Creatine kinase isoenzymes in the assessment of heart disease

Tongue sole creatine kinases function as DAMP and activate antimicrobial immunity via TLR2

Creatine kinase (CK) is an enzyme that regulates adenosine triphosphate (ATP) metabolism to maintain energy homeostasis. Although CK has been reported to be involved in pathogen infection, the immune function of CK remains elusive. In this study, we identified two muscle-type CK from the teleost tongue sole Cynoglossus semilaevis (designated CsCKM-1 and CsCKM-2). Bacterial infection modulated CsCKM-1/2 expression in tongue sole tissues and induced the release of CsCKM-1/2 into serum. Recombinant CsCKM-1/2 (rCsCKM-1/2) exhibited robust kinase activity and bound to bacterial pathogens and pathogen-associated molecular patterns. rCsCKM-1/2 also bound to tongue sole peripheral blood leukocytes (PBLs) and promoted PBLs to uptake bacterial pathogens, inhibit bacterial proliferation, and express proinflammatory cytokines. When co-expressed in HEK293T cells, CsCKM-1/2 were found to interact with the leucine rich domain of toll-like receptor 2 (TLR2). The presence of TLR2 antagonist significantly reduced CsCKM-1/2-induced immune response and antibacterial effect. Taken together, these results indicated that tongue sole creatine kinases function as damage-associated molecular pattern (DAMP) molecules and play an important role in antimicrobial immunity via TLR2.

Improving myocardial injury, infarct size, and myocardial salvage in the era of primary PCI for STEMI

ST-segment elevation myocardial infarction (STEMI) is a major cause of mortality and disability worldwide. Reperfusion therapy by thrombolysis or primary percutaneous coronary intervention (PPCI) improves survival and quality of life in patients with STEMI. Despite the proven efficacy of timely reperfusion, mortality from STEMI remains high, particularly among patients with suboptimal reperfusion. Reperfusion injury following opening of occluded coronary arteries mitigates the efficacy of PPCI by further accentuating ischemic damage and increasing infarct size (IS). On the basis of experimental studies, it is assumed that nearly 50% of the final IS is because of the reperfusion injury. IS is a marker of ischemic damage and adequacy of reperfusion that is strongly related to mortality in reperfused patients with STEMI. Many therapeutic strategies including pharmacological and conditioning agents have been proven effective in reducing reperfusion injury and IS in preclinical research. Mechanistically, these agents act either by inhibiting reperfusion injury cascades or by activating cellular prosurvival pathways. Although most of these agents/strategies are at the experimental stage, some of them have been tested clinically in patients with STEMI. This review provides an update on key pharmacological agents and postconditioning used in the setting of PPCI to reduce reperfusion injury and IS. Despite intensive research, no strategy or intervention has been shown to prevent reperfusion injury or enhance myocardial salvage in a consistent manner in a clinical setting. A number of novel therapeutic strategies to reduce reperfusion injury in the setting of PPCI in patients with STEMI are currently under investigation. They will lead to a better understanding of reperfusion injury and to more efficient strategies for its prevention.

Creatine kinase and recurrent myocardial infarction

Daily measurements of serum creatine kinase (CK) activity have been performed in 31 patients during hospitalization for acute myocardial infarction (MI). If CK was raised, isoenzyme B was analysed as well. In this way one probable silent MI and another two overt MIs were diagnosed. MI recurred within three months after discharge in another five patients. None of these eight patients showed even small increases in the daily CK activity when in hospital. This study does not support the concept that reinfarction is a stepwise damage of the myocardium.

Serial signal-averaged electrocardiography in children after cardiac transplantation

In patients with myocytolysis detected in endomyocardial biopsy, there is a tendency towards a shift of ventricular electrical axes from normal to strain pattern on surface ECG. Their 12-lead signal-averaged electrocardiogram (SAECG) show a significant increase in filtered QRS duration (QRSD) compared with those with specimens without myocytolysis. Late potentials were generally found more frequently in individual SAECG leads than in the vector magnitude. An increase in filtered QRSD and the presence of late potentials compared with a baseline study emphasizes the need for endomyocardial biopsy. Consequently, no change in these parameters may preclude the indication for endomyocardial biopsy.

The mouse muscle creatine kinase promoter faithfully drives reporter gene expression in transgenicXenopus laevis

Developing Xenopus laevis experience two periods of muscle differentiation, once during embryogenesis and again at metamorphosis. During metamorphosis, thyroid hormone induces both muscle growth in the limbs and muscle death in the tail. In mammals, the muscle creatine kinase (MCK) gene is activated during the differentiation from myoblasts to myocytes and has served as both a marker for muscle development and to drive transgene expression in transgenic mice. Transcriptional control elements are generally highly conserved throughout evolution, potentially allowing mouse promoter use in transgenic X. laevis. This paper compares endogenous X. laevis MCK gene expression and the mouse MCK (mMCK) promoter driving a green fluorescent protein reporter in transgenic X. laevis. The mMCK promoter demonstrated strong skeletal muscle-specific transgene expression in both the juvenile tadpole and adult frog. Therefore, our results clearly demonstrate the functional conservation of regulatory sequences in vertebrate muscle gene promoters and illustrate the utility of using X. laevis transgenesis for detailed comparative study of mammalian promoter activity in vivo.

Postoperative elevation of creatine kinase (CK-MB): does it contribute to diagnosis of myocardial infarction?

PURPOSE

This retrospective study sought to determine the benefit of measurement of changes in plasma creatine kinase-myocardial band (CK-MB) levels in elective postoperative high risk surgical patients beyond that obtained from the surface 12 lead ECG.

METHODS

The charts of 111 patients admitted to the surgical intensive care unit (SICU) of a tertiary level university teaching hospital were reviewed. They were screened using predetermined definitions of myocardial infarction (MI) (as reflected by changes in the 12 lead surface ECG (Minnesota code) or elevations in CK-MB) for complications such as pulmonary oedema, congestive heart failure, arrhythmias, or cardiogenic shock. Four groups were identified based on changes in the ECG indicative of MI (Present-ECG+ or Absent-ECG-) and elevations of CK-MB (Present-CKMB+ or Absent-CKMB-) and compared for the incidence of complications.

RESULTS

No patient with ECG- findings had a complication. Fifteen patients with ECG+ findings were identified and all had complications. Fourteen of these patients had CKMB+ results. In contrast, 29 patients with CKMB+ results alone (i.e., ECG-) had no complications.

CONCLUSION

Clinically important (i.e., requiring therapeutic intervention) postoperative myocardial infarction was detected by ECG changes. The benefit of determining changes in CK-MB was minimal from a therapeutic perspective.

Cryoprostatectomy consistently elevates serum creatine kinase-MB isoenzyme

STUDY OBJECTIVE

To measure serum CK-MB, a market of myocardial infarction (MI), in elderly men before and after cryoprostatectomy.

DESIGN

Serum CK-MB was measured on each patient before and after cryoprostatectomy. Each patient's preoperative result was used as control measurement for comparison with measurements made after cryoprostatectomy.

SETTING

Inpatient operating room and postanesthetic recovery unit of a university-affiliated general hospital.

PATIENTS

38 male patients, mean (SEM) age 69.1 +/- 1.4 years, undergoing cryoprostatectomy.

INTERVENTIONS

All patients had a 12-lead ECG prior to surgery, in the recovery room, and 24 hours after surgery. Serum CK-MB was measured prior to induction of anesthesia, on arrival in the recovery room, and at 8 and 24 hours after surgery. Lactate dehydrogenase (LDH) and isoenzymes also were measured in 10 patients before and after cryoprostatectomy.

MEASUREMENTS AND MAIN RESULTS

All patients underwent uneventful cryoprostatectomy. No patients had new ECG changes after surgery. All patients had normal serum CK and CK-MB concentrations before surgery. Serum CK and CK-MB were significantly elevated after cryoprostatectomy (p < 0.001). Enzyme values were greatest 8 hours after surgery: total CK mean 1453 +/- 145 U/L (range 199 to 3,356 U/L); CK-MB mean 52 +/- 3 ng/ml (range 12 to 114 ng/ml) or 5.0 +/- 0.5% of total CK (range 1.6% to 12.4%). All patients had significant elevations of LDH after cryoprostatectomy but did not show an increase in the ratio of LDH1 to LDH2 isoenzymes. Finally, unlike patients with an acute MI, the activity of CK-MB isoenzyme when measured by gel electrophoresis was two to three times greater (mean, 2.6 +/- 0.7) than the concentration measured with the monoclonal antibody assay in patients after cryoprostatectomy.

CONCLUSION

Serum CK-MB is an unreliable test to diagnose an MI in patients who have undergone cryoprostatectomy.

Time course of creatine kinase release after termination of sustained ventricular dysrhythmias

Differentiation between primary and secondary (caused by acute myocardial infarction) ventricular fibrillation has important therapeutic and prognostic implications. The diagnosis of myocardial infarction is based on clinical, ECG, and creatine kinase MB isoenzyme (MBCK) activity. Enzymatic criteria might not be able to confirm the diagnosis of myocardial infarction after recent cardioversion. The routine use of electrophysiologic studies involving the induction and termination of ventricular dysrhythmias provides a setting in which enzyme release as a result of cardioversion alone can be examined. Therefore a systematic investigation of the magnitude and time course of creatine kinase (CK) and MBCK release was performed after termination of ventricular dysrhythmias in 57 patients undergoing electrophysiologic studies. Of patients requiring external cardioversion, only 50% had an elevation in CK and MBCK activity. Elevation when present corrected with the number of shocks and cumulative energy delivered. The magnitude of MBCK release exceeded 10% of the total CK activity in 9% of observations. Pace-termination of ventricular tachycardia did not result in enzyme release. Arrhythmia characteristics, coronary artery disease, and left ventricular function did not affect the magnitude of the time course of enzyme release. These data suggest that cardioversion with multiple shocks may result in a component of MBCK release, and thus a false positive diagnosis of primary acute myocardial infarction may be made by relying exclusively on the enzyme release pattern.

The effects of fructose-1,6-diphosphate on myocardial damage in acute coronary artery occlusion

Acute myocardial infarction can result from thrombosis of a coronary artery. The purpose of this study was to evaluate the ability of fructose-1,6-diphosphate (FDP; Esafosfina) to reduce myocardial necrosis during acute thrombosis of a coronary artery. A canine model of acute myocardial infarction was used to produce intraluminal thrombosis by placement of a coil of wire in a coronary artery. After developing a coronary thrombosis of the left anterior descending artery, dogs were injected intravenously with 90 mg/kg, 175 mg/kg, or 350 mg/kg of FDP or normal saline (controls). Hemodynamic, biochemical and electrocardiographic parameters were evaluated before, and 30 min and 4 h after occlusion. Four hours after acute coronary occlusion, the animals were sacrificed, and the weights of ischemic and necrotic myocardial tissue were quantified using a histologic-staining method. There were no significant differences between control and treated animals in biochemical or hemodynamic parameters. All animal groups treated with FDP demonstrated significant reductions in the amount of necrotic and ischemic tissue compared to controls (P less than 0.05). However, only the 175 mg/kg group had a significant reduction compared to controls in necrotic tissue weight as a percentage of ischemic myocardium (24 +/- 15% vs. 72 +/- 22%, respectively, P less than 0.01). These data suggest that FDP may have a role in limiting the amount of myocardial damage after an acute coronary artery occlusion.

Early detection of acute myocardial infarction in patients presenting with chest pain and nondiagnostic ECGs: serial CK-MB sampling in the emergency department

STUDY OBJECTIVES

Patients presenting to the emergency department with chest discomfort are a difficult problem for emergency physicians. Nearly 50% of patients with acute myocardial infarction (AMI) will initially have nondiagnostic ECGs on ED presentation. The purpose of this study was to determine if patients with AMI having nondiagnostic ECGs could be identified using new immunochemical assays for serial CK-MB sampling in the ED.

DESIGN

Chest pain patients, more than 30 years old, with pain not caused by trauma or explained by radiographic findings, were eligible for the study. Serial serum samples were drawn on ED presentation (zero hours) and three hours after presentation, then analyzed for CK-MB using four immunochemical methods and electrophoresis. Standard World Health Organization criteria were used to establish the diagnosis of AMI, including new Q-wave formation or elevation of standard in-hospital serum cardiac enzyme markers.

SETTING

A tertiary cardiac care community hospital.

MEASUREMENTS AND MAIN RESULTS

The serum from 183 patients hospitalized for possible ischemic chest pain was collected and analyzed. Thirty-one of 183 patients (17%) were found to have AMI by standard in-hospital criteria. Sixteen of the 31 patients (52%) with AMI had nondiagnostic ECGs on presentation. Immunochemical determination of serial CK-MB levels provided a sensitive and specific method for detecting AMI in patients within three hours after ED presentation compared with standard electrophoresis. The four immunochemical methods demonstrated a range in sensitivity from 50% to 62.1% on ED presentation versus 92% to 96.7% three hours later. The immunochemical tests demonstrated specificities ranging from 83.0% to 96.4% at three hours, with three of the four tests having specificities of 92% or greater. Electrophoresis had a sensitivity of 34.5% on ED presentation, increasing to 76.9% at three hours, with a specificity of 98.6%.

CONCLUSIONS

Immunochemical CK-MB methods allowed rapid, sensitive detection of AMI in the ED. Early detection of AMI offers many potential advantages to the emergency physician. Early detection of AMI, while the patient is in the ED, could direct disposition of this potentially unstable patient to an intensive care setting. Such information may prevent the ED discharge of patients with AMI having nondiagnostic ECGs. The diagnosis of AMI within a six-hour period after symptom onset may allow thrombolytic therapy to be given to patients with AMI not having diagnostic ECGs. This study served as a pilot trial for a multicenter study of the Emergency Medicine Cardiac Research Group, which is currently ongoing.

Multivariate analysis in the prediction of death in hospital after acute myocardial infarction

Prognostic factors in patients with acute myocardial infarction based on clinical and investigative data on admission were evaluated prospectively in 111 consecutive patients. Seventeen patients (15.3%) died during hospital stay. Age, a previous infarct, high Killip class, cardiomegaly, high serum concentrations of cardiac enzymes, a low ejection fraction, and a high wall motion score index correlated significantly with in-hospital mortality; whereas sex, risk factors, and pericardial effusion did not. Multivariate analysis showed that age and the wall motion score index were the best predictors of death in hospital. Wall motion detected by cross sectional echocardiography may reflect the extent of myocardial involvement. Age and wall motion score index predicted in-hospital mortality with a sensitivity of 76.5%, a specificity of 91.5%, and a predictive accuracy of 89.2%. Age and the wall motion score index can be determined on admission and are useful for identifying patients at high risk of cardiac death who might benefit from early intervention.

Timing and magnitude of serum creatine kinase-MB after transcatheter cardiac tissue fulguration in man

This study examined the impact of transcatheter fulguration on creatine kinase-MB release in 21 patients (age range 17-71 years). Arrhythmia diagnoses were ventricular tachycardia 9, atrial fibrillation with a rapid ventricular response 7, atrioventricular nodal reentry 2, and reciprocating tachycardia utilizing a posteroseptal accessory pathway 3. Seven patients had apparently normal hearts while 8 had ischemic heart disease and 6 cardiomyopathy. Timing of initial elevated creatine kinase-MB activity (mean 1.34 +/- 0.69 SD hours) and peak creatine kinase-MB activity (mean 3.73 +/- 0.89 SD hours) was relatively uniform in all patients. Time to peak creatine kinase-MB activity was unrelated to either underlying cardiac disease (normal: 3.9 +/- 1.0 hours; ischemic heart disease: 3.5 +/- 0.9 hours; cardiomyopathy: 3.8 +/- 0.9 hours), or fulguration site (His bundle (n = 9): 4.2 +/- 0.9 hours, proximal coronary sinus (n = 3): 3.3 +/- 0.3 hours, ventricle (n = 9): 3.4 +/- 0.8 hours). The magnitude of peak serum creatine kinase-MB activity was independent of myocardial diagnosis or fulguration site, but was linearly related to total energy delivered (r = 0.5, P less than 0.022). The latter correlation was particularly strong within cardiac diagnosis subgroups (normal: r = 0.92, P less than 0.002; ischemic heart disease: 0.73, P less than 0.04; non-ischemic cardiomyopathy: r = 0.57, P = NS). Thus, serum creatine kinase-MB activity following transcatheter fulguration is linearly related to the magnitude of delivered energy, and is similar to that observed after transient coronary artery occlusion and reperfusion.

Treatment of human muscle creatine kinase with glutaraldehyde preferentially increases the immunogenicity of the native conformation and permits production of high-affinity monoclonal antibodies which recognize two distinct surface epitopes

Treatment of human muscle creatine kinase (MM-CK) with glutaraldehyde produced highly aggregated forms which retained the native antigenic structure. Immunization of BALB/c mice with CK aggregates instead of untreated CK produced over ten-fold higher titres of antibody against native CK without increasing the titres of antibody against denatured enzyme. Production of high-affinity monoclonal antibodies specific for both the muscle isoenzyme and the native conformation became possible where the use of untreated CK had failed. Four monoclonal antibodies have been characterized by an epitope mapping technique and compared with a commercially available monoclonal antibody. One antibody has a much higher affinity for MM-CK than the other three and the commercial antibody. Competition studies show that it also recognizes a different epitope on the CK surface from the other three monoclonal antibodies which bind to the same surface region as the commercial antibody. Immunoassays based on the high affinity antibody can easily measure less than 1 ng of CK, a sensitivity comparable to, or better than, standard enzymatic assays.

Neuroleptic malignant syndrome: another medical cause of acute abdomen

We present a patient with neuroleptic malignant syndrome and intestinal pseudo-obstruction misdiagnosed as being secondary to septicaemia. The management of the patient is discussed with emphasis on the role of creatine kinase and liver function tests.

Isolation of creatine kinase BB isoenzyme with high specific activity and adequate purity for radioimmunoassay from human placenta on preparative polyacrylamide gel electrophoresis

This report describes the procedures for isolation of creatine kinase BB isoenzyme (CK-BB) from human placenta on preparative polyacrylamide gel electrophoresis. 2.5 mg of CK-BB was purified from a 100-g portion of the human placenta, which had a mean specific activity of 957 kU/g and a mean yield of 16%. The placenta CK-BB exhibited single protein bands on several electrophoretic techniques. In addition, both of the placenta and brain CK-BB preparations were individually iodinated and the identical immunological properties of both the CK-BB preparations were confirmed in radioimmunoassay.

Serum creatine phosphokinase, lactic dehydrogenase, and their isoenzymes in the perioperative period

The purpose of the present investigation was to determine the normal perioperative variations in the serum concentration of creatine phosphokinase (CPK) and its isoenzymes MM, MB, and BB, and of lactic dehydrogenase (LDH) and its isoenzymes LDH1 to LDH5 to distinguish operation-induced changes in these enzymes from those due to acute myocardial infarction or malignant hyperthermia. In 30 patients, 52 to 75 years of age undergoing elective orthopedic operations, 10 serial blood samples were obtained in the perioperative period: two samples before skin incision and eight samples after the incision over a time span of 70 hours. The preinduction mean serum CPK level of 141 U/L increased gradually and significantly and reached a maximum mean concentration of 809 U/L 34 hours after incision (p less than 0.01). The CPK-MM percent increased after incision, whereas that of CPK-MB and CPK-BB decreased, although their absolute values in terms of U/L rose. The preinduction mean serum LDH value of 173 U/L increased gradually after incision and achieved peak levels at 34 hours (203 U/L) and 58 hours (210 U/L) after incision (p less than 0.05). The LDH1:LDH2 ratio did not change. The LDH5 percent increased and peaked 10 hours after incision (p less than 0.05). There was a significant correlation between severity of operation-induced tissue damage and the serum CPK concentration (p less than 0.001). The large increase in total CPK (primarily MM fraction) occurring after surgery may minimize the percentile effects caused by an increase in MB level due to myocardial infarction.

Clinical evaluation of pressure-controlled intermittent coronary sinus occlusion: randomized trial during coronary artery surgery

Pressure-controlled intermittent coronary sinus occlusion (PICSO) was evaluated in a randomized trial in 30 patients undergoing bypass surgery. PICSO was applied for one hour during early reperfusion. Myocardial function was determined from short-axis cross-sectional views of intraoperative two-dimensional echocardiography. Changes of sectional and segmental wall motion during extracorporeal circulation were analyzed. Although sectional wall motion did not change significantly, hypokinetic segments were preserved better in PICSO-treated patients than in controls (-1.3 +/- 2.4 versus -9.1 +/- 2.6 delta% fractional area change; p less than 0.04). Although not significant, the same trend was found for normal and severely hypokinetic segments. Cumulative enzyme release was related to coronary sinus occluded pressure (r = 0.94; p less than 0.006), indicating washout of metabolites during PICSO. Three months after operation, functional classification was similarly favorable in both groups. Long-term effects of PICSO cannot be predicted because PICSO was applied only during early reperfusion. We conclude that PICSO is a safe procedure and that its short-term beneficial effects on myocardial function suggest a preservation of myocardial viability.

Usefulness of lactate dehydrogenase and lactate dehydrogenase isoenzymes for diagnosis of acute myocardial infarction

The usefulness of lactate dehydrogenase (LD) and LD isoenzymes in the diagnosis of acute myocardial infarction (AMI) is controversial. The present study reviewed 507 consecutive patients in whom creatine kinase, creatine kinase isoenzymes, LD and LD isoenzymes were ordered over a 1-month period. Of these, 249 had an insufficient number of serial enzyme determinations to establish a laboratory diagnosis of AMI. After excluding an additional 11 patients for other reasons, 247 patients remained for analysis. Of these, only 2 (0.8%) had myocardial infarction by standard clinical criteria with normal creatine kinase and creatine kinase-MB but elevated LD and abnormal LD isoenzymes. Seven patients (7 of 247, 2.8%) had false-positive LD isoenzymes. Thus, the routine use of LD and LD isoenzymes was of no use in most patients (96%) and led to the incorrect diagnosis of AMI more than 3 times as often as it helped with a correct diagnosis. Total 1-month charges for all the LD and LD isoenzymes obtained equalled +42,450. Therefore, it appears that LD and LD isoenzymes are not routinely useful in the diagnosis of AMI and may result in considerable unnecessary expense. It is suggested that LD and LD isoenzymes be ordered only under suspicion of late presentation (greater than 48 hours) of AMI.

Lack of myocardial necrosis despite clinical and electrocardiographic criteria of acute transmural infarction

The development of "pathologic" Q waves with ST segment elevation is considered diagnostic of transmural myocardial infarction. Previous reports have suggested that myocardial ischemia without infarction can result in electrocardiographic abnormalities simulating those of acute infarction. However, lack of infarction has been poorly documented in these reports. If real, this phenomenon could have an impact on the management of patients with apparent acute infarction. This study describes a patient with documented severe myocardial ischemia and electrocardiographic evidence of acute transmural myocardial infarction, in whom significant myocardial necrosis has been excluded definitively.

Comparison of serum cardiac specific troponin-I with creatine kinase, creatine kinase-MB isoenzyme, tropomyosin, myoglobin and C-reactive protein release in marathon runners: cardiac or skeletal muscle trauma?

Problems arise in distinguishing skeletal from cardiac muscle trauma on the basis of serum enzyme tests following severe muscle exercise. The contributions of cardiac and skeletal sources have been assessed in eleven marathon runners by measuring pre- and post-race serum levels of cardiac-specific myofibrillar troponin-I together with total creatine kinase, creatine kinase-MB isoenzyme, myoglobin, myofibrillar tropomyosin and C-reactive protein. Total creatine kinase, creatine kinase-MB isoenzyme, tropomyosin and myoglobin were significantly elevated above pre-race levels in all runners between 1 h and 128 h post-race. Neither mean cardiac troponin-I nor C-reactive protein was elevated post-race. Nine out of sixty-three samples fulfilled conventional positive criteria for cardiac muscle damage on the basis of combined creatine kinase and creatine kinase-MB isoenzyme levels. Six runners had one or more positive samples. No samples had levels above twice the upper normal limit for either cardiac troponin-I or C-reactive protein. Correlation analysis of levels in each sample indicated skeletal and not cardiac muscle as the source of raised serum protein.

Skeletal muscle creatine kinase MB alterations in women marathon runners

Total creatine kinase (CK) and CK MB activities were determined in gastrocnemius muscle and serum obtained from 14 female marathon runners. The level of CK MB in muscle increased significantly (p less than 0.05) after chronic exercise training from 5.3% to 10.5% of the total CK activity, but not after acute exercise (post-marathon 8.9%). No significant differences in total CK activities were detected. However, the total CK activity in the muscles were significantly (p less than 0.05) less than those previously reported from the muscle of men runners (1800 U/g, 3000 U/g respectively). No significant correlation existed between fiber type and muscle CK MB activity. Additionally, trace amounts of mitochondrial CK and CK BB were present in muscle homogenates. A significant correlation was observed in the increase in mean serum total CK (597 UL-1) and CK MB (23 UL-1) activities 24 h after the race (r = 0.97, p less than 0.05). These results suggest that gastrocnemius muscle in women adapts to training with increased CK MB activities and imply that skeletal muscle is the major source of elevated serum CK MB activities in women marathon runners.

Utility of echocardiography for the early assessment of patients with nondiagnostic chest pain

A two-dimensional (2D) echocardiogram was recorded shortly after admission in 46 patients with nondiagnostic chest pain. Eighteen patients were studied during chest pain and 28 were studied following the resolution of chest pain. Of the 18 patients studied during chest pain, six of the eight patients who had a regional wall motion abnormality (RWMA) evolved an acute infarction and the remaining two patients had evidence of significant coronary artery disease. Only 1 of 10 patients without a RWMA evolved an infarction and none had significant coronary artery disease. Of the 28 patients studied following the resolution of chest pain, 8 of the 10 patients with a RWMA evolved an acute infarction and one patient had evidence of significant coronary artery disease, whereas of 18 patients without a RWMA, none evolved an acute infarction and five had evidence of significant coronary artery disease. These data suggest that in patients presenting with nondiagnostic chest pain, an early assessment of regional wall motion by 2D echocardiography can reliably differentiate patients with myocardial ischemia or early infarction from patients with nonischemic chest pain when performed during an episode of chest pain; can also identify those patients with early acute myocardial infarction, even when performed following the resolution of chest pain; but is not useful for the detection of patients with significant coronary artery disease without infarction when performed following the resolution of chest pain.

Use of cardiac enzymes in the evaluation of acute chest pain

Diagnosis of acute myocardial infarction (AMI) rests upon detailed clinical evaluation of the patient, careful examination of the ECG, and utilization of cardiac enzymes only in those patients admitted to rule out this diagnosis. Any tendency by physicians to diminish emphasis on either of these first two diagnostic criteria, or to inappropriately utilize cardiac enzymes as a screening device, contributes to costly and inefficient errors in diagnosis and disposition of patients with chest pain. Utilization of recently developed mathematical models may prove effective in enhancing clinical judgment and presenting such errors.

Creatine kinase and creatine kinase B-subunit in stable and unstable angina pectoris

Repetitive ischaemic episodes may have a cumulative effect leading to irreversible myocardial cell damage with enzyme release. Using plasma creatine kinase (CK) and creatine kinase B-subunit (CK-B) concentrations this theory has been tested in forty-eight patients admitted with acute chest pain, but without ECG signs of acute myocardial infarction (AMI). The patients were classified into four groups: Fourteen patients with non-ischaemic heart disease (non-IHD), seventeen with stable angina pectoris (SAP), ten with unstable angina pectoris (UAP), and seven patients who developed AMI during the study period. The enzyme variation in non-IHD delineates the background noise, and the increased variability in AMI indicates the full scale of the enzyme signals in cases of irreversible cell damage. Patients with SAP have the same enzyme signal as the background noise in respect of both CK and CK-B. However, in UAP the signal of CK-B equals the background noise, whereas the CK signal is separated from the latter. The reason may be that the signal to noise ratio of CK-B is poor and the analytical sensitivity low. Therefore, the behaviour of CK-B in this study does not support the above theory although our findings for CK indicate that the consequence of repeated ischaemic attacks is slight enzyme release.

Electrocardiographic, enzymatic and scintigraphic criteria of acute myocardial infarction as determined from study of 726 patients (A MILIS Study)

Methods for detecting acute myocardial infarction (AMI) were compared in a prospective study of 726 patients with pain presumed to be caused by ischemia that lasted 30 minutes or longer and was associated with electrocardiographic changes (ST-segment deviation greater than or equal to 0.1 mV and/or new Q waves or left bundle branch block). Using MB-CK values of more than 12 IU/liter as the standard criterion for detection of AMI, 639 patients (88%) were judged to have AMI. Total plasma CK values, technetium-99m stannous pyrophosphate images 48 to 72 hours after admission, and serial 12-lead electrocardiograms over 10 days were analyzed by investigators blinded to other clinical and laboratory data. For detection of AMI, total CK, electrocardiograms (ECGs) and pyrophosphate imaging were all highly accurate and sensitive (total CK accuracy 97%, ECG 92%, pyrophosphate 88%; total CK sensitivity 98%, ECG 96% and pyrophosphate 91%). However, both pyrophosphate and ECG were less specific than total CK (p less than 0.01) (total CK specificity 89%, pyrophosphate 64% and ECG 59%). The sensitivity (p less than 0.05) and accuracy (p less than 0.01) of total CK and pyrophosphate for those patients with Q-wave development were slightly greater than for those in whom Q waves did not evolve. The ECG was less accurate (p less than 0.02) and pyrophosphate was less specific (p less than 0.04) in patients with prior MI compared with those with initial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Late estimation of myocardial infarct size by total creatine kinase nomogram

We studied the possibility of enzymatic estimation of myocardial infarct size in patients late (between days 2 and 6) after the onset of acute myocardial infarction (AMI), in whom estimation of infarct size was difficult by analysis of time-activity curves of serum creatine kinase (CK) because of the lack of the enzymatic information during the initial 48 hours. Serial determinations of serum enzymes were performed in 32 patients within 6 hours after the onset of AMI and significantly close correlations were observed between cumulative total CK release and the cardiac fraction of lactate dehydrogenase isoenzyme (LDH1) activities from day 2 to day 6 after the onset of AMI (r = 0.863 to 0.870; p less than 0.001). We developed a nomogram to estimate cumulative total CK release by serum LDH1 activities obtained between days 2 and 6 after AMI and evaluated the reliability of the nomogram. Cumulative total CK release obtained from serial serum CK activities correlated closely with total CK release obtained from the nomogram in the second group of patients with AMI (r = 0.923 to 0.946; n = 24; p less than 0.001). Our total CK nomogram requiring few blood samples was useful in late estimation of infarct size in patients who were admitted to the hospital between days 2 and 6 after the onset of AMI.

Cellulose acetate and electroendosmosis-low agarose electrophoresis: advanced methods for the separation and quantitative determination of serum creatine kinase isoenzyme levels

Two methods for the separation and demonstration of creatine kinase isoenzymes are described i.e. electrophoresis on cellulose acetate and on electroendosmosis-low agarose. The fluorescence of NADPH as an indicator for the creatine kinase bands was used in both methods. The methods proved to be specific, reliable and highly reproducible, and allow a rather large number of samples (12-18) to be analysed in one run within a relatively short time. The prominent advantage of the proposed methods over others is their extreme sensitivity. Both methods allow linear quantification of creatine kinase isoenzymes up to 700 U/l at 25 degrees C with a lower detection limit of 3 U/l, using a minute amount of sample (2 microliters). The diagnostic value of the methods was shown by their application to sera of patients with myocardial infarction or other diseases.

Macro serum CK-BB in a woman with severe primary hypothyroidism

We report the case of a woman with severe hypothyroidism and without concomitant myocardial damage, in whom elevated CK-MB values were measured by radioimmunological and enzymatic methods before and after thyroid replacement therapy. The patient's CK-MB activity was shown to be actually due to an atypical CK band between CK-MM and CK-MB (also termed "macro CK" or "idiopathic serum CK-BB").

Role of two-dimensional echocardiography in the prediction of in-hospital complications after acute myocardial infarction

To evaluate prospectively the prognostic value of two-dimensional echocardiography after acute myocardial infarction, two-dimensional echocardiography was performed on 61 consecutive patients who were admitted to the hospital with this condition. A left ventricular wall motion score index was derived from analysis of regional wall motion; an index of 2.0 or more within 12 hours of admission identified patients at high risk for pump failure, malignant ventricular arrhythmia or death. These complications occurred in 24 of 27 patients with an initial wall motion score index of 2.0 or more, but in only 6 of 34 with an initial index of less than 2.0 (p less than 0.0005). Of the 47 patients who were in Killip class I on admission, complications developed in 11 (79%) of the 14 with an initial index of 2.0 or more, but in only 6 (18%) of the 33 with an initial index of less than 2.0. After acute myocardial infarction, early determination of the wall motion score index by two-dimensional echocardiography is useful for identifying patients at high risk for complications and is especially valuable in the subset of patients who initially seem to be in stable condition as judged from clinical variables.

Diagnosis of acute myocardial infarction by detection of circulating cardiac myosin light chains

A radioimmunoassay for human cardiac myosin light chains (CM-LC) was developed and evaluated as a selective diagnostic test for acute myocardial infarction (AMI). The assay had a sensitivity of 1.0 ng/ml (+/- 2 standard deviations) in serum. Eighty-three patients with confirmed AMI all showed an elevated plasma concentration of CM-LC at some time during the course of their illness. Of 9 patients from whom early blood samples were obtained, 7 had diagnostic concentrations within 6 hours from the onset of chest pain. Only 2 had an elevated total creatine kinase level at this time. CM-LC concentrations peaked on days 2 to 4, but remained elevated in patients with large AMIs for more than 1 week. In preinfarction syndrome, 8 of 15 patients had elevated CM-LC levels at least once. Of 15 patients with stable angina pectoris, only 1 patient, who had congestive heart failure, showed elevated light chain levels. CM-LC levels were not detectable by this method in the sera of healthy persons (n = 72), patients with recent intramuscular injection (n = 3), or those with a variety of systemic illnesses (n = 14). In initial studies using an antiserum having 25% cross-reactivity between cardiac and skeletal muscle myosin light chains, 3 patients who had extensive skeletal muscle damage appeared to have elevated concentrations. Patients with this finding have not yet been examined with a more specific antiserum (8% cross-reactivity).(ABSTRACT TRUNCATED AT 250 WORDS)

Creatine kinase isoenzyme MB determination on the ACA: dependence on serum matrix and other effectors

Creatine kinase isoenzyme MB catalytic activities in human serum, determined by ACA ion exchange chromatography and immunoinhibition, differ significantly, the correlation coefficient being 0.88. The reasons for this variation are interference of antibodies with the creatine kinase B subunit in the immunoinhibition assay, nonreproducible elution of creatine kinase isoenzyme MB from the ion exchange resin in the ACA pack, due to varying protein concentrations in the serum samples and increasing elution of creatine kinase isoenzyme MM from the ion exchange column caused by a preceding partial inactivation of creatine kinase isoenzyme MM. Pretreatment of serum samples with a solution containing magnesium sulphate, maleate and 2-oxoglutarate (solution A) prior to determination of creatine kinase isoenzyme MB catalytic activities on the ACA significantly improves the sensitivity and specificity of the method; the correlation coefficient for the values from the ACA and immunoinhibition then becomes 0.92. Dilution of serum samples with bovine serum albumin solution is now practicable.

Comparison of enzymatic and anatomic estimates of myocardial infarct size in man

Enzymatic estimates of myocardial infarct size based on plasma levels of MB creatine kinase (MB-CK) were compared with anatomic infarct size in 49 human hearts obtained at autopsy. The patients studied had been enrolled in the Multicenter Investigation of Limitation of Infarct Size (MILIS) study program within 18 hr of the onset of acute infarction and were treated at one of five participating hospitals. Infarct size was estimated from serial measurements of plasma MB-CK made at the core laboratory for CK analysis. Hearts obtained at autopsy were studied independently by the core pathology laboratory without knowledge of the MB-CK levels or clinical results. Data from the two laboratories were compared at the data coordinating center. Of 49 hearts, 12 were excluded either because anatomic infarct size could not be established or because the infarct occurring at the time of enrollment in the MILIS study could not be distinguished with certainty from other infarcts. Of the remaining 37 hearts, peak MB-CK level was available in 36, but samples sufficient for estimation of infarct size were available in only 25. The overall correlation coefficient (Spearman) was .87 for these 25 hearts, indicating that enzymatic estimates of infarct size correlate closely with anatomic measurements. The results indicate that CK estimates of myocardial infarct size represent a valid clinical end point for assessing myocardial infarct size, and the effect of therapy thereon, in groups of treated and control patients.

Creatine kinase levels after jogging in patients with cardiac disease

Acute muscle injury is a well-documented complication of strenuous exercise, but milder forms of exertion have not been studied in detail. This report describes a patient undergoing cardiac rehabilitation in whom atypical chest pain developed and who was treated for a myocardial infarction only because of an elevated creatine kinase level. Serum creatine kinase levels were determined before and after exercise in 27 patients undergoing cardiac rehabilitation. In 21 patients who jogged less than three miles, creatine kinase levels were not appreciably changed. In six patients who jogged more than three miles, the mean creatine kinase level rose from 41 to 54 mU/ml, an increase of 31 percent. In four of these six patients, creatine kinase levels rose to abnormal levels, but MB creatine kinase levels remained normal, with no clinical evidence of myocardial ischemia. Serum creatine kinase levels should be interpreted with caution in the setting of even modest exercise.

Serum enzyme determinations in the diagnosis of acute myocardial infarction: an update

Serum CK-MB and LD-1 have proved extremely useful in the diagnosis and differential diagnosis of acute myocardial infarction. However, CK-MB is present in skeletal muscle and can be released during ischemic attacks; thus, abnormal serum CK-MB activities cannot be equated with myocardial injury. Even wider is the distribution of LD-1, which is found particularly in erythrocytes and renal cortex; hence, an abnormal LD-1 level also cannot be equated with myocardial injury. The method of choice and the final arbiter for the CK and LD isoenzymes is electrophoresis. The possibility of interpreting the results visually fulfills, in part, quality-control needs, and makes the technique suitable for small and large laboratories. Extreme analytic sensitivity is not needed, and electrophoresis provides clinically useful and acceptable results.

Evaluation of an immunoradiometric assay specific for the CK-MB isoenzyme for detection of acute myocardial infarction

Clinical evaluation of patient's symptoms, electrocardiographic changes and increased serum enzyme levels, specifically creatine kinase (CK)-MB by electrophoresis, are established as the primary diagnostic indicators for myocardial infarction (MI). Two hundred fifteen patients were evaluated in this study. Of these patients, 102 were admitted to the coronary care unit and 113 were admitted to the emergency room and screened for possible MI. The immunoradiometric assay used in this study was a double antibody "sandwich" technique, which utilizes antibody to the M and B monomers of the CK isoenzymes. This assay is specific for the CK-MB isoenzyme, which is present in increased levels in MI. The intraassay coefficients of variation for 30 samples were 11.7% (mean 4.1 equivalent units [EU]/liter) and 8.4% (mean 15.4 EU/liter) and the interassay coefficients of variation for 30 samples were 11.1% (mean 2.6 EU/liter) and 8.1% (mean 13.6 EU/liter). The diagnostic sensitivity, specificity and accuracy in this study was 100%, respectively. The CK-MB by the immunoradiometric assay was found to be significantly more accurate than electrophoresis and, therefore, a reliable and also technically simpler replacement for electrophoresis.

Comparison of serum creatine kinase and creatine kinase MB activities post marathon race versus post myocardial infarction

Serial total creatine kinase (CK) and CK MB activities were determined in the serum of seven runners following a marathon race and compared to enzyme activities in the sera from five patients following acute myocardial infarction (AMI). In the runner's sera, total CK and CK MB activities were significantly elevated at 1, 24, 48 and 72 hours post marathon race when compared to the 1 hour pre-marathon samples (p less than 0.01). Serum CK MB activities peaked at 24 hours in both groups of subjects. The MB activities 24 hours following the marathon were substantially higher (91 +/- 30 U/l; mean +/- SD) than the MB activities 24 hours following AMI (46 +/- 38 U/l). However, the percentages of CK MB 24 hours following the marathon and AMI were almost identical (7.0 +/- 2.4% and 7.2 +/- 2.3%, respectively). Furthermore, CK and CK MB clearances were significantly prolonged (p less than 0.02 and p less than 0.001, respectively) following the marathon race (T 1/2 CK, 49 hours; T 1/2 CK MB, 29 hours) as compared to following AMI (T 1/2 CK, 27 hours; T 1/2 CK MB, 12 hours). These results suggest release of CK MB from the skeletal muscle of marathon runners. Therefore, we recommend that elevation of CK MB in the range indicative of myocardial damage be interpreted with caution in long-distance runners.

Significance of elevated MB creatine kinase in patients after cardiac catheterization

To clarify the etiology of elevations in plasma MB creatine kinase (CK) in patients after cardiac catheterization, we studied 32 consecutive patients undergoing cardiac catheterization and coronary arteriography. Total CK and MB CK were within the normal range in all patients prior to catheterization. Total CK activity rose from a mean of 61.46 +/- 33.8 IU/1 (SD) to 141 +/- 105 in the first sample after catheterization (p less than .005) and 121.6 +/- 92.4 in the second catheterization sample (p less than .0005). The MB CK activity also rose from a mean of 3.2 +/- 1.6 IU/1 prior to catheterization to a maximum value of 5.0 +/- 2.9. The mean increase in MB CK, though statistically significant (p less than .005), was only 1.8 IU/1. Only one patient's value for MB CK rose to outside of the normal range (greater than 12) likely due to cardiac injury. Thus, our data document that marked elevations in MB CK after cardiac catheterization are unusual. They likely represent cardiac muscle injury rather than MB CK released due to skeletal muscle injury induced by the catheterization itself.

The diagnostic specificity of creatine kinase isoenzymes after transurethral operations

It has been suggested recently that increases in the concentration of the MB isoenzyme of creatine kinase after transurethral operations could result from release of creatine kinase-MB by prostatic or bladder tissues and, therefore, that creatine kinase-MB is not specific for myocardial damage. Our study of 53 patients undergoing transurethral operations and 37 undergoing urethral dilations showed that creatine kinase-MB is not released in significant quantities from the prostate or bladder. Therefore, we believe that an elevated creatine kinase-MB concentration is specific for myocardial infarction in these patients. We also concluded that the increase in total serum creatine kinase activity in these patients probably results from release of the creatine kinase-MM isoenzyme from periurethral muscle damage by electrocautery.

Serum creatine kinase and creatine kinase MB isoenzyme responses of post-infarction patients after a graded exercise test

The response of total creatine kinase (CK) and the creatine kinase isoenzyme (CK MB) was studied in 22 male post-infarction patients (three to six months after myocardial infarction) after a functional graded exercise test, before entering a rehabilitation programme. Eleven subjects (group A) completed the test without developing significant electrocardiographic abnormalities. Eleven subjects (group B) showed changes that necessitated premature termination of the test. No significant differences were observed before the functional graded exercise test between the groups in serum concentration of CK, CK MB, and the percentage of CK MB to CK (MB/ CK%). The two groups were significantly different (p less than 0.01) 24 hours after the graded exercise test in CK MB and MB/CK%, but not in CK. In group B, CK and CK MB rose significantly after the graded exercise test (p less than 0.05) as did MB/CK% (p less than 0.01). In group A only CK showed a significant rise (p less than 0.05). It is probable that increases in CK MB after exercise arise from myocardial tissue efflux, reflecting reversible ischaemia. It is concluded from this study that CK MB appears to be a specific indicator of myocardial ischaemia and could, therefore, be of significant assistance in the clinical and functional assessment of the post-infarction patient.