Determinants of improvement in epicardial flow and myocardial perfusion for ST elevation myocardial infarction; insights from TIMI 14 and InTIME-II

The Canadian Cardiovascular Society Classification of Acute Atherothrombotic Myocardial Infarction Based on Stages of Tissue Injury Severity: An Expert Consensus Statement

Myocardial infarction (MI) remains a leading cause of morbidity and mortality. In atherothrombotic MI (ST-elevation MI and type 1 non-ST-elevation MI), coronary artery occlusion leads to ischemia. Subsequent cardiomyocyte necrosis evolves over time as a wavefront within the territory at risk. The spectrum of ischemia and reperfusion injury is wide: it can be minimal in aborted MI or myocardial necrosis can be large and complicated by microvascular obstruction and reperfusion hemorrhage. Established risk scores and infarct classifications help with patient management but do not consider tissue injury characteristics. This document outlines the Canadian Cardiovascular Society classification of acute MI. It is an expert consensus formed on the basis of decades of data on atherothrombotic MI with reperfusion therapy. Four stages of progressively worsening myocardial tissue injury are identified: (1) aborted MI (no/minimal myocardial necrosis); (2) MI with significant cardiomyocyte necrosis, but without microvascular injury; (3) cardiomyocyte necrosis and microvascular dysfunction leading to microvascular obstruction (ie, "no-reflow"); and (4) cardiomyocyte and microvascular necrosis leading to reperfusion hemorrhage. Each stage reflects progression of tissue pathology of myocardial ischemia and reperfusion injury from the previous stage. Clinical studies have shown worse remodeling and increase in adverse clinical outcomes with progressive injury. Notably, microvascular injury is of particular importance, with the most severe form (hemorrhagic MI) leading to infarct expansion and risk of mechanical complications. This classification has the potential to stratify risk in MI patients and lay the groundwork for development of new, injury stage-specific and tissue pathology-based therapies for MI.

Comparison of Angiographic and Clinical Outcomes After Primary Percutaneous Coronary Intervention for ST-elevation Myocardial Infarction Between Patients With and Without Concomitant COVID-19 Infection

OBJECTIVE

COVID-19 infection can involve the cardiovascular system and worsen the prognosis of the patients. This study aimed to investigate the adverse effects of COVID-19 on angiographic and clinical outcomes of primary percutaneous coronary intervention (PCI) in patients with acute ST-elevation MI and compare results with those patients without COVID-19 disease.

METHODS

The study was a retrospective observational cohort, in which patients presented with ST-elevation MI from February 2020 to April 2021, treated with primary PCI were divided into 2 groups based on the COVID-19 infection. Then, the procedural and angiographic indices and also clinical outcomes were compared between the 2 groups.

RESULTS

A total of 1150 patients were enrolled in the study. Those with established COVID-19 infection had worse baseline thrombolysis in myocardial infarction flow grade and also were at higher risk for worse procedural outcomes such as lower thrombolysis in myocardial infarction frame count, myocardial blush grade, and slow-flow coronary disease, after the primary PCI. Additionally, the presence of COVID-19 at the time of primary PCI was related to a significantly higher duration of hospitalization and in-hospital mortality. Given the potential impact of other factors on outcomes, analysis for all of the primary endpoints was done again after adjustment of these factors and the results were the same as before, suggesting the independent effect of COVID-19 infection.

CONCLUSIONS

The concomitant COVID-19 infection in the patients undergoing primary PCI is associated with significantly worse angiographic, procedural and clinical outcomes. Surprisingly, this finding is regardless of patients' baseline risk factors and demographical characteristics.

Imaging tools for assessment of myocardial fibrosis in humans: the need for greater detail

Myocardial fibrosis is recognized as a key pathological process in the development of cardiac disease and a target for future therapeutics. Despite this recognition, the assessment of fibrosis is not a part of routine clinical practice. This is primarily due to the difficulties in obtaining an accurate assessment of fibrosis non-invasively. Moreover, there is a clear discrepancy between the understandings of myocardial fibrosis clinically where fibrosis is predominately studied with comparatively low-resolution medical imaging technologies like MRI compared with the basic science laboratories where fibrosis can be visualized invasively with high resolution using molecularly specific fluorescence microscopes at the microscopic and nanoscopic scales. In this article, we will first review current medical imaging technologies for assessing fibrosis including echo and MRI. We will then highlight the need for greater microscopic and nanoscopic analysis of human tissue and how this can be addressed through greater utilization of human tissue available through endomyocardial biopsies and cardiac surgeries. We will then describe the relatively new field of molecular imaging that promises to translate research findings to the clinical practice by non-invasively monitoring the molecular signature of fibrosis in patients.

Targeting plasminogen activator inhibitor-1 in tetracycline-induced pleural injury in rabbits

Elevated active plasminogen activator inhibitor-1 (PAI-1) has an adverse effect on the outcomes of intrapleural fibrinolytic therapy (IPFT) in tetracycline-induced pleural injury in rabbits. To enhance IPFT with prourokinase (scuPA), two mechanistically distinct approaches to targeting PAI-1 were tested: slowing its reaction with urokinase (uPA) and monoclonal antibody (mAb)-mediated PAI-1 inactivation. Removing positively charged residues at the "PAI-1 docking site" (¹⁷⁹RHRGGS¹⁸⁴→¹⁷⁹AAAAAA¹⁸⁴) of uPA results in a 60-fold decrease in the rate of inhibition by PAI-1. Mutant prourokinase (0.0625-0.5 mg/kg; n = 12) showed efficacy comparable to wild-type scuPA and did not change IPFT outcomes ( P > 0.05). Notably, the rate of PAI-1-independent intrapleural inactivation of mutant uPA was 2 times higher ( P < 0.05) than that of the wild-type enzyme. Trapping PAI-1 in a "molecular sandwich"-type complex with catalytically inactive two-chain urokinase with Ser¹⁹⁵Ala substitution (S195A-tcuPA; 0.1 and 0.5 mg/kg) did not improve the efficacy of IPFT with scuPA (0.0625-0.5 mg/kg; n = 11). IPFT failed in the presence of MA-56A7C10 (0.5 mg/kg; n = 2), which forms a stable intrapleural molecular sandwich complex, allowing active PAI-1 to accumulate by blocking its transition to a latent form. In contrast, inactivation of PAI-1 by accelerating the active-to-latent transition mediated by mAb MA-33B8 (0.5 mg/kg; n = 2) improved the efficacy of IPFT with scuPA (0.25 mg/kg). Thus, under conditions of slow (4-8 h) fibrinolysis in tetracycline-induced pleural injury in rabbits, only the inactivation of PAI-1, but not a decrease in the rate of its reaction with uPA, enhances IPFT. Therefore the rate of fibrinolysis, which varies in different pathologic states, could affect the selection of PAI-1 inhibitors to enhance fibrinolytic therapy.

Cardiac death by rupture of the right ventricular wall and hemopericardium

Right Ventricular (RV) rupture is a rare and dangerous complication of acute myocardial infarction. There are limited reports on RV free wall rupture. In this paper we describe the outcome of an autopsy case of cardiac death by rupture of the free wall of the right ventricle in a 51-year-old man with coronary artery disease and hypertrophic-sclerotic cardiomyopathy.

Lytic failure in the current pharmacointensive ST-elevated acute myocardial infarction care: insights from a pilot real-world study

BACKGROUND

Thrombolysis remains a very acceptable reperfusion option for ST-elevated acute myocardial infarction (STEMI); however, it fails relatively frequently and unpredictably.

AIM AND METHODS

To investigate correlates of lytic failure (according to the standard ST resolution criterion) in current pharmacointensive STEMI care (dual antiplatelets with antithrombin), we analyzed retrospectively clinical data and echocardiographic left ventricular systolic function before initiation of reperfusion treatment in Killip I-III STEMI patients admitted to our 'spoke' intensive cardiac care unit between 1 January and 31 December 2010.

RESULTS

Of the 53 STEMI patients enrolled, 28% failed thrombolysis. Patients who did not reperfuse were less frequently active smokers (P < 0.05, odds ratio 4.33) and had a higher prevalence of hemodynamic instability [heart rate/SBP (i.e. shock index) >0.75; P < 0.05, odds ratio 13.45) and left ventricular systolic dysfunction (ejection fraction <45%; P < 0.005, odds ratio 11.14). In an exploratory multivariable logistic regression analysis, those variables were the only discriminators independently associated with lytic failure (adjusted odds ratio 8.74, 230.10, and 18.22, respectively, all P < 0.05). Moreover, the combined variables had a high accuracy for prediction of failed thrombolysis (all discriminators positive, 99% specificity and 83% positive predictive value).

CONCLUSION

Our pilot study indicates that thrombolysis still fails in about one-third of STEMI patients despite the current pharmacointensive approach and suggests that failed ST resolution might be independently associated with nonsmoking habit and pretreatment hemodynamic instability and left ventricular systolic dysfunction. Larger trials are needed to verify the potential clinical implications of our preliminary observation.

The sum of ST-segment elevation is the best predictor of microvascular obstruction in patients treated successfully by primary percutaneous coronary intervention. Cardiovascular magnetic resonance study

INTRODUCTION AND OBJECTIVES

The usefulness of ST-segment elevation resolution (STR) for predicting epicardial reperfusion is well established. However, it is still not clear how ST-segment changes are related to microvascular obstruction (MVO) observed by cardiovascular magnetic resonance (CMR) after primary percutaneous coronary intervention (pPCI) for ST-segment elevation myocardial infarction (STEMI).

METHODS

The study involved 85 consecutive patients admitted for a first STEMI and treated by pPCI who had a patent infarct-related artery. An ECG was recorded on admission and 90 min and 6, 24, 48 and 96 h after pPCI. Thereafter, STR and the sum of ST-segment elevation (sumSTE) in all leads were determined.

RESULTS

Overall, CMR revealed MVO in 37 patients. In infarcts with MVO, sumSTE was greater both before and after revascularization than in infarcts without MVO (P≤.001 at all times). In contrast, there was no significant difference in the magnitude of STR between infarcts with and without MVO 90 min after revascularization (P=.1), though there was after 6 h (P< .05 at all times). The area under the receiver operating characteristic curve for detecting MVO was greater for sumSTE than STR (P< .05 for all measurements). On multivariate analysis, after adjusting for clinical, angiographic and ECG characteristics, a sumSTE >3 mm 90 min after pPCI was an independent predictor of MVO on CMR, while an STR ≥70% was not (odds ratio=3.1; 95% confidence interval, 1.2-8.4; P=.02).

CONCLUSIONS

MVO was associated with a significantly increased sumSTE at all times after revascularization. The difference in the magnitude of STR between infarcts with and without MVO was significant only >6 h after revascularization. The best predictor of MVO was a sumSTE >3 mm 90 min after pPCI.

The sum of ST-segment elevation is the best predictor of microvascular obstruction in patients treated successfully by primary percutaneous coronary intervention. Cardiovascular magnetic resonance study

INTRODUCTION AND OBJECTIVES

The usefulness of ST-segment elevation resolution (STR) for predicting epicardial reperfusion is well established. However, it is still not clear how ST-segment changes are related to microvascular obstruction (MVO) observed by cardiovascular magnetic resonance (CMR) after primary percutaneous coronary intervention (pPCI) for ST-segment elevation myocardial infarction (STEMI).

METHODS

The study involved 85 consecutive patients admitted for a first STEMI and treated by pPCI who had a patent infarct-related artery. An ECG was recorded on admission and 90 min and 6, 24, 48 and 96 h after pPCI. Thereafter, STR and the sum of ST-segment elevation (sumSTE) in all leads were determined.

RESULTS

Overall, CMR revealed MVO in 37 patients. In infarcts with MVO, sumSTE was greater both before and after revascularization than in infarcts without MVO (P≤.001 at all times). In contrast, there was no significant difference in the magnitude of STR between infarcts with and without MVO 90 min after revascularization (P=.1), though there was after 6 h (P< .05 at all times). The area under the receiver operating characteristic curve for detecting MVO was greater for sumSTE than STR (P< .05 for all measurements). On multivariate analysis, after adjusting for clinical, angiographic and ECG characteristics, a sumSTE >3 mm 90 min after pPCI was an independent predictor of MVO on CMR, while an STR ≥70% was not (odds ratio=3.1; 95% confidence interval, 1.2-8.4; P=.02).

CONCLUSIONS

MVO was associated with a significantly increased sumSTE at all times after revascularization. The difference in the magnitude of STR between infarcts with and without MVO was significant only >6 h after revascularization. The best predictor of MVO was a sumSTE >3 mm 90 min after pPCI.

Predictive value of ST resolution analysis performed immediately versus at ninety minutes after primary percutaneous coronary intervention

ST segment resolution (STR) predicts epicardial and microvascular reperfusion after primary percutaneous coronary intervention (PPCI) or thrombolysis for ST-elevation myocardial infarction. Immediate restoration of epicardial coronary flow, with improved microvascular perfusion, is much more likely with PPCI. However, the predictive value of immediate STR compared to 90 minutes after PPCI remains unknown. In 622 consecutive patients with ST-elevation myocardial infarction (mean age 59 +/- 13 years), 217 had complete STR immediately after PPCI (group A), 188 had complete STR only at 90 minutes (group B), and 217 had incomplete STR at either point (group C). The primary end point was mortality and adverse cardiovascular events ([MACE] death, nonfatal repeat myocardial infarction, and heart failure). Group A had a greater left ventricular ejection fraction (53%, 47%, and 46%, p <0.001) and lower all-cause mortality (1.8%, 3.2%, and 6%, p = 0.07), lower heart failure (1.8%, 4.3%, and 7.8%, p <0.001), and MACE (5.1%, 9.6%, and 16.1%, p = 0.001) at 30 days compared to groups B and C, respectively. The rate of MACE at 1 year was 7.6%, 17.1%, and 20.2% in groups A, B, and C, respectively (p <0.001). Immediate STR independently predicted MACE (adjusted hazard ratio 0.36, 95% confidence interval 0.21 to 0.61, p = 0.001, group A vs C), and STR at 90 minutes did not. In conclusion, STR analysis performed immediately after PPCI provided superior differentiation for adverse cardiovascular events compared to STR at 90 minutes. Immediate STR should be the contemporary goal of reperfusion with PPCI.

Edema as a very early marker for acute myocardial ischemia: a cardiovascular magnetic resonance study

OBJECTIVES

This study was designed to determine whether imaging myocardial edema would identify acute myocardial ischemia before irreversible injury takes place.

BACKGROUND

Early identification of acute myocardial ischemia is a diagnostic challenge.

METHODS

We studied 15 dogs with serial T(2)-weighted and cine imaging at baseline, during transient coronary occlusion of up to 35 min, and after reperfusion in a 1.5-T magnetic resonance imaging system. Late gadolinium enhancement and troponin measurements were used to assess for the presence of irreversible injury. Myocardial water content was measured to assess myocardial edema.

RESULTS

We consistently observed a transmural area of high T(2) signal intensity matching areas with new onset regional akinesia 28 +/- 4 min after experimental coronary artery occlusion. At this time, the contrast-to-noise ratio between the ischemic and remote myocardium had significantly increased from 1.0 +/- 2.0 to 12.8 +/- 9.6 (p < 0.003), which further increased after reperfusion to 15.8 +/- 10.3 (p < 0.004 compared with baseline). Neither myocardial late gadolinium enhancement nor troponin elevation were noted at this time window. Myocardial water content of the ischemic segments was consistently higher (68.9 +/- 2% vs. 67.0 +/- 2%; p < 0.004) than in remote segments and the difference correlated significantly to the contrast-to-noise ratio in T(2) images (p < 0.04).

CONCLUSIONS

We provide the first evidence that T(2)-weighted cardiovascular magnetic resonance imaging of edema detects acute ischemic myocyte injury before the onset of irreversible injury. T(2)-weighted cardiovascular magnetic resonance imaging may serve as a very useful diagnostic marker in clinical settings such as unstable angina or evolving infarction.

Aborted myocardial infarction: is it real in the troponin era?

BACKGROUND

Cardiac troponins are the markers of choice for the diagnosis of acute myocardial infarction. The objective of this study was to compare the frequency of "aborted myocardial infarction" (no detectable myocardial injury) determined by measurement of troponin versus that determined by creatine kinase (CK) and creatine kinase-muscle brain (CK-MB) measurement criteria among patients with ST-elevation myocardial infarction (STEMI) who received reperfusion therapy.

METHODS

Since 2004, the Mayo Clinic (Rochester, MN) has had a standard reperfusion protocol for the treatment of patients with STEMI. During the study period, 767 patients presented with new or presumed new ST elevation or left bundle block.

RESULTS

The diagnosis of STEMI was confirmed in 765 (99.7%) patients. Using the 99th percentile cutoff value, troponin T elevations occurred in 765 (100%) of 765 patients when serial samples were available. Creatine kinase-MB levels of twice or more the upper limit of normal occurred in 681 (90.1%) of 749 patients with serial samples for CK-MB, and CK equal or greater than twice the gender-specific upper limits of normal occurred in 521 (78.8%) of 661 patients with serial samples for CK available.

CONCLUSION

The frequency of aborted myocardial infarction is 0% when using troponin at the 99th percentile cutoff as recommended by contemporary guidelines from the European Society of Cardiology (Nice, France) and American College of Cardiology (Washington, DC).

Prognostic value of ST-segment resolution after rescue percutaneous coronary intervention. Data from the RICO survey

OBJECTIVES

The goal of the present study was to test the impact of ST segment resolution (STR) after rescue percutaneous coronary intervention (PCI) on the short-term prognosis.

BACKGROUND

The prognostic value of STR after rescue PCI for acute ST elevation myocardial infarction (STEMI) remains undetermined.

METHODS

From the French regional database, we analyzed 168 consecutive patients with STEMI and failed lysis, defined by <50 percent STR, who underwent rescue PCI. Patients were classified into two groups according to the degree of STR from the maximal ST-elevation measured on the single worst ECG lead before lysis and after rescue PCI: the without STR group (<50% STR) vs. the with STR group (> or =50%).

RESULTS

After rescue PCI, 26 (15%) patients did not have STR and 142 (85%) patients did. No difference was observed between the two groups regarding baseline characteristics, risk factors, and median time delay either from symptom onset to thrombolysis or from failed lysis to rescue PCI. We observed a lower proportion of patients with TIMI 2/3 flow post PCI in the without STR group (respectively 61% vs. 97%, P < 0.001) but an increased use of intra-aortic balloon counterpulsation (34% vs. 8%, P < 0.001) in this group. Thirty-day mortality was markedly higher in the without STR group than in the with STR group (27% vs. 9% respectively, P = 0.025). Moreover, multivariate analysis showed that absence of STR (OR: 5.65; 95% CI: 1.24-25.67), was an independent prognostic factor for mortality.

CONCLUSIONS

We showed for the first time that analysis of ST-segment resolution may be a simple reliable tool to identify patients at high risk after rescue PCI, and may provide useful information for the elaboration of therapeutic strategies.

Association of TIMI myocardial perfusion grade and ST-segment resolution with cardiovascular magnetic resonance measures of microvascular obstruction and infarct size following ST-segment elevation myocardial infarction

BACKGROUND

Impairment of coronary microvascular perfusion is common among patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). Cardiovascular magnetic resonance imaging (CMR) can identify microvascular obstruction (MO) following reperfusion of STEMI. We hypothesized that myocardial perfusion, as assessed by the Thrombolysis in Myocardial Infarction (TIMI) Myocardial Perfusion Grade (TMPG), would be associated with a CMR metric of MO in this population.

METHODS

Twenty-one STEMI patients who underwent successful primary PCI were evaluated. Contrast-enhanced CMR was performed within 7 days of presentation and repeated at three months. TIMI Flow Grade (TFG), corrected TIMI Frame Count (cTFC), TMPG, MO, infarct size, and left ventricular ejection fraction (EF) were assessed.

RESULTS

The median peak creatine phosphokinase (CPK) was 1,775 IU/l (interquartile range 838-3,321). TFG 3 was present following PCI in 19 (90%) patients. CMR evidence of MO was present in 52% following PCI. Abnormal post-PCI TMPG (0/1/2) was present in 48% of subjects and was associated with MO on CMR (90% MO with TMPG 0/1/2 vs. 18% MO with TMPG 3, P < 0.01). Abnormal post-PCI TMPG was also associated with a greater peak CK (median 3,623 IU/l vs. 838 IU/l, P < 0.001) and greater relative infarct size (17.3% vs. 5.2%, P < 0.01).

CONCLUSION

Among STEMI patients undergoing primary PCI, post-PCI TMPG correlates with CMR measures of MO and infarct size. The combined use of both metrics in a comprehensive assessment of microvascular integrity and infarct size following STEMI may aid in the evaluation of future therapeutic strategies.

Prehospital fibrinolysis

Reperfusion therapy for ST-elevation acute coronary syndromes aims at early and complete recanalization of the infarct-related artery to salvage myocardium and improve both early and late clinical outcomes. Prehospital diagnosis of ST-elevation acute coronary syndrome can be made by electrocardiography with or without transtelephonic transmission, and subsequent fibrinolytic therapy can be instituted at home or in the ambulance. Prehospital fibrinolysis decreases time to treatment by approximately 1 hour compared with in-hospital therapy resulting in a significant 15% relative risk reduction in early mortality. This may compare well with primary angioplasty for ST-elevation acute coronary syndrome, although more studies are necessary.

Aborted myocardial infarction: a new target for reperfusion therapy

Reperfusion therapy for ST-elevation acute coronary syndromes aims at early and complete recanalization of the infarct-related artery in order to salvage myocardium and improve both early and late clinical outcomes. Myocardial necrosis is usually confirmed and quantified by myocardial enzyme release in plasma. However, over 10% of patients treated with reperfusion therapy fail to develop an enzyme rise, but do exhibit transient ECG changes, which are consistent with an aborted myocardial infarction. The earlier the reperfusion therapy is instituted, the higher the incidence of aborted infarction. Treatment within an hour after symptom onset may result in 25% of aborted infarction and is in combination with complete (70%) ST-segment resolution associated with better survival. This endpoint is easy to define and occurs promptly in time. The faster that effective treatment is initiated, the more likely aborted infarction will occur. Given that mortality, re-infarction, and stroke are declining in incidence, we suggest the introduction of aborted infarction as an endpoint in clinical trials of ST-elevation acute coronary syndromes.

Grade 3 ischemia on admission and absence of prior beta-blockade predict failure of ST resolution following thrombolysis for anterior myocardial infarction

BACKGROUND

ST segment resolution (STR) is a strong predictor of outcome following thrombolysis. If failure of STR could be predicted on admission, better selection of treatment may be possible. Among patients given reperfusion, those with terminal QRS distortion (grade 3 ischemia) have larger infarcts, but the mechanism underlying this association is unclear. Whether grade 3 ischemia on admission can predict STR is unknown.

METHODS

We studied 180 consecutive patients given thrombolysis for a first anterior acute myocardial infarction (AMI). Multiple variables available on admission were analyzed as predictors of STR at 1, 2, and 24 h and as predictors of the need for rescue percutaneous coronary intervention (PCI).

RESULTS

Multivariate predictors of failure of STR were: for 1 h: extent of ST elevation (OR: 1.09 [1.01-1.18]); for 2 h: no previous use of beta-blockers (OR: 4.71 [1.56-13.98]) and grade 3 ischemia (OR: 6.77 [3.27-13.95]); for 24 h: previous use of aspirin (OR: 6.70 [1.31-34.01]) and grade 3 ischemia (OR: 29.44 [7.30-118.1]). Grade 3 ischemia had a strong positive predictive value for failure of STR at 1 and 2 h and was the strongest predictor of the need for rescue PCI.

CONCLUSIONS

Grade 3 ischemia on admission is the strongest independent predictor of failure to achieve myocardial reperfusion after thrombolysis. This association may underlie the larger infarcts associated with grade 3 ischemia. Other predictors of reperfusion failure are the extent of ST segment elevation, prior use of aspirin and no prior use of beta-blockers.

Effect of clopidogrel plus aspirin on tissue perfusion and coronary flow in patients with ST-segment elevation myocardial infarction: a new reperfusion strategy

BACKGROUND

Current reperfusion strategies may fail to achieve optimal tissue perfusion in ST-elevation myocardial infarction (STEMI). We investigated the effect of clopidogrel plus aspirin on tissue perfusion and coronary flow in infarct patients treated with fibrinolytic agents.

METHODS

Consecutive 78 patients with STEMI were randomized to receive clopidogrel plus aspirin (clopidogrel group, n = 42) or placebo plus aspirin (placebo group, n = 36) before streptokinase. Maximum and total ST-segment resolutions (sumSTR) were calculated at 90 minutes after fibrinolysis. TIMI flow grade and corrected TIMI frame count in infarct-related artery were evaluated at predischarge. Inhospital ischemic and hemorrhagic events were also analyzed.

RESULTS

Baseline characteristics were comparable in both groups. Both mean maximum ST-segment resolution (54.5 +/- 21.3% vs 44.6 +/- 22.0%, P = .047 ) and sumSTR (52.7 +/- 21.1% vs 42.8 +/- 20.7%, P = .041) were slightly higher in the clopidogrel group than placebo group. The rate of complete sumSTR 70% was significantly higher in the clopidogrel group compared with placebo group (31% vs 11%, P = .021). TIMI flows were similar in both groups, but corrected TIMI frame count was significantly lower in the clopidogrel group compared with placebo group (25.5 +/- 10.5 vs 33.5 +/- 11.8 frames, P = .027). Clinical events were comparable in 2 groups; however, there were 1 death caused by heart failure and moderate bleeding in the clopidogrel group.

CONCLUSION

Our results suggest that clopidogrel plus aspirin compared with aspirin alone may improve myocardial tissue perfusion and coronary flow in STEMI patients receiving streptokinase.

Efficacy of tenecteplase in combination with enoxaparin, abciximab, or unfractionated heparin: one-year follow-up results of the Assessment of the Safety of a New Thrombolytic-3 (ASSENT-3) randomized trial in acute myocardial infarction

BACKGROUND

In the ASsessment of the Safety of a New Thrombolytic 3 (ASSENT-3) study, full-dose tenecteplase plus enoxaparin or half-dose tenecteplase plus abciximab reduced the frequency of ischemic complications of acute myocardial infarction, when compared to full-dose tenecteplase plus unfractionated heparin. The aim of the present study was to determine the effect of these fibrinolytic regimens on 1-year mortality.

METHODS AND RESULTS

Vital status at 1 year was available for 5942 patients (97.5%) of the 6095 initially enrolled in the study. At 1 year, 515 patients (8.7%) had died. Elderly or female patients and patients with low body weight, previous myocardial infarction, anterior wall myocardial infarction, and diabetes were at increased risk for death at 1 year. Mortality at 1 year was 7.9 % (n = 161) in the heparin group, 8.1% (n = 166) in the enoxaparin group, and 9.3% (n = 188) in the abciximab group (P =.226). Overall, pairwise comparisons did not show a significant difference among treatment regimens: relative risk 1.03 (95% CI 0.82-1.30) for enoxaparin versus heparin (P =.794) and relative risk 1.18 (95% CI 0.95-1.47) for abciximab versus heparin (P =.144). However, 1-year outcome tended to be worse with abciximab in diabetic patients.

CONCLUSION

Mortality at 1 year after acute myocardial infarction remains high. Despite a reduction in ischemic complications after acute myocardial infarction with the use of full-dose tenecteplase plus enoxaparin or half-dose tenecteplase plus abciximab, mortality at 1 year was similar in these treatment groups.

Prehospital versus hospital fibrinolytic therapy using automated versus cardiologist electrocardiographic diagnosis of myocardial infarction: abortion of myocardial infarction and unjustified fibrinolytic therapy

BACKGROUND

This study investigated the incidence of abortion of myocardial infarction and of unjustified fibrinolysis by using automated versus cardiologist-assisted diagnosis of acute ST-elevation myocardial infarction. The results of prehospital diagnosis and treatment (2 cities in the Netherlands) were compared with those of inhospital treatment. Unjustified fibrinolysis must be differentiated from justified thrombolysis resulting in aborted myocardial infarction. Both have the absence of a significant rise in cardiac enzymes in common. In aborted myocardial infarction, this is a result of timely reperfusion; in unjustified thrombolysis, this is the result of an incorrect diagnosis.

METHODS

In the city of Rotterdam, 118 patients were treated before hospitalization for myocardial infarction, diagnosed through the use of a mobile computer electrocardiogram; in the city of Nijmegen, 132 patients were treated before hospitalization with the use of transtelephonic transmission of the electrocardiogram to the coronary care unit and judged by a cardiologist. Their data were compared with those of 269 patients treated inhospital in the city of Arnhem, using the same electrocardiographic criteria. Abortion of myocardial infarction was diagnosed as the absence of a significant rise in cardiac enzymes and the presence of resolution of chest pain and 50% of ST-segment deviation within 2 hours after onset of therapy. Lacking these, the diagnosis of unjustified fibrinolytic therapy was made.

RESULTS

Unjustified treatment occurred in 8 (3.2%) prehospital-treated patients (4 in Rotterdam and 4 in Nijmegen). Of the inhospital-treated patients in Arnhem, 5 (1.9%) were treated unjustifiably (P =.49). Aborted myocardial infarction occurred in 15.3% and 18.2% in Rotterdam and Nijmegen, respectively, against 4.5% in inhospital treatment in Arnhem (P <.001).

CONCLUSIONS

Abortion of myocardial infarction is associated with prehospital thrombolysis. Unjustified fibrinolysis for acute myocardial infarction occurs in prehospital fibrinolysis as frequently as in the inhospital setting. The use of different electrocardiographic methods for diagnosing acute myocardial infarction does not appear to make any difference.

Prehospital thrombolysis with reteplase: the Nijmegen/Rotterdam study

OBJECTIVE

The objective of this observational study was to assess time from electrocardiogram diagnosis to treatment and time from pain onset to treatment with double bolus reteplase compared to current therapy with streptokinase or bolus anistreplase in 2 cities (Rotterdam and Nijmegen) in the Netherlands, where prehospital thrombolysis is an established way of treatment of acute myocardial infarction.

METHODS

Prehospital thrombolysis is performed using electrocardiogram diagnosis by the ambulance service as well as bolus anistreplase for treatment in Nijmegen, and streptokinase infusion in Rotterdam. Reteplase or anistreplase/streptokinase was assigned open label to patients according to order of presentation on a 1-to-1 basis. All patients were treated with nitrates sublingually and aspirin orally. Time intervals were recorded by the ambulance staff.

RESULTS

In total, 250 patients were treated between April 1, 1999 and August 1, 2000. Reteplase was used in 120 patients and anistreplase/streptokinase in 130 patients. Using double bolus reteplase resulted in a significantly shorter time to treatment: a median of 81 minutes compared to a median of 104 minutes with the established therapy (P <.0001). There were no differences in mortality, aborted myocardial infarction, hemorrhagic stroke or the need for rescue angioplasty between the groups.

CONCLUSION

In prehospital thrombolysis, double bolus reteplase is associated with a shorter time to treatment than bolus anistreplase or infusion of streptokinase.

ST-segment monitoring in patients with acute coronary syndromes

ST-segment analyses from electrocardiograms during acute coronary syndromes (ACS) have repeatedly shown strong mechanistic links to coronary artery patency and myocardial reperfusion. In these patients, such analyses have also consistently been reported to have close correlations with outcome--correlations superior even to those reported for invasive coronary flow measurements and outcome. Continuous multilead ST-monitoring of patients with ACS provides accurate and noninvasive information on the dynamics of the myocardial reperfusion process over time. This information can be used for improved early diagnostic accuracy, evaluation of treatment efficacy, early risk-stratification, and can be supportive in clinical decision making regarding these patients. Continuous multilead ST-monitoring during ACS is no longer a cumbersome source of more nuisance than benefit, but can be an accurate and useful tool in multicenter clinical trials, as well as in clinical medicine.