Evaluation of evolution of myocardial infarction by serial determinations of serum creatine kinase activity

Is the neonatal creatine phosphokinase level a reliable marker for fetal hypoxia?

AIM

The creatine phosphokinase (CPK) level is believed to increase in neonatal peripheral blood after tissue damage, including damage from perinatal hypoxia. However, it is not clear whether it is truly a reliable marker for fetal hypoxia. We investigated the chronological changes in neonatal CPK and the reliability of CPK as a marker for fetal hypoxia.

METHODS

Sixty term neonates admitted to the neonatal intensive care unit at Tokyo Women's Medical University Medical Center East from April 2009 to April 2010 were enrolled in this study. We evaluated whether asphyxia and fetal heart rate (FHR) abnormality could predict the neonatal CPK level by using receiver-operator curve analysis. We also compared umbilical cord blood pH levels with neonatal CPK levels. In addition, we investigated factors that influence neonatal CPK in non-asphyxia cases.

RESULTS

The median value of CPK peaked on day 1. There were no significant differences in CPK levels regardless of the presence of asphyxia or FHR abnormality. Non-asphyxiated neonates with older gestational ages and amniotic fluid abnormalities had significantly higher levels of CPK.

CONCLUSION

Our results indicate that the neonatal CPK level is not an appropriate marker for retrospectively predicting either asphyxia or FHR abnormality. There are influencing factors other than asphyxia that increase neonatal CPK. Therefore, one should be careful when making a diagnosis of perinatal hypoxia based solely on increased levels of neonatal CPK after birth.

The size of infarction as judged enzymatically in 1974 patients with acute myocardial infarction. Relation with symptomatology, infarct localization and type of infarction

A common data base of six coronary care units containing personal and clinical data of 17462 patients was used to investigate the relation between clinical symptoms of patients with acute myocardial infarction and size of infarction. In 1974 of the 5110 patients, in whom a final diagnosis of infarction was made, size of infarction was determined according to serially measured levels of serum alpha-hydroxybutyrate dehydrogenase. The episode of infarction was the first in 1396 patients, was recurrent in 497, and undetermined in 81 patients. We calculated the size factor (defined as the mean size of infarction of patients with a particular symptom divided by the mean size of infarction of patients without that symptom) to evaluate the role of the size of infarction to manifestation of certain clinical symptoms. Bradycardia, shock and right-sided failure when noted on admission to the coronary care unit, had factors for size of infarction significantly greater than 1.0 (1.15, 1.79 and 1.30, respectively) in patients suffering an initial infarction, but not significantly different from 1.0 in patients with recurrent infarction. The occurrence of primary and secondary ventricular tachycardia and/or fibrillation, left heart failure (Killip class II-IV), symptomatic supraventricular tachycardia, high-degree atrioventricular blocks, ruptures and death in the coronary care unit was associated with factors significantly greater than 1.0 in those patients having both initial and recurrent infarctions. The size of infarction as judged enzymatically was significantly larger in patients with anterior than inferior and lateral infarction. The size of infarctions without Q waves was judged to be generally 35% smaller than infarctions producing Q waves. It is concluded that the size of infarction determines the occurrence of several symptoms and complications diagnosed at admission or during stay in the coronary care unit.

Natural course of electrocardiographic components and stages in the first twelve hours of acute myocardial infarction

Time course evolution of R, Q, T and ST components of the electrocardiogram during the first 12 hours of an acute myocardial infarction was studied. A comparison between anterior-extensive and anteroseptal wall infarctions (anterior group), and inferior-extensive and inferior wall infarction (inferior group) showed appearance of significant Q waves within two hours in both groups. R wave loss was nearly a mirror image of Q wave development in both groups. T waves became negative and ST more isoelectric earlier in the inferior than in the anterior group. When combined variations of the four electrocardiographic components were analyzed, four stages of acute infarction were delineated. Stage I--tall R, no Q, ST elevation and positive T; Stage II--significant Q wave appearance; Stage III--negativity of T waves; and Stage IV--ST isoelectric. The inferior group reached stages III-IV within 12 hours; the anterior group remained mostly in stage II. An early appearance of Q waves correlated well with rapid progression to stages III-IV within 12 hours in both infarction groups.

Chest pain in acute myocardial infarction: a descriptive study according to subjective assessment and morphine requirement

In 722 patients with suspected acute myocardial infarction (MI) we have tried to describe the course of chest pain according to their own assessment and morphine requirement. Patients were asked to score pain from 0-10 every second hour after arrival in the coronary care unit (CCU) and also to score their maximal pain at home. A very high intensity of chest pain was observed at home (mean score 7.1). At arrival in the CCU the mean pain score already had declined to 1.8, although 51% still had chest pain. Pain score declined successively during the first 12 hours in the CCU. At 24 hours after arrival, 20% still had some chest discomfort. In one quarter of the series a score of more than 0 was observed later than 24 hours after arrival in CCU. Patients developing definite MI had, as expected, a longer duration of pain and a much higher requirement of morphine compared with those with no MI. The difference between MI and no MI patients regarding subjective assessment of the initial intensity of pain at home and in hospital was, however, surprisingly low.

Augmented thromboxane A2 generation and efficacy of its blockade in acute myocardial infarction

Serial changes in thromboxane B2, a stable catabolite of thromboxane A2, were measured by radioimmunoassay in peripheral plasma of 55 patients with acute myocardial infarction. Twenty two of 31 patients who were admitted within 6 hr after the onset of acute myocardial infarction, exhibited high thromboxane B2 levels (greater than 300 pg/ml plasma) during the first 24 hr, whereas thromboxane B2 levels of 9 patients never exceeded 300 pg/ml during that period. The former cases were associated with a higher frequency of transmural myocardial infarction, accompanying higher cumulative creatine kinase release (1173 +/- 134 mIU/ml, mean +/- SEM), as compared with the latter cases (393 +/- 104 mIU/ml, P less than 0.001). To evaluate the efficacy of selective thromboxane A2 blockade on diminution of propagating acute myocardial infarction, another group of patients (24 cases) showing transmural myocardial infarction were subjected to therapeutic examination employing OKY-1581, a potent thromboxane A2 synthetase inhibitor. Eleven randomly selected patients were treated with an infusion of OKY-1581 (initiated within 6 hr after onset, 2-3 micrograms/kg per min) for 48 hr, while 13 patient served as controls. The treated patients exhibited a precipitous decrease in thromboxane B2 levels, as compared with the controls, returning to the normal range within 12 hr. The creatine kinase release in the treated patients was markedly reduced (978 +/- 97 mIU/ml) as compared with that in the control patients (1295 +/- 95 mIU/ml, P less than 0.05). These results indicate that a marked increase in thromboxane B2 levels is seen during the early phase of transmural myocardial infarction, and that OKY-1581-induced reduction of thromboxane B2 levels is effective in diminishing creatine kinase release. We suggest that an excessive generation of thromboxane A2 is associated with the evolution of transmural myocardial infarction.

Time lapse from estimated onset of acute myocardial infarction to peak serum enzyme activity

In 581 patients with acute myocardial infarction (MI), the time lapse from estimated onset of infarction to estimated peak serum (S) enzyme activity was evaluated. Heat-stable lactate dehydrogenase (LD; E.C. 1.1.1.27) was analyzed every 12 h for 48-108 h after arrival in hospital (n = 581) and creatine kinase (CK; E.C. 2.7.3.2.; n = 224), and creatine kinase subunit B (CK-B; n = 211) were analyzed every 6 h for 48 h. Peak S-LD was observed between 14 and 110 h after estimated onset of MI (mean 46.6 +/- 0.6 h), peak S-CK was observed between 8 and 58 h (mean 25.0 +/- 0.6 h), and peak S-CK-B was also observed between 8 and 58 h (mean 22.8 +/- 0.7 h) after onset. In 86% of patients, peak LD was reached within 60 h after onset of MI, in 78%, peak CK was reached within 30 h, and in 82%, peak CK-B was observed within 30 h after onset of MI. A weak correlation was found between duration of pain and time lapse to S peak enzyme activity (r = 0.25 -0.27; p less than 0.001), while there was no correlation between S peak activity and time lapse from onset of MI to S peak activity. It is concluded, that although in the majority of patients with MI, peak serum-enzyme activity is reached within a predictable amount of time after estimated onset of MI there is wide variation, difficult to establish from the clinical course, among individual patients.

The time course in acute myocardial infarction evaluated with precordial mapping and standard ECG

Fifty-six patients with acute transmural anterior wall myocardial infarction (MI) were investigated with a 24-electrode grid and 34 patients with an acute transmural inferior wall MI were investigated with standard ECG leads II, III, and aVF in order to study the length of time after the onset of pain during which the development of Q waves and reduction of R waves progress. These ECG changes continued for 18-26 h after onset of pain but the majority appeared during the first 12 h.

Limitation of myocardial infarct size in patients less than 66 years treated with alprenolol

Two hundred and eighty-two patients less than 66 years of age admitted with suspected or definite myocardial infarction were allocated in a random fashion to treatment with alprenolol or placebo. Treatment was started immediately upon admission with 5-10 mg alprenolol or placebo intravenously, followed by 200 mg alprenolol or placebo orally twice a day for one year. In 178 patients a definite myocardial infarction was diagnosed. Myocardial infarct size could be estimated from serial determinations of serum total creatine kinase in 42 patients treated with alprenolol and 43 patients receiving placebos. Median infarct size was 20.6 CK g Eq/m2 body surface in the alprenolol group, the corresponding figure in the placebo group being 34.4 CK g Eq/m2 body surface. Median rate of release of creatine kinase from the ischaemic myocardium was 27.7 U/1 per hour and 48.0 U/1 per hour after alprenolol and placebo, respectively. Alprenolol limited infarct size significantly provided the treatment was started within 12 hours of the onset of symptoms.

Intravenous propranolol therapy for acute myocardial infarction in man: hemodynamic and serial creatine kinase assessment

Propranolol was administered intravenously to 12 patients with presumed acute myocardial infarction in the attempt to limit infarct size. Patients' conditions were uncomplicated (heart rate greater than or equal to 60/min, systolic blood pressure greater than or equal to 100 mm Hg, mean pulmonary capillary wedge pressure mean [PCWP] less than or equal to 20 mm mercury). The aim was to produce beta-blockade that was early, complete, and continuous. Target loading dose was achieved in seven patients and full maintenance was achieved in six patients. The remaining patients received smaller loading or maintenance doses or both because of varying degrees of bradycardia, hypotension, or elevated mean PCWP. Myocardial CK release in the propranolol group was 2651 mIU/ml +/- 843 (mean +/- SE, n = 12) vs 2987 mIU/ml +/- 422 in 21 comparison patients, a difference not statistically significant. The time to CK plateau (completion of infarction) was related to total CK release in both propranolol and comparison patients.

Variability of electrocardiographic and enzyme evolution of myocardial infarction in man

We have studied the time course of development of ST segment elevation, R wave loss, and Q wave development in 41 patients using 35 lead praecordial mapping or 12 lead electrocardiograms in those with anterior and inferior infarcts, respectively. The first recording was at a mean time of six hours after the onset of pain; subsequent records were taken every eight hours for 24 hours, every 12 hours for the second day, and every day thereafter. Serial CK MB estimates were obtained at every four hours for the first 72 hours. There was good agreement in the time course between the electrocardiogram and enzyme evolution. Forty-one per cent of patients showed rapid infarction with R wave and Q wave evolution complete within 12 hours of pain and accompanied by a short duration of enzyme release (mean = 19.30 hours). Fifty-nine per cent of patients showed more prolonged infarction with longer R wave and Q wave evolution and enzyme release (mean = 30 hours). Four patients also showed delayed reinfarction. ST segment elevation was maximal at six hours in the whole group and was significantly lower thereafter. Patients with rapid infarction showed high initial ST segment elevation which decreased promptly compared with those with prolonged infarction, who showed moderate but more persistent ST segment elevation. This study shows the variability in the time course of the electrocardiogram and enzyme evolution after myocardial infarction in man.

Site and severity of coronary narrowing and infarct size in man

The relation between the site and severity of coronary artery lesion and infarct size was investigated in 59 patients with acute myocardial infarction. All patients had no prior myocardial infarction and had at least one significant coronary narrowing (greater than or equal to 75%) in one of the major coronary arteries or in the first diagonal branch. Left ventriculography and selective coronary arteriography were performed on average 2.2 months after the onset of infarction to identify the site and severity of coronary narrowing and to assess the extent of the non-contracting segment (akinetic, dyskinetic, or aneurysmal). Thirty-four of 59 patients were studied enzymatically and total CK released was taken as an indication of infarct size. Non-contracting segment and total CK released in group L-I (narrowing proximal to the first diagonal branch) were significantly larger than those in group L-II (a coronary lesion distal to the branch). The data also indicate that the perfusion area of the first diagonal branch is as large as that of the left anterior descending artery below the first diagonal branch. In contrast to left anterior descending artery disease, the involvement of the right ventricular branch did not significantly influence the infarct size. However, infarct size was significantly larger in eight patients with the left ventricular branch of the right coronary artery supplying the predominantly large area of posterior wall of the left ventricle than in nine patients with small left ventricular branches. It was also shown that the severity of coronary narrowing does not correlate with the infarct size in either left anterior descending or right coronary artery disease.

Evaluation of praecordial ST segment mapping as an index of infarct size in patients with acute myocardial infarction

We evaluated the usefulness and limitations of praecordial ST segment mapping as a clinical means of assessing the size of acute myocardial infarction in 14 patients with anterior myocardial infarction and 13 patients with inferior myocardial infarction. sigma ST, the sum of ST segment elevations, and nST, the number of leads showing ST segment elevation, were obtained from serial electrocardiograms recorded through 39 praecordial leads. The infarct size and period of the evolution of myocardial infarction were estimated respectively from the total creatine kinase (CK) released and the serial changes of the CK releasing rate. sigma ST and nST obtained at the time when the CK release had ceased correlated closely with the total CK released. Peak sigma ST and nST, and values 48 hours after the onset of myocardial infarction, also correlated well with the total CK released; but those on admission or 12 hours after the onset correlated poorly. These results suggest that sigma ST and nST at the end of evolution of myocardial infarction or 48 hours after the onset may be two useful indices for the assessment of infarct size in patients with either anterior or inferior myocardial infarction.

PRediction of infarct size by enzymatic techniques: modification of a method and clinical application

In an attempt to develop improved methods of prediction of infarct size by enzymatic methods, Shell's original algorithm has been critically evaluated in an unselected series of patients. Poor performance of the model is partly the result of a systematic source of error associated with its mathematical formulation. A new model devoid of such limitations has therefore been developed. Residual deviations between predicted and observed CK release seem to be related to frequent and unpredictable extensions of infarction which could be verified by independent clinical, electrocardiographic, and enzymatic criteria. The modified model may possibly be applied to the evaluation of agents aimed at limiting the spread of irreversible injury.

Immunological determination of serum m-AST activity in patients with acute myocardial infarction

Serum m-AST (mitochondrial isoenzyme of AST) activity in patients with acute myocardial infarction was determined quantitatively by a new immunological technique which is sensitive and easily available. All 31 patients with acute myocardial infarction showed abnormally high levels of serum m-AST (more than 5 KU/ml); the mean serum m-AST activity attained its peak (42.0 +/- 4.9 KU/ml) on the first day after the onset of infarction 5 hours later than that of serum t-AST (total AST) activity in 15 patients whose peak m- and t-AST activities were identified clearly. The individual peak m-AST activity correlated with the total CK released (r = 0.83, n = 15), indicating that the release of m-AST also reflects the infarct size. The ratio of serum m-AST/t-AST increased following myocardial infarction and showed the maximal value (average 25.7%) on the third to seventh day after onset. This ratio in the patients with acute myocardial ifarction was also greater than that in patients with liver disease or with heart failure from causes other than acute myocardial infarction. In the patients who had the additional complication of heart failure and/or cardiogenic shock the ratio was also greater than that is the patients without these hazards. These results indicate that the ratio of serum m-AST/t-AST reflects the severity of the myocardial cellular damage in acute myocardial infarction.

Precordial ST-segment mapping 5. Analysis of maps and standard electrocardiograms in patients with inferior myocardial infarction

Measured and derived electrocardiographic parameters pertaining to ST-segment elevations, R and Q wave amplitudes from standard electrocardiograms, and 49-lead precordial maps from ten patients with acute inferior transmural myocardial infarction were analyzed. Sums of ST-segment elevations correlated well with corresponding values derived from various combinations of standard leads expressing inferior ischemic injury. Derived ECG R and Q wave data from maps did not correlate with corresponding parameters from the standard ECGs. Stability of parameters derived from ST-segment elevations over the course of the study and lack of correlation with data expressing changes in the R and Q waves were noted. An analytical pattern such as the one utilized in this study can be used for assessment of therapeutic interventions in the Coronary Care Unit.

Proposed metabolic vicious circle in patients with large myocardial infarcts and high plasma-free-fatty-acid concentrations

The relation between peak plasma-free-fatty-acid (F.F.A) concentration and size of infarct--as estimated by the plasma-creatine-kinase technique--was investigated in twenty patients with acute myocardial infarction. In eight patients with large infarcts (more than 65 g equivalents) mean infarct size was 136+/-21 g equivalents and mean peak F.F.A. value in the first 12 h was 1-99+/-0-14 mmol/l (mean +/-S.E.M.). In twelve patients with small infarcts, mean infarct size was 36+/-5 g equivalents and mean peak F.F.A. was 1-22+/-0-13 mmol/l (P less than 0-001). Experimental evidence suggests that high circulating F.F.A. concentrations could further extend ischaemic damage. The association between high plasma-F.F.A. and infarct size may give rise to a vicious circle which increases the severity of the ischaemic process in patients with high plasma-F.F.A.