Myoglobin in the early evaluation of acute chest pain

Two thirds of patients hospitalized to rule out acute myocardial infarction (AMI) are eventually found to have a non-AMI diagnosis, whereas 2% to 8% of patients with AMI are inappropriately discharged from the emergency department. Myoglobin has been shown to increase within 2 to 3 hours of myocardial injury. This study evaluates the usefulness of myoglobin in acute chest pain. Serial blood samples were obtained from 89 suspected AMI patients evaluated in the emergency department. Testing included creatine kinase (CK), a creatine kinase isoenzyme (CK-MB), and myoglobin. Twenty five of 89 patients (28%) had a diagnosis of AMI. The sensitivity of myoglobin for the detection of AMI was 56% at the time of admission and 100% 2 hours after admission. Thirteen of 25 AMI patients (52%) had a positive myoglobin before increases in CK or CK-MB, including one patient discharged from the emergency department. More importantly, the negative predictive value for myoglobin at the time of admission was 83% and was 100% two hours after admission. This potential for 100% predictability in excluding AMI by the use of serial myoglobin determinations will be very helpful in the correct triage of patients presenting with acute chest pain.     

A decision tree for the early diagnosis of acute myocardial infarction in nontraumatic chest pain patients at hospital admission

STUDY OBJECTIVE: To find an accurate algorithm for the diagnosis of acute myocardial infarction in nontraumatic chest pain patients on presentation to the emergency department. DESIGN: In a prospective clinical study, we compared the diagnostic performances of clinical symptoms, presenting ECG, creatinine kinase, creatine kinase MB activity and mass concentration, myoglobin, and cardiac troponin T test results of hospital admission blood samples. By classification and regression trees, a decision tree for the diagnosis of acute myocardial infarction was developed. SETTING: Emergency room of a Department of Internal Medicine (University Hospital). PATIENTS: One hundred fourteen nontraumatic chest pain patients (median delay from onset of chest pain to hospital admission, 3 h; range, 0.33 to 22): 26 Q-wave and 19 non-Q-wave myocardial infarctions, 49 patients with unstable angina pectoris, and 20 patients with chest pain caused by other diseases. MEASUREMENTS AND RESULTS: Of each parameter taken by itself, the ECG was tendentiously most informative (areas under receiver operating characteristic plots: 0.87 +/- 0.04 [ECG], 0.80 +/- 0.08 [myoglobin], 0.80 +/- 0.04 [creatine kinase MB mass], 0.77 +/- 0.04 [creatine kinase activity], 0.69 +/- 0.06 [clinical symptoms] 0.67 +/- 0.06 [creatine kinase MB activity], 0.67 +/- 0.05 [troponin T]). In patients presenting 3 h or less after the onset of chest pain, ECG signs of acute transmural myocardial ischemia were the best discriminator between patients with and without myocardial infarction. In patients presenting more than 3 h, however, creatine kinase MB mass concentrations (discriminator value, 6.7 micrograms/L) were superior to the ECG, clinical symptoms, and all other biochemical markers tested. This algorithm for diagnosing acute myocardial infarction was superior to each parameter by itself and was characterized by 0.91 sensitivity, a 0.90 specificity, a 0.90 positive and negative predictive value, and a 0.90 efficiency. CONCLUSIONS: We found an algorithm that could accurately separate the myocardial infarction patients from the others on admission to the emergency department. Therefore, this classifier could be a valuable diagnostic aid for rapid confirmation of a suspected myocardial infarction.     

Elevated serum cardiac markers in asymptomatic marathon runners after competition: is the myocardium stunned?

Prolonged strenuous exercise may trigger acute myocardial infarction (AMI), as exemplified by the occurrence of sudden cardiac death during marathon running. Serum creatine kinase MB (CK-MB) may be elevated in asymptomatic marathon runners after competition from exertional rhabdomyolysis of skeletal muscle altered by training, limiting its utility for evaluating acute cardiac injury in such athletes. Myoglobin and CK-MB2 isoform levels are emerging as earlier markers of AMI and troponin subunits as more specific than serum CK-MB mass. We tested runners before and sequentially after the 1995 Boston Marathon for conventional and newer markers including myoglobin, CK-MB mass and isoforms, cardiac troponin T, and cardiac troponin I using standard laboratory methods and rapid format assays if available. The mean serum values for myoglobin, CK-MB mass, CK-MB/myoglobin rapid panel tests, and CK-MB2 isoforms were normal or negative pre-race and elevated or positive 4 and 24 h after competition. These markers lack specificity for acute cardiac injury in trained runners. While the mean serum values for cardiac troponins T and I remained normal, 9 of 45 runners (20%) showed an increase in subunits by first-generation assays. All runners remained asymptomatic for cardiac disease and completed subsequent marathons 1 year later, making reversible myocardial injury or stunning unlikely. Elevated values of serum markers for AMI, including first-generation assays for both troponin subunits should be interpreted with caution in trained runners.     

Subcortical vascular dementia: survey of treatment patterns and research considerations

OBJECTIVE: The purpose of this study was to evaluate retrospectively the efficacy of a proposed panel of three cardiac markers (myoglobin, creatine kinase-MB mass [CK-MB], and cardiac troponin I) in the diagnosis of acute myocardial infarction (AMI) in patients with atraumatic chest pain. DESIGN: A total of 110 patients admitted for the evaluation of atraumatic chest pain were examined. Forty-one of these patients were diagnosed with AMI. RESULTS: Five of the 41 patients with AMI had abnormally elevated myoglobin levels, whereas values of CK-MB and/or cardiac troponin I remained negative. Creatine kinase-MB mass alone had a sensitivity of 92.7%, a specificity of 89.9%, a positive predictive value of 84.4%, and a negative predictive value of 95.0% for the diagnosis of AMI. Cardiac troponin I alone had a sensitivity of 90.2%, a specificity of 95.7%, a positive predictive value of 92.5%, and a negative predictive value of 94.3% for the diagnosis of AMI. Cardiac troponin I is a more specific marker for the diagnosis of AMI than CK-MB, particularly in patients with chronic renal failure who are evaluated for chest pain. The combination of CK-MB and cardiac troponin I increased the sensitivity to 100% and the negative predictive value to 100% and had a specificity of 88.4% and a positive predictive value of 83.7%. The panel was diagnostic for all patients with AMI within 12 hours after admission. CONCLUSIONS: Our preliminary results indicate that this panel is highly effective for evaluation of AMI in patients with atraumatic chest pain. Elevated myoglobin levels were useful in detecting patients at high risk for AMI who initially were not detected with other markers. The combination of CK-MB and cardiac troponin I provided much higher sensitivity and had a much higher negative predictive value for the evaluation of AMI than cardiac troponin I or CK-MB alone. The 100% negative predictive value is particularly important because it indicates that patients with negative CK-MB and cardiac troponin I values 12 hours after admission have a negligible likelihood of AMI.     

Value of acute rest sestamibi perfusion imaging for evaluation of patients admitted to the emergency department with chest pain

OBJECTIVES: This study sought to determine the ability of early perfusion imaging using technetium-99m sestamibi to predict adverse cardiac outcomes in patients who present to the emergency department with possible cardiac ischemia and nondiagnostic electrocardiograms (ECGs). BACKGROUND: Evaluation of patients presenting to the emergency department with possible acute coronary syndromes and nondiagnostic ECGs is problematic. Accurate risk stratification is necessary to prevent serious adverse outcomes. Initial results suggest that early perfusion imaging using technetium-99m sestamibi enables reliable risk stratification. METHODS: Patients presenting to the emergency department with a low to moderate probability of acute coronary syndromes underwent rapid sestamibi injection with gated single-photon emission computed tomographic imaging. Studies showing perfusion defects with associated wall motion abnormalities were considered positive. RESULTS: A total of 532 consecutive patients underwent serial myocardial marker analysis and rest perfusion imaging. Of these patients, perfusion imaging was positive in 171 (32%). Positive perfusion imaging was the only multivariate predictor of myocardial infarction (MI) (p < 0.0001, odds ratio [OR] 33, 95% confidence interval [CI] 7.7 to 141) and was the most important independent predictor of MI or revascularization (p < 0.0001, OR 14, 95% CI 7.3 to 25), followed by diabetes (p < 0.01, OR 2.8, 95% CI 1.5 to 5.1), typical angina (p = 0.01, OR 2.1, 95% CI 1.2 to 3.7) and male gender (p = 0.03, OR 1.9, 95% CI 1.1 to 3.5). The sensitivity of positive perfusion imaging for MI was 93% (95% CI 77% to 98%), and for MI or revascularization it was 81% (95% CI 71% to 88%), with negative predictive values of 99% (95% CI 98% to 100%) and 95% (95% CI 92% to 97%), respectively. CONCLUSIONS: Positive rest perfusion imaging accurately identified patients at high risk for adverse cardiac outcomes, whereas negative perfusion imaging identified a low risk patient group. Early perfusion imaging allows for rapid and accurate risk stratification of emergency department patients with possible cardiac ischemia and nondiagnostic ECGs.     

Cardiac markers in the early hours of acute myocardial infarction: clinical performance of creatine kinase, creatine kinase MB isoenzyme (activity and mass concentration), creatine kinase MM and MB subform ratios, myoglobin and cardiac troponin T

We compared early markers of acute myocardial infarction (AMI) in the first 6 h from the onset of symptoms in 133 non-traumatized patients arriving at the emergency department with chest pain suggestive of AMI. Clinical performance parameters were calculated on the basis of 45 patients with AMI and 88 patients with a non-AMI diagnosis. At admission and in the first 0-3 h after the onset of chest pain the creatine kinase-MB (CK-MB) subform ratio was the most sensitive test at a comparable specificity level of 0.95. In the time interval of 3-5 h, myoglobin, the CK-MB mass concentration and the CK-MB subform ratio were associated with the greatest areas under receiver operating characteristic (ROC) curves, but differences between these tests were small and non-significant. At 6 h from the onset of pain, differences in clinical performance between the same three tests were even smaller whether or not samples drawn after the start of thrombolytic treatment were included in the test comparison. For confirmation of AMI at 6 h after onset of pain, CK-MB (activity and mass concentration) demonstrated the highest positive likelihood ratio, and for exclusion of AMI at 6 h the CK-MB subform ratio was associated with the highest negative likelihood ratio. However, differences between the CK-MB subform ratio, CK-MB mass concentration and myoglobin were not significant as estimated by the substantial overlap between the confidence intervals of the likelihood ratios and the ROC areas at 6 h. Cardiac troponin T (cTnT) demonstrated an ROC area equal to the CK-MB isoform ratio and myoglobin at 6 h. However, the likelihood ratio for ruling out AMI was lower, mostly due to the elevated cTnT in unstable coronary disease not defined as AMI. We conclude that the CK-MB subform ratio, CK-MB mass concentration and myoglobin do not demonstrate any significant differences in clinical performance for ruling in or ruling out acute myocardial infarction at 6 h after the onset of chest pain.     

Comparison of myoglobin, creatine kinase-MB, and cardiac troponin I for diagnosis of acute myocardial infarction

Serial plasma concentrations of myoglobin, creatine kinase MB (CK-MB) isoenzyme, and cardiac troponin I (cTnI) were measured in 25 patients with a confirmed diagnosis of acute myocardial infarction (AMI), and 74 patients who were suspected of AMI but were subsequently ruled out for this diagnosis. The cutoff concentration for the cTnI assay was optimally determined to be 2.5 ng/mL. Of the three markers, myoglobin had the highest clinical sensitivity (50 percent) when blood was collected between 0 to 6 h after the onset of chest pain. Assays for all serum markers used had high clinical sensitivity (> 93 percent) 6 to 24 h after onset. The CK-MB remained highly sensitive for 48 h, while cTnI was sensitive for up to 72 h. Between 72 and 150 h, cTnI had a clinical sensitivity of 70 percent as compared to 21 percent and 18 percent for myoglobin and CK-MB, respectively. The clinical specificity of cTnI for non-AMI patients was equivalent to CK-MB and significantly higher than for myoglobin. The clinical efficiency of cTnI for all samples was better than either CK-MB or myoglobin, owing mainly to the wider diagnostic window. The specificity of cTnI for 59 patients with chronic renal failure, skeletal muscle trauma and disease was better than all of these markers including cardiac troponin T (cTnT). Results of this study show that cTnI is an effective marker for the retrospective diagnosis of AMI, and consideration should be given to its use in place of CK-MB.     

Class I-restricted cross-presentation of exogenous self-antigens leads to deletion of autoreactive CD8(+) T cells

Intracoronary thrombosis plays a key role in the pathogenesis of acute myocardial infarction (AMI), and the formation of an occlusive thrombus usually precedes the development of myocardial damage. Therefore we evaluated and compared the early sensitivities of thrombin-antithrombin III complex (TAT), D-dimer, myoglobin, creatine kinase (CK) MB mass concentration, and cardiac troponin T (cTnT) on admission to a coronary care unit (CCU) before heparin or thrombolytic therapy was started. We investigated 31 consecutive patients admitted to CCU for evolving AMI within 6 hours from the onset of infarct-related symptoms; the median delay from chest pain onset to CCU admission was 135 minutes. Of all biochemical markers tested TAT had the highest early sensitivity on admission to the CCU, and TAT was significantly more sensitive than cTnT, CKMB mass, myoglobin, and D-dimer. However, TAT increases give no information about the location of clot formation in the body, and the diagnosis of AMI must be subsequently verified by an increase in more cardiac specific proteins, such as troponins or CKMB.     

Measurement of cardiac troponin T is an effective method for predicting complications among emergency department patients with chest pain

STUDY OBJECTIVES: To determine the test performance characteristics of serum cardiac troponin T (cTnT) measurement for diagnosis of acute myocardial infarction (AMI), and to determine the ability of cTnT to stratify emergency department patients with chest pain into high- and low-risk groups for cardiac complications. METHODS: We conducted a prospective observational cohort study with convenience sampling in a tertiary care, urban ED. The study sample comprised 667 patients presenting to the ED with a complaint of chest pain or other symptoms suggesting acute ischemic coronary syndrome (AICS). Patients were assigned to different blood sampling protocols for cTnT therapy on the basis of their ECG at presentation: nondiagnostic for AMI at 0, 3, 6, 9, 12, and 24 hours after ED presentation; or ECG diagnostic for AMI at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 18, and 24 hours after ED presentation. RESULTS: Of 667 patients, 34 had AMI diagnosed within 24 hours of ED arrival. Using a .2 microgram/L discrimination level for cTnT, sensitivity for AMI within 24 hours of ED arrival was 97% (95% confidence interval, 91.4% to 99.9%), and specificity was 92% (89.8%-94.1%). When the effects of age, race, sex, and creatine kinase-MB isoenzyme subunit test results were controlled, a patient with cTnT of .2 microgram/L or greater was 3.5 (1.4 to 9.1) times more likely to have a cardiac complication within 60 days of ED arrival than a patient with a cTnT value below .2 microgram/L. CONCLUSION: Measurement of cTnT will accurately identify myocardial necrosis in patients presenting to the ED with possible AICS. Elevated cTnT values identify patients at increased risk of cardiac complications.     

Is myoglobin useful in the diagnosis of acute myocardial infarction in the emergency department setting?

The authors evaluated the usefulness of a rapid fluorometric enzyme immunoassay for myoglobin (Myo) for early diagnosis of acute myocardial infarction (AMI) in patients in the emergency department. The rapid fluorometric enzyme immunoassay for myoglobin was performed on timed blood samples collected previously for serial CK and CKMB determinations from 41 patients who initially presented to the ED with chest pain and were subsequently admitted to patient care units. Twenty-two patients were AMI positive and 19 were AMI negative. In 12 patients who were AMI positive, Myo increased rapidly and significantly peaking at 6.53 +/- 5.45 hours, whereas in the other 10 patients who were AMI positive, only the declining slopes of Myo were observed due to late AMI presentation. In the AMI negative group, Myo values were within reference range in 8 and persistently elevated in 11. Using the initial rate of Myo release of 20 ng/mL per hour as criteria of discrimination, this assay has a sensitivity of 90.1% and a specificity of 74%. Available samples for the two patients who were false negative were past the window of Myo release for AMI detection. All five patients who were false positive were associated with various degrees of muscular trauma or renal disorder. The authors conclude that the initial rate of Myo release demonstrates good utility both at early detection and early exclusion of AMI. However, its tissue nonspecificity may not permit AMI recognition in the presence of muscular injury.     

Concentration time courses of troponin and myosin subunits after acute myocardial infarction

BACKGROUND: As a result of the limited sensitivity and specificity of creatine kinase and lactate dehydrogenase (LDH) as well as their isoenzymes, there is increasing interest in the use of cardiac contractile proteins for the diagnosis of acute myocardial infarction (AMI) and myocardial damage. METHODS: This study compared the release of creatine kinase, creatine kinase MB, myoglobin, cardiac troponin I (cTnI), cardiac troponin T (cTnT), cardiac myosin light chain-1 (cMLC-1), and beta-type myosin heavy chains (bMHC) in serial blood samples from 13 patients (10 men, three women; median age 54 years, range 40-74 years) with first-time AMI (11 Q-wave, two non-Q-wave AMI; three anterior and 10 inferior wall AMI). All but one patient received intravenous thrombolytic treatment. RESULTS: Myoglobin was the first marker to increase in blood after AMI and showed the earliest peak levels, whereas bMHC increased latest, showing the latest peak levels. cTnI and cTnT increased significantly earlier than cMLC-1 and bMHC. cTnI and cTnT increased and reached peak levels parallel to each other, but the latter tended to stay increased longer. cTnT time courses were biphasic in the majority of AMI patients, unlike cTnI time courses. cMLC-1 release was mostly biphasic. cMLC-1 allows diagnosis during the acute phase as well as several days after the onset of AMI. The time courses of bMHC were usually monophasic. Its delayed appearance makes it useful for the diagnosis of remote infarction. In contrast to cTnI and cTnT, cMLC-1 and bMHC time courses were not significantly influenced by early reperfusion. CONCLUSION: Our results demonstrate the impact of the intracellular compartmentation of an intramyocardial protein (cytosolic, structurally bound, or structurally bound with soluble pool) on its concentration time course after AMI, particularly on the rapidity of its release.     

Normal frontal perfusion in patients with frozen gait

With the aim to compare the diagnostic efficacy as regards acute myocardial infarction of two rapid dry-strip tests, one with both creatine kinase MB (CK-MB) and myoglobin (C + M) and the other with troponin T, and to test the reliability of bedside diagnosis by the coronary care unit (CCU) nurse, 151 patients with acute chest pain admitted to the CCU were investigated. There was no difference in diagnostic performance between rapid tests and quantitative determinations. With <6-hour duration of symptoms, the sensitivity was better for C + M than for troponin T (72% vs 33%, p < 0.05). With symptoms lasting >12 hours on arrival, troponin T performed better, with 100% sensitivity and a negative predictive value of 100% in the 6-hour retest. For exclusion of damage, the two tests have similar and reliable diagnostic capacities 12 hours after the onset of symptoms. The bedside diagnosis or exclusion of acute myocardial infarction was carried out rapidly (within 20 minutes) and reliably by the CCU nurses.     

Discrimination between myocardial and skeletal muscle injury by assessment of the plasma ratio of myoglobin over fatty acid-binding protein

BACKGROUND: Myoglobin and fatty acid-binding protein (FABP) each are useful as early biochemical markers of muscle injury. We studied whether the ratio of myoglobin over FABP in plasma can be used to distinguish myocardial from skeletal muscle injury. METHODS AND RESULTS: Myoglobin and FABP were assayed immunochemically in tissue samples of human heart and skeletal muscle and in serial plasma samples from 22 patients with acute myocardial infarction (AMI), from 9 patients undergoing aortic surgery (causing injury of skeletal muscles), and from 10 patients undergoing cardiac surgery. In human heart tissue, the myoglobin/FABP ratio was 4.5 and in skeletal muscles varied from 21 to 73. After AMI, the plasma concentrations of both proteins were elevated between approximately 1 and 15 to 20 hours after the onset of symptoms. In this period, the myoglobin/FABP ratio was constant both in subgroups of patients receiving and those not receiving thrombolytics and amounted to 5.3 +/- 1.2 (SD). In serum from aortic surgery patients, both proteins were elevated between 6 and 24 hours after surgery; the myoglobin/FABP ratio was 45 +/- 22 (SD), which is significantly different from plasma values in AMI patients (P < .001). In patients with cardiac surgery, the ratio increased from 11.3 +/- 4.7 to 32.1 +/- 13.6 (SD) during 24 hours after surgery, indicating more rapid release of protein from injured myocardium than from skeletal muscles. CONCLUSIONS: The ratio of the concentrations of myoglobin over FABP in plasma from patients with muscle injury reflects the ratio found in the affected tissue. Since this ratio is different between heart (4.5) and skeletal muscle (20 to 70), its assessment in plasma allows the discrimination between myocardial and skeletal muscle injury in humans.     

Beyond the twelve-lead electrocardiogram: diagnostic tests in the evaluation for suspected acute myocardial infarction in the emergency department, part I

On a daily basis the emergency physician is faced with the difficult task of determining whether or not a patient with acute chest pain is sustaining an acute myocardial infarction. In most cases, this is not a straightforward decision. Although observation units are being used more often for chest pain evaluations, many emergency physicians currently admit such patients to an intensive care setting. Because fewer than one-third of emergency department chest pain patients actually suffer an acute myocardial infarction, expensive resources are, in retrospect, used unnecessarily. Conversely, patients who are infarcting, and are inadvertently discharged home from the emergency department, have a worse prognosis than those admitted. This two-part series reviews the newer modalities available that may help the emergency physician arrive at a more accurate diagnosis. The current article, Part I, examines the use of myocardial imaging, computer assisted diagnostic protocols, and newer uses of the electrocardiogram. Part II reviews the use of biochemical assays of cardiac proteins and the Chest Pain Observation Unit.     

Pseudoaneurysm of femoral artery after catheterisation: treatment by a mechanical compression device guided by colour Doppler ultrasound

A 28-year-old woman presented to the emergency department for evaluation of acute chest pain. She lacked risk factors for coronary artery disease and her initial electrocardiogram (ECG) was nondiagnostic. Within 45 minutes of presentation she developed nausea, vomiting, restrosternal chest pain, and ECG changes compatible with an acute inferoposterior myocardial infarction. Emergent cardiac catheterization revealed three-vessel coronary artery ectasia and two-vessel occlusion. She underwent emergency coronary artery bypass grafting. Her myocardial ischemia was believed to have been induced by methergine, which she had been taking over the preceding 3 days. The etiology and pathophysiology of coronary artery ectasia, as well as the cardiovascular effects of methergine and a related drug, ergotamine, are discussed.     

Analysis of creatine kinase, CK-MB, myoglobin, and troponin T time-activity curves for early assessment of coronary artery reperfusion after intravenous thrombolysis

BACKGROUND: Thrombolysis has become the standard therapeutic approach in patients with acute myocardial infarction. To identify patients who may benefit from early invasive procedures, reliable noninvasive assessment of success or failure of thrombolytic therapy is mandatory. METHODS AND RESULTS: In a prospective study in 63 consecutive patients undergoing thrombolysis for their first myocardial infarction, serial measurements of creatine kinase (CK), its isoenzyme CK-MB, myoglobin, and troponin T were done to determine their value for noninvasive prediction of coronary artery patency. Blood samples were drawn every 15 minutes during the first 90 minutes, every 30 minutes during the first 4 hours, every 4 hours during the first 24 hours, and every 8 hours during the first 72 hours. The perfusion status of the infarct-related artery was assessed angiographically 90 minutes after initiation of thrombolysis. For each marker, time to its peak concentration and its early initial slope (start of thrombolysis to 90 minutes thereafter) were determined. Areas under receiver operator characteristic (ROC) curves were 0.83, 0.76, 0.82, and 0.80 for maxima of CK, CK-MB, myoglobin, and troponin T, respectively (p = NS by univariate Z test). The corresponding values for early slopes of CK, CK-MB, myoglobin, and troponin T were 0.79, 0.82, 0.89, and 0.80 (p = 0.23 for comparison between myoglobin and CK-MB; p = 0.07 between myoglobin and CK). Sensitivity, specificity, and positive and negative predictive values regarding noninvasive prediction of coronary artery patency after 90 minutes were 80%, 82%, 95%, and 61% for time to CK maximum; 91%, 77%, 91%, and 77% for time to myoglobin maximum; 87%, 71%, 89%, and 67% for early CK slope; and 94%, 88%, 94%, and 82% for myoglobin slope, respectively. When myoglobin slope was assessed together with other clinical reperfusion markers (resolution of chest pain or ST segment elevation, occurrence of reperfusion arrhythmias) by logistic regression analysis, only the myoglobin slope was an independent predictor of coronary artery patency (p < 0.0001). CONCLUSIONS: With regard to noninvasive prediction of coronary artery patency after thrombolytic therapy, measurement of the early initial slopes of the serum markers within only 90 minutes after the initiation of therapy is as accurate as the determination of the time to their peak concentration. Compared with the other markers examined, myoglobin appears to have advantages because of its earlier rise, yielding a better negative predictive value and a higher area under the ROC curve for determination of its early initial slopes.     

Multiple attachment mechanisms of corneal epithelial cells to a polymer--cells can attach in the absence of exogenous adhesion proteins through a mechanism that requires microtubules

STUDY OBJECTIVE: To determine whether emergency patients with acute chest pain and low suspicion of acute myocardial infarction (AMI) can be managed cost-effectively and safely in a dedicated chest pain center (CPC) that incorporates mandatory stress testing. METHODS: We assembled a prospective observational case series of consecutive adult patients transferred from the emergency department to a nine-bed, 23-hour CPC in a 564-bed community hospital from January 13 through May 31, 1994. In our institution, all emergency patients with acute nontraumatic chest pain of unclear origin, suggestive of myocardial ischemia but with a low probability of AMI, are transferred to the CPC for further evaluation. All patients in whom AMI is ruled out undergo individually appropriate cardiac diagnostic testing in accordance with CPC clinical guidelines. Patients with end-stage coronary artery disease transferred to the CPC for a "rule-out" protocol only did not undergo further diagnostic testing. Admitted and discharged patients were followed through chart review and telephone survey, respectively. RESULTS: Of the 502 patients transferred to the CPC, 477 (95%) completed follow-up at 14 days. Four hundred ten (86%) were discharged home. Those discharged after diagnostic evaluation yielded negative findings had 100% survival and zero diagnosis of AMI at 5-month follow-up. Overall mortality and incidence of AMI on long-term follow-up for all patients transferred to the CPC were .4% and .2%, respectively. Sixty-seven patients (13%) were admitted from the CPC, of whom 44 (66%) had a final diagnosis of ischemic heart disease (IHD) or AMI. Twenty-four patients with IHD (55%; 6% of stress-tested group) were identified only on further stress testing. Of these patients, seven underwent percutaneous transluminal coronary angioplasty or coronary artery bypass grafting during hospitalization. All were discharged home without major morbidity. Four hundred twenty-four patients (84%) underwent stress testing. The cost of mandatory stress testing to identify one patient with IHD after AMI was ruled out was $3,125. An average cost-per-case savings of 62% was achieved for each patient transferred to the CPC who would have been hospitalized before the inception of the CPC. CONCLUSION: Mandatory stress testing is a safe, cost-effective, and valuable diagnostic and prognostic tool in CPC patients.     

An evaluation of serum troponin T and signal-averaged electrocardiography in predicting electrocardiographic abnormalities after blunt chest trauma

OBJECTIVE: Despite multiple inquiries, there are no available tests to definitively detect blunt myocardial injury. The evaluation of patients with chest wall injuries without other indications for intensive care unit (ICU) admission has ranged from a single emergency department electrocardiogram (ECG) to 72 hours of continuous electrocardiographic monitoring. Recently, signal-averaged ECG and serum cardiac troponin T have demonstrated clinical utility in the evaluation of ischemic heart disease. The purpose of this study is to determine the ability of these diagnostic tests to predict the occurrence of significant electrocardiographic rhythm disturbances for patients with chest wall injuries and no other indication for ICU admission. METHODS: We prospectively evaluated 71 consecutive adult patients admitted to a regional Level I trauma center with chest wall injuries not requiring ICU admission. We obtained admission signal-averaged ECG, serum troponin T level, standard ECG, and creatine phosphokinase (CPK-MB) level. Patients received continuous electrocardiographic monitoring, follow-up 12-lead electrocardiography, and serial monitoring of troponin and CPK-MB. Echocardiography was performed for patients with abnormal CPK-MB levels. Electrocardiographic events were graded as normal, abnormal but clinically insignificant, or clinically significant. Multiple stepwise logistic regression analysis was used to evaluate predictors for the development of clinically significant electrocardiographic events. RESULTS: On admission, 17 of 71 patients (23.9%) had normal sinus rhythm; 13 (18.3%) had a clinically significant finding. For 50 patients, follow-up ECG was abnormal; for 26, the findings were clinically significant. Of 17 patients with normal initial ECGs, 7 (41%) developed a clinically significant abnormality. Six patients received intervention for ECG findings. Eleven of 71 patients (16%) had positive troponin T; 5 of 71 (7%) had positive CPK-MB; 15 of 71 (21%) had positive signal-averaged ECG; and 4 of 13 had positive echocardiograms. Initial electrocardiographic abnormalities and a troponin T level > 0.20 microg/L were the only variables found to predict clinically significant electrocardiographic events. Sensitivity and specificity of troponin T in predicting clinically significant abnormalities were 27 and 91%, respectively. CONCLUSIONS: 1. The best predictors for the development of significant electrocardiographic changes are an admission ECG abnormality and an elevated serum troponin T level. 2. Both tests have high specificity with low to moderate sensitivity. 3. Patients with normal ECGs may develop clinically significant events. 4. CPK-MB and echocardiograms continue to be poor predictors of significant electrocardiographic events.     

Biochemical markers of myocardial damage for early diagnosis and prognosis in patients with acute coronary syndromes. Minireview based on a doctorial thesis

In patients with suspected AMI. Monitoring of a combination of myoglobin and CK-MB or tn-T allowed ruling-in AMI within 2-3 hours and ruling-out AMI within 3-6 hours in almost all patients admitted with chest pain and a nondiagnostic ECG. This might have a large impact on the early handling and treatment of these patients. The neural network methodology, with monitoring of myoglobin, CK-MB and tn-T allowed, within the first three hours, reliable diagnosis/exclusion of AMI/MMD and prediction of infarct size in patients admitted with suspicion of AMI. The computer system was faster than clinicians. Thus, neural network methodology might be a useful support for the early assessment of patients with suspected myocardial infarction. In patients with unstable CAD. The risk of subsequent cardiac events is increased by increasing maximal levels of tn-T obtained during the initial 24 hours. Thereby a normal, a slightly elevated and a clearly elevated tn-T level identified a low, intermediate and high risk group, respectively, for MI or death. The tn-T level was an independent prognostic variable for MI or death in a multivariate analysis comparing other early available risk indicators. Furthermore, tn-T seemed to be superior to CK-MB (mass) for risk stratification. In patients able to perform a predischarge ET both the tn-T level and the ET response were independent prognostic indicators for MI or death. The combination of tn-T and the ET response allowed a further improved risk stratification. In patients with tn-T elevation at inclusion, prolonged dalteparin treatment was beneficial. However, in patients without tn-T elevation, long term dalteparin treatment had no protective effect. Thus, tn-T determination provides independent and important prognostic information in unstable CAD. In the selection of treatment strategy for the individual patient, this simple, inexpensive and early available biochemical test might be useful.     

Uterine lymphoma: sonographic, Doppler, and CT findings before and after chemotherapy

We studied the performance of the CARDIAC STATus, a new rapid, easy to perform qualitative whole blood bedside test for detection of elevated CK-MB and myoglobin in the emergency room. Blood samples from 182 consecutive patients with chest pain were drawn on admission and at five and seven hours after the onset of symptoms. The CARDIAC STATus tests were performed by coronary care unit nurses and, independently, by a trained laboratory technician. The results were compared with quantitative assays for CK-MB mass and myoglobin. At the end of the study, a second test series using a new lot number of cartridges was performed on the same blood samples because of possible elution buffer contamination. Nurses produced more false negative results than the technician (CK-MB 43 vs. 27 %, p=0.01, myoglobin 31 vs. 13%, p<0.0001), but the technician produced more false positive myoglobin results (9.3 vs. 5.5%, p=0.0001). In the second test series, the nurses produced significantly fewer false negative tests both for CK-MB (19%, p<0.0001) and myoglobin (13%, p=0.0002). The false negative rate for the technician was not different between the first and the second test series. The CARDIAC STATus yields a substantial number of false negative results both for CK-MB and myoglobin when compared to a quantitative assay, and therefore at present has limited value for ruling out an acute myocardial infarction.