Early diagnosis of acute myocardial infarction by a newly developed rapid immunoturbidimetric assay for myoglobin

Objective—To evaluate a rapid immunoturbidimetric assay for myoglobin and to investigate its clinical usefulness in the early detection of acute myocardial infarction.

Design—Prospective study. Immunoturbidimetrically determined myoglobin concentrations were compared with radioimmunoassay results obtained with the same blood samples. The diagnostic performance of myoglobin determination was compared with creatine kinase and creatine kinase MB activity (current standard of routine diagnosis).

Settings—Part 1: coronary care unit. Part 2: emergency room in a university hospital.

Patients—Part 1: 30 patients with acute myocardial infarction admitted not later than four hours (median two hours) after the onset of symptoms. Part 2: 126 patients admitted to the emergency room with chest pain not caused by trauma (51 cases of acute myocardial infarction, 51 cases of angina pectoris, and 24 cases of chest pain not related to coronary artery disease).

Interventions—Part 1: routine treatment including intravenous thrombolytic treatment (28 patients). Part 2: routine emergency treatment without thrombolytic treatment.

Main outcome measures—The analytical quality of the immunoturbidimetric myoglobin assay and a comparison between the myoglobin assay and creatine kinase and creatine kinase MB for diagnostic sensitivity and performance.

Results—The immunoturbidimetric myoglobin assay was fast and convenient and gave myoglobin determinations of high analytical quality. The concentration of myoglobin increased, peaked, and returned to the reference range significantly earlier than creatine kinase (p≤ 0·0001) and creatine kinase MB (p≤ 0·0002). Before thrombolytic therapy was started the diagnostic sensitivity of myoglobin was significantly higher than that of creatine kinase MB activity 0–6 h after the onset of chest pain and significantly higher (0·82 ν 0·29) than creatine kinase 2–4 h after the onset of chest pain. In almost all patients (92%) plasma myoglobin concentrations were increased 4–6 h after the onset of chest pain.

Conclusion—Myoglobin was more sensitive in detecting early myocardial infarction than creatine kinase and creatine kinase MB activity. Immunoturbidimetric myoglobin measurements could be useful in the early evaluation of patients with suspected myocardial infarction because this assay takes less than two minutes.

     

Serum Myoglobin,Creatine Kinase and Creatine Kinase–MB as Mutually Supportive Indices of Myocardial Infarction and Infarct Size*

Abstract: Serum myoglobin, creatine kinase and creatine kinase–MB as mutually supportive indices of myocardial infarction and infarct size *. R. N. Johnson, W. F. Lubbe, C. J. Mercer, N. L. Sammel and R. M. Norris, Aust. N.Z. J. Med., 1982, 12, pp. 160–165. A comparison was made between the appearance of serum myoglobin and creatine kinase in 22 patients with acute myocardial infarction who were admitted to a coronary–care unit within four hours of onset of chest pain. The MB isoenzyme of creatine kinase was measured in 12 patients. The more rapid appearance and disappearance of myoglobin relative to creatine kinase and creatine kinase–MB was confirmed, as was the correspondence between their respective peak values. A significant correlation was also obtained between the area under the myoglobin time–course and the respective peak levels. Whereas creatine kinase activity declined exponentially from a single peak, myoglobin appeared in multiple episodes inadequately represented by a single peak value and having no clear clinical correlation. The role of myoglobin as a diagnostic aid in myocardial infarction is probably limited to its ability to support creatine kinase and creatine kinase–MB as indices of infarct size.     

Contribution of creatine kinase MB mass concentration at admission to early diagnosis of acute myocardial infarction.

OBJECTIVE--To assess the diagnostic value at admission of creatine kinase MB mass concentration, alone or in combination with electrocardiographic changes, in suspected myocardial infarction. DESIGN--Prospective study of all consecutive patients admitted within 12 hours after onset of chest pain to a coronary care unit for evaluation of suspected myocardial infarction. SETTING--Large regional hospital. PATIENTS--In 297 patients creatine kinase and creatine kinase MB activities and creatine kinase MB mass concentration were determined. Myocardial infarction according to the criteria of the World Health Organisation was diagnosed in 154 patients and excluded in 143 patients (including 70 with unstable angina pectoris). RESULTS--Sensitivity/specificity for creatine kinase MB mass concentration in patients admitted within 4 hours and 4-12 hours after onset of chest pain were 45%/94% and 76%/79% respectively. Corresponding values for creatine kinase activity were 20%/89% and 59%/83%, and for creatine kinase MB activity 16%/87% and 53%/87%. Raised creatine kinase MB mass concentration was seen in 17% of patients with unstable angina pectoris. Stepwise logistic regression analysis showed that independent predictors of acute myocardial infarction in patients admitted within 4 hours after onset of chest pain were electrocardiographic changes and creatine kinase MB mass concentration on admission; in patients admitted 4-12 hours after the onset of pain independent predictors were electrocardiographic changes and creatine kinase MB mass concentration and activity. CONCLUSION--Creatine kinase MB mass concentration is a more sensitive marker for myocardial infarction than the activity of creatine kinase and its MB isoenzyme. Electrocardiographic changes on admission in combination with creatine kinase MB mass concentration (instead of creatine kinase and creatine kinase MB activities) are best in diagnosing myocardial infarction.     

Cocaine and chest pain: clinical features and outcome of patients hospitalized to rule out myocardial infarction

OBJECTIVE: To investigate the clinical features, electrocardiographic findings, and hospital course in patients admitted with acute chest pain temporally related to cocaine use. DESIGN: Retrospective data analysis. SETTING: A 485-bed county hospital. PATIENTS: One hundred and one consecutive patients with cocaine-related chest pain admitted to the hospital to rule out myocardial infarction. MEASUREMENTS AND MAIN RESULTS: The quality of the chest pain frequently suggested myocardial ischemia. Dyspnea was common (56%). The onset of chest pain occurred during cocaine use in 21% of patients, within 1 hour of use in 37%, and after 1 hour of use in 42%. Admission electrocardiographic findings were interpreted as normal in 32% of patients; as acute myocardial injury in 8%; as early repolarization variant in 32%; as left ventricular hypertrophy in 16%; and as "other" in 12%. Forty-three percent of patients had ST-segment elevation meeting the electrocardiographic criteria for use of thrombolytic therapy, but such elevation was usually due to the early repolarization variant. The initial total creatine kinase was elevated more than 3.3 mu kat/L (200 U/L) in 43% of patients, and an elevated total creatine kinase was recorded at some time during the hospital course in 47% of patients. The creatine kinase MB fraction was less than 0.02 in all patients. Myocardial infarction was ruled out in all patients. No patient experienced in-hospital cardiovascular complications. CONCLUSION: The quality of acute chest pain related to cocaine use is indistinguishable from that experienced in acute myocardial ischemia. Abnormal or normal variant electrocardiographic findings are common in patients with chest pain related to cocaine use, but nevertheless the incidence of acute myocardial infarction is low. The ST-segment and T-wave changes can mimic acute myocardial injury and are most likely normal findings in young black men that can be readily recognized in the emergency department. Most of these patients do not require admission to an intensive care unit.     

四种新的心肌损伤标记物在急性心肌梗死早期诊断中的比较研究

目的 :探讨新的生化标记物对急性心肌梗死 (AMI)早期诊断价值。　　方法 :动态监测 98例AMI患者血清肌红蛋白 (Mb) ,心肌肌钙蛋白I、T (cTnI、cTnT )及肌酸激酶MB同工酶(CK MB)的变化 ,对比分析它们对AMI的早期诊断及对预后的判断。　　结果 :AMI起病 6小时之内 ,以Mb诊断敏感性最高 (90 2 0 % ) ,cTnI次之 (5 2 94% ) ,CK MB最低 (2 7 45 % ) ;cTnI和cTnT升高显著且较长时间不降者预后差。　　结论 :早期确诊或排除AMI以cTnI和Mb组合更为可取 ;判断溶栓是否再通以cTnI和CK MB更为准确可靠 ;对那些心肌损伤标记物升高显著 ,且较长时间居高不降者 ,提示预后欠佳。     

Myoglobinemia in the early phase of acute myocardial infarction

Close-meshed determinations of plasma myoglobin, creatine kinase, and its isoenzyme MB were carried out in nine patients admitted to the clinic less than 4 hours after the onset of symptoms in the course of acute myocardial infarction (AMI). Myoglobin clearly appears earlier (mean 2 hours and 30 minutes) in the plasma than creatine kinase (mean 4 hours and 15 minutes) and isoenzyme MB (mean 5 hours and 30 minutes after the onset of symptoms). During the first hours of AMI plasma myoglobin shows multiple peaks in all patients. Because this pattern is observed only with myoglobin but not with creatine kinase, it appears that myoglobin mirrors the early course of the necrosis more distinctly than creatine kinase. Plasma myoglobin was also found elevated after intramuscular injections and a high voltage accident. Myoglobinuria was not detectable after myocardial infarction.     

Usefulness of Combining Necrosis and Platelet Markers in Triaging Patients Presenting with Chest Pain to the Emergency Department

Background: Myocardial injury and platelet activation play important roles in the pathogenesis of unstable coronary syndromes. We sought to determine whether the combined measurement of platelet and necrosis markers would improve risk stratification, and yield higher diagnostic utility in patients presenting to the emergency department with chest pain. Methods and Results: Platelet and soluble P-selectin together with myoglobin, creatine kinase, CK-MB fraction, and troponin I were measured from the autologous samples in 122 consecutive patients. Statistical analysis revealed strong Spearman correlation coefficients (0.141–0.412; p<0.001) between platelet expression of P-selectin and plasma levels of necrosis markers. Platelet P-selectin and necrosis markers were independent predictors (c-index>0.7) for acute myocardial infarction, while plasma P-selectin exhibited random distribution. Elevated soluble P-selectin and myoglobin were the most valuable in identifying patients with congestive heart failure. None of the markers were useful for triaging chest pain patients with unstable angina. Analysis of incremental gains (Chi-squares) reveals that with respect to platelet P-selectin, myoglobin adds 50%% to AMI diagnostic value, and creatine kinase yields an additional 20%% in triaging these patients. The diagnostic value of soluble P-selectin is substantially (72%%) increased by myoglobin measurements, and enhanced even further (44%%) by adding cardiac troponin I for identifying heart failure patients among the chest pain population. Conclusion: Simultaneous determination of platelet and necrosis markers improve the early diagnosis of acute myocardial infarction and congestive heart failure among patients with chest pain presenting into the Emergency Department. Well controlled clinical trials are needed to prove the advantage of combining platelet and necrosis data over presently used techniques in emergency medicine.     

Value of additional two-hour myoglobin for the diagnosis of myocardial infarction in the emergency department

Myoglobin has been described as an early marker of myocardial injury. It increases within 1 to 3 hours of myocardial injury, and falls back to normal early after the event. Few data suggest that myoglobin can be used to triage patients with chest pain. To assess the diagnostic utility of second myoglobin levels drawn within 2 to 3 hours after presentation to the emergency department for detecting myocardial infarction, we prospectively collected myoglobin levels in 368 patients aged > or = 30 years who were admitted with chest pain. Myoglobin levels were measured at admission and 2 to 3 hours later. Sensitivity and specificity for detecting acute myocardial infarction for a twofold increase in myoglobin level from baseline were 39% and 98%, respectively. The early diagnostic performance of myoglobin at admission, the second level drawn 2 to 3 hours later, and creatine kinase-MB mass drawn at admission were similar (receiver-operating characteristic curves 0.80, 0.86, and 0.85). The diagnostic performance of each of these markers was significantly superior to the absolute change from baseline to second myoglobin (receiver-operating characteristic curve 0.77). In patients who presented within 4 hours of symptom onset, myoglobin drawn 2 to 3 hours later had the highest yield for detecting myocardial infarction. These results suggest that serial myoglobin measurement aiming to detect changes over time is not superior to single marker determinations. Myoglobin measured in 2 to 3 hours from admission may be helpful in triaging patients who present within 4 hours from onset of symptoms.     

Serum myoglobin levels in patients with ischemic myocardial insult

Serum myoglobin levels were studied in 178 consecutive patients admitted for chest pain due to ischemic cardiac injury. Serum myoglobin level was compared with the clinical condition, electrocardiographic changes, and serum creatine kinase levels. Elevated serum myoglobin concentration was present in all patients with acute myocardial infarction, as defined by World Health Organization, Geneva, criteria, and, in addition, in about 50% of patients with so-called acute coronary insufficiency. On this basis we could define two different groups of patients with acute coronary insufficiency: cases exhibiting elevated serum myoglobin levels (group 1) and those with normal levels (group 2). In group 1 although creatine kinase levels were in the normal range, they were significantly higher than in group 2. Four patients from group 1 developed heart failure and another a typical acute myocardial infarction during hospitalization, whereas no patients of group 2 had such complications. In patients with acute myocardial infarction, the elevation of serum myoglobin preceded that of creatine kinase in most cases. Myoglobin release appears to be related to infarct size, the highest levels were found in extensive myocardial infarction and less marked elevations in cases of subendocardial infarction and in half of the cases with acute coronary insufficiency. It is proposed that serum myoglobin is a reliable measure of myocardial necrosis and serves to detect a hitherto undefined population of small-size acute myocardial infarction, with its attendant clinical and prognostic implications.     

Early detection of acute myocardial infarction: additional diagnostic information from serum concentrations of myoglobin in patients without ST elevation

The value of the 12 lead electrocardiogram, serum total creatine kinase, creatine kinase MB isoenzyme, and myoglobin for the early detection of infarction was evaluated within one hour of admission to the coronary care unit in 82 consecutive patients with suspected myocardial infarction. The 51 patients in whom infarction was diagnosed during the first 24 hours after admission had a higher prevalence of ST elevation (64% v 11%), higher median serum myoglobin (136 micrograms/l v 34 micrograms/l), higher serum creatine kinase (77 IU/l v 34 IU/l), and higher MB isoenzyme (7 IU/l v 4 IU/l) than those in whom it was not. Stepwise logistic regression analysis in 70 patients in whom the electrocardiogram and serum myoglobin were suitable for analysis showed that serum myoglobin was the variable most closely associated with infarction, and contributed additional diagnostic information when ST elevation was entered into the model first. Serum myoglobin remained associated with myocardial infarction when patients who had had symptoms for less than six hours were analysed. An algorithm based on a rapid agglutination test for myoglobin and ST elevation on the electrocardiogram gave an accurate diagnosis in 82% of patients. This approach gave early and rapid recognition of acute myocardial infarction and warrants further examination.     

Early detection of acute myocardial infarction: additional diagnostic information from serum concentrations of myoglobin in patients without ST elevation.

The value of the 12 lead electrocardiogram, serum total creatine kinase, creatine kinase MB isoenzyme, and myoglobin for the early detection of infarction was evaluated within one hour of admission to the coronary care unit in 82 consecutive patients with suspected myocardial infarction. The 51 patients in whom infarction was diagnosed during the first 24 hours after admission had a higher prevalence of ST elevation (64% v 11%), higher median serum myoglobin (136 micrograms/l v 34 micrograms/l), higher serum creatine kinase (77 IU/l v 34 IU/l), and higher MB isoenzyme (7 IU/l v 4 IU/l) than those in whom it was not. Stepwise logistic regression analysis in 70 patients in whom the electrocardiogram and serum myoglobin were suitable for analysis showed that serum myoglobin was the variable most closely associated with infarction, and contributed additional diagnostic information when ST elevation was entered into the model first. Serum myoglobin remained associated with myocardial infarction when patients who had had symptoms for less than six hours were analysed. An algorithm based on a rapid agglutination test for myoglobin and ST elevation on the electrocardiogram gave an accurate diagnosis in 82% of patients. This approach gave early and rapid recognition of acute myocardial infarction and warrants further examination.     

Serum myoglobin level as diagnostic test in patients with acute myocardial infarction.

Serum myoglobin levels were measured in normal subjects and patients by means of a newly developed radioimmunoassay. Myoglobin was identified in all of 135 sera from normal adults and ranged between 6 and 85 ng/ml (mean +/- SE 31 +/- 1.3). Raised myoglobin levels were present in 62 of 64 patients with documented acute myocardial infarction, the mean serum concentration being 528 +/- 76 ng/ml. Serial determinations in 46 patients with acute infarct showed that maximum values usually occurred within 4 hours after admission. In 19 of 42 cases, raised myoglobin levels preceded the rise in creatine kinase (CK) values; in the remaining patients, both serum myoglobin and creatine kinase were increased on admission. Only 2 of an additional 44 patients admitted with chest pain but without subsequent electrocardiographic, enzyme, or technetium-99m stannous pyrophosphate myocardial scintigraphic evidence of acute myocardial infarction had raised myoglobin levels; the mean value for this group was within the normal range (44 +/- 6 ng/ml). Serum myoglobin values also were normal in patients with congestive heart failure without acute myocardial infarction, and in patients after moderate exercise and cardiac catheterisation. Trasient myoglobinaemia appears to be one of the earliest laboratory abnormalities occurring in acute myocardial infarction and, therefore, should prove useful as a diagnostic aid in patients.     

Early diagnosis of acute myocardial infarction by myoglobin latex agglutination test

Early elevation of the serum myoglobin level in acute myocardial infarction (AMI) has been noted for years. In this study, 39 patients admitted to the Coronary Care Unit with acute chest pain within 72 hours (mean 12 +/- 15 hours) or electrocardiographic changes suspected of acute myocardial infarction had a serum myoglobin latex agglutination test to evaluate its diagnostic accuracy in acute myocardial infarction. Of these 39 patients, 24 had documented acute myocardial infarction as their final diagnosis. By the time of admission, 18 of the 24 cases with infarction had positive myoglobin tests (sensitivity 75%). Of those 15 cases without myocardial infarction, 13 had negative myoglobin tests (specificity 87%). If only those 17 cases admitted within 5 hours of the onset of chest pain were analyzed, the serum myoglobin test became positive in 8 of 10 cases with documented AMI but the 2 cases with negative results turned positive 2 hours later (sensitivity 80% to 100%). Due to the fact that myoglobin tests were negative in all other 7 cases without infarction, the specificity was 7/7 (100%). In contrast, the creatine phosphokinase isoenzyme study was positive only in 3 of these 10 patients with documented AMI in the first blood sample taken during admission. In conclusion, the serum myoglobin latex agglutination test is a quick and reliable method that helps in the early diagnosis of acute myocardial infarction.     

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.     

Use of rapid serial sampling of creatine kinase MB for very early detection of myocardial infarction in patients with acute chest pain.

To determine how early myocardial infarction can be detected, serial creatine kinase MB concentrations were sampled in 313 patients during triage of acute (less than 12 hours) chest pain. Serum was sampled on hospital arrival (baseline) and hourly for 3 hours (total of four samples). Creatine kinase MB concentrations were subsequently analyzed for their ability to detect infarction. Infarction was present in 70 patients (22%) and was diagnosable from the index electrocardiograms in 27 of these (39%). Sensitivity and specificity for detection of infarction were 76% and 72%, respectively, as determined from baseline MB values only and increased with each additional sample to a maximum of 92% and 96%, respectively, in all four samples. Analysis of two serum samples taken 2 hours apart showed a sensitivity of 94% and a specificity of 91%. If these results are confirmed, improved initial diagnostic accuracy with this rapid assay technique in acute chest pain may (1) conserve resources when initial suspicion of infarction is low, (2) identify patients with infarction appropriate for early intervention, and (3) avoid premature hospital discharge of patients with infarction.     

A randomized trial of the effects of early cardiac serum marker availability on reperfusion therapy in patients with acute myocardial infarction: the serial markers, acute myocardial infarction and rapid treatment trial (SMARTT)

OBJECTIVES: The purpose of this study was to assess whether the immediate availability of serum markers would increase the appropriate use of thrombolytic therapy. BACKGROUND: Serum markers such as myoglobin and creatine kinase, MB fraction (CK-MB) are effective in detecting acute myocardial infarction (AMI) in the emergency setting. Appropriate candidates for thrombolytic therapy are not always identified in the emergency department (ED), as 20% to 30% of eligible patients go untreated, representing 10% to 15% of all patients with AMI. Patients presenting with chest pain consistent with acute coronary syndrome were evaluated in the EDs of 12 hospitals throughout North America. METHODS: In this randomized, controlled clinical trial, physicians received either the immediate myoglobin/CK-MB results at 0 and 1 h after enrollment (stat) or conventional reporting of myoglobin/CK-MB 3 h or more after hospital admission (control). The primary end point was the comparison of the proportion of patients within the stat group versus control group who received appropriate thrombolytic therapy. Secondary end points included the emergent use of any reperfusion treatment in both groups, initial hospital disposition of patients (coronary care unit, monitor or nonmonitor beds) and the proportion of patients appropriately discharged from the ED. RESULTS: Of 6,352 patients enrolled, 814 (12.8%) were diagnosed as having AMI. For patients having AMI, there were no statistically significant differences in the proportion of patients treated with thrombolytic therapy between the stat and control groups (15.1% vs. 17.1%, p = 0.45). When only patients with ST segment elevation on their initial electrocardiogram were compared, there were still no significant differences between the groups. Also, there was no difference in the hospital placement of patients in critical care and non- critical care beds. The availability of early markers was associated with more hospital admissions as compared to the control group, as the number of patients discharged from the ED was decreased in the stat versus control groups (28.4% vs. 31.5%, p = 0.023). CONCLUSIONS: The availability of 0- and 1-h myoglobin and CK-MB results after ED evaluation had no effect on the use of thrombolytic therapy for patients presenting with AMI, and it slightly increased the number of patients admitted to the hospital who had no evidence of acute myocardial necrosis.     

Very early diagnosis and risk stratification of patients admitted with suspected acute myocardial infarction by the combined evaluation of a single serum value of cardiac troponin-T, myoglobin, and creatine kinase MB(mass)

AIMS: The diagnostic and prognostic capacity of biochemical markers of acute myocardial infarction in the emergency department were evaluated in consecutive patients (n=155) with suspected acute myocardial infarction. METHODS AND RESULTS: Serum myoglobin >/=110 microg. l(-1)and creatine kinase MB(mass)>/=5 microg. l(-1)had a high accuracy (0.77-0.85) (ns) for acute myocardial infarction diagnosis in patients presenting >2 h after symptom onset. Troponin-T (>/=0.10 microg. l(-1)) had a lower accuracy (0.53-0.70) for acute myocardial infarction diagnosis, but was the most important 1-year prognostic marker (cardiac death or non-fatal acute myocardial infarction). In patients without ST elevation, combined analysis of two biochemical tests would accurately identify an additional 20% of acute myocardial infarction patients (predictive value of a positive test=0.82) and also identify those without acute myocardial infarction (predictive value of a negative test=0.80). One-year event-free survival was excellent (96%) for patients with two negative biochemical tests, intermediate (74%) for those with discordant tests, and only 53% for patients with two positive biochemical tests. CONCLUSIONS: Analysis of biochemical tests in the emergency department prior to hospital admission could accurately identify approximately 20% additional acute myocardial infarction patients. The prognosis of these patients is poor, and they may be a target for primary PTCA or new early initiated aggressive medical therapies.     

Early release of glycogen phosphorylase in patients with unstable angina and transient ST-T alterations.

OBJECTIVE--To determine whether transient ST-T alterations in patients with unstable angina are associated with an increase in plasma glycogen phosphorylase BB concentrations on admission to hospital. DESIGN--Prospective screening of patients with unstable angina for markers of myocardial cell damage. SETTING--Accident and emergency department of university hospital. PATIENTS--48 consecutive patients admitted for angina pectoris (18 with transient ST-T alterations). None of the patients had acute myocardial infarction according to standard criteria. MAIN OUTCOME MEASURES--Creatine kinase and creatine kinase MB activities, creatine kinase MB mass concentration, and myoglobin, cardiac troponin T, and glycogen phosphorylase BB concentrations on admission. RESULTS--All variables except for creatine kinase and creatine kinase MB activities were significantly higher on admission in patients with unstable angina and transient ST-T alterations than in patients without. However, glycogen phosphorylase BB concentration was the only marker that was significantly (p = 0.0001) increased above its discriminator value in most patients (16). In the 18 patients with transient ST-T alterations creatine kinase MB mass concentration and troponin T and myoglobin concentrations were significantly (p = 0.0001) less commonly increased on admission (in five, three, and two patients, respectively). CONCLUSIONS--The early release of glycogen phosphorylase BB may help to identify high risk patients with unstable angina even on admission to an emergency department. Glycogen phosphorylase BB concentrations could help to guide decisions about patient management.     

Human heart-type fatty acid-binding protein as an early diagnostic and prognostic marker in acute coronary syndrome

Although heart-type fatty acid-binding protein (H-FABP) can be a marker of sarcolemmal injury due to acute myocardial ischemia, the diagnostic or prognostic value is not established in patients with acute chest pain. This multicenter prospective study aimed to determine the diagnostic and prognostic values of H-FABP in 133 patients presenting to an emergency room with suspected acute coronary syndrome (ACS) by comparing with those of conventional biomarkers. H-FABP and myoglobin had greater positive results than did creatine kinase-MB or troponin T. Receiver operating characteristics analysis revealed that H-FABP was the most reliable for detection of ACS and that H-FABP had the greatest sensitivities for identification of patients requiring emergency hospitalization, coronary angiography, and interventional therapy within 7 days among the biomarkers. Thus, H-FABP can be an early diagnostic and prognostic biochemical marker, particularly within the first 6 h from the onset of chest symptoms, in patients with chest pain at an emergency department.     

Epidemiological classification of acute myocardial infarction: time for a change?

AIMS: The classification of an acute ischaemic cardiac event is traditionally based on cardiac enzymes, electrocardiography (ECG) and clinical symptoms. The impact of new specific cardiac markers on the diagnostic classification of suspected acute myocardial infarction remains poorly studied. We therefore set out to compare the diagnostic and prognostic information provided by the MONICA code and a patient classification based on the maximal level of creatine kinase MB isoenzyme. The significance of typical pain and various ECG algorithms were separately analysed. METHODS AND RESULTS: The study population consisted of 311 consecutive patients who were evaluated for suspected acute myocardial infarction in a regional referral hospital. Patients were retrospectively classified according to the MONICA criteria, by a simplified code combining symptoms and creatine kinase MB, and solely using the maximal creatine kinase MB concentration. Total mortality was followed for 1 and 5 years. The creatine kinase MB based classification was shown to be the strongest predictor of mortality (OR=2.8-3.7, p<0.001) for outcome both at 1 and 5 years. Typical pain and a positive Minnesota ECG had no prognostic relevance. However, an analysis algorithm of the admission ECG was predictive of 1- and 5-year survival. CONCLUSIONS: The epidemiological classification of suspected acute myocardial infarction could be based solely on a specific cardiac marker, such as creatine kinase MB mass. This approach contains prognostic information and is accurate enough for the structured diagnosis of acute myocardial infarction. Other outcome predictors could be used to identify patient subgroups and assess therapy.