Clinical value of biochemical markers in the diagnosis of acute myocardial infarction

Current strategy for the use of biochemical markers in the diagnosis of acute myocardial infarction is not yet uniform. New markers of myocardial damage have significantly altered the former viewpoints. The study included 41 patients with confirmed acute myocardial infarction (25 males and 16 females, age range 42-85 years). Control group comprised of 25 patients with chronic renal failure without signs of acute coronary event (n = 11) and patients with confirmed coronary artery disease (n = 14). The level and activity of CKMB (microgram/L and U/L), and the level of myoglobin and cTnl were determined. The results showed the sensitivity of CKMB (microgram/L) in the first six hours from the onset of pain to be statistically significantly higher than the sensitivity of cTnl, while myoglobin was confirmed to be the earliest marker. Determination of CKMB (U/L) activity should be abandoned since it was found to have the lowest sensitivity and specificity. Also, a combination of myoglobin and CKMB (microgram/L) showed a statistically significantly higher sensitivity and diagnostic efficacy but lower diagnostic specificity compared to the combination of myoglobin and cTnl.     

CardioDetect rapid test for the diagnosis of early acute myocardial infarction

Two hundreds patients suspected of acute myocardial infarction presenting to the hospital with a median symptom onset of 2.3 h (IQR 1.7-4.0 h) were enrolled in this study. The diagnostic performances of CardioDetect?, a one-step immunotest for heart-type fatty acid-binding protein (H-FABP), and its combination with cardiac troponin I (cTnI) at admission and 2 h after admission, were compared with different cardiac markers. The H-FABP immunotest had better sensitivities (76.6% and 94.4%) than the other cardiac markers and better specificities (88.2% and 81.7%) than myoglobin at admission and 2 h after admission. Both sensitivity and negative predictive value increased to over 90.0% at 2 h after admission. The areas under the receiver operator characteristic curve for the combination of H-FABP with cTnI were the greatest at admission [0.834 (95% CI: 0.774-0.894)].     

早期诊断心肌损伤肌球蛋白胶体金免疫层析法研究

目的建立一种简便、快速、准确检测人心肌损伤的胶体金免疫层析法（GICA）。方法制备胶体金标记抗Myosin多肽抗体，抗Myosin单克隆抗体，结合垫和样品垫的处理，组装免疫层析试纸条。检测患者血清中Myosin，进行敏感性和特异性评定。结果测试条灵敏度可达5ng／mL。检测30例急性心肌梗塞（AMI）患者血清Myosin水平，并与Roche肌钙蛋白胶体金免疫层析试剂条比较，符合率达84.2％。结论本方法特异性强、灵敏度高、简便快速、可用于急性心肌损伤的早期诊断。     

Usefulness of CK-MM isoforms for early stage of acute myocardial infarction using electrophoretic technique]

MM isoform of CK (EC 2.7.3.2) was able to detect by high voltage electrophoresis. Sequential blood samples were collected from the patients with acute myocardial infarction and MM isoform (as MM3/MM1 ratio), CK activity and CK-MB activity were tested. Time of the maximum MM3/MM1 ratio from the onset was 9.4 hrs (average of 16 cases) whereas 15.9 hrs on CK-MB activity and 17.3 hrs on CK activity were detected. In vitro time course of CK-MM isoform from myocardial and skeletal muscle extracts was tested. MM3 band was gradually converted into MM2 and then MM1 band, but MM3 isoform from myocardium was changed less than skeletal muscle. From these results, it is suggested that abnormal MM3/MM1 ratio on myocardial infarction continues relatively longer time than that on skeletal muscle disease.     

心电向量图诊断早期心肌梗死的实验研究

目的通过心电向量图(VCG)与心电图(ECG)两种方法描记犬发生心肌梗死时体表心电信号,通过VCG和ECG两种诊断标准的对比,确定诊断心肌梗死的诊断阳性率。方法将30只正常犬的冠状动脉结扎人为造成心肌梗死,通过VCG、ECG两种方法记录每一时段的心电信号。结果VCG对心肌梗死的诊断阳性率(93.3%)明显高于ECG(73.3%)。结论VCG对心肌梗死的诊断和定位准确于ECG。     

敏感型心肌钙蛋白T对早期诊断急性心肌梗死的价值

目的探讨敏感型心肌钙蛋白T（hs-cTnT）对早期诊断急性心肌梗死（AMI）的临床应用价值。方法应用发光免疫法分别测定67例AMI患者和58例非AMI患者,同一份血清标本作标准型心肌钙蛋白I（cTnI）和hs-cTnT检测。结果标准型cTnI检测AMI患者的敏感度和特异性分别为68.7%和53.4%,hs-cTnT为74.6%和51.7%。hs-cTnT检测的接受者操作特征（ROC）曲线下面积（AUC）和诊断灵敏度分别为0.659和70.2%,均高于标准型cTnI检测的0.639和59.7%;标准型cTnI检测的最佳cutoff值为0.035μg/L,hs-cTnT检测为0.0125μg/L。结论应用hs-cTnT早期诊断AMI的准确性和灵敏度优于标准型cTnI的检测。     

Cardiac isoenzyme methodology and the diagnosis of acute myocardial infarction

In view of rapidly evolving technology, a thorough appreciation of the subtle nuances of isoenzyme analysis is mandatory in the selection of appropriate methods. The effectiveness of a given laboratory in diagnosing and monitoring ischemic heart disease is related to the sensitivity and specificity of the methods employed. The occurrence of variants of creatine kinase will decrease the specificity of some isoenzyme methods. This study compares the sensitivity and efficiency of four methods for CK-MB and two methods for LD isoenzymes currently available to the laboratory community. The significance of isoenzyme patterns in confirming myocardial infarction was compared with other cardiac diagnostic parameters to determine the most effective laboratory methods. The selection of methods for measurement of cardiac isoenzymes will determine the effectiveness of the laboratory in the diagnosis of myocardial infarction.     

急性心肌梗塞早期心室易损性的电生理实验研究

本文采用Ｓ１－Ｓ２程控电刺激方法同时测定心室易期和室颤阈，并结合其它有关电生理指标，评价了急性心肌梗塞早期心室易损性。结果表明，急性心肌梗塞早期，心室易损期明显延长，室颤阈显著下降，起搏阈值降低，有效不应期缩短，强度间期曲线下移，心室易损期外缘向Ｔ波方向延伸，联律间期与折回间期呈负相关。根据上述指标分析了急性心肌梗塞早期室性心动过速和／或心室颤动产生的电生理机制以及心室易损期在ｒｏｎＴ室性早搏触发     

In situ apoptosis assay for the detection of early acute myocardial infarction.

Detection and age determination of myocardial infarction (MI) is often necessary in both clinical and pathological settings. Conventional histopathological techniques are of limited utility in the demonstration of myocardial ischemic cell death (MICD) within the first 6 hours of MI. In this study, an in situ apoptosis assay was evaluated for the determination of early MICD or early MI. Sections of formalin-fixed, paraffin-embedded archival tissue blocks from 80 hearts were stained for the presence of apoptotic cells by specific labeling of nuclear DNA fragmentation. Conventional hematoxylin and eosin stain showed acute MI (group A, n = 32), equivocal evidence for MICD or early infarction (group B, n = 35), or no abnormal findings (group C, n = 13). The sensitivity and specificity of the in situ apoptosis assay for MICD were confirmed in groups A and C patients. We showed that apoptosis of myocardial cells can occur after ischemic myocardial cell injury. Virtually all documented cases of acute MI (group A) revealed a sizeable distribution of apoptotic cells visible on gross examination of glass slides. Special attention was given to patients in group B, who were at high risk for MI and for suspected but not proved cardiac death. In this group, 34/35 cases (97%) showed focal or diffuse nuclear positivity of varying degrees for apoptosis, confirming the presence of MICD. A sizeable distribution of apoptotic cells, similar to that observed in group A, was noted in 13/35 cases (37%) of group B, suggesting acute MI in these cases. The in situ assay of DNA fragmentation can detect MICD while the histological diagnosis is still inconclusive. It is estimated that with this assay one can detect MICD as early as 2 to 4 hours.     

Biochemical diagnosis for acute myocardial infarction; myosin light chain]

Immunoassays for cardiac myosin light chains (LC) are important biochemical tests for diagnosis of acute myocardial infarction (AMI). LC appears in the serum 4-12 hours after AMI. The most unique characteristic of the time-course of LC is that the elevation of LC in the serum lasts for 1-2 weeks, which allows the retrospective diagnosis of AMI when cardiac enzymes in the serum are decreased to the normal level. This long time-course is due to the continuous liberation of LC from the infarcted myocardium, which could be confirmed by the cardiac scintigram using anti-myosin heavy chain antibody. The serum LC level is also useful in predicting the extent of the cardiac wall damage since the peak LC level reflected well the ventricular ejection fraction or the presence of mechanical complications, such as the formation of ventricular aneurysm. Immunoassays for cardiac LC have recently been improved by the introduction of ELISA using two monoclonal anti-light chain antibodies. ELISA can be finished within 3 hours, which will help to make cardiac LC measurement one of the most important biochemical tests for diagnosis of acute myocardial infarction.     

Role of myeloperoxidase in early diagnosis of acute myocardial infarction in patients admitted with chest pain

Myeloperoxidase (MPO) is an inflammatory marker, elevated in acute coronary syndromes (ACSs), especially in acute myocardial infarction (AMI) cases. This study aimed to evaluate the diagnostic power of MPO in AMI patients. MPO, creatine kinase (CK) MB, and Troponin I (cTn I) were performed for all study patients. Area under the curves (AUCs) and 95% confidence intervals (CI); P values of baseline levels of MPO for discriminating AMI patients from noncoronary chest pain (NCCP) patients, stable angina (SA) patients, and unstable angina (UA) patients were 0.91, 95% CI: 0.82–0.99; P < 0.0001, 0.87, 95% CI: 0.77–0.98; P < 0.0001, and 0.72, 95% CI: 0.58–0.85; P = 0.002, respectively. For diagnosing AMI from ACS patients, MPO was the most efficient marker than others markers with efficiency 82.5% within 0–6 hr after the onset time of chest pain. A predictive score that depends on a combination of baseline levels of three markers (MPO, CK-MB, and TnI) was correctly discriminated 91% of the AMI patients with high specificity 76%. In conclusion, the use of baseline levels of three biomarkers in combination could confer the information that is required for best available early diagnosis of AMI.     

Intravenous thrombolytic treatment for acute myocardial infarction. Effects of early intervention and early examination

Intravenous thrombolytic treatment (streptokinase or anisoylated plasminogen streptokinase activator complex (APSAC) was given to 50 consecutive patients within 3 hours after onset of symptoms of acute myocardial infarction. Left heart catheterisation with coronary angiography and simultaneous double view left ventriculography were performed approximately 4 hours after start of thrombolytic treatment. This examination showed that the acute infarct-related coronary artery was open in 36 patients (72%) and closed in 14 patients (28%). A higher left ventricular ejection fraction was found among patients with open, than among patients with closed infarct-related artery (58.8% vs. 48.4%, p = 0.05). The group with open artery also had a lower score of regional left ventricular dysfunction (1.7 vs. 2.4, p less than 0.05, on a scale from 0-3). Single, double and triple vessel coronary heart disease was found in 22, 14 and 13 patients respectively. Mean age was lower in the group with single vessel disease as compared to double and triple vessel disease (48.4 years vs. 53.4 and 55.4 years, p less than 0.05 and p less than 0.005). Independently of whether the infarct-related artery was open or closed, there tended to be an inverse correlation between number of diseased vessels and preservation of left ventricular function (statistical significance only for single vessel versus triple vessel disease with respect to score of regional left ventricular dysfunction, 1.8 vs. 2.4, p less than 0.05). These findings suggest that early thrombolytic treatment within 3 hours of onset of symptoms may preserve myocardial tissue during the evolution of acute infarction. Furthermore, a presumably better collateralisation from adjacent coronary arteries without stenoses may be important for myocardial preservation. Finally, early angiographic examination can be performed safely and is a good support for determination of further treatment, which in the actual patients was coronary bypass surgery in 8 cases, transluminal angioplasty, PTCA, in 20 cases, and medical treatment alone in 22 cases.     

Cost effectiveness of early discharge after uncomplicated acute myocardial infarction

BACKGROUND: Reducing the length of hospitalizations can reduce short-term costs, but there are few data on the long-term clinical and economic consequences of early discharge. METHODS: Using data from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-1) trial, we identified 22,361 patients with acute myocardial infarction who had an uncomplicated course for 72 hours after thrombolysis. Then, using a decision-analytic model, we examined the cost effectiveness of an additional day of hospitalization in this group. We defined incremental survival attributable to another day of monitored hospitalization, using Kaplan-Meier estimates to determine the rate of resuscitation after cardiac arrest between 72 and 96 hours. Lifetime survival curves for each group in the decision-analytic model were estimated from empirical one-year survival data from GUSTO-1. The costs of key hospital resources (e.g., room and monitoring) were derived from data in the GUSTO-1 cost-effectiveness analysis. RESULTS: Of the patients with an uncomplicated course within 72 hours after thrombolysis, 16 had ventricular arrhythmias during the next 24 hours; 13 of these patients (81 percent) survived for at least 24 hours. On average, another 0.006 year of life per patient could be saved by keeping patients with an uncomplicated course in the hospital another day. At a cost of $624 for hospital and physicians' services, extending the hospital stay by another day would cost $105,629 per year of life saved. In sensitivity analyses, it was found that a fourth day of hospitalization would be economically attractive only if its cost could be reduced by more than 50 percent or if a high-risk subgroup could be identified in which the estimated survival benefit would be doubled. CONCLUSIONS: Hospitalization of patients with uncomplicated myocardial infarction beyond three days after thrombolysis is economically unattractive by conventional standards.     

The efficiency of lactate dehydrogenase isoenzyme determination for the diagnosis of acute myocardial infarction

Values for total lactate dehydrogenase (LDH; EC 1.1.1.27) activity and LDH isoenzymes 1 and 2 were determined in 80 patients with acute myocardial infarction (AMI) and in 40 without AMI every 24 hours up to 15 days after admission, when total serum LDH level returned to normal. The sensitivity, specificity, and efficiency of three LDH isoenzyme factors (LDH-1, greater than 90 U/L; LDH-1 greater than LDH-2; LDH-1/LDH ratio, greater than 0.4) for diagnosing AMI were assessed in three groups of patients according to total serum LDH values--group A, LDH level over 600 U/L; group B, 400 to 599 U/L; group C, 225 to 399 U/L--and in five groups of patients according to the time after admission--(1) first 48 hours; (2) three to five days; (3) six to eight days; (4) nine to 11 days; (5) 12 to 15 days. All three factors were found to be highly efficient for diagnosing AMI (91.5% to 97.5%) in groups A and B, but the most efficient factor in each group was LDH-1 value above 90 U/L. In group C, the only efficient factor was the LDH-1 value over 90 U/L (96%). The most efficient factor for diagnosing AMI in relation to time after admission up to 15 days after AMI was the LDH-1 value over 90 U/L (96% to 97.5%). The factors LDH-1 greater than LDH-2 and LDH-1/LDH above 0.4 were more efficient in patients up to five days after AMI (91.5% to 97.5%) than in patients six to 15 days after admission. We conclude that the most efficient LDH value for diagnosing AMI is the absolute value of LDH-1 above 90 U/L. Its superiority over other LDH isoenzyme values is best documented in a group of patients six to 15 days after admission and with only slight to moderate elevation of total serum LDH values (225 to 399 U/L).