Effects of coronary artery reperfusion on relation between creatine kinase-MB release and infarct size estimated by myocardial emission tomography with thallium-201 in man

Shorter door-to-balloon time, better long-term clinical outcomes in ST-segment elevation myocardial infarction patients: J-MINUET substudy

BACKGROUND

The impact of shorter door-to-balloon (DTB time on long-term outcomes in ST-segment elevation myocardial infarction (STEMI treated with primary percutaneous coronary intervention (PPCI has not been fully elucidated.

METHODS

We investigated 3283 consecutive patients with acute myocardial infarction selected from a prospective, nationwide, multicenter registry (J-MINUET database comprising 28 institutions in Japan between July 2012 and March 2014. Among the study population, we analyzed 1639 STEMI patients who had PPCI within 12 h of onset. Patients were stratified into four groups (DTB time < 45 min, 45-60 min, 61-90 min, >90 min. The primary endpoint was a composite of all-cause death, non-fatal MI, non-fatal stroke, cardiac failure, and urgent revascularization for unstable angina up to 3 years. We performed landmark analysis for incidence of the primary endpoint from 31 days to 3 years among the four groups.

RESULTS

The primary endpoint rate from 31 days to 3 years increased significantly and time-dependently with DTB time (10.2 % vs. 15.3 % vs. 16.2 % vs. 19.3 %, respectively; log-rank p = 0.0129. Higher logarithm-transformed DTB time was associated with greater risk of a primary endpoint from 31 days to 3 years, and the increased number of adverse long-term clinical outcomes persisted even after adjusting for other independent variables.

CONCLUSION

Shorter DTB time was associated with better long-term clinical outcomes in STEMI patients treated with PPCI in contemporary clinical practice. Further efforts to shorten DTB time are recommended to improve long-term clinical outcomes in STEMI patients.

TRIAL REGISTRATION

UMIN Unique trial Number: UMIN000010037.

Peak CK-MB has a strong association with chronic scar size and wall motion abnormalities after revascularized non-transmural myocardial infarction - a prospective CMR study

BACKGROUND

Large myocardial infarction (MI) is associated with adverse left ventricular (LV) remodeling (LVR). We studied the nature of LVR, with specific attention to non-transmural MIs, and the association of peak CK-MB with recovery and chronic phase scar size and LVR.

METHODS

Altogether 41 patients underwent prospectively repeated cardiovascular magnetic resonance at a median of 22 (interquartile range 9-29) days and 10 (8-16) months after the first revascularized MI. Transmural MI was defined as ≥75% enhancement in at least one myocardial segment.

RESULTS

Peak CK-MB was 86 (40-216) μg/L in median, while recovery and chronic phase scar size were 13 (3-23) % and 8 (2-19) %. Altogether 33 patients (81%) had a non-transmural MI. Peak CK-MB had a strong correlation with recovery and chronic scar size (r ≥ 0.80 for all, r ≥ 0.74 for non-transmural MIs; p < 0.001). Peak CK-MB, recovery scar size, and chronic scar size, were all strongly correlated with chronic wall motion abnormality index (WMAi) (r ≥ 0.75 for all, r ≥ 0.73 for non-transmural MIs; p < 0.001). There was proportional scar size and LV mass resorption of 26% (0-50%) and 6% (- 2-14%) in median. Young age (< 60 years, median) was associated with greater LV mass resorption (median 9%vs.1%, p = 0.007).

CONCLUSIONS

Peak CK-MB has a strong association with chronic scar size and wall motion abnormalities after revascularized non-transmural MI. Considerable infarct resorption happens after the first-month recovery phase. LV mass resorption is related to age, being more common in younger patients.

Assessment of myocardial infarct size with body surface potential mapping: validation against contrast-enhanced cardiac magnetic resonance imaging

BACKGROUND

Assessment of myocardial infarct (MI) size is important for therapeutic and prognostic reasons. We used body surface potential mapping (BSPM) to evaluate whether single-lead electrocardiographic variables can assess MI size.

METHODS

We performed BSPM with 120 leads covering the front and back chest (plus limb leads) on 57 patients at different phases of MI: acutely, during healing, and in the chronic phase. Final MI size was determined by contrast-enhanced cardiac magnetic resonance imaging (DE-CMR) and correlated with various computed depolarization- and repolarization-phase BSPM variables. We also calculated correlations between BSPM variables and enzymatic MI size (peak CK-MBm).

RESULTS

BSPM variables reflecting the Q- and R wave showed strong correlations with MI size at all stages of MI. R width performed the best, showing its strongest correlation with MI size on the upper right back, there representing the width of the "reciprocal Q wave" (r = 0.64-0.71 for DE-CMR, r = 0.57-0.64 for CK-MBm, P < 0.0001). Repolarization-phase variables showed only weak correlations with MI size in the acute phase, but these correlations improved during MI healing. T-wave variables and the QRSSTT integral showed their best correlations with DE-CMR defined MI size on the precordial area, at best r = -0.57, P < 0.0001 in the chronic phase. The best performing BSPM variables could differentiate between large and small infarcts at all stages of MI.

CONCLUSIONS

Computed, single-lead electrocardiographic variables can estimate the final infarct size at all stages of MI, and differentiate large infarcts from small.

Significance of 99mTc-sestamibi myocardial scintigraphy after percutaneous coronary intervention in patients with acute myocardial infarction

Background

This study was designed to clarify the significance of washout rate (WR) determined from ^99mTc-sestamibi myocardial scintigraphic images and the levels of cardiac enzymes in patients with acute myocardial infarction (AMI) after percutaneous coronary intervention (PCI).

Material/Methods

A total of 56 consecutive patients with AMI (mean age 65.8±8.5 years), who underwent PCI on admission, were included. Cardiac enzyme, the MB isoenzyme of creatinine kinase (CK-MB), was measured every 3 h after admission. Two weeks after the onset of AMI, ^99mTc-sestamibi myocardial scintigraphy was performed at early (30 min) and delayed (4 h) phases after tracer injection. The heart-to-mediastinum ratio (H/M) and WR were calculated from the planar images.

Results

PCI was performed at 9.4±6.0 h after the onset of AMI. In 26 patients the culprit lesion was located in the right coronary artery and in 24 patients it was located in the left anterior descending coronary artery. The peak CK-MB was 274.1±169.4 IU/L (13.5±3.9 h). The early and delayed H/Ms and WR of ^99mTc-sestamibi were 2.74±0.58, 3.00±0.70, and 58.8±10.0%, respectively. The delayed H/M was significantly correlated with the peak CK-MB (r=−0.37, p=0.005). The WR of ^99mTc-sestamibi was also significantly correlated with the peak CK-MB (r=−0.34, p=0.012).

Conclusions

These results suggest that the WR determined from ^99mTc-sestamibi myocardial scintigraphic images reflects the extent of myocardial damage in AMI patients.

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.

Prognostic Implications of Creatine Kinase Elevation After Primary Percutaneous Coronary Intervention for Acute Myocardial Infarction

OBJECTIVES

We examined the prognostic implications of the absolute level and rate of increase of creatine kinase (CK) elevation after primary percutaneous coronary intervention (PCI).

BACKGROUND

Peak creatine kinase (CK(peak)) and the rate of CK increase are related to reperfusion success and clinical outcomes after thrombolytic therapy for acute myocardial infarction (AMI). The utility of routine serial CK monitoring after primary PCI, in which normal antegrade blood flow is restored in most patients, is unknown.

METHODS

In the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial, 1,529 patients with AMI randomized to either stenting or balloon angioplasty, each with or without abciximab, had CK levels determined at baseline and at 8 +/- 1 h, 16 +/- 1 h, and 24 +/- 1 h after PCI.

RESULTS

The CK(peak) occurred at baseline in 3.9% of patients, at 8 +/- 1 h in 69.6%, at 16 +/- 1 h in 20.0%, and at 24 +/- 1 h in 6.5%. The CK levels at all post-procedural time points were significantly higher in patients who died compared with the one-year survivors, as was CK(peak) (mean, 2,865 U/l vs. 1,885 U/l, respectively, p < or = 0.001). By multivariate analysis, CK(peak) was a significant predictor of one-year mortality (hazard ratio = 2.15, p = 0.0002), independent from post-PCI Thrombolysis In Myocardial Infarction (TIMI) flow. Both the improvement in left ventricular ejection fraction from baseline to seven months and its absolute level were inversely correlated with CK(peak) (p < 0.001 for both). In contrast, the time to CK(peak) was not an independent predictor of mortality or myocardial recovery.

CONCLUSIONS

The CK(peak) after primary PCI is a powerful predictor of one-year mortality independent of other clinical and angiographic measures.

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.

Time-dependent changes in plasma osteopontin levels in patients with anterior-wall acute myocardial infarction after successful reperfusion: Correlation with left-ventricular volume and function

Osteopontin is a secreted extracellular-matrix glycoprotein that plays a role in the healing of remodeling tissue. We examined the relationship of plasma osteopontin levels with left-ventricular (LV) volume and function in 18 consecutive patients who underwent successful reperfusion after anterior-wall acute myocardial infarction (AMI). The plasma osteopontin level was within the control range at admission (mean +/- SD 420 +/- 195 ng/mL), began to increase on day 2 (935 +/- 464 ng/mL), and reached a maximum around day 3 (1139 +/- 482 ng/mL). The level remained high on days 4, 5, and 7 ( approximately 1000 ng/mL) and then decreased on day 14. Maximal plasma osteopontin levels and the difference between maximal and minimal levels were positively correlated with LV end-systolic volume index (r = .58, P < .05; and r = .65, P < .01, respectively) and negatively correlated with LV ejection fraction (r = -.52, P < .05; and r = -.60, P < .01, respectively). The area under the curve of plasma osteopontin levels for 14 days after AMI was significantly correlated with LV end-systolic volume index (r = .66, P < .01), LV end-diastolic volume index (r = .50, P < .05), and LV ejection fraction (r = -.55, P < .05). In subgroup patients with the same area of risk for myocardial infarction (ie, responsible lesions located at the same proximal left anterior descending coronary artery), essentially the same or a closer relationship between plasma osteopontin level and LV volume and function was noted. Plasma osteopontin levels were correlated substantially with plasma levels of high-sensitivity C-reactive protein (hsCRP) and weakly with serum creatine kinase release. In conclusion, the plasma level of osteopontin changes in a time-dependent fashion and is correlated with LV volumes and function and associated substantially with the extent of the inflammatory response indicated by the plasma hsCRP level and weakly with infarct size estimated on the basis of cardiac-enzyme release.

Transmural extent of acute myocardial infarction predicts long-term improvement in contractile function

BACKGROUND

Previous animal studies have demonstrated that the transmural extent of acute myocardial infarction defined by contrast-enhanced MRI (ceMRI) relates to early restoration of flow and future improvements in contractile function. We tested the hypothesis that ceMRI would have similar predictive value in humans.

METHODS AND RESULTS

Twenty-four patients who presented with their first myocardial infarction and were successfully revascularized underwent cine and ceMRI of their heart within 7 days (scan 1) of the peak MB band of creatine kinase. Cine MRI was repeated 8 to 12 weeks later (scan 2). The transmural extent of infarction on scan 1 and wall thickening on both scans were determined using a 72-segment model. A total of 524 of 1571 segments (33%) were dysfunctional on scan 1. Improvement in segmental contractile function on scan 2 was inversely related to the transmural extent of infarction on scan 1 (P=0.001). Improvement in global contractile function, as assessed by ejection fraction and mean wall thickening score, was not predicted by peak creatine kinase-MB (P=0.66) or by total infarct size, as defined by MRI (P=0.70). The best predictor of global improvement was the extent of dysfunctional myocardium that was not infarcted or had infarction comprising <25% of left ventricular wall thickness (P<0.005 for ejection fraction, P<0.001 for mean wall thickening score).

CONCLUSION

In patients with acute myocardial infarction, the transmural extent of infarction defined by ceMRI predicts improvement in contractile function.

Assessment of Regional Viability in the Infarct Zone Following Myocardial Infarction

The goal of reperfusion strategies in patients with acute myocardial infarction is to salvage myocardium within the infarct zone at risk from the acute occlusion. The status of wall motion and thickening within the infarct zone is an imprecise guide to the extent of salvage and viability within the infarct zone, based on the well-described phenomenon of myocardial stunning. However, knowledge of significant salvage and preserved viability within an infarct zone soon after infarction has important implications regarding clinical decision making for catheterization and potential revascularization: given preserved viability, restoration of normal coronary flow in the setting of a severe residual stenosis or occlusion would be expected to result in significant recovery of regional, and possibly global left ventricular function, with attendant implications for prognosis and outcome.This review will critically explore imaging techniques regarding their ability to discern myocardial viability within the infarct zone soon after myocardial infarction, including electrocardiography, angiography, echocardiography, and radionuclide studies of myocardial perfusion, metabolism and cell membrane integrity.

Thrombolytic therapy does not change the release ratios of enzymatic and non-enzymatic myocardial marker proteins

Measurements of cardiac marker proteins in plasma from patients with acute myocardial infarction (AMI) have become important in the evaluation of recanalization therapy. The validity of this approach has however been questioned, because it was claimed that coronary reperfusion may increase the recovery in plasma of cardiac enzymes, such as creatine kinase (CK). In the present study, possible effects of thrombolytic therapy on the release of enzymatic and nonenzymatic marker proteins were investigated. Activities of CK and lactate dehydrogenase (LDH), and concentrations of myoglobin (Mb) and fatty acid-binding protein (FABP) were determined in serial plasma samples obtained from 50 patients with confirmed AMI, of whom 36 received thrombolytic therapy, and 14 did not. Treatment delay was 2.8+/-1.6 (mean+/-SD) h, and hospital delay in untreated patients was 2.7+/-1.8 h. Average infarct size, expressed in gram-equivalents of heart muscle per litre of plasma (g-eq/l), varied between 5.5 and 7.2 g-eq/l for the four marker proteins in patients treated with thrombolytic therapy, and between 4.6 and 6.4 g-eq/l in untreated patients, with a tendency to larger infarct sizes for Mb and FABP than for CK and LDH. Thrombolytic therapy, although significantly accelerating protein release rates, did not influence the release ratios. These results indicate that thrombolytic therapy has no significant effects on the recovery of cardiac marker proteins in plasma.

Myosin light chain I grade: a simple marker for the severity and prognosis of patients with acute myocardial infarction

To establish serum myosin light chain I (MLCI) as a severity and prognostic marker for patients with acute myocardial infarction (AMI), we measured the serum levels of MLCI in 71 patients with first AMI daily for 1 week after the onset and classified them into four groups by the peak LCI: group 1, > or =2.5 ng/ml but <10 ng/ml; group 2, > or =10 ng/ml but <25 ng/ml; group 3, > or =25 ng/ml but <50 ng/ml; and group 4, > or =50 ng/ml (MLCI grade). The patients in group 1 were likely to show non-Q-wave infarction. The patients in groups 1 and 2 were likely to show redistribution on exercise thallium-201 scintigraphy, suggesting frequent residual ischemia in these groups. The patients in group 4 were likely to show higher Forrester's subset and lower cardiac index at admission and lower left ventricular ejection fraction at discharge. Recurrent angina was equally found in all groups. Severe complications or death were found in patients in groups 3 and 4. Thus the MLCI grade can be used as a simple marker for evaluating the severity of patients with AMI.

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.

Electrocardiographic measurement of infarct size after thrombolytic therapy

OBJECTIVES

We examined the utility of the 32-point QRS score from the 12-lead electrocardiogram (ECG) for measurement of the ischemic risk region and infarct size in patients receiving thrombolytic therapy.

BACKGROUND

The QRS score offers a means of evaluating the therapeutic benefit of thrombolytic therapy by comparing final infarct size with the initial extent of ischemic myocardium.

METHODS

The study included 38 patients (34 men, 4 women; mean [+/-SD] age 54 +/- 10 years) with a first infarction (18 anterior, 20 inferior). The maximal potential QRS score (QRS0) was assigned to all leads with >/= 100-microV ST elevation on the initial ECG. The QRS scores were calculated at 7 and 30 days after infarction. Left ventricular ejection fraction was measured by radionuclide ventriculography at 1 month. Twenty-eight patients had thallium (Tl)-201 and technetium (Tc)-99m pyrophosphate tomographic measurement of the ischemic region and infarct size.

RESULTS

The QRS0 was 10.3 +/- 3.1 (mean +/- SD) for anterior and 10.4 +/- 3.5 for inferior infarcts. The QRS scores were similar at 7 and 30 days for both anterior (5.6 +/- 3.4 vs. 5.5 +/- 3.4) and inferior infarcts (3.7 +/- 2.6 vs. 2.9 +/- 2.2). The day 7 QRS score and ejection fraction at 1 month were inversely correlated (r = -0.74, p < 0.01). The Tl-201 perfusion defect was 34 +/- 11% of the left ventricle for anterior and 32 +/- 7% for inferior infarcts. Subsequent Tc-99m pyrophosphate infarct size was 15 +/- 9% of the left ventricle for anterior and 17 +/- 9% for inferior infarcts. The QRS0 was correlated with the extent of the Tl-201 perfusion defect (r = 0.79, p < 0.001), and the day 7 QRS score was correlated with Tc-99m pyrophosphate infarct size (r = 0.79, p < 0.005).

CONCLUSIONS

The 32-point QRS score can provide useful immediate measurements of the ischemic risk region and subsequent infarct size.

Effect of successful angioplasty following thrombolysis on infarct size and left ventricular function

The role of the angioplasty following thrombolysis in acute myocardial infarction has been discussed in several studies, however the effect of successful angioplasty on infarct size and left ventricular function has not been properly evaluated. Successful reperfusion was achieved in 79 out of 104 patients with primary anterior acute myocardial infarction. These patients were classified as follows, according to the type of intervention during the acute phase: 50 patients in which thrombolysis was successful (the thrombolysis group); 12 patients who underwent successful immediate angioplasty following successful thrombolysis (the immediate angioplasty group); and 17 patients in which rescue angioplasty was successful (the rescue angioplasty group). The 25 patients whose infarct-related vessels were not reperfused after intervention were classified as the non-reperfused group. Infarct size, evaluated as defect volume by T1-201 SPECT, 1 month after the onset, was 840 +/- 154 units (mean +/- S.D.) in the immediate angioplasty group and was similar to that in the thrombolysis group (948 +/- 88 units), but significantly smaller than in the non-reperfused group (1759 +/- 108 units). There were no significant differences in left ventricular function in the immediate angioplasty group and the thrombolysis group. Successful rescue angioplasty did not have any beneficial effect on left ventricular functions or infarct size, when compared with the failed thrombolytic group (1105 +/- 169 units vs. 1617 +/- 169 units). End-diastolic volume (52 +/- 3 ml/m2) in the successful rescue angioplasty group, however, was significantly smaller than in the failed thrombolysis group (67 +/- 3 ml/m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of infarct size by thallium-201 single-photon emission computed tomography using the unfolded map method. Comparison with QRS score and angiographic infarct size at 4 weeks after infarction

A new technique of data processing, the unfolded map method, was used with thallium-201 single-photon emission computed tomography to quantify infarct size in 35 patients with single-vessel disease at 4 weeks after their first myocardial infarction (24 anterior and 11 inferior infarcts), and the results were compared with those obtained by electrocardiography and contrast left ventriculography. The myocardial borders and the infarcted region were defined using the threshold technique and a cutoff value of 55%. Count profile data for each short-axis slice were unfolded zonally into single planes with the same ratio, and their areas were calculated from the slice thickness and radius. Thus, the size of the unfolded map represented the actual left ventricular myocardial area Infarct size was quantitated from the ratio of pixels in the infarcted region to those in the whole map, and the ratio itself was used as the percent infarct size. Although a defect 1 cm in diameter (0.8 cm2) could not be detected in a phantom study, defects > or = 2 cm in diameter (> or = 3.1 cm2) could be measured satisfactorily. The infarct size and percent infarct size determined by the unfolded map method correlated well with the QRS score (r = 0.841 and r = 0.838), the percentage of abnormally contracting segments on left ventriculography (r = 0.835 and r = 0.877), and the ejection fraction (r = -0.835 and r = 0.856). These data indicate that the unfolded map method provides adequate quantification of infarct size, even in the chronic phase, without complicated data processing.

Late reperfusion for acute myocardial infarction limits the dilatation of left ventricle without the reduction of infarct size

BACKGROUND

While previous clinical studies have shown a possible beneficial effect of the reperfusion performed at a relatively late phase of acute myocardial infarction ("late reperfusion") in preventing left ventricular enlargement, the mechanism has not been clarified.

METHODS AND RESULTS

Of 89 patients with an initial anterior myocardial infarction, reperfusion was successful in 69. These 69 were divided into three groups according to the time required to achieve reperfusion after the onset of symptoms: early-reperfused (< 3 hours from the onset to reperfusion; n = 22), intermediate-reperfused (3 to 6 hours from the onset to reperfusion; n = 28), and late-reperfused (> 6 hours from the onset to reperfusion; n = 19). The 20 patients whose infarct-related artery were occluded in the acute phase as well as 1 month later was classified as nonreperfused. Infarct size, evaluated as defect volume by 201Tl single-photon emission computed tomography 1 month after the onset, was 1593 +/- 652 units (mean +/- SD) in the late-reperfused group, significantly larger (P < .05) than that of the intermediate-reperfused (1066 +/- 546 U) or the early-reperfused groups (372 +/- 453 U) but not different from that of the nonreperfused group (1736 +/- 562 U). Wall motion abnormality index as well as global ejection fraction evaluated by left ventriculography 1 month after the onset showed that late reperfusion did not preserve the left ventricular wall motion and function. These results indicate that the earlier reperfusion decreased the size of the infarction and preserved left ventricular function, whereas late reperfusion (> 6 hours after onset) did not limit infarct size or preserve left ventricular function. In contrast, the end-diastolic volume index did not differ significantly among the early-reperfused (50 +/- 15 mL/m2), intermediate-reperfused (54 +/- 14 mL/m2), and late-reperfused (53 +/- 19 mL/m2) groups; those were significantly smaller than that of the nonreperfused group (68 +/- 12 mL/m2; P < .05). Left ventriculographic data obtained in both the acute and chronic phase in 39 patients showed that left ventricular volumes increased significantly during the course of myocardial infarction only in the nonreperfused group.

CONCLUSIONS

Late reperfusion appeared to prevent ventricular dilatation acute myocardial infarction independent of the limitation of infarct size.

Blood flow-dependent uptake of indium-111 monoclonal antimyosin antibody in canine acute myocardial infarction

OBJECTIVES

The relation of myocardial blood flow and indium-111 (111In) antimyosin antibody uptake was studied by inducing myocardial infarction in 18 dogs, 8 with closed chest left anterior descending artery balloon occlusion for 3 h followed by reperfusion (group A) and 10 dogs with open chest left anterior descending artery ligation (without reperfusion, group B).

BACKGROUND

The relation of antimyosin uptake to myocardial injury has been documented. However, its relation to tracer delivery by myocardial blood flow has not been studied and has been assumed to be independent.

METHODS

Indium-111 antimyosin antibody, 2 mCi, was injected 20 min after reperfusion and 3 h after coronary artery ligation in groups A and B, respectively. Regional blood flows were determined by radiolabeled microspheres during occlusion and 24 h later in both groups. On day 2, dogs were killed after risk zone delineation with gentian violet. The heart was excised and stained with triphenyltetrazolium chloride solution and graded for increasing severity of tissue injury based on extent of staining. Microsphere activity and 111In antimyosin activity were measured in control tissue (grade 1), noninfarct tissue at risk (grade 2), mixed tissue (grade 3), infarct tissue (grade 4) and hemorrhagic infarct tissue (grade 5, present only in group A dogs). Count activity was normalized to that of the mean value in control tissue (grade 1) and expressed as a ratio of activity.

RESULTS

Indium-111 antimyosin activity was high in triphenyltetrazolium chloride grade 4 tissue in both groups but was attenuated in grade 4 tissue in group B dogs (10.6 +/- 5.1 vs. 5.0 +/- 4.5; p < 0.05 group A vs. group B), which had lower blood flow on day 2 (0.51 +/- 0.36 vs. 0.23 vs. 0.22; p < 0.01). Normalizing 111In antimyosin activity for blood flow on day 2 resulted in equivalent 111In antimyosin uptake for infarct tissue (32.6 +/- 21.6 vs. 36.6 +/- 29.8 for group A vs. group B; p = NS).

CONCLUSIONS

Thus, 111In antimyosin uptake is a specific marker of necrotic tissue with a high signal ratio in reperfused tissue. However, its uptake is dependent on residual blood flow in the infarct territory. Indium-111 antimyosin could potentially serve as a suitable tracer for infarct sizing if myocardial blood flow in the same region were factored simultaneously.

Myocardial salvage after reperfusion. Observations from analysis of serial electrocardiographic and biochemical indices

Careful assessment of the ECG and the release patterns of biochemical markers after established reperfusion has made it possible to relate the observed changes to the degree of myocardial salvage, left ventricular function, and clinical outcomes. These observations will become increasingly important in assisting the clinician to stratify patients into different prognostic categories during acute MI treated with thrombolytic therapy. In the future, risk stratification based on noninvasive indices provided by ECG and biochemical markers will aid physicians in optimally using thrombolytic therapy.

Quantitative estimation of infarct size by simultaneous dual radionuclide single photon emission computed tomography: comparison with peak serum creatine kinase activity

To test the hypothesis that simultaneous dual energy single photon emission computed tomography (SPECT) with technetium-99m (99mTc) pyrophosphate and thallium-201 (201TI) can provide an accurate estimate of the size of myocardial infarction and to assess the correlation between infarct size and peak serum creatine kinase activity, 165 patients with acute myocardial infarction underwent SPECT 3.2 +/- 1.3 (SD) days after the onset of acute myocardial infarction. In the present study, the difference in the intensity of 99mTc-pyrophosphate accumulation was assumed to be attributable to difference in the volume of infarcted myocardium, and the infarct volume was corrected by the ratio of the myocardial activity to the osseous activity to quantify the intensity of 99mTc-pyrophosphate accumulation. The correlation of measured infarct volume with peak serum creatine kinase activity was significant (r = 0.60, p less than 0.01). There was also a significant linear correlation between the corrected infarct volume and peak serum creatine kinase activity (r = 0.71, p less than 0.01). Subgroup analysis showed a high correlation between corrected volume and peak creatine kinase activity in patients with anterior infarctions (r = 0.75, p less than 0.01) but a poor correlation in patients with inferior or posterior infarctions (r = 0.50, p less than 0.01). In both the early reperfusion and the no reperfusion groups, a good correlation was found between corrected infarct volume and peak serum creatine kinase activity (r = 0.76 and r = 0.76, respectively; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Single photon emission computed tomography with technetium-99m hexakis 2-methoxyisobutyl isonitrile in acute myocardial infarction before and after thrombolytic treatment: assessment of salvaged myocardium and prediction of late functional recovery

Single photon emission computed tomography (SPECT) with technetium-99m hexakis 2-methoxyisobutyl isonitrile was investigated as a method to evaluate the results of intravenous thrombolytic treatment in 14 patients (11 men and 3 women) with acute myocardial infarction admitted to the coronary care unit within 4 h of the onset of symptoms. All patients received an injection of 740 MBq of the tracer before starting the thrombolytic therapy, and isonitrile tomography was performed 3 to 4 h later. The tomographic study was repeated 5 days after the acute event. The results of thrombolytic treatment were independently evaluated taking into account the clinical, electrocardiographic (ECG) and enzymatic data and the findings of left ventricular and coronary angiography. Furthermore, all patients were studied with two-dimensional echocardiography on admission, 5 days later and 1 month later. The site and extent of the perfusion defects on admission scintigraphy were consonant with the ECG and echocardiographic findings. A good correlation could be established between the 5 day scintigraphic estimate of infarct dimension and the enzymatic infarct size (r = 0.907, p less than 0.00002). The comparison between pre- and postthrombolytic treatment images enabled the identification of successful and unsuccessful reperfusion even in patients whose other noninvasive findings were inconclusive. Finally, the reduction in defect size predicted late functional improvement that was demonstrated by echocardiography performed 1 month later (r = 0.89, p less than 0.00005). The results of the study suggest the feasibility and the possible usefulness of isonitrile tomography in demonstrating the presence and size of myocardial damage and in assessing the extent of myocardial salvage after thrombolytic therapy in acute myocardial infarction.

Quantification of myocardial infarct size after coronary reperfusion by serum cardiac myosin light chain II in conscious dogs

The effects of early coronary artery reperfusion on the relation between the extent of myocardial infarction and serum levels of cardiac myosin light chain II or plasma creatine kinase levels were evaluated in the conscious dog. Hydraulic occluders were placed on the left anterior descending arteries of 38 dogs. Seven to 10 days later, myocardial infarction was produced. Coronary reperfusion was performed 3 hours (group A1, n = 13) and 6 hours (group A2, n = 12) after the occlusion. In the other 13 dogs, coronary occlusion was sustained throughout the course of the experiment (group B). Seven days after the occlusion, the heart was cut from the apex to the base into 4-mm slices, and infarct size was determined macroscopically. Rapid appearance and early peaking of creatine kinase were observed in group A. Cumulative release of creatine kinase significantly correlated with infarct size in group A (infarct size ranged from 0.1 to 20.1 g, r = 0.90) and group B (from 0.6 to 26.8 g, r = 0.91). However, since creatine kinase release in group A was greater in comparison with that from infarcts of the same size in group B, the slope of the regression line for group A was significantly steeper (p less than 0.05). Cardiac myosin light chain II appeared as early as creatine kinase did and continued to be elevated for 7 days. A very close relation was observed between infarct size and total cardiac myosin light chain II release (r = 0.87 for group A, and r = 0.88 for group B) or peak level of light chain II (r = 0.85 for group A, and r = 0.81 for group B). In addition, the slopes of the regression lines for infarct size and both peak and total release of light chain II did not differ between group A and group B. On histological examination, viable myocardium was frequently observed in the epicardium of the ischemic area in group A1; therefore, infarct size was greater in group B than in group A1 (p less than 0.05). Also, myocardial creatine kinase content in the epicardium of the center of the ischemic area in group A1 was greater than that in group B. Cardiac myosin light chain II release in group A1 was less than that in group B, whereas no difference was found in plasma creatine kinase release among groups A1, A2, and B.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of antimyosin antibodies in acute myocardial infarction

Antimyosin is an Fab fragment of a monoclonal antibody that binds with human myosin exposed in myocytes irreversibly damaged by an ischemic event. Labeled with 111In, the antibody is taken up into acutely necrotic tissue and can be imaged by planar or single photon emission computed tomography (SPECT) techniques. A large, multicenter clinical trial has demonstrated a high degree of both sensitivity for detecting infarction and specificity for excluding a recent ischemic event in patients admitted with chest pain syndrome. No allergic reactions to antibody injection have occurred, nor have there been documented significant increases in human antimouse antibody titers postinjection. Due to relatively slow blood clearance, the optimal imaging time is 24 to 48 hours post-injection. Between 13% and 21% of 24-hour scans are nondiagnostic due to persistent blood pool activity. In two thirds of these patients, 48-hour scans confirm negative tracer uptake. Moderate to intense cardiac uptake occurs in greater than 80% of scans. Faint tracer uptake, which occurs in a small minority of patients, is associated with inferoposterior infarct location and an occluded infarct vessel. Potential clinical uses include both diagnostic and prognostic areas. A negative scan in a patient with chest pain syndrome and no ECG changes rules out a recent significant ischemic event. The extent of antimyosin uptake (infarct size), measured semiquantitatively from planar scans or quantitatively from SPECT reconstructions, has been shown to correlate with future cardiac events. Relative patterns of distribution of indium-antimyosin and 201TI on simultaneous dual isotope SPECT reconstructions may identify patients with residual myocardium at further ischemic risk.

Measurement of acute Q-wave myocardial infarct size with single photon emission computed tomography imaging of indium-111 antimyosin

Myocardial infarct size was measured by single photon emission computed tomography (SPECT) following injection of indium-111 antimyosin in 27 patients (18 male and 9 female; mean age 57.4 +/- 10.5 years, range 37 to 75) who had acute transmural myocardial infarction (MI). These 27 patients represent 27 of 35 (77%) consecutive patients with acute Q-wave infarctions who were injected with indium-111 antimyosin. In the remaining 8 patients either tracer uptake was too faint or the scans were technically inadequate to permit infarct sizing from SPECT reconstructions. In the 27 patients studied, infarct location by electrocardiogram was anterior in 15 and inferoposterior in 12. Nine patients had a history of prior infarction. Each patient received 2 mCi of indium-111 antimyosin followed by SPECT imaging 48 hours later. Infarct mass was determined from coronal slices using a threshold value obtained from a human torso/cardiac phantom. Infarct size ranged from 11 to 87 g mean 48.5 +/- 24). Anterior infarcts were significantly (p less than 0.01) larger (60 +/- 20 g) than inferoposterior infarcts (34 +/- 21 g). For patients without prior MI, there were significant inverse correlations between infarct size and ejection fraction (r = 0.71, p less than 0.01) and wall motion score (r = 0.58, p less than 0.01) obtained from predischarge gated blood pool scans. Peak creatine kinase-MB correlated significantly with infarct size for patients without either reperfusion or right ventricular infarction (r = 0.66). Seven patients without prior infarcts had additional simultaneous indium-111/thallium-201 SPECT studies using dual energy windows.(ABSTRACT TRUNCATED AT 250 WORDS)

Rate of disappearance of creatine kinase-MB after acute myocardial infarction: clinical determinants of variability

The apparent rate of disappearance (Kd) of creatine kinase (CK)-MB is used in the calculation of the size of acute myocardial infarction (AMI), but little is known about the determinants of variability of this parameter. We therefore evaluated the relationship between clinical characteristics and apparent Kd in 328 patients with AMI without evidence of recurrent infarction. Patients with a history of cigarette smoking within 6 months had higher rates of disappearance of CK-MB, but no relationship was found between renal function and apparent Kd. Slower rates of disappearance of CK-MB were correlated with longer times from the onset of symptoms to peak CK-MB value (p less than 0.001), while higher peak CK-MB levels were not correlated with apparent rates of enzyme clearance. Decreased rates of disappearance of CK-MB were found in patients who had congestive heart failure during or after the hospitalization (both p less than 0.05), and who died during the hospitalization or during study follow-up (both p less than 0.05). Slower rates of disappearance were also significantly correlated with lower ejection fractions on radionuclide ventriculography at 10 days (p less than 0.001) and at 3 months (p less than 0.05) after AMI. These data suggest that patients with slower rates of disappearance of CK-MB may have poorer prognoses, perhaps reflecting continuing necrosis and enzyme release from jeopardized myocardium.

Lack of correlation after reperfusion between ventricular function and infarct size estimated by thallium single-photon emission computed tomography

In 32 patients with acute myocardial infarction, who had undergone successful intracoronary thrombolysis, the results of regional wall motion measured from contrast cineangiograms 10 to 21 days after thrombolysis were related to the results of thallium single-photon emission computed tomography (SPECT) after intravenous dipyridamole. Wall motion was measured by means of the centerline method, and thallium defect size was estimated by comparing the patient's circumferential profile with that of 20 normals. No correlation was found between ejection fraction or regional wall motion and thallium defect size. The time from symptom onset to thrombolysis was inversely correlated with the degree of hypokinesis (r = -0.51) but not with thallium defect size. In patients treated within 3 hours, hypokinesis was significantly less than in patients treated later (-1.1 +/- 0.6 SD vs -2.2 +/- 0.8 SD, p less than 0.01) whereas thallium defect size was not significantly different in both groups. It is concluded that, in patients after thrombolysis, thallium defect size determined by SPECT does not reflect the degree of left ventricular dysfunction.

Prognostic significance of an early rise to peak creatine kinase after acute myocardial infarction

Because an early rise to peak creatine kinase (CK) is regarded as a noninvasive marker of early coronary reperfusion, the short- and long-term significance of this phenomenon was studied. In a series of consecutive patients admitted between 1974 and 1976 with acute myocardial infarction (AMI), 2 hourly CK estimations were performed. Complete CK curves were obtained in 102 patients, all of whom have been followed for 10 years. Without reference to their clinical course or follow-up, patients were divided into those with CK curves peaking less than or equal to 15 hours (mean 11 hours; n = 41) and those with curves peaking greater than 15 hours (mean 21 hours; n = 61). There were no differences in age, Norris index, location of AMI or past history of coronary artery disease between the groups; however, the mean peak CK was higher in the late peak group (p less than 0.05) and there were more non-Q-wave infarcts in the early peak group (p less than 0.01). In the first 9 months of follow-up there were fewer cardiac deaths in the early peak group (5 vs 13%), but this difference was not significant, and at 12 months the survival curves crossed. At 10 years, survival was 42% in the early peak group and 65% in the late peak group (p less than 0.05). Cox regression analysis showed that early peaking of the CK curve was an independent marker for cardiac death overall (relative risk 2.3, p less than 0.02). In 1-year survivors the relative risk increased to 3.8 (p less than 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid enzyme release from acutely infarcted myocardium after early thrombolytic therapy: washout or reperfusion damage?

In a randomized study on early intracoronary thrombolytic therapy in patients with acute myocardial infarction (AMI), serial plasma enzyme activities were measured to analyze the rate of enzyme appearance in plasma with reference to treatment allocation, area at risk, and infarct size. Cumulative activities of alpha-hydroxybutyrate dehydrogenase (HBDH) appearing in plasma in the first 24 hours (Q24), 48 hours (Q48), and 72 hours (Q72) were calculated to obtain infarct size (= Q72) and rate of HBDH appearance in plasma (= Q24/Q72). Analyzed on the basis of "intention to treat" in 448 patients with AMI, the mean Q24/Q72 value (+/- SEM) was 0.653 +/- 0.011 in 230 patients receiving thrombolytic therapy; this value was significantly (p less than 0.001) higher than that observed in 218 patients receiving conventional therapy (0.504 +/- 0.012). In the thrombolysis group Q24/Q72 was independent of infarct size, whereas in the control group Q24/Q72 was negatively correlated with infarct size (r = -0.26; p less than 0.001). Plotted against the sum of ST segment elevations at admission (sigma ST) mean Q24 values were similar in both treatment groups, but mean Q48 and especially Q72 values were larger in the control group than in the thrombolysis group. We conclude that: (1) in reperfused infarctions the time course for development of infarct is accelerated in comparison to unreperfused infarcts; (2) this accelerated process of necrosis lasts about 40 to 50 hours, a duration that is hardly influenced by infarct size; and (3) the reperfusion-induced acceleration of enzyme release resembles the reoxygenation-induced enzyme release from anoxic hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between infarct size and left ventricular performance assessed in patients with first acute myocardial infarction randomized to intracoronary thrombolytic therapy or to conventional treatment

Reperfusion of ischemic myocardium has been reported to increase the cumulative creatine kinase activity in plasma per gram of infarcted myocardium as assessed with the method of Shell et al. In an attempt to find out whether infarct size assessment using the method of Witteveen et al was affected by reperfusion, the relation between enzymatic infarct size was analyzed using Witteveen's method and left ventricular (LV) function parameters in 266 patients with first acute myocardial infarction randomized to intracoronary thrombolysis (n = 134) or conventional therapy (n = 132). Compared with patients allocated to conventional therapy, patients allocated to intracoronary thrombolysis had smaller enzymatic infarct size by 29% (p less than 0.001), smaller LV end-diastolic and end-systolic volume indexes by 10% (p less than 0.05) and 20% (p less than 0.005), respectively, and higher LV ejection fraction (55 +/- 1% vs 49 +/- 1%; p less than 0.001). The beneficial effects of thrombolytic therapy on LV performance were closely associated with thrombolysis-induced limitation of infarct size. The dependence from infarct size of LV end-diastolic volume, LV end-systolic volume, and ejection fraction was not different in the 2 therapy groups. It was concluded that Witteveen's method of infarct size assessment is not influenced by the presence of reperfusion. Therefore, this method was recommended for trials on recanalization in patients with acute myocardial infarction.

Quantitative relationship between left ventricular function and serum cardiac myosin light chain I levels after coronary reperfusion in patients with acute myocardial infarction

To estimate the extent of myocardial infarction after coronary artery reperfusion, serum levels of cardiac myosin light chain (LC) I and creatine kinase (CK) were determined serially in 49 patients with acute myocardial infarction. Intracoronary thrombolysis was successful in 25 patients (reperfusion group), and 24 patients were treated in a conventional manner (control group). The peak level of CK appeared significantly earlier in the reperfusion group (11.3 +/- 3.1 hr, mean +/- SD) than in the control group (21.6 +/- 7.2 hr). Cumulative release of CK was significantly related to angiographically determined left ventricular ejection fraction 1 month after the attack in both groups (r = -.50; -.45, respectively). However, the amount of cumulative release of CK in the reperfusion group was greater compared with that in those with the same left ventricular ejection fraction in the control group. Peak appearance time of LCI was almost equal in the two groups (3.8 +/- 1.4 vs 3.9 +/- 1.2 days). Peak levels of LCI were related to the left ventricular ejection fraction in the reperfusion group (r = -.63) and in the control group (r = -.74), and the slopes of their regression lines were similar. The cardiac index obtained on the day of onset in the two groups was related to peak levels of LCI but not to total release of CK. These results suggest that serum levels of LCI reflect the changes in left ventricular function after acute myocardial infarction, regardless of the presence of coronary reperfusion. Thus, serial determinations of LCI in serum facilitate noninvasive assessment of the effects of intracoronary thrombolysis on infarct size.

Early estimation of acute myocardial infarct size soon after coronary reperfusion using emission computed tomography with technetium-99m pyrophosphate

Early appearance of positive findings on a technetium-99m pyrophosphate scan has been shown to be associated with the presence of a reperfused acute myocardial infarction (AMI). Early technetium-99m pyrophosphate imaging was performed by emission computed tomography to evaluate reperfusion and to test the feasibility of estimating infarct size soon after coronary reperfusion based on acute positive tomographic findings. Twenty-seven patients with transmural AMI who were treated with intracoronary urokinase infusion followed by percutaneous transluminal coronary angioplasty underwent pyrophosphate imaging 8.7 +/- 2.1 hours after the onset of AMI. None of the 8 patients in whom reperfusion was unsuccessful had acute positive findings. Of 19 patients in whom reperfusion was successful, 17 had acute positive findings (p less than 0.001). In these 17, tomographic infarct volumes were determined from reconstructed transaxial images. The threshold for areas of increased pyrophosphate uptake within the infarct was set at 60% of peak activity by the computerized edge-detection algorithm. The total number of pixels in all transaxial sections showing increased tracer uptake were added and multiplied by a size factor and 1.05 g/cm3 muscle to determine infarct volume. The correlations of tomographic infarct volumes with peak serum creatine kinase (CK) levels (r = 0.82) and with cumulative release of CK-MB isoenzyme (r = 0.89) were good. Moreover, the time to positive imaging was significantly shorter than that to peak CK level (8.5 +/- 2.3 vs 10.4 +/- 2.2 hours, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic implications of an early peak in plasma MB creatine kinase in patients with acute myocardial infarction

To determine the prognostic implications of an early peak in plasma MB creatine kinase (MB CK) in patients with acute myocardial infarction who were not treated with an acute intervention, 342 patients with myocardial infarction confirmed by MB CK were retrospectively studied. The patients were classified into those with an early peak MB CK (less than or equal to 15 hours after the onset of symptoms, n = 84) and those with a late peak MB CK (greater than 15 hours after the onset of symptoms, n = 258). Patients with an early peak MB CK were slightly older, were more frequently female and had a higher incidence of prior myocardial infarction, congestive heart failure and arrhythmias compared with patients with a late peak MB CK. Patients with an early peak MB CK more frequently presented with ST segment depression (23 versus 11%, p less than 0.01), with anterior location of ischemia or infarction (71 versus 52%, p less than 0.01) and with a lower mean left ventricular ejection fraction (41.4 versus 47.4%, p less than 0.01). Despite more extensive left ventricular dysfunction at initial presentation, patients with an early peak MB CK had a smaller mean MB CK infarct size index (12.6 versus 18.9 g-Eq/m2, p less than 0.01), with no difference in the incidence of in-hospital complications, including death. The early left ventricular dysfunction improved in the patients with an early peak MB CK, evidenced by a 4.5% increase in ejection fraction from admission to 10 days after infarction, whereas the ejection fraction did not improve in patients with a late peak MB CK. However, the patients with an early peaking MB CK had myocardium in jeopardy as reflected by a higher incidence of ST segment depression and a decrement in the global left ventricular ejection fraction with exercise. The 4 year life table estimate for the rate of recurrent myocardial infarction after hospital discharge was higher in patients with an early peak MB CK (33 versus 22%, p less than 0.05), with an even more striking difference in the 4 year estimate for the rate of fatal recurrent infarction (20 versus 8%, p less than 0.001). The 4 year mortality estimate was markedly higher in hospital survivors with an early peak MB CK than in those with a late peak (47 versus 19%, p less than 0.0001) and, even after adjustment for differences in baseline characteristics, the residual excess mortality in those with an early peak was still significant (p less than 0.02).(ABSTRACT TRUNCATED AT 400 WORDS)

Thallium imaging with single photon emission computed tomography

Evaluation of myocardial perfusion with thallium-201 SPECT has advantages over planar images. These advantages are related to better contrast of the images, lack of superimposition of normal and abnormal areas, and a three-dimensional representation of the site and extent of perfusion abnormalities (ischemia, scar, or both). For this reason, rotational tomography is superior to planar imaging in assessing the extent of coronary artery disease, in the detection of small infarcts, and for quantitative measurements. Several techniques have provided accurate quantitative data for infarct sizing both in animals and men. The ability to quantitate infarct size (or ischemia) will be extremely important in studies of myocardial salvage, risk stratification, and longitudinal studies to evaluate the effects of medical and surgical interventions.

Importance of coronary collateral circulation for kinetics of serum creatine kinase in acute myocardial infarction

The effect of coronary collateral perfusion on the kinetics of creatine kinase (CK) was examined in 32 patients undergoing intracoronary thrombolysis within 6 hours after the onset of a first acute myocardial infarction (AMI). Blood sampling for CK was performed every 2 to 4 hours for a period of 72 hours after AMI. The cumulative CK release was determined using the integrated appearance function curve with the individual disappearance rate. In 19 patients in whom thrombolysis was successful (group A), time to peak CK level was 11 +/- 1 (standard error of the mean) hours after AMI and cumulative CK release was 2,599 +/- 424 U/liter. In 6 patients who had a significant collateral circulation to the infarct-related coronary artery and unsuccessful reperfusion (group B), the time to peak CK was 16 +/- 1 hours (p less than 0.05 compared with group A) and cumulative CK release was 1,897 +/- 478 U/liter (difference not significant compared with group A). In the remaining 7 patients, with neither recanalization nor significant collateral perfusion group C, time to peak CK was 21 +/- 1 hours and significantly (p less than 0.05) longer than groups A and B. Cumulative CK release (2,707 +/- 776 U/liter) was not significantly different from groups A and B. Thus, collateral perfusion is an important determinant of the CK time-activity curve during AMI. Early peaking of CK levels does not reliably identify spontaneous or drug-induced recanalization of the infarct-related coronary artery.

Clinical experience with urokinase in intracoronary thrombolysis

A prospective nonrandomized study of the thrombolytic efficacy and dose-response effect of a high-molecular-weight urokinase, administered into the coronary artery, was conducted in 63 patients with acute myocardial infarction. Urokinase was infused (up to 180 min) at rates of 2000, 4000, 6000, and 10,000 IU/min in four consecutive groups of patients within 184 +/- 70 min following onset of chest pain. Of 54 patients with complete occlusion of the infarct-related vessel, 48 (89%) exhibited complete reperfusion. In 9 patients with incomplete occlusion, the degree of coronary stenosis was reduced with concomitant improvement in antegrade flow. The median effective dosage requirement of urokinase to reperfuse 50% of the treated patients was 180,000 IU. A relationship between the four infusion regimens and successful reperfusion was not found. The time to reperfusion, however, ranging from 42 +/- 30 to 60 +/- 41 min, appeared to be dose dependent. The reocclusion rate at follow-up (10-14 days) was 18%. Ejection fraction improved (40 +/- 8 vs. 47 +/- 8%, p = 0.002) in patients with low pretreatment values and in those treated within 2 h of the onset of symptoms. In-hospital mortality was 9%. Hemorrhage requiring transfusion occurred in 8% of the patients. None of the patients had levels of circulating fibrinogen inferior to 100 mg/dl. We conclude that urokinase can induce timely coronary reperfusion in patients with evolving myocardial infarction, at moderate infusion rates, and with concomitant induction of an only mild systemic lytic state.

Role of myocardial perfusion imaging in evaluating thrombolytic therapy for acute myocardial infarction

Myocardial thallium-201 scintigraphy is being increasingly employed as a method for assessing the efficacy of coronary reperfusion in acute myocardial infarction. New thallium uptake after intracoronary tracer administration after successful recanalization indicates that nutrient blood flow has been successfully restored. One may also presume that some myocardial salvage occurred if thallium administered in this manner is transported intracellularly by myocytes with intact sarcolemmal membranes. However, if one injects thallium by way of the intracoronary route immediately after reperfusion, the initial uptake of thallium in reperfused myocardium may predominantly represent hyperemic flow and regional thallium counts measured may not be proportional to the mass of viable myocytes. When thallium is injected intravenously during the occlusion phase the degree of redistribution after thrombolysis is proportional to the degree of flow restoration and myocardial viability. When thallium is injected for the first time intravenously immediately after reperfusion, an overestimation of myocardial salvage may occur because of "excess" thallium uptake in the infarct zone consequent to significant hyperemia. Another approach to myocardial thallium scintigraphy in patients undergoing thrombolytic therapy is to administer two separate intravenous injections before and 24 hours or later after treatment. Clinical studies have demonstrated that the improvement in defect size on serial images predicts improvement in regional function and patency of the infarct-related vessel. Finally, patients with acute myocardial infarction who receive intravenous thrombolytic therapy are candidates for predischarge exercise thallium-201 scintigraphy for risk stratification and detection of residual ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of early intracoronary streptokinase on infarct size estimated from cumulative enzyme release and on enzyme release rate: a randomized trial of 533 patients with acute myocardial infarction

The effects of early intracoronary streptokinase (SK) on enzymatic infarct size and rate of enzyme release were studied in a randomized multicenter trial. A total of 533 patients with acute myocardial infarction (AMI) were allocated to either the SK treatment group (n = 269) or the conventional (control) treatment group (n = 264). Enzymatic infarct size was represented by the cumulative quantity of alpha-hydroxybutyrate dehydrogenase (HBDH) released by the heart per liter of plasma in the first 72 hours. Rate of enzyme release was represented by the ratio of HBDH quantities released in 24 hours and 72 hours. On an "intention to treat" basis, the SK group had a smaller (by 30%; p = 0.0001) median enzymatic infarct size and a higher (by 35%; p = 0.0001) median rate of enzyme release than the control group. Limitation of infarct size was less apparent in patients treated with intracoronary SK only (25%) than in patients treated with intravenous plus intracoronary SK (34%). Compared to the control group, the enzyme release rate in patients treated with intracoronary SK only was slightly less (34%) than that in patients treated with intravenous plus intracoronary SK (38%). Patients with a patent infarct-related coronary artery at acute angiography had a median infarct size which was 55% (p = 0.0001) smaller than the median infarct size of the control group, and the median rate of enzyme release was 38% (p = 0.001) higher than the median release rate of the control group. Patients with successful recanalization during intracoronary SK infusion had a median infarct size which was 31% (p = 0.002) smaller than the median infarct size of the control group and a median rate of enzyme release which was 42% (p = 0.0001) higher than the median release rate of the control group. Patients with persistent coronary occlusion in spite of thrombolytic therapy had a median infarct size which was 11% (NS) higher than the median infarct size of the control group, although the median rate of enzyme release was still 23% (p = 0.02) higher than the median release rate of the control group. It is concluded that thrombolysis in the early phase of AMI limits infarct size and that intracoronary SK treatment itself accelerates the process of enzyme release from infarcted myocardium, independent of the angiographic result.

Reperfusion arrhythmias during coronary reperfusion therapy in man. Clinical and angiographic correlations

We hypothesized that patients suffering acute myocardial infarction who have reperfusion arrhythmias (RPA) during intracoronary streptokinase infusion (ICSK) would have different clinical and angiographic characteristics and a larger infarction size than those who achieved reperfusion without RPA. Of 35 patients who received intracoronary streptokinase, 27 had successful reperfusion documented by angiography. Successful reperfusion was accompanied by RPA in eight patients and no RPA in 19 patients. RPA included episodes of ventricular tachycardia in one, idioventricular rhythm in four, junctional bradycardia in one, or AV block in two patients which occurred at the time of reperfusion. Myocardial infarction size was calculated using creatine kinase-MB (CK-MB) isoenzyme time activity curves using standard methods. The mean CK-MB g equivalents (eq) for those with RPA was 71 +/- 25 (+/- 1 SD) and for those with no RPA was 45 +/- 24 (p less than .04). In patients with RPA, ejection fraction rose 5 +/- 14 percentage points before discharge, but fell 10 +/- 13 points in those with RPA (p less than .03). There was no difference between groups in total dose of streptokinase, final degree of stenosis of the affected vessel, reocclusion rate, or time from onset of symptoms to reperfusion. We conclude that patients suffering acute myocardial infarction who have RPA during ICSK in most cases have a larger infarction site or a more "stunned myocardium," as indicated by greater CK-MB release and fall in ejection fraction which is not due to increased time of ischemia.

A new approach for the enzymatic estimation of infarct size: serum peak creatine kinase and time to peak creatine kinase activity

The relations of several creatine kinase (CK) variables to angiographic left ventricular ejection fraction and abnormally contracting segments in the chronic phase were examined in 2 groups of patients with a first anterior acute myocardial infarction. In group A (n = 22), emergency coronary angiography was performed and nonsurgical early reperfusion was attempted. Such an early revascularization, which was considered partially present in group B (n = 16), which received conventional therapy, shifted the CK time-activity curve to the left and altered its relation to angiographic cardiac function. At similar levels of peak CK, myocardial damage was significantly smaller in patients with successful thrombolysis than in those with unsuccessful reperfusion and conventional therapy (p less than 0.01). In patients whose infarct was considered to be moderate according to peak CK (1,000 to 3,000 U/liter), there was significant correlation between time to peak CK and left ventricular ejection fraction or percent abnormally contracting segments irrespective of their group. The results suggest that one should take into account rapid washout and shorter time to peak CK when estimating enzymatic infarct size in humans. The multivariate analysis of cardiac function with peak CK and time to peak CK resulted in a closer correlation in all patients. Such a correction in the time to peak CK may be a clinically useful approach for better interpretation of infarct size.

The effects of the rate of intravenous infusion of streptokinase and the duration of symptoms on the time interval to reperfusion in patients with acute myocardial infarction

We studied the influence of the following variables on the time interval from initiation of an intravenous infusion of 750,000 U of streptokinase until reperfusion (reperfusion time) in 140 consecutive patients with an evolving acute myocardial infarction: (1) the rate of infusion of streptokinase, (2) the duration of chest pain before initiation of treatment, (3) patient age, (4) patient sex, (5) location of infarction, (6) history of previous myocardial infarction, and (7) pretreatment pathologic Q waves. The time of reperfusion was recognized by clinical criteria that were completely concordant with the anatomic findings in all 119 patients in whom patency or occlusion of the artery of infarction was established at delayed angiography (n = 116) or at postmortem examination (n = 3). The mean reperfusion time for the 129 patients for whom data were available was 49 +/- 36 min. The reperfusion time was inversely related to the rate of infusion of streptokinase (r = .41, p less than .001), but this effect of infusion rate appeared to plateau at rates of greater than 500 U/kg/min. In the 64 patients receiving infusions at rates of 500 U/kg/min or less, the mean reperfusion time was 60 +/- 40 min, whereas in the 58 patients receiving the drug at rates greater than 500 U/kg/min it was 35 +/- 22 min (p less than .001). The duration of chest pain before treatment was the only other studied variable found to influence the reperfusion time, but only at infusion rates of less than 250 U/kg/min (r = .6, p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Normal results of post-race thallium-201 myocardial perfusion imaging in marathon runners with elevated serum MB creatine kinase levels

Elevated cardiac enzyme values in asymptomatic marathon runners after competition can arise from skeletal muscle through exertional rhabdomyolysis, silent injury to the myocardium, or a combined tissue source. Peak post-race levels of the MB isoenzyme of creatine kinase are similar to values in patients with acute myocardial infarction. Previously reported normal results of infarct-avid myocardial scintigraphy with technetium 99m pyrophosphate in runners after competition suggest a non-cardiac source but cannot exclude silent injury to the myocardium. Therefore, thallium 201 myocardial perfusion imaging was performed in runners immediately after competition together with determination of sequential cardiac enzyme levels. Among 15 runners tested, the average peak in serum MB creatine kinase 24 hours after the race was 128 IU/liter with a cumulative MB creatine kinase release of 117 IU/liter; these values are comparable to those in patients with acute transmural myocardial infarction. Thallium 201 myocardial scintigraphic results were normal in five runners randomly selected from those who volunteered for determination of sequential blood levels. Serum lactate dehydrogenase isoenzymes showed only a peripheral pattern of release. It is concluded that elevations of serum MB creatine kinase in marathon runners arise from a skeletal muscle source and that thallium 201 myocardial scintigraphy is useful to assess runners for myocardial injury when clinical questions arise.

Lactate metabolism in acute myocardial infarction and its relation to regional ventricular performance

Myocardial metabolism was assessed in 20 patients with acute anterior myocardial infarction using lactate uptake (defined as (aortic lactate - great cardiac venous lactate)/aortic lactate X 100) as an index. The regional ejection fraction of the anterior wall was obtained from left ventriculography. There was a linear relation between lactate uptake and regional ejection fraction (r = 0.79, p less than 0.001). Four patients without total occlusion in the infarct vessel had a higher lactate uptake (19.6 +/- 6.7 versus 4.2 +/- 13.4%, p less than 0.05) and regional ejection fraction (26.3 +/- 7.9 versus 14.9 +/- 7.0%, p less than 0.05) than did 16 patients with total occlusion. The latter group of patients underwent intracoronary infusion of urokinase, which resulted in reperfusion in 13 patients. Lactate uptake before urokinase infusion (sample I), just after reperfusion (sample II), 30 minutes after reperfusion (sample III) and 4 weeks after reperfusion (sample IV) was 5.7 +/- 13.2, -13.9 +/- 14.7, 2.9 +/- 15.2 and 20.2 +/- 11.0%, respectively (sample I versus II and II versus III, p less than 0.01; sample I versus IV and III versus IV, p less than 0.05). The decrease in lactate uptake immediately after reperfusion, which was accompanied by an increase in creatine kinase-MB isoenzyme release into the blood, was considered to be the result of a "washout" effect. Lactate uptake was ameliorated 4 weeks later, accompanied by an improvement (from 15.1 +/- 7.1 to 23.4 +/- 7.2%, p less than 0.01) in the regional ejection fraction. It is concluded that the degree of asynergy was closely related to the extent of metabolic deterioration in myocardial infarction.

Coronary artery reperfusion in acute myocardial infarction: assessment by pre- and postintervention thallium-201 myocardial perfusion imaging

In a randomized trial of intracoronary streptokinase (STK) therapy in acute myocardial infarction, 44 patients (21 control subjects and 23 patients treated with STK) underwent sequential thallium-201 planar imaging before angiography and after 4 hours (redistribution), 4 days and 6 weeks. Patients were classified according to the presence or absence of angiographic reperfusion of the infarct-related artery. The semiquantitative score of myocardial thallium uptake was expressed as percent of maximal defect score. Both in control and in STK-treated groups, thallium defect scores decreased over time, but this decrease was smaller in the control group (before angiography, 33 +/- 4%; redistribution, 29 +/- 4%; 4 days, 25 +/- 4%; and 6 weeks, 22 +/- 4%) than in the STK group (44 +/- 4%, 38 +/- 4%, 26 +/- 4% and 21 +/- 3%, respectively). In patients in whom reperfusion was achieved (20 STK-treated, 6 control subjects), a marked decrease in thallium score was observed (before angiography, 40 +/- 4%; redistribution, 32 +/- 4%; 4 days, 20 +/- 5%; and 6 weeks, 14 +/- 22%) compared with patients in whom reperfusion was not achieved (37 +/- 4%, 36 +/- 5%, 33 +/- 5% and 33 +/- 4%, respectively). These results indicate that serial thallium imaging is an accurate method of assessing changes in myocardial perfusion after acute myocardial infarction. Restoration of thallium uptake was observed after reperfusion of the infarct-related artery whether this recanalization was seen spontaneously or after successful thrombolysis.

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.

A randomized trial of intravenous and intracoronary streptokinase in patients with acute myocardial infarction

The clinical effects of intravenous streptokinase in patients with acute myocardial infarction were compared with those of intracoronary streptokinase in a randomized, prospective study. Comparisons were also made with a historical control group. Fifty patients were entered into the study at 2.4 +/- 1.2 hr after onset of pain, and 27 were assigned to intravenous and 23 to intracoronary therapy. The doses of streptokinase averaged 212,000 U ic and 845,000 U iv (0.75 X 10(6) U/5 hr, n = 14 or 10(6) U/1 hr, n = 13). Results of studies of the two intravenous dosage schedules were similar and so were combined. Streptokinase was administered at 2.8 +/- 1.0 hr after onset of pain in the intravenous and at 4.3 +/- 1.4 hr in the intracoronary drug group (p less than .001). Convalescent (day 10) radionuclide ejection fractions were 54 +/- 14% for the intravenous and 50 +/- 16% for the intracoronary drug group. Change in ejection fraction from day 1 to 10 tended to be greater after intravenous drug: 5.1% (p less than .08) vs 1.2% (NS). Semiquantitative regional wall motion indexes in the infarct zone showed significant and similar modest improvement from admission to day 10 in both groups (p less than .02). Accelerated enzyme-release kinetics were noted after both therapies. Times of peak enzyme levels for patients on intravenous and intracoronary drug were, respectively, 12.5 +/- 5.0 and 11.5 +/- 4.3 hr for creatine kinase MB isoenzyme and 31.7 +/- 11.8 and 28.1 +/- 12.7 hr for lactic dehydrogenase (LDH). Peak LDH-1 level was lower in patients receiving intravenous drug than in the historical control group (p less than .05). Electrocardiographically summed ST segments diminished rapidly after therapy in both groups; Q wave development was similar and overall R wave loss was equivalent and less extensive compared with in historical control subjects. Infarct pain requiring morphine was diminished similarly in both treatment groups. Incidence of early arrhythmias and heart failure also did not differ. Posttherapy ischemic events and early surgery tended to be more common in the intracoronary group and bleeding was more common in the intravenous group. Intravenous drug did not decrease early hospital mortality (intravenous drug = 5, historical control = 4, intracoronary drug = 1); the differences in this parameter among groups were not significant. At convalescent angiographic evaluation, anterograde perfusion was present in 73% of those receiving intravenous and 76% of those receiving intracoronary drug.(ABSTRACT TRUNCATED AT 400 WORDS)