Value of mass dosage of the MB isoenzyme of creatinine phosphokinase in the diagnosis of recent myocardial infarction

In 391 patients admitted 3.7 hours (h) (median) after experiencing infarct-like pain, kinetic monitoring of CK-MB "mass" (threshold: 7 micrograms/l), myoglobin (threshold: 90 micrograms/l) and total CK (threshold: 290 micrograms/l) was carried out at the time of admission and after 1.5, 3, 6, 9, 12, 24 and 48 h. When myocardial infarction (MI) was treated conventionally (102 patients). CK-MB peaked 11 h (median) after the onset of pain, later than myoglobin (9 h), but before total CK (12 h). The peak of the markers was higher in Q+ than in Q-MI (p < 0.05). When MI was treated by thrombolytic medications (44 patients), the increases in CK-MB, myoglobin and total CK were larger, and occurred sooner (peaks 9, 6 and 6 h, after the onset of pain respectively), but did not last as long. In 245 patients who had not had MI (including 123 with spontaneous angina), the levels of the three markers remained stable and well below the decision thresholds. The sensitivities of CK-MB, myoglobin and total CK were respectively 47.1, 51.8 and 34.8% at the time of admission, 67.3, 82.7 and 57.1% after 3 h and 83.1, 76.9 and 88.9% after 6 h. The combined determination of CK-MB and of myoglobin had a higher sensitivity (67.7% at the time of admission, 84.9% after 1.5% and 88.2% after 3 h: but most of this gain was due to myoglobin. The specificity of the three markers and their diagnostic accuracy are comparable. In the course of recent MI, the kinetics of CK-MB mass are thus slower than those of myoglobin, but a little faster than those of total CK. The choice of the most effective biochemical marker depends upon the interval between onset of chest pain and hospitalization of the patient. Repetition of the determinations improves the diagnostic situation.     

Comparison of serum myoglobin and creatine kinase MB isoenzyme in early diagnosis of acute myocardial infarction

We compared the clinical usefulness of serum myoglobin and creatine kinase MB (CK MB) isoenzyme determinations in the early diagnosis of acute myocardial infarction in 109 consecutive patients admitted to a coronary care unit. Of these, 37 patients were diagnosed as having definite infarction, three possible infarction, and 69 no infarction, using World Heath Organisation criteria. Blood samples were taken on admission and two to four hours later, Both CK MB and myoglobin were raised in the initial serum samples in 24 of the 37 patients with definite infarction. In an additional seven patients both CK MB and myoglobin were negative in the first specimen though both were detected in the second sample. In five patients CK MB preceded the appearance of myoglobin while in the remaining patient myoglobin appeared before CK MB. We conclude that the detection of serum myoglobin does not offer any clinical advantage over CK MG as an early indicator of myocardial infarction.     

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.     

Rapid MB CK subform assay and the early diagnosis of myocardial infarction

Seventy percent of patients admitted to coronary care units are ruled out for acute myocardial infarction. It has been estimated that 2-3 billion dollars each year could be saved if these non-AMI patients could be identified early, allowing the patient to be admitted to a less intensive setting. This study evaluated a new bedside device, the Cardiac STATus CK-MB/Myoglobin device for its utility in rapidly ruling out AMI. The device demonstrated a 99% negative predictive value within three hours of patient presentation.     

The specificity of the CPK MB enzyme kinetic test for the diagnosis of acute myocardial infarction (author's transl)

The clinical usefullness of the CPK MB test (spectophotometric method) was evaluated on 139 patients admitted to a Cardiovascular Diseases Department with a diagnosis of suspected myocardial infarction. Serial determinations of serum MB isoenzyme creatine kinase, total creatine kinase, lacate dehydrogenase and hydrossibutirrate dehydrogenase were made at 1st, 2th, 3th, 4th, 5th, 6th, 7th day. Incidence of CPK MB false positive and false negative data were also determined and correlated with the electrocardiogram pattern and serum levels of other standard enzymes. Results indicate that the CPK MB kinetic test is highly specific (94%) and promptly available in the early diagnosis of acute myocardial infarction.     

Levels of CK MB mass in patients with acute myocardial infarct treatedwith fibrinolysis. Comparison with levels of CK, CKMB, CKMB mass and troponin T in the diagnosis of coronary ischemia]

In a group of 26 patients with AIM the CKMB value was raised above the discrimination level already on admission--on average 2.7 +/- 1.4 hours after development of ischaemic pain--in 46% patients. The maximal value of CKMB mass was achieved in the group with probable reperfusion 12.1 +/- 3.8 hours after the development of ischaemic pain and this value was elevated in relation to the discrimination value 41.5 +/- 17x and in relation to the so-called basal value 145 +/- 117x. In the group without probable reperfusion the maximal value was achieved significantly later, after 19.8 +/- hours and was elevated in relation to the discrimination value 31 +/- 17x and in relation to the final value 84 +/- 42 times. The value of CKMB mass increased above the discrimination limit from the onset of ischaemic pain after 4.0 +/- 1.5 and after 5.7 +/- 3 hours in the group with probable and without probable reperfusion and declined below the discrimination limit after 00 +/- 60 and 119 +/- 98.0 hours in the same groups. On comparison of CK, CKBM, CKBM mass and troponin T on admission the CKMB mass value was elevated in 46% patients, the value of CK in 23%, of CKMB in 27% and the troponin T value in 96% patients. With regard to the assembled experience that haemolytic serum raises false troponin T values, the percentage of elevated troponin T values on admission declines from the original 96% to 81% when all haemolytic samples are eliminated. The time of reaching maximal values of CKMB mass in patients with AIM and probable reperfusion was significantly shorter than in CK values and is similar as in CKMB values. The time taken to raise the CKBMB mass value above the discrimination value is significantly shorter than the time taken by CK levels, but significantly longer than the time before troponin T levels are raised. The time of total elevation of CKMB mass levels above the discrimination limit does not differ from the time taken to raise CK values, it is however shorter than the increase of troponin T values, although the exact time of persistence of raised levels of troponin T was not assessed in our work. The time of increase above and decrease below the discrimination limit was not assessed in CKMB values. Based on mutual comparison of the impact of indicators for assessment of the diagnosis of ischaemic heart attacks the authors consider it best regardless of financial costs--to assess troponin T, possibly along with levels of CKMB mass.     

Vectorcardiographic diagnosis of diaphragmatic myocardial infarction

Vectorcardiograms of 31 patients with arteriographic evidence of complete occlusion of the right coronary artery were analyzed in order to evaluate and attempt to improve the vectorcardiographic criteria for the diagnosis of an old diaphragmatic myocardial infarction. The electrocardiogram showed no evidence of a diaphragmatic infarction in 48 percent of these patients. This was advantageous, since the intent of the study was to develop vectorcardiographic criteria that exceeded the capability of the electrocardiogram. The criteria that appeared optimal were: (1) an instantaneous 0.02 second QRS vector equal or superior to 315 degrees (-45 degrees) in the sagittal plane, or (2) ratio of voltages of 0 to left x-intercept to maximal QRS vector greater than 0.22 in the frontal plane. These criteria identified a diaphragmatic infarction in 77 percent of patients (24 of 31) with complete occlusion of the right coronary artery. There were no false positive findings in 40 normal subjects. A group of criteria previously defined by others, based upon rotation, contour of initial forces, duration of superior forces relative to the contour, magnitude of 0 to left x-intercept, and maximal QRS vecotr, was equally sensitive. Other previously defined criteria were less sensitive. The criteria developed in this study, when tested in 22 patients with prominent Q waves indicative of an old diaphragmatic infarction, properly diagnosed the infarction in all 22 patients. All previous criteria also successfully detected infarction in these patients. However, the new criteria identified a greater number of patients without electrocardiographic evidence of diaphragmatic infarction than were identified with previously defined vectorcardiographic criteria unless the latter were complex.     

Natural history and evaluation of ST segment changes and MB CK release in acute myocardial infarction

The experimental evidence relating ST segment elevation in the electrocardiogram to the progress and extent of ischaemic myocardial damage is discussed. There are difficulties in applying this to patients: the reproducibility of praecordial mapping was tested using a multiple analysis of variance. This showed that factors such as time after the onset of myocardial infarction and posture can affect measurements of sigmaST elevation significantly. There was a pattern of changes in segmaST elevation and of changes in plasma MB CK activity in a group of patients with uncomplicated anterior infarction. A significant byt weak correlation was found between sigmaST elevation in the first hour and the total MB CK activity released into the plasma, but not at any other time. The use of sigmaST elevation as a measure of the extent of ischaemic damage is unreliable. In 5 patients with a variety of complications of acute anterior infarction, changes in sigmaST elevation werr significantly different from the uncomplicated group, and MB CK release profiles suggested further necrosis. The pattern and time course of ST segment changes may be of use in assessing the progress of ischaemic myocardial damage.     

Using serum markers in the early diagnosis of myocardial infarction

Because thrombolytic therapy can save lives and salvage left ventricular function after acute myocardial infarction, rapid and precise diagnosis is essential. Electrocardiographic changes, and the patient's history and physical examination may not confirm the diagnosis of myocardial infarction. Serum markers have specific advantages and disadvantages in confirming this diagnosis. An understanding of the advantages and disadvantages of using serum markers can enhance the clinician's ability to efficiently and accurately triage patients to appropriate care.