J. P. M. C. Gorgels

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

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

The Mass Concentrations of Serum Troponin T and Creatine Kinase-MB are Elevated before Creatine Kinase and Creatine Kinase-MB Activities in Acute Myocardial Infarction

The time-related frequency of elevated results for the mass concentrations of the MB isoenzyme of creatine kinase and of troponin T were compared with that of creatine kinase and creatine kinase-MB activity in patients with acute myocardial infarction. Patients (322; 175 with and 147 without myocardial infarction) consecutively admitted for evaluation of possible acute myocardial infarction were investigated. Reference limits for troponin T (0.1 microgram/l) and creatine kinase-MB mass concentration (5.0 micrograms/l) were exceeded frequently in patients with unstable angina pectoris (troponin T 43%, creatine kinase-MB mass concentration 24%) in contrast to patients with no acute ischaemic heart disease (both < 5%). Within 4 and between 4-8 hours after onset of chest pain, the frequency of elevated results for creatine kinase-MB mass concentration and troponin T in patients with acute myocardial infarction was considerably higher (20-30%) than for creatine kinase and creatine kinase-MB activity. Creatine kinase-MB mass concentration and troponin T both allowed earlier diagnosis of acute myocardial infarction than creatine kinase and creatine kinase-MB activity, but troponin T was not elevated before the creatine kinase-MB mass concentration.

Clinical evaluation of the CARDIAC STATus, a rapid immunochromatographic assay for simultaneous detection of elevated concentrations of CK-MB and myoglobin in whole blood

Abstract We studied the performance of the CARDIAC STATusTM, 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 STATusTM 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 STATusTM 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.

Exclusion of Acute Myocardial Infarction The Value of Measuring Creatine Kinase Slope

For the exclusion (and diagnosis) of acute myocardial infarction, we studied timed sequential (slope) measurements of creatine kinase and creatine kinase-MB catalytic activity concentration, creatine kinase-MB mass concentration, troponin T and myoglobin, using data from 242 patients consecutively admitted for evaluation of suspected acute myocardial infarction in the 12 hours before admission. Three biochemical strategies based on measurements in two consecutive samples obtained within 12 hours after admission were evaluated. The highest sensitivities were encountered for a biochemical strategy based on the sole measurement of creatine kinase mass concentration (98%) or troponin T (96%) and a strategy based on measurements of creatine kinase activity concentrations, which includes creatine kinase slope calculation and measurement of creatine kinase mass concentration (95%). Both strategies were applied in subgroups of patients based on the electrocardiographic findings. In patients with a normal electrocardiogram, the sensitivity of the strategy using sole measurements of creatine kinase mass concentration was 100%, but this was true for the strategy based on creatine kinase slope measurements, which is the cheaper and therefore preferred procedure for excluding myocardial infarction. This approach, however, does not account for detecting minor myocardial cell damage in patients not yet fulfilling the criteria of the World Health Organization for diagnosing acute myocardial infarction.

Evaluation of the Hitachi 911 for Routine Urine Analysis and for Measurement of Various Special Serum Analytes

The Boehringer Mannheim Hitachi 911 is a selective analyzer for 35 different methods including 3 ion-selective electrode (ISE) methods. We have evaluated this analyzer primarily to obtain objective information on its applicability for routine urine analyses in our laboratory. We also implemented appropriate assays for various special serum- and whole blood-tests, some for the first time on the Hitachi 911 and some with modified settings. Analytical evaluation involved NCCLS EP5-T2 (imprecision), NCCLS EP6-P (linearity), Krouwer 27 (multifactor) and Passing & Bablok (method comparison) evaluation protocols. With the exception of evidence of systematic erroneous sample predilution, overall results were favourable. Practicability of the Hitachi 911 was judged by simulating daily routine. During a period of two weeks, daily urine samples were rerun on the Hitachi 911, leading to a gain of about 50% in total processing time. It was concluded that the Hitachi 911 meets the requirements in terms of analytical performance, reliability, versatility and speed for an analyzer to be used in a routine (urine) setting, while having a distinct role in special (serum/whole blood) measurements.