 AMI,不同时间段各项指标的敏感性和特异性有差异,联合测定可以提高对 AMI 的诊断率。     

The combination of creatine kinase-myocardial band isoenzyme and point-of-care cardiac troponin/ contemporary cardiac troponin for the early diagnosis of acute myocardial infarction

BACKGROUND:The early diagnosis of acute myocardial infarction (AMI) remains challenging, especially for institutions without the high-sensitive cardiac troponin (hs-cTn) assay. Herein, we aim to assess the value of creatine kinase-myocardial band isoenzyme (CK-MB) combined with different cardiac troponin (cTn) assays in AMI diagnosis.METHODS:This multicenter, observational study included 3,706 patients with acute chest pain from September 1, 2015, to September 30, 2017. We classified the participants into three groups according to the cTn assays: the point-of-care cTn (POC-cTn) group, the contemporary cTn (c-cTn) group, and hs-cTn group. The diagnostic value was quantified using sensitivity and the area under the curve (AUC).RESULTS:Compared to the single POC-cTn/c-cTn assays, combining CK-MB and POC-cTn/c-cTn increased the diagnostic sensitivity of AMI (56.1% vs. 63.9%, P<0.001; 82.7% vs. 84.3%, P=0.025). In contrast, combining CK-MB and hs-cTn did not change the sensitivity compared with hs-cTn alone (95.0% vs. 95.0%, P>0.999). In the subgroup analysis, the sensitivity of combining CK-MB and c-cTn increased with time from symptom onset <6 h compared with c-cTn alone (72.8% vs. 75.0%, P=0.046), while the sensitivity did not increase with time from symptom onset >6 h (97.5% vs. 98.3%, P=0.317). The AUC of the combination of CK-MB and POC-cTn significantly increased compared to the single POC-cTn assay (0.776 vs. 0.750, P=0.002). The AUC of the combined CK-MB and c-cTn/hs-cTn assays did not significantly decrease compared with that of the single c-cTn/hs-cTn assays within 6 h.CONCLUSIONS:The combination of CK-MB and POC-cTn or c-cTn may be valuable for the early diagnosis of AMI, especially when hs-cTn is not available.     

心型脂肪酸结合蛋白金标记免疫层析法的建立

目的建立胶体金免疫层析检测人心型脂肪酸结合蛋白(H-FABP)的方法。方法采用胶体金标记抗H-FABP单克隆抗体67D3,将其与生物素化的抗H-FABP单抗66E2包被于吸水纤维,将链霉亲合素结合于硝酸纤维素膜,制成免疫层析试条,依据试剂条上出现肉[可见的红色线条判定结果。用其检测93例发病6h内的胸痛患者血浆中的H-FABP,与心肌肌钙蛋白Ⅰ(cTnI)和肌酸激酶MB同工酶(CK-MB)的检测结果比较,评价其诊断急性心肌梗死(AMI)的敏感性和特异性。结果金标记试条检测H-FABP的浓度低限值为16.8ng/ml,检测结果与ELISA方法比较符合率达96.9%,诊断发病3h内和6h内AMI的敏感性分别为64.29%和84.38%,高于cTnI(28.57%、53.13%)和CK-MB(21.43%、56.25%)(P<0.05),特异性无显著性差异。结论本法简便、快速、准确,可用于AMI早期筛查。     

Effect of Continuous Quality Improvement Methods on Reducing Triage to Thrombolytic Interval for Acute Myocardial Infarction

Objectives: To assess the timeliness of thrombolytic therapy in the ED for selected patients with acute myocardial infarction (AMI) following continuous quality improvement (CQI) interventions.
Methods: A retrospective, historical comparison study was performed of triage-to-thrombolytic time intervals for AMI patients using chart review for data collection. Patients treated after implementation of the CQI process vs a historical control group were compared. The patients with AMI who had received thrombolytics during the one-year period prior to the CQI interventions and who had documentation of time intervals served as the control group. The patients treated during a four-month period, beginning about one and a half years following introduction of the CQI interventions, served as the intervention group. Interventions included: a triage protocol, CQI review, and staff feedback.
Results: The mean triage-to-thrombolytic interval was longer for the control group (72 ± 25 vs 40.0 ± 22 min; p < 0.0001). The mean triage-to-ECG interval also was longer for the control group (16.5 ± 8.9 vs 8.5 ± 7.5 min; p < 0.0001). Most (79%) of the study group received thrombolytic therapy within 60 minutes, and 39% within 30 minutes, whereas 39% of the control group received thrombolytic therapy within 60 minutes, and 3% within 30 minutes.
Conclusion: The implementation of CQI techniques, including 100% chart review, intensive systems analysis, and staff feedback, had a positive effect on the timeliness of thrombolytic therapy for the ED patients who had AMI. As a result, most (79%) of the patients received therapy within the 60-minute time window recommended currently by the American Heart Association.