Intravenous and intracoronary fibrinolytic therapy in acute myocardial infarction: overview of results on mortality, reinfarction and side-effects from 33 randomized controlled trials

How women label and respond to symptoms of acute myocardial infarction: responses to hypothetical symptom scenarios

OBJECTIVE

To investigate how women label and intend to respond to common and less common symptoms of acute myocardial infarction (AMI).

DESIGN

Telephone interviews were conducted with 862 women older than age 50 years in the state of Washington.

OUTCOME MEASURES

Intended coping strategies, labeling of hypothetical symptoms, perceived risk of AMI, knowledge of AMI symptoms, medical and family history of AMI and demographics.

RESULTS

Women who labeled common or less common symptoms as a heart attack (65% and 36%, respectively) were more likely to report they would call 911 or go to a hospital right away than women who labeled these symptoms as something else. The results of a multiple logistic regression analysis suggests that knowledge of less common AMI symptoms, AMI information seeking, and personal risk perceptions were significant predictors of labeling less common symptoms as a heart attack.

CONCLUSIONS

The findings suggest that many women might be in danger of mislabeling their symptoms and not taking appropriate action. Women need to be educated about the less common symptoms of AMI and need to be encouraged to seek out information regarding AMI.

Comparison of myocardial perfusion imaging and cardiac troponin I in patients admitted to the emergency department with chest pain

BACKGROUND

Identification of patients with acute coronary syndromes (ACS) among those who present to emergency departments with possible myocardial ischemia is difficult. Myocardial perfusion imaging with 99mTc sestamibi and measurement of serum cardiac troponin I (cTnI) both can identify patients with ACS.

METHODS AND RESULTS

Patients considered at low to moderate risk for ACS underwent gated single-photon emission CT sestamibi imaging and serial myocardial marker measurements of creatine kinase-MB, total creatine kinase activity, and cTnI over 8 hours. Positive perfusion imaging was defined as a perfusion defect with associated abnormalities in wall motion or thickening. cTnI >/=2.0 ng/mL was considered abnormal. Among the 620 patients studied, 59 (9%) had myocardial infarction and 81 (13%) had significant coronary disease; of these patients, 58 underwent revascularization. Perfusion imaging was positive in 241 patients (39%), initial cTnI was positive in 37 (6%), and cTnI was >/=2.0 ng/mL in 74 (12%). Sensitivity for detecting myocardial infarction was not significantly different between perfusion imaging (92%) and cTnI (90%), and both were significantly higher than the initial cTnI (39%). Sensitivity for predicting revascularization or significant coronary disease was significantly higher for perfusion imaging than for serial cTnI, although specificity for all end points was significantly lower. Lowering the cutoff value of cTnI to 1.0 ng/mL did not significantly change the results.

CONCLUSIONS

Early perfusion imaging and serial cTnI have comparable sensitivities for identifying myocardial infarction. Perfusion imaging identified more patients who underwent revascularization or who had significant coronary disease, but it had lower specificity. The 2 tests can provide complementary information for identifying patients at risk for ACS.

The importance of randomized clinical trials and evidence-based medicine: a clinician's perspective

Clinical evaluation of therapies for patient care has evolved during the twentieth century from a variety of scientific methods. As a result of medical, political, and economic changes that occurred in the 1990s, randomized clinical trials and evidence-based methods are presently in the forefront of the physician's thinking in the decision-making process for therapeutic interventions. A new standard of patient care has emerged during this process. This report provides a clinician's viewpoint of the importance and interpretation of evidence-based methods and suggests a strategy when such evidence does not exist.

Emergency management of acute myocardial infarction. Focus on pharmacologic therapy

Treatment of acute myocardial infarction has evolved significantly in the past two decades. Reperfusion therapies of thrombolysis and percutaneous angioplasty are major advances that can be employed to save infarcting myocardium and reduce mortality. When reperfusion therapy is combined with the use of aspirin, beta-blockade, heparin, and nitroglycerin, the emergency management of the patient with myocardial infarction can be completed. Outcomes in patients are determined by what happens in the first few minutes to hours after onset, and any delay in diagnosis or treatment may have significant consequences. This article reviews intervention and treatment strategies for acute myocardial infarction.

Thrombolytic therapy: a review of its use in acute myocardial infarction

OBJECTIVE

To review the literature on the use of thrombolytic agents in the pharmacotherapeutic management of acute myocardial infarction (AMI).

DATA SOURCE

English-language clinical trials, reviews, and editorials derived from MEDLINE (January 1966-September 1997) and/or cross-referencing of selected articles.

STUDY SELECTION

Articles that were selected best represent the clinical trials researching the role for thrombolytics in the therapy of AMI to improve morbidity and mortality.

DATA SYNTHESIS

AMI is one of the leading causes of mortality in the US. Following supportive data that the most common cause of an AMI is an intracoronary thrombus, clinical investigation has demonstrated that intravenous thrombolytic agents improve survival rates in patients who experience an AMI. Several clinical trials have been conducted to determine whether one thrombolytic agent is superior to others with respect to improving mortality. At present, only the first Global Use of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) trial has reported any statistically significant difference in mortality rate. In this trial, "front-loaded" alteplase induced a statistically significant (p < 0.001) 1% absolute reduction in 30-day and 1-year mortality compared with streptokinase. This has led to alteplase being the preferred thrombolytic at many US institutions. However, the results of GUSTO-I have been questioned by some on the basis of either study design or clinical significance.

CONCLUSIONS

Thrombolytic agents have secured a place in the treatment of AMI due to their well-proven reduction in mortality rates. In general, comparative trials have demonstrated minimal differences in efficacy among these agents. Probably just as important as choosing which thrombolytic agent to use is ensuring that a patient experiencing an AMI is administered thrombolytic therapy unless a contraindication to receive such therapy exists in the patient and/or the patient is a candidate to receive an emergent intracoronary procedure. Trials also indicate that the sooner thrombolytics can be administered, the greater the benefit to the patient.

Effects of aspirin on angiotensin-converting enzyme inhibition and left ventricular dilation one year after acute myocardial infarction

There are conflicting reports on the interaction of aspirin with angiotensin-converting enzyme inhibitors in heart failure and systemic hypertension. A post hoc analysis of the Captopril and Thrombolysis Study (CATS) study was conducted. At randomization, 94 patients (31.5%) took aspirin. In patients who took aspirin, the cumulative alpha-hydroxy butyrate dehydrogenase release was 1,151 +/- 132 IU/L in patients randomized to captopril compared with 1,401 +/- 136 IU/L in patients randomized to placebo (difference -250 +/- 189 [95% confidence interval (CI) -620 to 120]). This difference was comparable to the difference in patients who did not use aspirin (-199 +/- 147 [95% CI -488 to 897]). One year after acute myocardial infarction, an increase in left ventricular end-diastolic volume index of 2.2 +/- 3.0 ml/m2 in captopril-treated and 1.9 +/- 2.9 ml/m2 in placebo-treated patients was observed in patients who took aspirin (difference 0.4 +/- 4.2 [95% CI -8.2 to 8.9]). This difference was also comparable to the difference in patients who did not take aspirin (2.2 +/- 3.8 [95% CI -5.2 to 9.7]). One year after acute myocardial infarction, patients who did take aspirin had a mean change in LV end-diastolic volume index of 2.1 +/- 2.1 ml/m2 compared with 8.4 +/- 1.9 ml/m2 in patients who did not use aspirin (p = 0.02). Thus, aspirin does not attenuate the acute and long-term effects of angiotensin-converting enzyme inhibition after acute myocardial infarction, but independently reduces LV dilation after myocardial infarction.

Thrombolysis for acute myocardial infarction

Thrombolytic therapy has been a major advance in the management of acute myocardial infarction. Unfortunately, it continues to be underused or is administered later than is optimal. Thrombolytic therapy works by lysing infarct artery thrombi and achieving reperfusion, thereby reducing infarct size, preserving left ventricular function, and improving survival. The most effective thrombolytic regimens achieve angiographic epicardial infarct-artery patency in only approximately 50% of patients within 90 minutes. Bleeding requiring transfusion occurs in approximately 5% of patients and stroke in approximately 1.8% with these regimens, which include adjunctive aspirin and intravenous heparin. There are several ways in which reperfusion rates and thus patient outcomes might be improved, such as different dosing regimens of established agents; combinations of different agents; improved adjunctive therapy such as direct antithrombin agents, low-molecular-weight heparin, or glycoprotein IIb/IIIa receptor antagonists; or the development of novel thrombolytic agents with enhanced fibrin specificity, resistance to native inhibitors, or prolonged half-lives allowing bolus administration. All of these strategies are being tested in clinical trials. The best approach currently is to administer thrombolytic therapy as soon as possible to all patients without contraindications who present within 12 hours of symptom onset and have ST-segment elevation on the ECG or new-onset left bundle-branch block, unless an alternative reperfusion strategy is planned.

Thrombolytic Therapy in Acute Myocardial Infarction Part II: 1997 Update

Thrombolytic therapy has become an established treatment for acute myocardial infarction. Streptokinase was first demonstrated in 1988 to reduce mortality rates. In 1993, tissue plasminogen activator was shown to have a slight superiority over streptokinase in reducing mortality rates (approximately 1%). Reteplase is a second generation thrombolytic agent that is given in two bolus injections intravenously over 30 minutes. Studies demonstrated slightly better and more rapid improvement in myocardial perfusion with reteplase compared to tissue plasminogen activator. However, recent studies showed 30-day mortality rates in patients treated with reteplase were similar as those treated with tissue plasminogen activator. The use of angioplasty, aspirin, beta blockers, angiotensin converting enzyme inhibitors, and lipid lowering agents also contribute to the reduction of mortality from acute myocardial infarction.

Meta-analysis of randomized trials: looking back and looking ahead

Meta-analyses as currently practiced are usually retrospective. They can be made more rigorous by developing a protocol that incorporates prospectively the elements that are usually necessary in a well-designed trial. Meta-analysis and large trials are complementary. Meta-analysis of small trials is useful in generating the hypotheses and assisting in the design of the large trials that are needed. Once the large trials have been completed, they could be brought together within the framework of a meta-analysis to estimate the overall treatment effect with greater confidence and to explore the effects in various subgroups. This article explores the value and limitations of meta-analyses and suggests ways of improving their conduct and interpretation.

Approaches to informed consent

Informed consent (IC) is an indicator, or a pivotal point, in broader and more fundamental questions dealing with the way clinical experimentation and, more specifically, randomized controlled trials (RCTs) relate to routine clinical practice; the rules that characterize the doctor-patient relationship; the self-perception of medicine with respect to its capacity, duty, and autonomy in the production of new knowledge; and the role of medicine in society. The asymmetry of knowledge and power that characterizes the usual relationship between care providers and patients does not resolve when something experimental enters the relationship. The real world of clinical investigation is not uniformly distinct from clinical practice. Experimentation is more appropriately considered a continuum with respect to appropriate or recommended care. Fundamental patient rights come first and are more binding than compliance with procedures and regulations. The view that IC is the most important component of the "ethical" aspects of experimentation is highly misleading. The responsibility to foster well-informed decisions shapes the contents, the timing, the validity, and the credibility of IC. Documented, evaluable decisions are the natural substitute for individual IC when the patient is not able to handle information autonomously. Positive examples of IC practices and approaches suggest that IC may be important in improving the way medicine responds to its responsibilities and communicates with society.

Strengths and limitations of meta-analysis: larger studies may be more reliable

Meta-analysis of randomized controlled trials combines information from independent studies that address a similar question to provide more reliable estimates of treatment effects. At the present time, the methodology and usefulness of meta-analysis is under scrutiny. In the first part of this paper, we summarize the limitations of meta-analysis and make suggestions for improvements. In the second part, we illustrate strengths and limitations using examples of meta-analyses and subsequent large trials that address the same question. We develop the hypothesis that the size of the meta-analysis may be a useful measure of reliability. Small meta-analyses (i.e., those with less than 200 outcome events) may only be useful for summarizing the available information and generating hypotheses for future research. The results of small meta-analyses should be regarded with caution, even if the p value shows extreme statistical significance. Larger meta-analyses (i.e., those with several hundred events) are likely to be more reliable and may be clinically useful. Well-conducted meta-analyses of large trials using individual patient data may provide the best estimates of treatment effects in the cohort overall and in clinically important subgroups.

'Call fast, Call 911': a direct mail campaign to reduce patient delay in acute myocardial infarction

OBJECTIVES

A 10-month direct mail campaign was implemented to increase use of emergency medical services via 911 calls and to reduce prehospital delay for individuals experiencing acute myocardial infarction symptoms.

METHODS

This prospective, randomized, controlled trial involved three intervention groups (receiving brochures with informational, emotional, or social messages) and a control group.

RESULTS

Intervention effects were not observed except for individuals who had a history of acute myocardial infarction and who were discharged with a diagnosis of acute myocardial infarction; their 911 use was meaningfully higher in each intervention group than in the control group.

CONCLUSIONS

The mailings affected only the individuals at greatest risk.

Discrepancies between meta-analyses and subsequent large randomized, controlled trials

BACKGROUND

Meta-analyses are now widely used to provide evidence to support clinical strategies. However, large randomized, controlled trials are considered the gold standard in evaluating the efficacy of clinical interventions.

METHODS

We compared the results of large randomized, controlled trials (involving 1000 patients or more) that were published in four journals (the New England Journal of Medicine, the Lancet, the Annals of Internal Medicine, and the Journal of the American Medical Association) with the results of meta-analyses published earlier on the same topics. Regarding the principal and secondary outcomes, we judged whether the findings of the randomized trials agreed with those of the corresponding meta-analyses, and we determined whether the study results were positive (indicating that treatment improved the outcome) or negative (indicating that the outcome with treatment was the same or worse than without it) at the conventional level of statistical significance (P<0.05).

RESULTS

We identified 12 large randomized, controlled trials and 19 meta-analyses addressing the same questions. For a total of 40 primary and secondary outcomes, agreement between the meta-analyses and the large clinical trials was only fair (kappa= 0.35; 95 percent confidence interval, 0.06 to 0.64). The positive predictive value of the meta-analyses was 68 percent, and the negative predictive value 67 percent. However, the difference in point estimates between the randomized trials and the meta-analyses was statistically significant for only 5 of the 40 comparisons (12 percent). Furthermore, in each case of disagreement a statistically significant effect of treatment was found by one method, whereas no statistically significant effect was found by the other.

CONCLUSIONS

The outcomes of the 12 large randomized, controlled trials that we studied were not predicted accurately 35 percent of the time by the meta-analyses published previously on the same topics.

Diagnostic criteria and management of subacute ventricular free wall rupture complicating acute myocardial infarction

In this prospective study we evaluated the value of the main diagnostic criteria for postinfarction subacute rupture of the ventricular free wall. Two-dimensional echocardiograms and recordings of right atrial pressure and waveform were immediately obtained in every patient exhibiting rapid clinical and/or hemodynamic compromise in the acute infarction setting. The same protocol was applied to patients referred from other hospitals for suspected myocardial rupture. In 28 cases a subacute free wall rupture was identified. In most of the patients the diagnosis was based on the demonstration of hemopericardium and cardiac tamponade by echocardiography, cardiac catheterization and, occasionally, by pericardiocentesis. In 2 instances, the identification of intrapericardial echo densities suggesting clots, in the absence of cardiac tamponade, allowed a diagnosis of subacute rupture. Direct, but indistinct visualization of myocardial rupture was obtained in 4 cases. Among the 28 patients with this complication, 4 died while awaiting surgery and 24 underwent surgical repair (mortality rate 33%). Long-term outcome of survivors was favorable. Various myocardial lesions underlie postinfarction subacute free wall rupture. Clinical presentation varied widely. The diagnosis was based, usually but not always, on the association of hemopericardium and signs of cardiac tamponade. An organized approach to management of this complication of acute myocardial infarction was suggested.

Evolution of late potential parameters in thrombolyzed acute myocardial infarction might predict patency of the infarct-related artery

The objective was to predict the patency grade of an infarct-related artery by identifying the time course of the changes of the late potential parameters before, during, and shortly after thrombolysis. The study population consisted of 51 patients with acute myocardial infarction (AMI) who received thrombolytic therapy within 3.2 +/- 1.3 hours from the onset of symptoms. Multiple signal-averaged electrocardiograms (SAECGs) were recorded before, during, and shortly after thrombolysis. A total of 489 single-averaged electrocardiographic tracings were evaluated. Late potentials were defined as: QRS duration > 114 ms, low amplitude signals (LASs) > 38 ms, and root mean square (RMS) < 20 microV. Late potentials were found in 37% of patients (21 before and 16 during the first 2 hours of thrombolysis), disappeared in all of patients within 89 +/- 75 minutes (range 25 to 350) but reappeared and persisted in 12% of patients, all with an occluded artery (grade 0). The late potential parameters (QRS, LAS, RMS) showed a gradual improvement which occurred earlier (2 vs 4 hours) and was more marked (0.01 vs 0.05) in cases with a patent artery. This improvement expressed by the late potential parameter index (LnQRS + LnLAS - LnRMS) predicts the patent artery with a sensitivity of 0.94 and specificity of 0.79. The improvement of late potential parameters jointly with close to normal initial values or the late potential parameter index and its changes constituted a satisfactory prediction of the patency grade. Thus, the signal-averaged electrocardiographic technique is capable of predicting the early success or failure of thrombolytic therapy.

Meta-analysis and investigation of anti-infective therapies

Meta-analysis offers an alternative approach to examining specific sub-groups, such as classes of antibiotics, types of bacteria as well as patient groups whose response to the agent under investigation may not be equivalent. In this review, the strengths and pitfalls of meta-analyses of anti-infective therapies will be discussed.

Prognostic value of exercise 201Tl tomography in patients treated with thrombolytic therapy during acute myocardial infarction

BACKGROUND

Although myocardial perfusion scintigraphy is of proven value in the risk stratification of patients with a recent myocardial infarction who receive conventional therapy, its value in patients undergoing thrombolytic therapy remains controversial.

METHODS AND RESULTS

Seventy-one patients who received thrombolytic therapy for acute myocardial infarction had exercise 201Tl tomography and coronary angiography before hospital discharge. Eleven (15%) of 71 patients had ischemic ST-segment depression during exercise, whereas 27 patients (38%) had scintigraphic ischemia. Twenty-five (37%) of 68 patients had a cardiac event consisting of either death (n = 2), recurrent myocardial infarction (n = 5), congestive heart failure (n = 7), or unstable angina (n = 11) during a follow-up of 26 +/- 18 months. Univariate predictors of cardiac events were as follows: Killip class (P = .04); left ventricular ejection fraction (P < .0005); total (P = .002) and ischemic (P < .0005) perfusion defect size; percent thallium lung uptake (P = .001); presence of infarct-zone redistribution (P = .02); and multivessel coronary artery disease (P = .01). By multivariate analysis, the significant joint predictors of risk were ejection fraction (P < .0005) and ischemic perfusion defect size (P = .005). The combination of ejection fraction and thallium tomography added significant incremental prognostic information to the clinical data, whereas angiography did not further improve a model that included clinical, ejection fraction, and tomographic variables.

CONCLUSIONS

Quantitative exercise 201Tl tomography provides important incremental, long-term prognostic information in patients receiving thrombolytic therapy for acute myocardial infarction.

Angiotensin-converting enzyme inhibitors and coronary artery disease

The renin-angiotensin system and angiotensin converting enzyme (ACE) are increasingly being implicated in the pathogenesis of coronary artery disease and its sequelae. Genetic studies of ACE gene polymorphism hint at an association between the ACE genotype and atherosclerosis. Animal studies have demonstrated the potential beneficial effects of ACE inhibition at a variety of sites, including improvement of endothelial function, inhibition of platelet aggregation, reduction of atherosclerosis, and inhibition of myointimal proliferation. Although these have not all been validated in human studies, the reduction of ischemic events in studies of ACE inhibition in left ventricular dysfunction cannot be explained solely by improved hemodynamics, and it is possible that actions on the endothelium, the atherosclerotic process, and platelets are at least in part responsible. The results of studies in humans looking more directly at the influence of ACE inhibitors on atherosclerosis and ischemic heart disease are awaited.

Timing of ventricular septal rupture after acute myocardial infarction and its relation to thrombolytic therapy

The clinical and treatment characteristics of 71 patients who had acute myocardial infarction complicated by ventricular septal rupture were assessed retrospectively. A history of hypertension was strongly associated with "early" septal rupture (p < 0.001); other clinical and treatment characteristics, including the use and timing of thrombolytic therapy, were not.

Thrombolytic therapy for cerebral infarction

Until recently, no clinically effective therapy for acute ischemic stroke has been available. Recent advances in the use of thrombolytic therapy for ischemic stroke appear promising in clinical care. As the use of thrombolytic therapy in acute stroke progress, emergency physicians (EPs) will become increasingly involved in its implementation. The EP must be cognizant of both prior and ongoing investigations in acute ischemic stroke therapy. To that end, this article reviews research in the field of thrombolytic therapy for acute ischemic stroke.

Trends and variations in use of antenatal corticosteroids to prevent neonatal respiratory distress syndrome: recommendations for national and international comparative audit. Scottish Neonatal Consultants' Collaborative Study Group, International Neonatal Network

OBJECTIVES

In 1990 a meta-analysis of randomised trials showed 70% lower mortality after antenatal corticosteroid therapy for 24 h or more for infants born before 31 weeks gestation. We investigated whether antenatal corticosteroid therapy has increased in these infants since 1990 and studied variations in use by hospital of birth.

DESIGN

Retrospective cohort study in 1601 infants in nine neonatal units.

SUBJECTS

Neonatal admissions before 31 weeks of gestation from January 1988 to October 1993. MEASURE OF OUTCOME: Corticosteroids administered for 24 h or more before delivery.

RESULTS

Data were obtained in 1579 (99%) infants. The proportion (range) in each hospital whose mothers had antenatal corticosteroids for 24 h or more was 16% (0-43) in 1988-89 and 29% (0-36) in 1990-93 (P < 0.001). In post hoc analyses, 65/347 (20%) births in district hospitals had treatment for 24 h or more compared with 354/1254 (28%) in teaching hospitals (P = 0.001).

CONCLUSIONS

Antenatal corticosteroid therapy increased but varied by hospital of birth. This may reflect varying performance, or bias from reporting, selection or referral. Ideally, corticosteroid therapy should be compared in women at risk of preterm delivery, but standardising risk or indications for delivery between hospitals and accurate ascertainment presents major difficulties. To minimise selection or referral bias, hospitals should publish, for all mothers delivering between 24 and 33 weeks and 6 days gestation 48 h or more after admission, the proportions treated 1. for 24 h or more (target: > 70%), or 2. at all (target: > 90%).

Early management of acute myocardial infarction: thrombolysis, angioplasty, and adjunctive therapies

Early identification and treatment, including administration of intravenous thrombolytics, coronary angioplasty, and adjunctive therapies, has been shown to benefit patients who present with acute myocardial infarction. However, only a small percentage of these patients receive such therapies because of late presentation, associated risks, and controversies around certain myocardial infarct subsets. The logistics involved in carrying out these treatments have resulted in unnecessary prehospital and in-hospital delays. These issues make essential the availability of a streamlined protocol that should be updated at regular intervals to ensure that these time-dependent therapies are more routinely and rapidly utilized. This article discusses these topics in conceptual format and provides a ready-to-use protocol.

Thrombolytic therapy. From myocardial to cerebral infarction. The MAST-I Group. Multicentre Acute Stroke Trial

Thrombolysis is proposed for the acute treatment of cerebral infarction as it is able to recanalize occluded arteries and thus potentially restore normal perfusion of the cerebral parenchyma, but the results concerning the efficacy of this treatment are still inconclusive. However, it has been fully demonstrated that thrombolytic treatment, leads to a significant reduction in mortality, in patients with acute myocardial infarction. Data from all of the pilot studies using SK or tPA treatment in acute stroke are described in this review, which underlines the incidence of hemorrhagic transformation (hemorrhagic infart and parenchymal hematoma) and its possible correlation to clinical worsening. Pharmacological, experimental and clinical studies encourage the carrying out of large-scale clinical trials using thrombolytics in patients with acute cerebral infarction. Significant data relating to ongoing controlled clinical trials will be available in the near future; only after the analysis of these results will it be possible to confirm the efficacy of thrombolytics in acute stroke.

Decreased free radical scavengers with reperfusion after coronary angioplasty in patients with acute myocardial infarction

Early reperfusion after myocardial infarction improves survival rate and is thought to preserve myocardial function, but the reperfusion of ischemic tissue may release oxygen free radicals, which could adversely affect left ventricular function and diminish the beneficial effects of reperfusion. Measurements related to free radical scavenging (plasma and erythrocyte enzyme systems, which are involved in free radical control, alpha-tocopherol, selenium, and manganese superoxide dismutase) may be indirect markers of free radical production. We evaluated 10 patients undergoing coronary angioplasty within 4 hours of myocardial infarction to measure the impact of abrupt reperfusion on free radical scavenger-related indexes. Pulmonary artery samples were taken before, immediately after, and 3 hours after angioplasty. During reperfusion, significant reductions occurred in alpha-tocopherol (1.1 +/- 0.3 mg/dl before, 0.9 +/- 0.2 mg/dl immediately after [p = 0.03], and 0.8 +/- 0.2 mg/dl 3 hours after percutaneous transluminal coronary angioplasty [p = 0.02]), and selenium levels (13.7 +/- 2.4 micrograms/dl before, 12.9 +/- 2.4 micrograms/dl immediately after, and 10.2 +/- 3.0 micrograms/dl 3 hours after angioplasty [p = 0.0006]). Erythrocyte markers (glutathione peroxidase and superoxide dismutase) were not altered by reperfusion, possibly reflecting the relatively long half-life of the erythrocyte. The erythrocyte glutathione peroxidase value before reperfusion in patients (30.8 +/- 5.1 IU/gm of hemoglobin) was lower than in a control group (36.1 +/- 6.5 IU/gm of hemoglobin; p = 0.01). Thus the decrease in plasma alpha-tocopherol and selenium after reperfusion in this group of patients may reflect a general alteration in plasma free radical scavenger levels, suggesting consumption of plasma free radical scavengers with reperfusion after acute myocardial infarction.

Chronic-intermittent urokinase therapy in patients with end-stage coronary artery disease and refractory angina pectoris--a pilot study

Patients with coronary artery disease and severe angina pectoris refractory to conventional medical treatment (beta blockers, nitrates, calcium antagonists) and without the option for invasive revascularization procedures represent an increasing clinical problem. For these patients, chronic-intermittent urokinase therapy has been developed. Twenty patients received 500,000 IU urokinase as intravenous bolus injection 3 times a week over a period of 12 weeks. The average reduction in anginal symptoms in 19 patients was 74%, from 23.5 +/- 10.8 to 5.2 +/- 4.8 events/week (p < 0.001); 1 patient was excluded from further treatment because of an increase of > 66% in anginal events. Fibrinogen decreased by 34% from 370 +/- 57 to 244 +/- 44 mg/dl (p < 0.001), the rheological parameters plasma viscosity by 6.1% from 1.39 +/- 0.04 to 1.31 +/- 0.03 mPas (< 0.001), and red blood cell aggregation by 18% from 13.9 +/- 2.4 to 11.2 +/- 2.2 (p < 0.001). Exercise tolerance increased by 51%. Average ST-segment depression decreased from 0.16 +/- 0.10 to 0.12 +/- 0.09 (p < 0.01). After 12 weeks of follow-up, angina pectoris and fibrinogen levels were still significantly reduced compared with baseline values. Chronic-intermittent urokinase therapy represents an effective anti-ischemic and antianginal approach in patients with refractory angina pectoris and end-stage coronary artery disease. Improvement of rheological blood properties and thrombolytic effects are likely therapeutic mechanisms.

Thrombolysis acute ischemic stroke

Thrombolysis is an attractive but potentially dangerous they for cerebral ischemia: it is capable of dissolving an arterial thrombus, but can also transform a pale infarct into a hematoma and/or may cause severe oedema and herniation. The safety and efficacy of the treatment critically depend on the timing of intervention ad on patient selection. In recent studies on ischemic stroke, spontaneous hemorrhagic transformation of an infarct seems to be related to the size of the lesion, and can be reliably predicted as early as five hours from stroke onset by the presence of focal hypodensity in the CT scan. That is why in the European Co-operative Acute Stroke (ECASS), a randomised, double blind trial on intravenous rt-PA in hemispheric stroke, patients showing, on the admission CT scan, extended early hypodensity, involving more than one third of the territory of the middle cerebral artery, were excluded from the day. Other ongoing trials on thrombolytic agents are expected to provide further indications on how to identify those patients most likely to benefit and least likely to experience adverse effects from this treatment.

Gender differences and factors associated with the receipt of thrombolytic therapy in patients with acute myocardial infarction: a community-wide perspective

In spite of national interest in gender differences in the presentation and management of chronic disease, limited information is available about possible gender differences in the receipt of thrombolytic therapy after acute myocardial infarction (AMI). As part of an ongoing community-based study of AMI, we examined gender differences in the receipt of thrombolytic therapy among 2885 patients with confirmed AMI. The study sample consisted of 1680 males and 1205 females with validated AMI who were admitted to 16 hospitals in the Worcester, Massachusetts, metropolitan area in four study periods between 1986 and 1991. During the years under study, 24.4% of men and 14.4% of women received thrombolytic therapy. Increases over time in the use of thrombolytic therapy were seen in both men (13.9% in 1986; 31.6% in 1991) and women (3.2% in 1986; and 19.0% in 1991). After controlling for a variety of factors that might affect use of thrombolytic agents, younger age, absence of a history of either congestive heart failure or stroke, and experiencing a Q-wave AMI were associated with receipt of thrombolytic therapy in both men and women; having an anterior AMI also was associated with use of thrombolytic agents in men. Women without as compared with those with a history of angina pectoris were significantly more likely to receive thrombolytics. Men who had Medicare insurance were significantly less likely to receive thrombolytics than were men with other types of health insurance. When this analysis was restricted to patients who were seen in area-wide hospitals within 6 hours of the onset of symptoms suggestive of AMI, similar factors were associated with the receipt of thrombolytic agents in men and women. The results of this community-wide study suggest a marked increase over the 5-year study period in the use of thrombolytic therapy in both men and women, with a greater relative increase observed in women. A relatively similar profile of patients likely to receive thrombolytic therapy was seen in both men and women.

Incomplete, delayed functional recovery late after reperfusion following acute myocardial infarction: "maimed myocardium"

The objective of the current editorial is to introduce a new concept ("maimed myocardium") that we believe describes more accurately the incomplete, delayed recovery of LV function that may occur late after reperfusion after AMI. It has been demonstrated previously that myocardium remains viable for a prolonged period in many patients with nonsustained coronary occlusion, despite the occurrence of myocardial necrosis; late reperfusion may result in myocardial salvage in reversibly ischemic (stunned) segments (complete recovery) and in intensely injured (maimed) segments that display partial return of LV function over time (incomplete recovery). Clinically, the basis for maimed myocardium is the observation that delayed, LV functional recovery may occur in partially infarcted segments where there has been an antecedent ischemic insult of sufficient duration to result in some degree of myocardial necrosis. Certain acute coronary syndromes characterized by nonsustained coronary occlusion followed by spontaneous reperfusion (e.g., non-Q-wave AMI) or drug-induced reperfusion induced by the exogenous administration of thrombolytic therapy are associated with incomplete, delayed recovery of LV function as detected clinically by partial improvement in serial radionuclide-ejection measurement, enhanced metabolic integrity of cardiac tissue by F-18 deoxyglucose myocardial imaging, and scintigraphic findings of reverse thallium redistribution--findings that support the presence of partially viable myocardium that has been incompletely salvaged during reperfusion late after AMI. Experimentally, delayed LV functional recovery has been reported in animal models in which prolonged coronary occlusion (hours to days) followed by reperfusion is associated with late recovery of regional LV function in myocardial segments subtending border (stunned) zones and central infarct (maimed) zones. In studies in animals and human beings, postextrasystolic potentiation and pharmacologic inotropic interventions may augment maimed and stunned segments, although the magnitude of regional contractile reserve that can be unmasked with these interventions is quantitatively less in the maimed than in stunned segments. In summary, the propensity of intensely injured or partially infarcted LV segments to display intermediate functional recovery followed by reperfusion late after coronary occlusion suggests that even severely depressed but residually viable cardiac muscle can be salvaged incompletely over time.(ABSTRACT TRUNCATED AT 400 WORDS)

Finger-like lysing patterns of blood clots

One-dimensional modeling of fibrinolysis (Senf, 1979; Zidansek and Blinc, 1991; Diamond and Anand, 1993) has accounted for the dissolution velocity, but the shape of the lysing patterns can be explained only by two- or three- drug-induced blood clot dissolution patterns obtained by proton nuclear magnetic resonance imaging, which can be described by the enzyme transport-limited system of fibrinolytic chemical equations with diffusion and perfusion terms (Zidansek and Blinc, 1991) in the reaction time approximation if the random character of gel porosity is taken into account. A two-dimensional calculation based on the Hele-Shaw random walk models (Kadanoff, 1985; Liang, 1986) leads to fractal lysing patterns as, indeed, is observed. The fractal dimension of the experimental lysing patterns changes from 1.2 at the beginning of the experiments to a maximum of approximately 1.3 in the middle and then decreases toward one when the clot is recanalized.

[Myocardial infarction and revascularization. Current indications]

The physiopathologic role of thrombosis in the genesis of myocardial infarction, began to be suspected early in the 20th century but its logical treatment, thrombolysis, was first used on a large scale only ten years ago. Today, it is well established that short, middle and long-term mortality is correlated to coronary permeability, the delay in the revascularization treatment start-up, its efficacy, its swiftness of action, and to the maintaining of permeability following reperfusion. The importance of time elapse before reperfusion is obtained was demonstrated as early as 1986 by the GISSI study. According to this study, the administration of streptokinase (compared to a conventional treatment) reduced mortality at 21 days respectively by 47%, 23%, and 17%, depending on whether patients were treated within one hour, three hours, or between 3 and 6 hours following the onset of the painful symptoms. One of the major teachings of the GUSTO study, reported at the end of 1993, was the confirmation of the so-called "open artery" theory: mortality at 30 days was of 4.5% among patients whose coronary circulation was restored at the 90th minute, whatever thrombolytic treatment was used, compared to 8.9% when the coronary artery remained occluded. The value of aspirin in preserving coronary permeability following thrombolysis was demonstrated by the ISIS-2 study: mortality at 5 weeks was reduced by 23% in the group of patients randomised to receive only aspirin, while it was reduced by 25% in the group of patients randomised to be treated with streptokinase, and by 42% in the group randomised to receive both aspirin and streptokinase, compared to the group who received neither aspirin nor streptokinase. However, mortality during the first days following randomisation was identical among the groups, with or without aspirin, which suggested its action was rather one of prevention against reocclusion than one of accelerating dissolution of the thrombus. However, in spite of improved therapeutical protocols, a normal flow, which is the major criteria for a reduced mortality, is only obtained at the 90th minute in 54% of the patients who were administered the up-to-date treatment ie aspirin-accelerated t-PA-heparin in combination.(ABSTRACT TRUNCATED AT 400 WORDS)

Delay times in the administration of thrombolytic therapy: the Brighton experience

We reviewed the effectiveness of a strategy involving paramedic ambulances and community education to reduce the delay to thrombolytic therapy in patients admitted with acute myocardial infarction, by analysing delay times recorded during routine treatment. Rapid identification and treatment of patients with acute myocardial infarction who were eligible for thrombolysis was carried out in the Accident and Emergency and Cardiac Care Units. Two hundred seventy-four patients were admitted with acute myocardial infarction over an 18-month period and treated with anistreplase (168) or streptokinase (106). The following median times were recorded: symptom onset to administration of thrombolytic therapy, 142 min (range 43-980 min); symptom onset to ambulance arrival, 60 min; ambulance with patient to arrival in hospital, 35 min; time to treatment in hospital ('door to needle time'), 25 min; in-hospital delays were notably shorter for patients given anistreplase as opposed to streptokinase. Shortened delays for the delivery of thrombolytic therapy can be achieved by a strategy involving public education, the availability of resuscitation ambulances, and close liaison with the Accident and Emergency Department.

Timing, mode, and predictors of death after direct angioplasty for acute myocardial infarction

The timing and mechanisms of early (30 day) mortality in 330 consecutive patients treated with direct angioplasty less than 12 hr after onset of myocardial infarction without antecedent thrombolysis were studied. There were 38 deaths (11.5% of pts), with a majority being due to cardiogenic shock (76%). Other causes included acute closure (11%), death after emergency bypass surgery (5%), ventricular arrhythmias (5%), and respiratory failure (3%). No deaths from stroke or cardiac rupture were seen, in contrast to trials of thrombolytic agents. Most deaths were seen early, with 47% occurring within 1 day, 35% from days 2-7, and 18% from days 8-30. Death from cardiogenic shock was the most common cause of death throughout this period: 83% of deaths in days 0-3, 88% of deaths in days 4-6, and 43% of deaths in days 8-30. Significant predictors of early death included older age (P < .0001), multi-vessel disease (P < .05), direct angioplasty failure (P < .05), reduced ejection fraction (P < .0001), and anterior myocardial infarction (P < .0005). Gender, prior myocardial infarction, and prior bypass surgery did not affect mortality. Cardiogenic shock is the most common cause of early death after direct angioplasty for myocardial infarction. Patients with one or more risk factors for early death may benefit from additional myocardial salvage or revascularization efforts in the early post-infarct period. Certain causes of death after direct angioplasty (cardiac, rupture, stroke) appear to be less common than data reported for lytic therapy for myocardial infarction.

[Introduction to meta-analytic methodology]

General considerations about meta-analysis and the different steps of this technique are successively discussed: definition of the main objective, identification of the outcome, description of the retrieval and selection of trials, description of the statistical analysis and interpretation of the results. Advantages and drawbacks of the meta-analytical technique are then described: 1) scientific approach, possible quantification of the therapeutic effect, increase of the power of a future clinical trial, synthesis of contradicting results, assessment of the homogeneity, subgroup analysis, analysis of sensibility, scientific collaboration, help for therapeutic information. 2) retrospective approach, inconsistency among trials, potential biases, persistence of some unsolved methodological problems, difficulties for a critical reading and for the interpretation of conclusions. In addition, some examples of published meta-analyses are given to illustrate the advantages and limits mentioned above.

Serum lipids four weeks after acute myocardial infarction are a valid basis for lipid lowering intervention in patients receiving thrombolysis

OBJECTIVE

To compare serum concentrations of total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, and triglycerides four weeks after acute myocardial infarction with baseline levels measured within 24 hours after onset of symptoms.

DESIGN

A prospective study including 141 patients with acute myocardial infarction who were admitted to the coronary care unit at a general hospital.

MEASUREMENTS

Fasting serum concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.

MAIN RESULTS

In patients receiving thrombolytic therapy, no significant differences were found in serum lipids four weeks after admission compared to values estimated within 24 hours from onset of symptoms. In patients not receiving thrombolytic therapy, total cholesterol and low density lipoprotein cholesterol showed a minor increase four weeks after admission compared to values obtained within 24 hours after onset of symptoms. High density lipoprotein cholesterol and triglycerides remained unchanged.

CONCLUSIONS

In patients with acute myocardial infarction receiving thrombolytic therapy, serum lipids measured four weeks after onset of infarction are reasonably valid estimates of baseline lipid levels and may be used to decide about lipid lowering interventions. This information can be a basis for actions against hyperlipidaemia early after hospital discharge when the patient is highly motivated to change lifestyles and is still in close contact with a cardiologist or other physician.