The creatine kinase curve area and peak creatine kinase after acute myocardial infarction: usefulness and limitations

The prevalence of acute stress disorder after acute myocardial infarction and its psychosocial risk factors among young and middle-aged patients

Young and middle-aged people are vulnerable to developing acute stress disorder (ASD) following acute myocardial infarction (AMI). This study aims to explore the factors that contribute to ASD in young and middle-aged AMI patients. 190 AMI patients aged 18 to 60 years were enrolled in this study. We assessed the association between ASD and demographic data, adult attachment, and social support. This study examined a total of 190 young and middle-aged people. Among them, 65 participants were diagnosed with ASD, representing a 34.21% positive rate. Multivariate stepwise regression showed that adult attachment, infarct-related artery, social support, in-hospital complications are the main factors affecting ASD. Path analysis showed that social support had mediated the relationship between adult attachment and ASD. The incidence of ASD in young and middle-aged patients with AMI is high. Social support plays an important role in adult attachment and ASD relationships. Adult attachment and social support should be incorporated into post-traumatic cardiac rehabilitation to help patients cope with traumatic occurrences.

Circulating MIF Levels Predict Clinical Outcomes in Patients With ST-Elevation Myocardial Infarction After Percutaneous Coronary Intervention

BACKGROUND

The purpose of the study was to assess the value of admission macrophage migration inhibitory factor (MIF) levels in predicting clinical outcomes in ST-elevation myocardial infarction (STEMI) patients.

METHODS

For this study we recruited 498 STEMI patients after they received percutaneous coronary intervention (PCI), 40 with stable angina pectoris and 137 healthy participants. Plasma MIF levels were measured at admission and after PCI. The primary end points were in-hospital mortality and major adverse cardio-and/or cerebrovascular events (MACCE) during hospitalization and 3.2-year follow-up period.

RESULTS

Admission MIF levels were elevated in 88.4% of STEMI patients over the upper reference limit of healthy controls and it was 3- to 7-fold higher than that in stable angina pectoris and control groups (122 ± 61 vs 39 ± 19 vs 17 ± 8 ng/mL; P < 0.001). Admission MIF levels were significantly higher in patients who died after myocardial infarction vs survivors. For predicting in-hospital mortality using the optimal cutoff value (127.8 ng/mL) of MIF, the area under the receiver operating characteristic curve for MIF was 0.820, similar area under the receiver operating characteristic curve values for predicting short-term outcomes were observed for high-sensitivity troponin T, CK-MB, N-terminal probrain natriuretic peptide, and Global Registry of Acute Coronary Events (GRACE) score. Although peak high-sensitivity troponin T and N-terminal probrain natriuretic peptide also predicted MACCE during the follow-up period, only higher admission MIF levels predicted in-hospital mortality and MACCE during the 3.2-year follow-up. Multivariate regression analysis showed the independent predictive value of a higher admission MIF level (≥ 127.8 ng/mL) on in-hospital mortality (odds ratio, 9.1; 95% confidence interval, 1.7-47.2) and 3.2-year MACCE (hazard ratio, 2.8; 95% confidence interval, 1.5-5.6).

CONCLUSIONS

A higher admission MIF level is an independent predictor for in-hospital mortality and long-term MACCE in STEMI patients who underwent PCI.

The Correlation between Infarct Size and the QRS Axis Change after Thrombolytic Therapy in ST Elevation Acute Myocardial Infarction

OBJECTIVE

Electrocardiography (ECG) may be a practical guiding tool for prognostic infarct sizing in ST elevation acute myocardial infarction (STEAMI). In this study, we sought to find a relation between the infarct size and the change in the QRS axis after thrombolytic therapy.

MATERIALS AND METHODS

Patients with STEAMI who received thrombolytic therapy were selected retrospectively. The mean QRS axes of two ECGs (before and 90 minutes after thrombolytic therapy) were calculated. Creatinine kinase MB (CKMB) was used as the marker of infarct size.

RESULTS

We did not detect any correlation between infarct size and change in the QRS axis with respect to any myocardial infarction MI localizations (p=0.80). However, in the isolated inferior MI group, there was a good correlation between CKMB and change in the QRS axis (r=-0.52 p=0.049).

CONCLUSION

The change in the QRS axis is rarely emphasized, providing a practical and promising tool for evaluating both the efficiency of the thrombolytic therapy and prognostic infarct sizing.

Prognostic importance of creatine kinase and creatine kinase-MB after primary percutaneous coronary intervention for ST-elevation myocardial infarction

BACKGROUND

Although the prognostic significance of creatine kinase (CK) and creatine kinase-MB (CK-MB) after myocardial infarction has been established after thrombolysis or no reperfusion therapy, there is limited evidence of the prognostic importance after primary percutaneous coronary intervention (PCI).

METHODS

In this prospective, observational study, individual data from all patients who survived at least 2 days after primary PCI between 1991 and 2004 in our hospital were recorded. The association between enzymatic infarct size (examined by peak CK and peak CK-MB levels, each divided into tertiles) and both left ventricular ejection fraction (LVEF) and 1-year mortality was evaluated.

RESULTS

In the study group of 4670 patients, mean peak CK was 2327 U/L (SD 2008) and mean peak CK-MB was 244 U/L (SD 208). Both increased CK and CK-MB were associated with a lower LVEF. A total of 252 patients (5.4%) died between 2 days and 1 year after admission. Both peak CK and peak CK-MB were higher in those who died. Particularly, patients in the highest tertile of either peak CK or peak CK-MB had increased mortality, whereas the differences between the lower tertiles were not significant. In 2738 patients, after multivariable analysis including LVEF, the hazard ratio for 1-year mortality in patients in the highest CK tertile was 2.28 (95% CI 1.32-3.91) and for CK-MB, 1.91 (95% CI 1.11-3.26), compared to those in the other tertiles.

CONCLUSIONS

According to this large-scale study, peak CK and peak CK-MB are comparable independent predictors of LV function and 1-year mortality in patients after primary PCI.

Patients with large myocardial infarction gain a greater improvement in exercise capacity after exercise training than those with small to medium infarction

BACKGROUND

It remains unclear whether patients with large-size myocardial infarction (MI) achieve the same benefit from exercise training as do those with small- to medium-size MI.

HYPOTHESIS

This study was designed to determine the magnitude and mechanisms underlying improvement in exercise capacity in patients with large-size MI after cardiac rehabilitation.

METHODS

In all, 296 patients who participated in a cardiac rehabilitation program after acute MI were divided into two groups according to the peak serum creatine phosphokinase (CPK) level: the group with large infarction (Group 1) (> or = 5000 U/l peak CPK, 64 patients) and the group with less extensive infarction (Group 2) (< 5000 U/I, 232 patients). Exercise capacity was assessed before and after a 3-month cardiac rehabilitation program that included exercise training.

RESULTS

Before exercise training, both the peak work rate (p < 0.05) and peak oxygen uptake (VO2) (p < 0.01) were significantly lower in Group 1 than in Group 2. After exercise training, the changes in peak work rate and peak VO2 were significantly greater in Group 1 than in Group 2 (both p < 0.01). The infarction size measured by the peak CPK level correlated significantly with both the baseline exercise capacity and its improvement after exercise training, although these correlations were insignificant in a multivariate analysis. In the multivariate analysis, the improvement in exercise capacity is determined by age and baseline exercise capacity, which is determined by the duration of inactivity, minute ventilation (VE)/VCO2 slope and left ventricular end-diastolic pressure.

CONCLUSIONS

Compared with patients with small- to medium-size myocardial infarction, patients with large infarction gain a greater improvement in exercise capacity after exercise training due to reversal of physical deconditioning and improvement in congestive heart failure.

Enzyme estimates of infarct size correlate with functional and clinical outcomes in the setting of ST-segment elevation myocardial infarction

Background

Cardiac biomarkers are routinely obtained in the setting of suspected myocardial ischemia and infarction. Evidence suggests these markers may correlate with functional and clinical outcomes, but the strength of this correlation is unclear. The relationship between enzyme measures of myocardial necrosis and left ventricular performance and adverse clinical outcomes were explored.

Methods

Creatine kinase (CK) and CK-MB data were analyzed, as were left ventricular ejection fraction (LVEF) by angiogram, and infarct size by single-photon emission computed tomography (SPECT) imaging in patients in 2 trials: Prompt Reperfusion In Myocardial-infarction Evolution (PRIME), and Efegatran and Streptokinase to Canalize Arteries Like Accelerated Tissue plasminogen activator (ESCALAT). Both trials evaluated efegatran combined with thrombolysis for treating acute ST-segment elevation myocardial infarction (STEMI).

Results

Peak CK and CK area-under-the-curve (AUC) correlated significantly with SPECT-determined infarct size 5 to 10 days after enrollment. Peak CK had a statistically significant correlation with LVEF, but CK-AUC and LVEF correlation were less robust. Statistically significant correlations exist between SPECT-determined infarct size and peak CK-MB and CK-MB AUC. However, there was no correlation with LVEF for peak CK-MB and CK-MB AUC. The combined outcome of congestive heart failure and death were significantly associated with CK AUC, CK-MB AUC, peak CK, and peak CK-MB measurements.

Conclusion

Peak CK and CK-MB values and AUC calculations have significant correlation with functional outcomes (LVEF- and SPECT-determined infarct size) and death or CHF outcomes in the setting of STEMI. Cardiac biomarkers provide prognostic information and may serve as valid endpoint measurements for phase II clinical trials.

Ethnic differences in utilization of invasive cardiac procedures and in long-term survival following acute myocardial infarction

BACKGROUND

Ethnic differences in coronary mortality have been documented, and South Asians from the Indian subcontinent are particularly vulnerable.

HYPOTHESIS

This study sought to determine whether there was a difference in the utilization of invasive cardiac procedures and long-term mortality in survivors of myocardial infarction (MI) among Chinese, Malays, and South Asians in Singapore.

METHODS

All MI events in the country were identified and defined by the Singapore Myocardial Infarction Register, which uses modified procedures of the World Health Organization MONICA Project. Information on utilization of coronary angiography, coronary angioplasty, coronary artery bypass graft, and survival was obtained by data linkage with national billing and death registries. Hazard ratios (HR) were calculated using the Cox proportional hazards model with adjustment for baseline characteristics.

RESULTS

From 1991 to 1999, there were 10,294 patients who survived > or = 3 days of MI. Of these, 40.6% underwent coronary angiography and 16.5% a revascularization procedure < or = 28 days. Malays received substantially less angiography (34.0%) and revascularization (11.4%) than Chinese (41.9%, 17.9%) and South Asians (40.0%, 16.3%). The ethnic disparity increased during the 1990s, particularly in the performance of coronary angiography (p = 0.038). While fatality declined during the study period for Chinese and South Asians, the rate remained stable for Malays. After a median follow-up period of 4.1 years, survival was lowest among Malays (adjusted HR, 1.28; 95% confidence interval, 1.15-1.42, compared with Chinese).

CONCLUSION

Ethnic inequalities in invasive cardiac procedures exist in Singapore and were exacerbated in the 1990s. Inequalities in medical care may contribute to the poorer longterm survival among Malays.

Diagnostic value of routine clinical parameters in acute myocardial infarction: a comparison to delayed contrast enhanced magnetic resonance imaging. Delayed enhancement and routine clinical parameters after myocardial infarction

AIMS

Contrast enhanced magnetic resonance imaging (ceMRI) has been shown to reliably identify irreversible myocardial injury. The aim of this study was to compare the findings on ceMRI with routine clinical markers of myocardial injury in patients with acute myocardial infarction (MI).

METHODS AND RESULTS

Twenty-four patients with acute MI were investigated at 1.5 T. The global myocardial function was analysed with a standard cine MR protocol and a stack of short axis slices encompassing the entire left ventricle. Corresponding short axis slices were acquired for delayed ceMRI 15-20 min after the administration of 0.2 mmol gadolinium-DTPA/kg body weight. Mass of hyperenhancement and peak creatine kinase release (peak CK) was determined for each patient. The presenting 12-lead ECG was analysed for ST-elevation on admission and later development of Q-waves. Mass of hyperenhancement correlated moderately well to peak CK (r = 0.65, p < 0.01) and endsystolic volume index (r = 0.55, p < 0.01). Mass of hyperenhancement was inversely correlated to ejection fraction (r = -0.50, p = 0.02). Neither the presence of ST elevation on the admission ECG nor the later development of Q-waves did relate to the transmural extent of hyperenhancement and to the mass of hyperenhancement.

CONCLUSION

Mass of hyperenhancement significantly correlates to global myocardial function and to peak CK. However, there is no relationship between the findings in ceMRI and 12-lead ECG abnormalities on admission suggesting an advantage of ceMRI in defining transmural extent and depicting small areas of necrosis.

Relation of temporal creatine kinase-MB release and outcome after thrombolytic therapy for acute myocardial infarction. TAMI Study Group

Measuring biochemical marker release after acute myocardial infarction helps in estimating infarct size and prognosis. We sought to relate in-hospital outcomes and curve-fitted creatine kinase (CK)-MB variables after thrombolysis. We measured CK-MB mass initially and at 30 and 90 minutes, and at 3, 8, and 20 hours after thrombolysis in 130 patients also undergoing cardiac catheterization at 90 minutes and at 5 to 7 days. Data were fitted, and maximums and curve areas calculated. CK-MB maximums related to infarct location (p = 0.014) and time to therapy (p = 0.002); curve area did not. Neither maximums nor curve area related to Thrombolysis in Myocardial Infarction trial flow grade at 90 minutes. Maximums related to ejection fraction at 90 minutes (p = 0.0004) and at 5 to 7 days (p = 0.0014), as did curve area (p = 0.0076 and 0.030, respectively). Maximums related to infarct zone function at 90 minutes (p = 0.024) and at 5 to 7 days (p = 0.042); curve area related only at 90 minutes (p = 0.027). Both maximums and curve area predicted congestive heart failure (p = 0.008 and p = 0.042, respectively) and a composite of congestive heart failure or death (p = 0.004 and p = 0.047, respectively); however, after adjusting for maximums, curve area no longer predicted congestive heart failure (p = 0.92). Maximums predicted the composite outcome after adjustment for curve area, and showed a trend toward predicting congestive heart failure (p = 0.089). We conclude that CK-MB maximums relate to infarct zone function, left ventricular function, and in-hospital outcomes after thrombolysis for acute myocardial infarction.

Estimation of enzymatic infarct size: direct comparison of the marker enzymes creatine kinase and alpha-hydroxybutyrate dehydrogenase

BACKGROUND

Estimation of infarct size with serum-time activity curves of creatine kinase (CK) (or CKMB) or alpha-hydroxybutyrate dehydrogenase (HBDH) is widely used in clinical trials. However, an independent variable such as left ventricular function has not been directly compared with CK and HBDH infarct size measurements in the same group of patients.

METHODS AND RESULTS

Infarct size was calculated by the CK area under the curve (AUC) and by the cumulative release of HBDH in 90 patients with acute myocardial infarction undergoing early thrombolysis. Infarct size estimates by CK AUC and HBDH release were closely correlated (r = 0.88, p < 0.0001). HBDH release was significantly better (p < 0.001) correlated to angiographically assessed ejection fraction 8 days after infarction (r = 0.74) than to CK AUC (r = 0.60), as was maximum HBDH (r = 0.71) compared with CK maximum (r = 0.59). In contrast to CK, maximum levels of HBDH only slightly overestimate myocardial damage in patients with early reperfusion. Data reanalyzed from the former placebo-controlled Intravenous Streptokinase in Acute Myocardial Infarction (ISAM) study revealed significant differences in favor of streptokinase for CK and CKMB AUC and for HBDH maximum, but no difference for CK and CKMB maximums.

CONCLUSIONS

For comparative clinical trials HBDH appears to be the preferable marker enzyme for estimates of infarct size and measure of reperfusion effectiveness. In clinical practice one routine measure of HBDH serum activity on the second day after infarction may be a useful approximate value of infarct size.

Influence of carbon monoxide (CO) on the early course of acute myocardial infarction

OBJECTIVE

To clarify the influence of an elevated carboxyhemoglobin (COHb) blood level on the course of acute myocardial infarction and to evaluate the administration of supplemental oxygen on the COHb level and the incidence of complications.

DESIGN

Prospective clinical study with randomized, unblinded intervention.

SETTING

Coronary Care Unit of a university hospital.

PATIENTS

78 consecutive patients with acute myocardial infarction. Excluded were patients with severe dyspnea, pulmonary edema or any other medical indication for supplemental oxygen therapy.

INTERVENTIONS

Randomized therapy with 41/min oxygen in 35 patients.

MEASUREMENTS AND RESULTS

COHb was measured at admission and 4 h later. The incidence of serious arrhythmias and the maximal creatine kinase (CK) values were recorded. In patients with initial COHb > or = 5%, there were significantly more arrhythmias and significantly higher maximal CK values than in those with normal COHb admission (89 vs 33%, p < 0.001; and 1897 +/- 1602 u/l vs 960 +/- 1097 u/l, p=0.05). This effect was seen only in patients with Q-wave infarction, not in those with non-Q-wave infarction. Supplemental oxygen had no effect on the incidence of arrhythmias.

CONCLUSIONS

We conclude that myocardial infarction patients with acute Q-wave infarction and increased COHb levels at admission suffer a more severe course of the disease. This outcome was not influenced by oxygen therapy. Whether this finding indicates a casual relationship and whether higher oxygen concentrations would favorably alter the course of acute myocardial infarction remains to be determined.

Use of biochemical tests for myocardial infarction in the county of Västernorrland, a clinical chemistry routine for the diagnosis of myocardial infarction

A study of 116 patients admitted on the suspicion of myocardial infarction is presented. Twenty three of the patients were found to have infarction. For the diagnosis of infarct the most reliable biochemical analyses at present appear to be serum creatine kinase (S-CK, E.C.2.7.3.2.) with its isoenzyme S-CKMB and serum lactate dehydrogenase (S-LD, E.C.1.1.1.27.) with its isoenzyme S-LD-1. If an organization with blood samples at fixed intervals after the appearance of symptoms could be arranged, this would be most recommendable. In many hospitals this is, however, difficult and the blood samples have to be drawn at specified hours. In the four hospitals in the county of Västernorrland, Sweden, this latter procedure has been introduced. Blood is drawn at the arrival of the patient, at 8 am and 8 pm the first day, and at 8 am the next two days of the stay in hospital. In the first two samples S-CK and S-LD are determined, in the third S-CK, in the fourth S-CK and S-LD and in the fifth S-CK. If the values are elevated, S-CKMB and S-LD-1 are determined. S-Myoglobin has been found valuable in the early exclusion of the diagnosis of infarction.

Prognostic significance of a low peak serum creatine kinase level in acute myocardial infarction

To assess the prognostic significance of a low peak creatine kinase (CK) level, 723 consecutive patients admitted with acute myocardial infarction (AMI) within 16 hours after onset of symptoms were studied. Thrombolytic therapy was not attempted during the study. Patients were dichotomized according to their peak CK levels, determined from a cluster analysis of peak CK distribution among the population of patients who died within 3 years after hospital discharge. The 139 patients with low peak CK (less than or equal to 650 IU/liter) (group 1) were compared to the 584 patients with high peak CK (greater than 650 IU/liter) (group 2). Patients in group 1 were older and had a higher incidence of previous AMI, angina pectoris before AMI and non-Q-wave AMI. Despite a lower incidence of in-hospital complications and a nonsignificantly lower hospital mortality rate (4 vs 9%) the group 1 three-year posthospital mortality rate was higher (26 vs 17%; p less than 0.02), especially in the subgroup of patients with a Q-wave infarct (mortality 31% in group 1 vs 16% in group 2; p less than 0.001). Among the 491 patients who had a first Q-wave AMI, 55 had a peak CK less than or equal to 650 IU/liter. Compared to the 436 patients with a higher peak CK, these 55 patients had a higher incidence of early postinfarction angina (31 vs 14%; p less than 0.01), a similar hospital mortality (4 vs 7%) but a higher 3-year posthospital mortality (23 vs 12%; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of diltiazem on myocardial infarct size estimated by enzyme release, serial thallium-201 single-photon emission computed tomography and radionuclide angiography

Diltiazem is a calcium antagonist with demonstrated experimental cardioprotective effects. Its effects on myocardial infarct size were studied in 34 patients admitted within 6 hours after the first symptoms of acute myocardial infarction. These patients were randomized, double-blind to placebo or diltiazem (10-mg intravenous bolus followed by 15 mg/hr intravenous infusion during 72 hours, followed by 4 X 60 mg during 21 days). Myocardial infarct size was assessed by plasma creatine kinase and creatine kinase-MB indexes, perfusion defect scores using single-photon emission computed tomography with thallium-201 and left ventricular ejection fraction measured by radionuclide angiography. Tomographic and angiographic scanning was performed serially before randomization, after 48 hours and 21 days later. Groups were comparable in terms of age, sex, inclusion time and baseline infarct location and size. Results showed no difference in creatine kinase and creatine kinase-MB data between controls and treated patients, a significant decrease in the perfusion defect scores in the diltiazem group (+0.1 +/- 3.0 placebo vs -2.2 +/- 1.9 diltiazem, p less than 0.02) and a better ejection fraction recovery in the diltiazem group (-4.2 +/- 7.4 placebo vs +7.7 +/- 11.2 diltiazem, p less than 0.05). Myocardial infarct size estimates from perfusion defect scores and enzyme data were closely correlated. These preliminary results suggest that diltiazem may reduce ischemic injury in acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

A comprehensive estimation of acute myocardial infarct size using enzymatic, electrocardiographic and mechanical methods

This prospective study compares the estimated size of acute myocardial infarction (AMI) by cumulative serum creatine kinase isoenzyme MB (CK-MB), Selvester QRS score, and 2-dimensional (2-D) echocardiographic dyssynergy of the left ventricle in 63 consecutive patients with their first anterior (n = 31) or inferior AMI (n = 32). The correlations among these parameters were good for patients with anterior AMI (r = 0.74 to 0.78, standard error of the estimate = 29 to 33%) but only fair for those with inferior AMI (r = 0.35 to 0.47, standard error of the estimate = 38 to 73%). Based on previous autopsy studies, estimates of CK-MB and QRS score were then converted to percent of infarcted left ventricle. Linear regression analyses between mean percent AMI size by cumulative CK-MB plus QRS score vs the number of dyssynergic segments by 2-D echocardiography were used to develop a comprehensive formula for estimating AMI size by a combination of all 3 techniques. Thus, a formula is proposed that may optimally estimate AMI size derived from leakage of cytosolic enzymes, changes in the sequence of myocardial depolarization, and irregularities of left ventricular contraction.

The time course of creatine kinase elevation following concentric needle EMG

The electromyographic (EMG) exam and creatine kinase (CK) are commonly used to evaluate patients with neuromuscular diseases. Prior studies have demonstrated minimal elevation of CK following monopolar needle examination, indicating that a false positive elevation does not occur in normal individuals. We studied the magnitude and time course of CK change resulting from concentric (CNEMG) and monopolar (MNEMG) needle EMG examination on healthy volunteers. CK increased in all subjects following CNEMG and MNEMG. Statistically significant mean CK elevations over baseline were observed at 4, 8, 12, and 24 hours for CNEMG and at 12 and 24 hours for MNEMG. Maximum elevation occurred at 12 and 24 hours for both CNEMG (mean, 178% of baseline) and MNEMG (mean, 134% of baseline). CK returned to baseline by 48 to 72 hours. In 25-30% of subjects CK elevation significantly exceeded the normal range. The magnitude of CK elevation is greater and the time course more prolonged than previously reported. CK measurements should be avoided 4 to 48 hours following CNEMG because of the potential for false positive results. Measurements immediately after and at 72 hours are not affected by the CNEMG or MNEMG. The time course for CK change following MNEMG is similar to CNEMG, but the magnitude is less.

Effects of full-dose heparin anticoagulation on the development of left ventricular thrombosis in acute transmural myocardial infarction

The incidence of left ventricular thrombosis after acute transmural myocardial infarction has been evaluated with two-dimensional echocardiography. To assess the preventive action of early anticoagulation with full-dose heparin, 90 patients, admitted within 5.2 +/- 4.6 hours after the onset of symptoms of their first episode of acute myocardial infarction (46 anterior and 44 inferior), were prospectively studied. Patients were randomly assigned either to therapeutic anticoagulation with heparin or to no anticoagulant therapy. Serial two-dimensional echocardiograms were recorded on the day of admission, the next day, days 4 to 7 and days 20 to 50 to detect left ventricular thrombus and to assess global left ventricular performance. On the first echocardiogram (10.3 +/- 8.0 hours after the onset of symptoms) no thrombus was visualized. In 44 patients with inferior myocardial infarction (23 receiving heparin and 21 not receiving heparin) no further left ventricular thrombus developed. In 46 patients with anterior myocardial infarction, 21 additional thrombi developed (45.6%) within 4.3 +/- 3.0 days after the acute event. Thrombus developed in 8 (38%) of 21 patients receiving heparin, compared with 13 (52%) of 25 patients not receiving heparin. This difference in ventricular thrombosis was not statistically significant (chi-square with the Yates correction = 0.76; NS). No difference was found between the subgroups in terms of clinical variables, infarct size, hemodynamic impairment, intensity of the inflammatory process and quantitative two-dimensional echocardiographic and cineangiographic left ventricular function. It is concluded that early anticoagulation with heparin reduced by 27% the incidence of left ventricular thrombus formation in anterior acute transmural myocardial infarction, and this relative risk reduction was not statistically significant when compared with findings in the untreated group.

Relation between electrocardiographic and enzymatic methods of estimating acute myocardial infarct size

The extent of initial acute myocardial infarction (AMI) and subsequent patient prognosis were studied using 2 independent indicators of AMI size. Two inexpensive, readily available techniques, the complete Selvester QRS score from the standard 12-lead electrocardiogram and the peak value of the isoenzyme MB of creatine kinase (CK-MB), were evaluated in 125 patients with initial AMI. The overall correlation between peak CK-MB and QRS score was fair (0.57), with marked difference according to anterior (0.72) or inferior (0.35) location. The prognostic capabilities of each measurement varied. Peak CK-MB provided significant information concerning hospital morbidity or early mortality (within 30 days) for both anterior (chi 2 = 9.83) and inferior (chi 2 = 7.68) AMI locations; however, the QRS score was significant only for anterior AMI (chi 2 = 9.50). For total 24-month mortality, the QRS score alone provided the most information (chi 2 = 10.0, p = 0.0016), which was not improved with the addition of CK-MB (chi 2 = 0.07, p = 0.79). This study shows a good relation between these 2 independent estimates of AMI size for patients with anterior AMI location. Both QRS and CK-MB results are significantly related to early morbidity and mortality; however, only the QRS score is related to total 24-month prognosis.

Myocardial infarction size; effect on the training response

The influence of myocardial infarction size, as indicated by the maximum elevation of creatine kinase (CK) and its iso-enzyme CK-MB, on the exercise training response and resting left ventricular function was studied in 15 male patients who underwent exercise training for 8 weeks. Patients were found to divide themselves into two subgroups; those with maximum CK less than or equal to 200 IU/l (n = 7) and greater than or equal to 400 IU/l (n = 8). All were evaluated by treadmill exercise testing (Bruce Protocol), M-mode echocardiography and radionuclide ventriculography before training, immediately after, 3 and 6 months after training. Both of the subgroups showed statistically significant improvements in exercise duration, heart rates for doing equal workloads, energy expenditure and functional aerobic impairment immediately after training which were maintained 3 and 6 months later, with no inter-group differences. Resting left ventricular function, both by radionuclide and echocardiography, did not demonstrate significant changes throughout the study period, again with no inter-group differences. It is suggested that myocardial infarction size in the absence of heart failure does not appear to have a significant influence on the exercise training response and resting left ventricular function in those patients who recovered sufficiently to participate in exercise training.

Prediction of left ventricular function in acute anterior myocardial infarction by serum creatine kinase activity and precordial ECG mapping

Right cardiac catheterization, serial determination of creatine phosphokinase (CPK) and of CPK-MB activities, and precordial 35-lead ECG mapping were performed in 17 consecutive patients with a first anterior acute myocardial infarction (AMI) within 6 hours of the onset of symptoms. Left ventricular function as determined by the stroke index (SI, ml/m2) to mean pulmonary capillary wedge pressure (PCWP, mmHg) ratio inversely correlated either with the total CPK and CPK-MB released and with peak enzymatic activity, or with the entity of early (6th hour ECG) ST-segment elevation. Conversely, a direct correlation was found between the SI/PCWP ratio and the ratio of R to Q+S waves from late (48th hour) ECG. Residual left ventricular function after a first anterior AMI can therefore be estimated noninvasively in the individual patient by early precordial ECG mapping and by peak enzymatic activity.

Indirect measurement of infarct size. Correlative variability of enzyme, radionuclear angiographic, and body-surface-map variables in 34 patients during the acute phase of first myocardial infarction

To gain a correlative perspective of indirect indications of the size of a myocardial infarct, we measured several body-surface electrocardiographic variables and several enzyme and radionuclear angiographic indicators of an infarct's size in 34 patients during the acute phase of first infarction. We found that bivariate correlations ranged widely, from an r value of 0.05 to an r value of 0.92, but were significantly (p less than 0.001) higher when variables from the same technique were correlated (mean r, 0.60 +/- 0.27), as opposed to correlations of variables from different techniques (mean r, 0.27 +/- 0.18). Trivariate comparisons among techniques produced significantly (p less than 0.001) higher r values, but the highest, an r value of 0.76 (total wall motion abnormality score; peak lactic dehydrogenase level; ST-segment integral maximum), indicated that even in this best case, only about 60 percent of the variation of one variable was dependent on or due to the two other variables. These data demonstrate that multiple indirect quantitative indicators of myocardial injury can vary widely in their correlations within the same population of infarcts, and much remains unknown in their relationships during the acute phase. Caution should be exercised, therefore, in their clinical application to predict an infarct's size in individual patients with acute myocardial infarction.

Isosorbide dinitrate sublingual therapy for inferior myocardial infarction: randomized trial to assess infarct size limitation

To assess the potential of isosorbide dinitrate sublingual therapy for limiting myocardial infarct size, 41 patients with inferior acute myocardial infarction (AMI) were studied. Twenty patients were randomly assigned to the control group and 21 to the treatment group. Patients in the treatment group received 10 mg of isosorbide dinitrate every 2 hours for 72 hours. To estimate infarct size, QRS scoring, peak creatine kinase (CK) serum levels and CK curves were used. There were no significant differences between the 2 groups in maximal or cumulative activity of CK or QRS score (percent of left ventricle infarcted: 16% in the control group, 17% in the treatment group). In both groups the QRS score increased significantly by 13 hours after AMI, and the increase was highly significant by 19 to 23 hours. Thus, sublingual isosorbide dinitrate at the dosage given did not reduce infarct size in patients with inferior AMI.

Improved detection of myocardial infarction by emission computed tomography with thallium-201. Relation to infarct size

Emission computed tomography with thallium-201 was compared with planar imaging in its ability to detect myocardial infarctions of various sizes four weeks after the onset. Tomography was performed after planar imaging at rest in 160 patients with a first myocardial infarction, in whom infarct size was prospectively estimated by the peak value of creatine kinase activity at the time of the acute episode and in 39 patients without infarction. The planar images and the transaxial, short axial, and long axial tomograms were interpreted qualitatively. Tomography was significantly more sensitive than planar imaging in detecting anterior (87% v 96%), inferior (73% v 97%), and non-transmural (47% v 87%) infarcts. The increased sensitivity was confined to detecting small infarcts as assessed by the peak creatine kinase value (44% v 89% when peak creatine kinase activity was less than or equal to 1000 IU/l). The overall sensitivity was 96% for tomography and 78% for planar imaging. The specificity was similar (92%) with the two techniques. Thus emission computed tomography can improve the detection rate of small infarcts that cannot be identified on planar images, by showing the three dimensional distribution of thallium-201, and increases the diagnostic value of thallium-201 scintigraphy.

Evolution of infarct size during the early use of nifedipine in patients with acute myocardial infarction: the Norwegian Nifedipine Multicenter Trial

In a multicenter double-blind study, 227 patients with suspected acute myocardial infarction (AMI) were randomized within 12 hr from onset of symptoms to treatment with nifedipine (112 patients) or placebo (115 patients). AMI was confirmed in 74 patients on nifedipine and in 83 on placebo. Patients with AMI received nifedipine 5.5 +/- 2.9 hr (mean +/- SD) after onset of symptoms. Infarct size was assessed by the release of creatine kinase isoenzyme MB (CK-MB). Infarct size index (CK-MB geq/m2) was 25 +/- 16 (n = 71) in the nifedipine group and 23 +/- 13 (n = 77) in the placebo group (NS). After the first 10 mg of nifedipine systolic blood pressure fell from 147 +/- 30 to 135 +/- 28 mm Hg (p less than .01) and heart rate rose from 75 +/- 18 to 79 +/- 19 beats/min (p less than .01). No change was observed after the first placebo dose. The treatment was continued for 6 weeks. Over this period there were 10 deaths in each group. Early treatment with nifedipine in patients with AMI does not seem to reduce infarct size as determined by enzyme level.

Intravenous streptokinase in evolving acute myocardial infarction

Eighty-one consecutive patients presenting within 3 hours of the onset of acute myocardial infarction (AMI) and without contraindications to thrombolytic or anticoagulant therapy received a 15- to 30-minute intravenous infusion of 750,000 or 1.5 million units of streptokinase (STK) followed by anticoagulation. Treatment was instituted 130 +/- 41 minutes after the onset of symptoms and reperfusion was achieved 36 +/- 26 minutes later. Reperfusion of the "infarct artery" was recognized by indirect clinical criteria in 78 patients (96%). In all 66 patients who underwent coronary angiography 3 to 7 days later, there was complete concordance between indirect and angiographic evidence of reperfusion. In 6 patients there was early reocclusion within 24 hours of treatment; in 4 of these patients, the artery was reopened with an additional dose of STK. Two elderly patients suffered an intracranial hemorrhage and there were 8 other major hemorrhagic complications, of which 7 were related to procedural trauma. Five patients (6.2%) died in the hospital. The results of intravenous STK thrombolytic therapy are compared with those of our previous study using intracoronary STK.

Mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase in sera of patients after myocardial infarction

Mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase (AST) were studied in the sera of 42 patients following acute myocardial infarction and compared to creatine kinase (CK), lactate dehydrogenase (LDH) and alanine aminotransferase (ALT). Mitochondrial AST( ASTm ) was detected in 93% (39/42) of patients. Maximum recorded ASTm activity was 59.5 +/- 8.8 U/l and was found 39.4 +/- 3.5 hours after the onset of symptoms (chest pain) of myocardial infarction. In contrast the maximum recorded cytoplasmic AST ( ASTc ) activity was greater (327 +/- 23 U/l) and it occurred earlier (33.5 +/- 2.2 hours) after onset of infarction compared to ASTm . ASTm correlated significantly (p less than 0.05) with ASTc , LDH and ALT but not with total CK or CK-MB. ASTc correlated significantly (p less than 0.05) with total CK, CK-MB and LDH but not ALT. Maximum recorded ASTm activity was significantly associated with the clinical assessment of left ventricular failure ( Killip classification) but not with ventricular arrhythmias. In a subset of 15 patients evaluated with invasive hemodynamic measurements of cardiac output and pulmonary capillary wedge pressure. ASTm correlated significantly (p less than 0.05) and better than CK-MB with the hemodynamic assessment of left ventricular dysfunction. Thus ASTSm can be readily identified in sera of patients after acute myocardial infarction and may be of value in the evaluation of patients with acute myocardial infarction.

Serum creatine kinase in obese subjects before and during weight reduction

Obese subjects are at increased risk for cardiovascular disease manifestations. The CK value is an important aid in the diagnosis of myocardial infarction, but may also be increased by factors such as muscle mass or breakdown of muscle tissue. We analysed CK values in 120 obese patients in our Obesity Unit and also monitored CK values during a weight reduction programme in 26 of these patients. CK values did not increase with body weight, and during weight loss in a diet programme no systematic CK changes were observed. We conclude that in the evaluation of an elevated CK value in a coronary care unit, such an increased value cannot be accounted for by the overweight per se.

Endogenous cortisol and thyroid hormone levels in patients with acute myocardial infarction

Thyroid hormones and cortisol levels were serially measured over seven mornings and evenings in 23 consecutive patients with acute myocardial infarction (AMI) or acute coronary insufficiency (ACI). The patients were divided into two groups, high level cortisol (HLC) and low level cortisol (LLC) groups, according to mean morning and evening cortisol levels. The transient increase in plasma rT3, decrease in T3 and TSH was significantly greater in the HLC group. A diurnal variation in cortisol levels was observed in the LLC group 48 h and in the HLC group 72 h after admission. Taking the 23 patients together, no significant correlation was observed between infarct size (peak CPK levels) and the altered rT3, T4 or TSH levels. However, a significant correlation was obtained between the maximal change in T3, rT3 or TSH and the mean cortisol levels preceding these alterations, as well as between cortisol levels and infarct size. It is suggested that cortisol rather than infarct size may be the dominant factor involved in the alteration of thyroidal levels in AMI patients.

Sustained regional dysfunction produced by prolonged coronary stenosis: gradual recovery after reperfusion

Prolonged nontransmural ischemia was produced and the early and late effects of reperfusion were studied in 10 conscious dogs instrumented over the long term. Five hours of partial circumflex coronary artery stenosis was produced with a hydraulic occluder, followed by gradual release over 20 min, with measurements of left ventricular pressure, regional myocardial function (systolic wall thickening by sonomicrometry), coronary blood flow velocity (pulsed Doppler), and myocardial blood flow (microspheres). During coronary stenosis the occluder was adjusted frequently to maintain a reduction of systolic wall thickening to 50% to 75% of control (average 62.6% of control). Myocardial blood flow in the ischemic area at 4 hr of partial coronary stenosis was reduced in the inner layers of the myocardium (subendocardium, from 0.81 +/- 0.18 at control to 0.36 +/- 0.08 SD, p less than .01; midwall, from 0.77 +/- 0.20 to 0.46 +/- 0.07 ml/min/g, p less than .01), accompanied by significant ST segment elevation on the subendocardial electrogram (0.83 +/- 0.96 to 4.58 +/- 4.10 mV; p less than .05) and decreased left ventricular dP/dt (3503 +/- 462 to 2991 +/- 339 mm Hg/sec; p less than .01). Within a few minutes after complete release of partial coronary stenosis, ST segments returned to control and myocardial blood flow of the inner layers was increased (subendocardium, 1.37 +/- 0.39, p less than .01; midwall, 0.97 +/- 0.28, p less than .05), but systolic wall thickening and left ventricular dP/dt were significantly depressed and remained reduced at 24, 48, and 72 hr when myocardial blood flow was normal. By seven days, systolic wall thickening and left ventricular dP/dt had returned to control (94.1 +/- 7.0% of control, 3353 +/- 605 mm Hg/sec, respectively; NS). Histologic changes caused by ischemia constituted only 2.7% (average) of the tissue between the crystals in the ischemic wall, but ischemic damage in the posterior papillary muscle, which did not contain crystals, was 31.9%. Thus, regional myocardial dysfunction reduced by nontransmural ischemia for 5 hr persisted for at least 3 days, with only slight damage to the left ventricular free wall but considerable infarction of the posterior papillary muscle. Full recovery of regional and global contractile function of the free wall then occurred within a period of 1 week.

Limitation of enzymatic models for predicting myocardial infarct size

The possibility of predicting myocardial infarct size from early enzyme measurements was studied using a physiological two compartment distribution model. Based on this the time dependent appearance function in plasma was calculated for creatine kinase, aspartate aminotransferase, and lactate dehydrogenase in 29 patients suffering from acute myocardial infarction. On average, the appearance function of the three enzymes started four hours after the onset of symptoms, and the maximum was reached after 12 hours for creatine kinase, 13 hours for aspartate aminotransferase, and 22 hours for lactate dehydrogenase. The cumulated appearance function was used as an acceptable estimate of infarct size. The prediction of infarct size from defined points of the appearance function curve for each of the three enzymes was attempted according to a set schedule during the first 25 hours after the onset of myocardial infarction. The prediction using creatine kinase was superior to the other enzymes. Even so, a reliable prediction could only be established at the very earliest from nine hours and this is too late, as irreversible loss of myocardium occurs rapidly after the onset of symptoms. This, together with the fact that other models have unacceptable variability of the prediction, lead to the conclusion that enzymatic predictive models are of no practical value in clinical intervention studies to reduce infarct size.

Enzymatic estimation of myocardial infarct size when early creatine kinase values are not available

Estimates of myocardial infarct (MI) size based on plasma creatine kinase (CK) are used widely for prognosis and in the assessment of therapy designed to salvage ischemic myocardium. However, if the initial plasma CK activity is elevated, MI size will be underestimated. To determine the impact of loss of early CK values on estimates of MI size and to develop a procedure to compensate for it, estimates of MI size based on complete and incomplete MB and total CK time-activity curves from 120 patients (experimental group) were compared. Estimates of MI size based on data inclusion intervals beginning at 24, 12, 8, and 4 hours before peak CK were 11, 14, 23, and 47% smaller than values based on complete CK curves, but the correlation was good between complete and incomplete estimates of MI size at any given interval, with r values ranging from 0.91 to 0.98. The derived correction factors were then prospectively applied to a new population (n = 25) with complete CK curves to compensate for purposely omitted early CK values. The corrected estimates of MI size were within 7% of those based on the complete CK curves. Similar results were obtained for transmural and nontransmural and anterior or inferior MI. Thus, if peak plasma CK is known, underestimation of MI size can be compensated for despite the unavailability of early CK values. Since greater than 90% of patients present before plasma CK has reached its peak (24 hours), MI size can be obtained in nearly all patients. Thus, being able to correct for unavailable early CK values makes MI size a more widely applicable endpoint for use in clinical trials and patient management.

Infarct size estimation from serial CK MB determinations: peak activity and predictability

In 198 patients with acute myocardial infarction serial measurements of plasma creatine kinase isoenzyme MB (CK MB) were performed at four hour intervals. In every patient, maximal CK MB activity (peak activity) was compared with calculated total release per litre plasma. In 28 patients (group 1) sufficient plasma samples were available for calculation of the apparent first order inactivation constant kd. Mean apparent kd in group 1 patients was 0 . 085 +/- 0 . 018 h-1 (mean +/- SD). Total release in group 1 was calculated with individual apparent kd values (Q) and with the mean kd value (Q*). In the remaining 170 patients (group 2), Q* only was calculated. A linear relation between peak activity P and total release (both Q and Q*) was found, extending over the whole range of CK MB peak activities that are routinely observed (4-216 U/l). It was immaterial whether a one or a two compartment model was used: both yielded a close linear relation. Though the mean ratio between Q* and peak activity depends on the value of kd chosen for calculation of total release (the ratio increasing with increasing kd), linearity between peak activity and Q* was found for any value of kd up to 0 . 4 h-1. In group 1, shapes of calculated CK MB release curves Q*(t), expressed relative to maximal release Q(40), were sufficiently similar so as to be superimposable; the section of the release curves extending from 12 hours before until two hours after peak time could be tentatively described by a linear time course with a slope of 4 . 2 +/- 0 . 5% per hour (mean +/- SD). We conclude that peak activity of CK MB is a reliable estimate of cumulative CK MB release and may be clinically more practicable than calculation of Q(40). Both the similarity and the large apparently linear section of the calculated enzyme release curves possibly permit early prediction of Q(40), with acceptable precision.