Early diagnosis of myocardial infarct: value of the combined use of creatine kinase and MB isoenzyme determinations

To define the optimal diagnostic strategy for acute myocardial infarction, 225 patients with suspected myocardial infarction were studied by serial (3 hour intervals) sampling for CK and CK-MB enzyme activity. In 12 patients the diagnosis of myocardial infarction was rejected. In the remaining 213 the myocardial infarction was transmural in 183 (anterior in 79, postero-inferior in 95, anterior and inferior in 9), non transmural in 30. In these patients the mean increase of enzyme activity, the time to pick activity and the infarct size (Sobel method) were measured. The best diagnostic sensitivity in the early phases of myocardial infarction was obtained by the combined use of CK and CK-MB determinations (95.9% of the diagnosis at 9 hours after the acute event). However the percent of positivity of CK & CK-MB values occurred significantly (p less than 0.01) later in non transmural (4.3% at 3, 34.7% at 6 and 86.9% at 9 hours after the onset of the chest pain) than in transmural myocardial infarction (25.2% at 3, 54.4% at 6 and 97.6% at 9 hours) and among these in inferior as compared to anterior (18.7% vs 32.2% at 3 hours, 46.8% vs 62.7% at 6 hours and 96.8% vs 98.3% at 9 hours). The CK/CK-MB ratio was of limited diagnostic value because it was increased (greater than 8) in most of the patients, either with normal or abnormal enzymes activities. Early kinetics differed in the different anatomo-clinical types of infarction. In all locations of myocardial infarction the mean enzyme activity increase was significantly correlated with the calculated enzymatic infarct size.(ABSTRACT TRUNCATED AT 250 WORDS)     

Creatine kinase isoenzymes. Predictive value in the early diagnosis of acute myocardial infarction.

This is a prospective study of the value of the creatine kinase (CK) isoenzyme determination in the early diagnosis of acute myocardial infarction. The presence or absence of the MB isoenzyme was correlated with electrocardiogram and standard enzymes. The frequency of falsely positive and falsely negative results for CK-MB, electrocardiogram and each standard enzyme was calculated and, using the elements of conditional probability theory, their predictive values for the diagnosis of acute myocardial infarction were determined. Results indicate that CK-MB combines the best attributes of the electrocardiogram and standard enzyme tests: detectable MB isoenzyme activity by acrylamide slab electrophoresis has a predictive value for the diagnosis if acute myocardial infarction comparable to that of a positive electrocardiogram; absence of MB isoenzyme activity, in the 24 hour period following the onset of symptoms, excludes the diagnosis of acute myocardial infarction with a probability equivalent to that provided by normal standard enzyme results.     

Evaluation of creatine kinase and creatine kinase-MB for diagnosing myocardial infarction. Clinical impact in the emergency room

We prospectively studied the performance of emergency room strategies using a single sampling of total creatine kinase (CK) only and total CK with, if total CK levels were elevated, CK-MB levels in 639 patients with acute chest pain, including 386 patients who were admitted and 253 patients who were discharged. Acute myocardial infarction was diagnosed in 104 patients and excluded in 535. An elevated total CK level had a sensitivity of only 38% and specificity of only 80%, whereas a CK-MB level over 5% of an elevated total CK level had a sensitivity of only 34% and specificity of 88%. The sensitivities of both CK and CK-MB were higher in patients who arrived more than four hours after the onset of symptoms, and, in this population, the strategy using CK-MB performed significantly better than the strategy using total CK alone. Since a very positive CK-MB in a low-risk patient can greatly raise the probability of myocardial infarction, future strategies using CK-MB may have a role in selected subsets in determining which patients should not be sent home. However, the sensitivity of a single sampling of CK and CK-MB is too low for these assays to be used to exclude myocardial infarction in the emergency room or to be used as the rationale for deciding not to admit a patient.     

Incidence of high-risk acute coronary syndromes and eligibility for glycoprotein IIb/IIIa inhibitors among patients admitted for possible myocardial ischemia

Objective Recent studies have demonstrated that glycoprotein (GP) IIb/IIIa inhibitors can reduce cardiac events in patients with acute coronary syndromes (ACS). However, little is known about how many patients are actually eligible for treatment. Our purpose was to determine how many patients admitted for possible myocardial infarction (MI) meet GP IIb/IIIa inhibitor treatment criteria. Methods Patients admitted for possible MI who underwent a standard protocol that included serial sampling of total creatine kinase (CK), CK-MB, and troponin I (TnI) were retrospectively assigned to different treatment algorithms on the basis of criteria from GP IIb/IIIa inhibitor trials: an electrocardiogram (ECG) consistent with acute MI or ischemia, and myocardial marker elevations. Elevated CK-MB was considered diagnostic of MI. High-risk ACS was defined as ischemic ECG changes or troponin elevations without CK-MB elevations. Results A total of 2179 patients were admitted for MI exclusion. MI was identified in 304 patients (14.0%) (123 ST-elevation, 49 ischemic ECG, 132 nonischemic ECG). Another 273 patients (12.5%) without CK-MB criteria for MI met high-risk ACS criteria (172 ischemic ECG, 120 TnI elevations). Ischemic ECGs or elevated myocardial markers identified 454 (21%) patients as eligible for treatment. Inclusion of patients with ST elevation increased eligibility to 26.5%. Of the 454 non-ST-elevation ACS patients, 340 (74%) were identified early by the ECG or the initial markers. Conclusions A large proportion of patients admitted for possible MI met criteria for treatment with GP IIb/IIIa inhibitors. The non-ST-elevation ACS group was >3 times larger than the ST-elevation MI group. These findings have important implications for treatment of patients with ACS. (Am Heart J 2002;143:70-5.)     

Serial ECGs are less accurate than serial CK-MB results for emergency department diagnosis of myocardial infarction.

HYPOTHESIS: Serial creatine kinase-MB (CK-MB) levels provide more accurate predictive information regarding myocardial infarction than serial ECGs in emergency department patients with chest discomfort and no ST-segment elevation on the initial ECG. DESIGN: Prospective, observational study. SETTING: University hospital and university-affiliated Veterans Affairs Medical Center EDs. PARTICIPANTS: Two hundred sixty-one patients 30 years or older with chest discomfort warranting an ECG and consenting to observation. Exclusions included hemodynamic or rhythm instability and ST-segment elevation of 0.1 mV or more in two or more electrically contiguous leads at presentation. MEASUREMENTS: ECGs were obtained at presentation and three to four hours after presentation. Significant serial ECG changes sought on comparison of initial and three- to four-hour ECGs were 0.05 mV or more ST elevation or depression, Q-wave development, or T-wave inversion changes in two or more electrically contiguous leads. CK-MB levels were obtained at presentation and hourly for three hours (positive level, 8 or more ng/mL). Myocardial infarction was determined by record review and was based on independent CK-MB measurements. RESULTS: Twenty-eight (11%) patients were diagnosed with a myocardial infarction. Thirty-eight (15%) patients had a serial ECG change. Eleven of the myocardial infarction patients (39%) had a serial ECG change compared with 27 (12%) of the non-myocardial infarction patients (P < .001). Sensitivities and specificities of a serial ECG change versus serial CK-MBs for myocardial infarction were 39% versus 68% (sensitivity) and 88% versus 95% (specificity), respectively. Serial CK-MBs were more accurate than a serial ECG change for predicting myocardial infarction (P < .03). CONCLUSION: Serial changes in ECGs during a three- to four-hour interval were associated with the diagnosis of myocardial infarction but were infrequent and less accurate than serial CK-MB levels obtained for the same interval.     

尿激酶对血管升压素诱发的大鼠梗死心肌的保护作用

目的 :探讨尿激酶对血管升压素 （Pit）诱发大鼠梗死心肌的保护作用。方法 :以 SD大鼠腹腔注射 Pit（3 0 U/kg）造成心肌梗死模型 ,观察腹腔注射尿激酶 （5万 U / kg）对血清心肌酶 （CK、CK-MB、L DH）释放量、心电图 ST段抬高程度以及心肌病理损伤程度的影响。结果 :Pit组较对照组心肌酶 （CK、CK-MB、L DH）释放量以及心肌病理损伤程度均显著增加 （P<0 .0 1） ,ST段显著抬高 （P<0 .0 1） ;Pit+ UK组则较 Pit组心肌损伤程度明显减轻 （P<0 .0 1） ,CK、CK-MB、L DH和 ST段分别降低 54.2 %、54.5%、48.4%和 56.5% （均为 P<0 .0 1）。结论 :尿激酶对 Pit性心肌梗死大鼠的心肌具有明显的保护作用     

Value of a new fast CK-MB determination for the diagnosis of myocardial infarction during the 1st hours. Preliminary study]

This study evaluated the time for a new, rapid and reliable CK-MB analysis to become positive in myocardial infarction and compared it with classical total CK analyses. Serial analyses of total CK and CK-MB were performed in 49 consecutive patients referred to the Coronary Care Unit for suspected acute myocardial infarction. Twenty of these patients had myocardial infarction with rising enzyme levels, which enabled comparison of the precocity of one analysis compared to another. In these patients, the CK-MB analysis became positive on average 85 to 110 minutes before that of total CK. This result shows that CK-MB analysis can be a diagnostic sign of acute myocardial infarction at an earlier stage than the total CK analysis. The authors discuss the clinical value of this test in difficult indications of fibrinolytic therapy and underline that it enables a more objective assessment of the time of onset of necrosis than clinical data alone.     

Serum myocardial creatine kinase (CK-MB) after coronary arterial bypass surgery.

Serum myocardial creatine kinase, MB isoenzyme (CK?MB) was measured at 6 hour intervals for 36 hours after surgery by ion exchange column chromatography for detection of perioperative myocardial infarction and was compared with serial electrocardiograms, serum glutamic oxaloacetic transaminase (SGOT) and lactate dehydrogenase (LDH) isoenzyme determination and technetium-99m pyrophosphate myocardial scintigraphy in 100 consecutive patients undergoing coronary artery bypass surgery. Results were compared with those in a control group of 10 patients with normal coronary arteries after closure of an atrial septal defect or mitral valvotomy. Total CK-MB release was estimated by calculating the concentration time integral for 36 hours after surgery. In 77 of 87 patients with a peak CK-MB and total CK-MB release lower than the highest control value (or mean + 2 standard deviations), all other tests were also negative for perioperative myocardial infarction. The other 10 patients had an isolated positive laboratory test (5 patients showed ischemic electrocardiographic changes, 3 patients an SGOT level of more than 90 IU/liter and 2 patients LDH₁ equal to or greater than LDH₂). All 13 patients with CK-MB values higher than the highest control value (or mean ± 2 standard deviations) had at least two additional positive laboratory tests indicating perioperative myocardial infarction (8 patients had new Q waves, 3 patients ischemic electrocardiographic changes, 11 patients LDH₁ equal to or greater than LDH₂, 11 patients SGOT greater than 90 IU/liter and 8 of 10 patients a positive myocardial scintigram). Thus, CK-MB by column chromatography is a reliable test for recognition of perioperative myocardial infarction and appears to be more sensitive than electrocardiography or scintigraphy for detection of myocardial necrosis. Reliability may be strengthened by the association of elevated CK-MB with additional positive tests.     

Creatine kinase-MB mass concentration versus creatine kinase-B activity for the detection of acute myocardial infarction in patients with slightly elevated total creatine kinase activity in serum

Abstract. Objective . The diagnostic value of creatine kinase-MB mass concentration (CK-MB mass) was compared with that of creatine kinase-B (CK-B) activity in patients with suspected acute myocardial infarction (AMI) but with total serum CK activity only slightly above the reference range. Design . One hundred consecutive blood samples with total CK activity between 120 and 360 U I^-1 and CK-B activity ≥ 9 U I^-1 were analysed. Electrophoresis of CK isoenzymes was also performed. Setting . Patients from all departments of the hospital were included. About half of the patients originated from the coronary care unit. Subjects . The blood samples derived from 49 patients. Thirteen patients had at least one serum sample with total CK activity above 360 U I^-1. These and another three patients were omitted from the study. Results . Acute myocardial infarction had been diagnosed clinically (with CK and CK-B methods) in 12 of 33 patients. However, using the CK-MB mass concentration of the reference method, five of these 12 patients did not have myocardial infarction whereas nine patients with small infarctions were undetected. A good correlation was seen between the results from CK-MB mass concentration and CK isoenzyme electrophoresis, but there was a poor correlation between these methods and CK-B activity including the CK-B/CK ratio. A relatively high proportion (24%) of the selected patients had increased levels of macro CK. Conclusion . CK-B activity was inaccurate for the detection of probable myocardial infarction in patients with slightly elevated total CK activity. Increased levels of macro CK interfering with the CK-B assay was one explanation for this observation.     

Clinical applicability of creatine kinase MB mass and the electrocardiogram versus conventional cardiac enzymes in the diagnosis of acute myocardial infarction

We compared creatine kinase MB (CK-MB) mass and total creatine kinase (CK) sampled three times daily with conventional cardiac enzymes. The influence of the electrocardiogram (ECG) on admission, frequency of blood sampling, thrombolytic therapy, different upper reference limits of the biochemical markers and duration of symptoms were assessed in 100 consecutive patients with suspected AMI of whom 63 were confirmed according to WHO criteria. Early sensitivity but not specificity of CK-MB mass, with and without ECG, for cut points <8 μg/l was significantly better than total CK sampled frequently. The sensitivity of ECG on admission (52%) was significantly improved by CK-MB analysis (79%) but not by total CK. Duration of symptoms (range of means 3.5–9 h) or thrombolytic treatment had no influence on the sensitivity and specificity of CK-MB mass. In AMI with inconclusive ECG, CK-MB mass performed best of the markers with a sensitivity of 70% versus 17% of total CK (P<0.001) on admission. CK-MB mass was also elevated in 8 patients classified conventionally as unstable angina. We conclude that CK-MB mass is a more useful marker of AMI during the first 16 h of chest pain than frequently sampled total CK, ECG and conventional cardiac enzymes.     

Use of biochemical markers of infarction for diagnosing perioperative myocardial infarction and early graft occlusion after coronary artery bypass surgery.

STUDY OBJECTIVES: Perioperative myocardial infarction (PMI) during coronary artery bypass grafting (CABG) is an important clinical problem because it is closely associated with increased morbidity and mortality. The diagnosis of PMI is, however, associated with several problems. Due to the surgical trauma, the usual indicators of myocardial infarction (pain, ECG changes, and elevated biochemical markers of infarction) have uncertain diagnostic value. The primary aim of this study was to illustrate the levels of the biochemical markers after uncomplicated bypass surgery defined as no clinical or ECG evidence of PMI, and no graft occlusion at 7 days by repeat angiography; and secondarily, to establish biochemical diagnostic discrimination limits for detection of in-hospital graft occlusion. METHODS AND RESULTS: One hundred three patients undergoing elective CABG were closely monitored by serial measurements of creatine kinase (CK)-MB mass, myoglobin, troponin T, and troponin I, and underwent a repeat angiography before discharge. Seven patients had ECG evidence of PMI. Peak troponin T and CK-MB values were significantly higher in these seven patients, although the diagnostic performances of the optimally chosen cutoff levels for diagnosing AMI were fair. Twelve patients had at least one occluded graft shown by repeat angiography. Peak values of CK-MB and troponin T were significantly higher in patients with graft occlusion (52.2 microg/L vs 24.7 microg/L, p = 0.01; and 3.7 microg/L vs 1.0 microg/L, p = 0.05, respectively). By multivariate analysis, a diagnostic discrimination level of 30 microg/L for CK-MB did not reach statistical significance; however, the independent diagnostic value of a cutoff level for troponin T at 3 microg/L reached a level of significance (p = 0.06). DISCUSSION: We have suggested normal values of four different biochemical markers of infarction after uncomplicated coronary bypass surgery. Patients with in-hospital graft occlusion had higher peak CK-MB and troponin T values. However, the overlap with patients without graft occlusion is substantial, and the patency status in the individual cannot be reliably predicted from these noninvasive tests.     

The diagnosis of perioperative myocardial infarction in heart surgery

Fifty three consecutive patients undergoing open heart surgery were prospectively studied to assess current techniques for diagnosing perioperative myocardial infarction (PMI). All patients had preoperative and postoperative electrocardiograms, serial determinations of serum creatine phosphokinase (CK), myocardial fraction of CK (CK-MB) and scintigraphy with technetium-99m labeled pyrophosphate. Seven patients (13.2%) sustained perioperative myocardial infarction. Four of these patients exhibited abnormal Q waves, and one poor R wave progression. Three of them had a positive scintigram. Two patients with a non-Q-wave infarction had a abnormal radioisotopic imaging. The CK and CK-MB were higher in patients with infarction (818.1 U) than in those without this complication (349 U) p less than 0.05. The relative sensitivity and relative specificity of given variables in the diagnosis of PMI were as follows: electrocardiogram 71.4% and 97.5% respectively; scintigraphy 71.4% and 94.1%; and serum enzymes 100% and 71.8%. Age, incidence of prior myocardial infarction, unstable angina, elevated left ventricular filling pressure, number of diseased coronary arteries, and number of grafts per patient did not correlate with PMI. Duration of extracorporeal circulation and number of electric shocks during surgery were slightly higher in the infarction group, but the difference was not significant. These results indicate that the combination of these three diagnostic procedures is the best way to evaluate myocardial damage after open heart surgery.     

Acute myocardial infarction in chest pain patients with nondiagnostic ECGs: serial CK-MB sampling in the emergency department. The Emergency Medicine Cardiac Research Group.

STUDY OBJECTIVES: This study tested the hypothesis that serial creatine phosphokinase (CK)-MB sampling in the emergency department can identify acute myocardial infarction (AMI) in patients presenting to the ED with chest pain and nondiagnostic ECGs. DESIGN: Patients more than 30 years old who were evaluated initially in the ED and hospitalized for chest pain were studied. Serial CK-MB levels were analyzed prospectively using a rapid serum immunochemical assay for identification of AMI patients in the ED. Presenting ECGs showing new, greater than 1-mm ST elevation in two or more contiguous leads were considered diagnostic for AMI. All other ECGs were considered nondiagnostic ECGs. CK-MB levels were determined at ED presentation and hourly for three hours (total of four levels). Patients with at least one level of more than 7 ng/mL were considered to have a positive enzyme study. The in-hospital diagnosis of AMI was determined by the development of typical serial ECG changes or separate standard cardiac enzyme changes after admission. SETTING: Eight tertiary-care medical center hospitals. METHODS AND MAIN RESULTS: Of the 616 study patients, 108 (17.5%) were diagnosed in the hospital as AMI; 69 of these AMI patients (63.9%) had nondiagnostic ECGs in the ED. Of the patients with nondiagnostic ECGs, 55 (sensitivity, 79.7%) had a positive ED serial CK-MB enzyme study within three hours after presentation. Combining serial ED CK-MB assay results with diagnostic ECGs yielded an 88.4% sensitivity for AMI detection within three hours of ED presentation. The predictive value of a negative serial ED enzyme study for no AMI was 96.2% (specificity, 93.7%). CONCLUSION: Serial CK-MB determination in the ED can help identify AMI patients with initial nondiagnostic ECGs. Use of serial CK-MB analysis may facilitate optimal in-hospital disposition and help guide therapeutic interventions in patients with suspected AMI despite a nondiagnostic ECG.     

急性ST段抬高型心肌梗死直接PCI术后ST段回落的临床研究

目的：通过观察急性ST段抬高型心肌梗塞（STEMI）直接经皮冠状动脉介入治疗（PCI）术后,梗塞相关动脉（IRA）达心肌梗塞溶栓（TIMI）血流3级患者心电图ST段回落程度,探讨ST段回落与心肌损伤及心脏收缩功能的关系。方法：选择在发病12h内接受直接PCI治疗后TIMI血流达到3级的STEMI患者115例,PCI术前、术后行心电图检查,观察ST段回落情况,术前、后测定患者肌酸激酶（CK）、肌酸激酶同工酶（CK-MB）及肌钙蛋白T（cTnT）,术后测定左室射血分数（LVEF）;按照ST段回落幅度（∑STR）不同,患者被分为两组：A组：∑STR〈50%,21例,为心肌灌注不良组,B组：∑STD≥50%,94例,为心肌灌注良好组;分析两组患者ST段回落程度与CK、CK-MB、cTnT及LVEF的关系。结果：（1）两组患者IRA部位、病变血管支数,PCI治疗前TIMI血流分级、cTnT水平,发病到PCI时间等差异均无显著性（P〉0.05）;（2）两组患者术前、后CK、CK-MB水平差异无显著性（P〉0.05）;（3）术后A组cTnT水平明显高于B组[（1.30±0.43）μg/L∶（1.0±0.45）μg/L,P〈0.05];（4）术后A组LVEF明显低于B组[（44.13±4.83）%∶（47.93±5.23）%,P〈0.05]。结论：急性ST段抬高型心肌梗塞直接PCI术后,TIMI血流达到3级,ST段回落良好的患者,心肌组织水平灌注程度较好,心肌损伤程度轻,左心收缩功能较好。     

Myonecrosis After Revascularization Procedures

The detection of elevated cardiac enzyme levels and the occurrence of electrocardiographic (ECG) abnormalities after revascularization procedures have been the subject of recent controversy. This report represents an effort to achieve a consensus among a group of researchers with data on this subject. Creatine kinase (CK) or CK-MB isoenzyme (CK-MB) elevations occur in 5% to 30% of patients after a percutaneous intervention and commonly during coronary artery bypass graft surgery (CABG). Although Q wave formation is rare, other ECG changes are common. The rate of detection is highly dependent on the intensity of enzyme and ECG measurement. Because most events occur without the development of a Q wave, the ECG will not definitively diagnose them; even the ECG criteria for Q wave formation signifying an important clinical event have been variable. At least 10 studies evaluating >10,000 patients undergoing percutaneous intervention have demonstrated that elevation of CK or CK-MB is associated not only with a higher mortality, but also with a higher risk of subsequent cardiac events and higher cost. Efforts to identify a specific cutoff value below which the prognosis is not impaired have not been successful. Rather, the risk of adverse outcomes increases with any elevation of CK or CK-MB and increases further in proportion to the level of intervention. This information complements similar previous data on CABG. Obtaining preprocedural and postprocedural ECGs and measurement of serial cardiac enzymes after revascularization are recommended. Patients with enzyme levels elevated more than threefold above the upper limit of normal or with ECG changes diagnostic for Q wave myocardial infarction (MI) should be treated as patients with an MI. Patients with more modest elevations should be observed carefully. Clinical trials should ensure systematic evaluation for myocardial necrosis, with attention paid to multivariable analysis of risk factors for poor long-term outcome, to determine the extent to which enzyme elevation is an independent risk factor after considering clinical history, coronary anatomy, left ventricular function and clinical evidence of ischemia. In addition, tracking of enzyme levels in clinical trials is needed to determine whether interventions that reduce periprocedural enzyme elevation also improve mortality.     

Troponin I as a specific marker of myocardial injury: from theory to clinical practice in the diagnosis of acute coronary syndrome

OBJECTIVE: To assess the diagnostic accuracy of troponin I (TnI) elevation in patients with acute coronary syndrome (ACS) in the emergency department (ED). METHODS: We retrospectively studied 166 patients with elevated TnI and electrocardiographic (ECG) change consistent with non-ST-segment elevation myocardial infarction. They were transferred from the ED to our coronary care unit (CCU) to undergo coronary angiography. RESULTS: Significant coronary stenosis were identified in 101 (61%) of patients. The other 65 patients were found to have different cardiac diseases (n=52) and in 13 patients diagnoses were not even related to the cardiovascular system. Wall motion abnormalities were assessed by echocardiographic wall motion score index (WMSI). Positive predictive value (PPV) of TnI varied from 53 to 65% for higher progressive values of the biomarker. The following PPVs were then calculated: PPV(TnI+CK-MB)=64%; PPV(TnI+WMSI)=72%, PPV(TnI+CK-MB+WMSI)=74%. CONCLUSIONS: Abnormal values of TnI were detected in a variety of diseases not related to ACS. Even if troponin release indicates myocardial injury, it is not always synonymous with infarction or ischemia. A misinterpretation of TnI elevation may give rise to a diagnostic dilemma and cause unnecessary morbidity. An integration of biomarkers (TnI and CK-MB), ECG and WMSI will help identify false-positive ACS patients and avoid inappropriate admissions to CCU.     

Comparison of Troponin T to creatine kinase and to radionuclide cardiac imaging infarct size in patients with ST-elevation myocardial infarction undergoing primary angioplasty

Troponin is used mainly for detection of minor myocardial damage, whereas repeated measurements of creatine kinase (CK) and myocardial band (CK-MB) are used for assessing infarct size in patients with myocardial infarction. The purpose of this study was to correlate peak level and area under the curve (AUC) of troponin T to that of CK and CK-MB and with single-photon emission computed tomographic infarct size and left ventricular function in patients with ST elevation myocardial infarction. In this multicenter study (29 centers, 5 countries), we included 267 patients who underwent primary coronary intervention within 6 hours of onset of symptoms. All had repeated measurements of troponin T, CK, and CK-MB. Infarct size and left ventricular function were assessed by single-photon emission computed tomography performed on days 7 and 30. Mean infarct sizes were 14% on day 7 and 10% on day 30, and mean ejection fractions were 42% on day 7 and 45% on day 30 after the acute infarct. Very high correlation (r >0.85, Spearman correlation) was found between peak level and AUC of troponin T, CK, and CK-MB. Similar high correlation was found between peak level and AUC of troponin, CK, and CK-MB with single-photon emission computed tomographic infarct size (r >0.70). In conclusion, based on the results of this multicenter study, we suggest that peak levels and AUC of troponin are as accurate as CK and CK-MB in estimating myocardial infarct size.     

Weak diagnostic performance of troponin,creatine kinase and creatine kinase-MB to diagnose or exclude myocardial infarction after successful resuscitation

Background

The aim of this study is to evaluate the diagnostic accuracy of the cardiac injury markers troponin (TNT), creatine kinase (CK) and creatine kinase-MB (CK-MB) to diagnose or exclude acute myocardial infarction after cardiac arrest.

Methods

226 patients who underwent diagnostic coronary angiography after sudden cardiac arrest were analyzed retrospectively. Levels of TNT, CK and CK-MB on admission and 6 h, 24 h and 36 h later were retrieved from the files and compared with the results of coronary angiography.

Results

Acute myocardial infarction (AMI) as well as non-AMI patients showed increasing levels of TNT and CK after resuscitation, although the AMI group showed significantly higher TNT and CK levels. Receiver operator curves were calculated to determine the diagnostic precision of TNT, CK and CK-MB to differentiate AMI and non-AMI patients. All analyzed markers yielded mediocre diagnostic precision with an area under the ROC curve of 0.7020, 0.6802 and 0.6508 for 6 h TNT, CK and CK-MB, respectively. Applying a modified cut-off of 1 μg/l the 6 h TNT measurement had a sensitivity of 70.9% and specificity of 61.2% to diagnose AMI after cardiac arrest. Using CK 800 U/l as cut-off level resulted in a sensitivity of 62.5% and specificity of 73.7%, CK-MB levels higher than 100 U/l yielded a sensitivity of 58.8% and specificity of 72.7%.

Conclusion

Cardiac injury markers cannot be used to reliably diagnose or rule out AMI after resuscitation. Consequently we propose that indication for coronary angiography should be extended to all patients without a certain alternative diagnosis explaining the occurrence of cardiac arrest.     

Cardiac troponin I is increased after interventional closure of atrial septal defects.

This study was designed to assess possible myocardial injury caused by interventional closure of atrial septal defects (ASDs) compared to diagnostic catheterization by measuring cardiac troponin I (cTn-I). Forty patients were enrolled; in 33 ASDs were successfully closed, while in 7 a diagnostic balloon sizing of the defect was performed only. Total cTn-I increased significantly from 0.1 to 1.9 microg/l at the end of the intervention and 2.23 at 4 hr and decreased to 1.35 at 15 hr. No significant increase could be detected in patients with diagnostic balloon sizing only or of CK/CK-MB levels either. Following interventional closure of ASDs with Amplatzer septum/PFO occluders, increased cTn-I levels for several hours indicate some transient, reversible myocardial membrane instability due to the device. Discrimination of ventricular myocardial infarction might be possible by estimating less sensitive CK and CK-MB levels only.     

Myocardial infarct extension: Prevalence,clinical significance,and problems in diagnosis

To examine the prevalence, clinical significance, and problems in the diagnosis of myocardial infarct (MI) extension, 103 patients with acute MI were studied. Each patient underwent enzymatic infarct sizing in the initial 72 hours and then had quantitative CK-MB (myocardial isoenzyme of serum creatine kinase) analysis at 8-hour intervals over the remaining hospitalization. In addition, daily standard 12-lead ECGs and documentation of prolonged (>15 minutes) resting ischemic chest pain were recorded. MI extension, by CK-MB methods, occurred in 32 (31%) of 103 patients at 5.9 ± 0.3 days after initial infarction. ECG changes suggesting MI extension occurred in 14 (14%), but only six of these patients had extension by CK-MB. Similarly, recurrent chest pain following initial MI occurred in 28 (27%), but enzymatic extension was evident in only 11 of these patients. MI extension resulted in significantly greater early in-hospital mortality (16%) compared to those patients without MI extension (2.8%, p < 0.05). Thus MI extension occurs commonly and may explain some early in-hospital deaths post MI. The usual clinical and ECG diagnostic parameters utilized are insensitive indicators of enzymatic MI extension.