Stroke after thrombolysis. Mortality and functional outcomes in the GUSTO-I trial. Global Use of Strategies to Open Occluded Coronary Arteries

Clinical predictors of early infarct-related artery patency following thrombolytic therapy: importance of body weight, smoking history, infarct-related artery and choice of thrombolytic regimen: the GUSTO-I experience. Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries

OBJECTIVES

The purpose of this study was to determine patient characteristics that are a priori predictors of early infarct related artery patency following thrombolytic therapy, and to provide a paradigm which may identify patients who would be most likely to achieve restoration of normal (TIMI 3) coronary flow in response to thrombolytic therapy.

BACKGROUND

Restoration of infarct-related artery perfusion in acute myocardial infarction is necessary for preservation of ventricular function and mortality reduction. Clinical variables that are a priori predictors of early patency with currently available thrombolytic regimens have not been fully characterized.

METHODS

The probability of early infarct-related artery patency (TIMI 3 flow) was determined by multivariable logistic regression. We determined a reduced (parsimonious) model for predicting early (90 min) infarct-related artery patency (TIMI grade 3) based on data from 1,030 patients in the GUSTO-I Angiographic study.

RESULTS

Predictors of 90 min TIMI 3 flow are use of an accelerated t-PA regimen (vs. streptokinase containing regimens) (chi2=39.1; p < or = 0.0001), infarct related artery (RCA/Lcx vs. LAD) (chi2=12.7; p=0.0004), body weight (chi2=10.3; p=0.001) and history of smoking (chi2=7.4; p=0.007). Time from symptom onset to treatment was not significant (p=0.71).

CONCLUSIONS

The efficacy of currently available thrombolytic regimens is chiefly dependent on choice of thrombolytic regimen, body weight, infarct-related coronary artery and smoking history. Clinical variables alone correctly predict a priori TIMI 3 flow in the infarct-related artery 64% of the time. Patients with body weights greater than 85 kg are at a significant disadvantage with regard to achieving successful thrombolysis compared to those with lesser body weights.

Impact of time to treatment with tissue plasminogen activator on morbidity and mortality following acute myocardial infarction (The second National Registry of Myocardial Infarction)

This study examines the association between time to treatment with thrombolytic therapy and hospital outcomes in patients with acute myocardial infarction (AMI) enrolled in a national registry. A total of 71,253 patients hospitalized with AMI from June 1994 to July 1996 who received tissue plasminogen activator (t-PA) therapy in 1,474 United States hospitals were studied. In this study sample, approximately 39% of patients presented to participating hospitals within 2 hours of acute symptom onset and received t-PA; 36% were treated within 2.1 to 4 hours, 12% between 4.1 to 6 hours, and the remaining 13% thereafter. After controlling for potentially confounding factors, in-hospital death rates increased progressively with increasing delays in time of administration of t-PA. The lowest risk for dying during acute hospitalization was seen for those treated with t-PA within 2 hours of acute symptoms. No significant association was seen between time of administration of t-PA and in-hospital risk of recurrent AMI, myocardial ischemia, cardiogenic shock, major bleeding episodes, or stroke and/or intracranial bleeding. The incidence of sustained ventricular arrhythmias declined with progressively longer time to administration of t-PA. The results of this multihospital observational study suggest that patients with AMI treated earlier with t-PA are significantly more likely to survive the acute hospitalization than patients treated later. These data reinforce the benefits to be gained by treatment with t-PA as soon as possible following the onset of acute ischemic symptoms, and for community-wide efforts to reduce the duration of prehospital delay in patients with acute coronary disease.

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.

Clinical experience with primary percutaneous transluminal coronary angioplasty compared with alteplase (recombinant tissue-type plasminogen activator) in patients with acute myocardial infarction: a report from the Second National Registry of Myocardial Infarction (NRMI-2)

OBJECTIVES

We sought to compare outcomes after primary percutaneous transluminal coronary angioplasty (PTCA) or thrombolytic therapy for acute myocardial infarction (MI).

BACKGROUND

Primary PTCA and thrombolytic therapy are alternative means of achieving reperfusion in patients with acute MI. The Second National Registry of Myocardial Infarction (NRMI-2) offers an opportunity to study the clinical experience with these modalities in a large patient group.

METHODS

Data from NRMI-2 were reviewed.

RESULTS

From June 1, 1994 through October 31, 1995, 4,939 nontransfer patients underwent primary PTCA within 12 h of symptom onset, and 24,705 patients received alteplase (recombinant tissue-type plasminogen activator [rt-PA]). When lytic-ineligible patients and patients presenting in cardiogenic shock were excluded, baseline characteristics were similar. The median time from presentation to initiation of rt-PA in the thrombolytic group was 42 min; the median time to first balloon inflation in the primary PTCA group was 111 min (p < 0.0001). In-hospital mortality was higher in patients in shock after rt-PA than after PTCA (52% vs. 32%, p < 0.0001). In-hospital mortality was the same in lytic-eligible patients not in shock: 5.4% after rt-PA and 5.2% after PTCA. The stroke rate was higher after lytic therapy (1.6% vs. 0.7% after PTCA, p < 0.0001), but the combined end point of death and nonfatal stroke was not significantly different between the two groups (6.2% after rt-PA and 5.6% after PTCA). There was no difference in the rate of reinfarction (2.9% after rt-PA and 2.5% after PTCA).

CONCLUSIONS

These findings suggest that in lytic-eligible patients not in shock, PTCA and rt-PA are comparable alternative methods of reperfusion when analyzed in terms of in-hospital mortality, mortality plus nonfatal stroke and reinfarction.

Thrombin generation, inhibition and clinical outcomes in patients with acute myocardial infarction treated with thrombolytic therapy and heparin: results from the GUSTO-I Trial. GUSTO-I Hemostasis Substudy Group. Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries

OBJECTIVES

We sought to assess the effects of antithrombotic therapy after thrombolysis for acute myocardial infarction on markers of thrombin generation and activity and to determine the relation of these markers with clinical outcomes.

BACKGROUND

Thrombin activation and generation often occur with thrombolysis for acute myocardial infarction. Antithrombotic regimens have been developed to reduce the resulting thrombotic complications.

METHODS

We sampled plasma markers of thrombin generation and activity after thrombolysis in 292 patients. We assessed the relations of these markers with clinical outcomes at 30 days.

RESULTS

Fibrinopeptide A (FPA), a marker of thrombin activity toward fibrinogen, was elevated at baseline (12.3 ng/ml) and increased to 18.4 ng/ml by 90 min after streptokinase and subcutaneous heparin treatment. With intravenous heparin, this increase was attenuated, but intravenous heparin did not prevent thrombin generation, as measured by prothrombin fragment 1.2 (F1.2). Heparin level, measured by anti-Xa activity, correlated with activated partial thromboplastin time (aPTT, r = 0.62 to 0.67). Thrombin activity, measured by FPA, was as closely related to aPTT as to the heparin level. Baseline levels of F1.2 were significantly related to the risk of death or reinfarction at 30 days (p = 0.008); values 12 h after enrollment also were related to 30-day mortality (p = 0.05).

CONCLUSIONS

Although intravenous heparin partly suppresses the increased thrombin activity associated with thrombolysis, it does not inhibit thrombin generation. The aPTT was as good a measure of suppression of thrombin activity as the heparin level itself. Hematologic markers of thrombin generation were found to be related to the subsequent risk of thrombotic events.

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.

Benefit of early sustained reperfusion in patients with prior myocardial infarction (the GUSTO-I trial). Global Utilization of Streptokinase and TPA for occluded arteries

The primary objective of this study was to characterize a large cohort of patients receiving thrombolytic therapy for acute myocardial infarction with respect to the group with a prior event. Patients were randomly assigned to 1 of 4 thrombolytic strategies. Baseline characteristics, 30-day outcomes, and 1-year mortality were compared between patients with (n = 6,704) and without (n = 34,143) prior myocardial infarction. Patients with prior myocardial infarction presented to the hospital earlier than those having their first event, but institution of thrombolytic therapy was delayed. Mortality at 30 days (11.7% vs 5.9%, p = 0.001) and 1 year (17.3% vs 8.2%, p < 0.001) was greater among patients with prior infarction, and independent of other demographic variables. Accelerated alteplase was more effective than streptokinase or combination therapy (30-day mortality 10.4% vs 12.2%, p = 0.012; 1-year mortality 15.9% vs 17.8%, p = 0.041). Infarct vessel patency did not differ between those with and without prior myocardial infarction (67.3% vs 67% at 90 minutes, p = 0.92); however, recurrent ischemia was more common in patients with prior myocardial infarction. Patients with healed myocardial infarction should be educated to ensure early hospital admission if they develop symptoms suggestive of acute infarction, and upon hospital arrival should be promptly triaged to receive reperfusion therapy with accelerated alteplase.

Developing systems for cost-effective auditing of clinical trials

Auditing a clinical trial is a complex process designed to ensure that the trial will provide a reliable answer to the question being posed. Traditional auditing methods are expensive, and escalate the cost of clinical trials. This paper describes approaches to cost-effective monitoring of clinical trials, such as integrating them with clinical practice and focusing the data being collected. Sampling methods for source documentation can be used to eliminate costs incurred by reviewing every record. These measures, coupled with prospective clinical judgment about areas of concern in the conduct of trials, can reduce complications and costs without sacrificing quality.

Incidence and mortality from early stroke associated with acute myocardial infarction in the prethrombolytic and thrombolytic eras. Secondary Prevention Reinfarction Israeli Nifedipine Trial (SPRINT) and Israeli Thrombolytic Survey Groups

OBJECTIVES

This study sought to compare the incidence of early cerebrovascular events and subsequent mortality in two cohorts of consecutive patients with acute myocardial infarction (AMI), admitted to coronary care units (CCUs) in Israel, in the prethrombolytic and thrombolytic eras.

BACKGROUND

During the past decade, substantial changes have occurred in the medical treatment of AMI, and important new therapies have been introduced that could all affect stroke risk and type by diverse mechanisms. Yet the overall impact of these new therapeutic modalities on the incidence of stroke complicating AMI is not clear.

METHODS

We compared the incidence and mortality rates of cerebrovascular events complicating AMI within CCUs among 5,839 consecutive patients admitted in the period 1981 to 1983 versus 2,012 patients from two prospective nationwide surveys conducted in all CCUs operating in Israel in 1992 and 1994.

RESULTS

The demographic and clinical characteristics of patients with AMI in both periods were comparable. Patients admitted in the period 1981 to 1983 did not receive thrombolysis and reperfusion therapy; those admitted in 1992 and 1994 received thrombolysis (45%) and coronary angioplasty or coronary artery bypass graft surgery (14%), and antiplatelet and anticoagulant treatments were more frequently used. The incidence of early cerebrovascular events was 0.74% (43 of 5,839) in 1981 to 1983 versus 0.75% (15 of 2,012) in the 1992 to 1994 cohort. Patients with an AMI who experienced a cerebrovascular event were somewhat older in both groups and had a high rate of previous cerebrovascular events, congestive heart failure and atrial and ventricular arrhythmias during the hospital period. Mortality declined by one-third between the two periods. However, the mortality rate of patients with AMI who sustained a cerebrovascular event remained high (> or =40% for 30 days, 60% for 1 year).

CONCLUSIONS

The overall incidence of early cerebrovascular events complicating AMI remained similar (0.75%) in the prethrombolytic and thrombolytic eras. Mortality rates of patients with an AMI but no cerebrovascular events decreased substantially over the past decade but not in patients with AMI with a cerebrovascular event.

A comparison of reteplase with alteplase for acute myocardial infarction

BACKGROUND

Reteplase (recombinant plasminogen activator), a mutant of alteplase tissue plasminogen activator, has a longer half-life than its parent molecule and produced superior angiographic results in pilot studies of acute myocardial infarction. In this large clinical trial, we compared the efficacy and safety of these two thrombolytic agents.

METHODS

A total of 15,059 patients from 807 hospitals in 20 countries who presented within 6 hours after the onset of symptoms with ST-segment elevation or bundle-branch block were randomly assigned in a 2:1 ratio to receive reteplase, in two bolus doses or 10 MU each given 30 minutes apart, or an accelerated infusion of alteplase, up to 100 mg infused over a period of 90 minutes. The primary hypothesis was that mortality at 30 days would be significantly lower with reteplase.

RESULTS

The mortality rate at 30 days was 7.47 percent for reteplase and 7.24 percent for alteplase (adjusted P=0.54; odds ratio, 1.03; 95 percent confidence interval, 0.91 to 1.18). The 95 percent confidence interval for the absolute difference in mortality rates was -1.1 to 0.66 percent. Stroke occurred in 1.64 percent of patients treated with reteplase and in 1.79 percent of those treated with alteplase (P= 0.50). The respective rates of the combined end point of death or nonfatal, disabling stroke were 7.89 percent and 7.91 percent (P=0.97; odds ratio, 1.0; 95 percent confidence interval, 0.88 to 1.13).

CONCLUSIONS

As compared with an accelerated infusion of alteplase, reteplase, although easier to administer, did not provide any additional survival benefit in the treatment of acute myocardial infarction. Other results, particularly for the combined end point of death or nonfatal, disabling stroke, were remarkably similar for the two plasminogen activators.

Transferring patients for primary angioplasty: a retrospective analysis of 104 selected high risk patients with acute myocardial infarction

OBJECTIVE

To investigate the feasibility of primary coronary angioplasty as a treatment option in patients with acute myocardial infarction after initial diagnosis in a local community hospital.

SETTING

Referral centre for interventional treatment of coronary artery disease.

METHODS

During a five year period, 520 candidates for primary coronary angioplasty were treated in our institution, 104 after transfer from a community hospital. The transferred patients and the non-transferred patients (n = 416) were compared with regard to baseline clinical characteristics, time interval from symptom onset to treatment, and clinical outcome at six months.

RESULTS

In this setting, the influence of transportation on total ischaemic time was limited, and there was no difference in clinical outcome between the transferred and the non-transferred patients. Clinical outcome was mainly dependent on the indication for transfer.

CONCLUSIONS

Safe and expedient transportation may facilitate the more widespread use of primary angioplasty in patients with acute myocardial infarction. A large randomised multicentre trial is needed to compare the relative merits of intravenous thrombolytic treatment in a local hospital with primary angioplasty after transfer in selected high risk patients with acute myocardial infarction.

Atrial fibrillation in the setting of acute myocardial infarction: the GUSTO-I experience. Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries

OBJECTIVES

We examined the clinical predictors and angiographic and clinical outcomes associated with atrial fibrillation in the setting of acute myocardial infarction (MI).

BACKGROUND

This condition has been studied primarily in prethrombolytic era small trials.

METHODS

We compared baseline clinical characteristics, short-term clinical and angiographic outcomes and 1-year mortality of patients enrolled in the Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO-I) trial with atrial fibrillation on admission electrocardiography (n = 1,026 [2.5%]) or after enrollment (n = 3,254 [7.9%]) and those without atrial fibrillation (n = 36,611 [89.6%]). Univariable and multivariable analyses were used to assess relations between baseline factors and the development of atrial fibrillation.

RESULTS

Patients with any atrial fibrillation more often had three-vessel coronary artery disease and initial Thrombolysis in Myocardial Infarction (TIMI) grade < 3 flow than those without the arrhythmia. In-hospital stroke was increased in patients with atrial fibrillation (3.1% vs. 1.3%, p = 0.0001), mainly ischemic stroke (1.8% vs. 0.5%, p = 0.0001). Significant multivariable predictors of later atrial fibrillation included advanced age, higher peak creatine kinase levels, worse Killip class and increased heart rate. The unadjusted mortality rate was significantly higher at 30 days (14.3% vs. 6.2%, p = 0.0001) and at 1 year (21.5% vs. 8.6%, p < 0.0001) in patients with atrial fibrillation. The adjusted 30-day mortality rate remained significantly higher with any (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.2 to 1.4) or later (OR 1.4, 95% CI 1.3 to 1.5) atrial fibrillation but not with baseline atrial fibrillation (OR 1.1, 95% CI 0.88 to 1.3).

CONCLUSIONS

Atrial fibrillation in the setting of acute MI independently predicts stroke and 30-day mortality. More aggressive treatment strategies in this subgroup may be warranted and deserve further study.

Influence of diabetes mellitus on clinical outcome in the thrombolytic era of acute myocardial infarction. GUSTO-I Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries

OBJECTIVES

This study was undertaken to define and better understand the characteristics and outcomes of patients with diabetes treated for acute myocardial infarction with contemporary thrombolysis.

BACKGROUND

Although thrombolysis has substantially improved survival of patients with myocardial infarction, diabetes mellitus remains an independent predictor for a poor prognosis.

METHODS

We characterized the contemporary relation between diabetes and outcome after myocardial infarction treated with thrombolytic agents from a large international cohort. Of 41,021 patients randomized to receive accelerated tissue-type plasminogen activator (t-PA), streptokinase or a combination of both agents in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries study, there were 5,944 patients with diabetes and 34,888 patients without diabetes.

RESULTS

Patients with diabetes were older and more likely to be female, to present with anterior wall infarction, to receive thrombolysis later and to have triple-vessel coronary artery disease. Mortality at 30 days was highest among diabetic patients treated with insulin (12.5%) compared with non-insulin-treated diabetic (9.7%) and nondiabetic (6.2%) patients (p < 0.001). Mortality was lowest among those with diabetes receiving accelerated t-PA, which is consistent with the results of the overall patient cohort. Although stroke occurred more frequently among diabetic (1.9%) than nondiabetic patients (1.4%, p < 0.001), there was no significant difference in the rates of intracranial hemorrhage. Cardiac failure, shock, atrioventricular block and atrial flutter/ fibrillation were more common among diabetic patients. The proportion of patients undergoing revascularization was similar between patients with and without diabetes, although diabetic patients were more likely to undergo coronary artery bypass graft surgery (10.4% vs. 8.3%). Diabetes remained an independent predictor for mortality at 1-year follow-up (14.5% vs. 8.9%, p < 0.001).

CONCLUSIONS

Diabetes, alone and in association with its comorbidities, portends a substantially worse 30-day and 1-year prognosis for patients with myocardial infarction.

A clinical trial comparing primary coronary angioplasty with tissue plasminogen activator for acute myocardial infarction

BACKGROUND

Among physicians who treat patients with acute myocardial infarction, there is controversy about the magnitude of the clinical benefit of primary (i.e., immediate) coronary angioplasty as compared with thrombolytic therapy.

METHODS

As part of the Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO IIb) trial, we randomly assigned, 1138 patients from 57 hospitals who presented within 12 hours of acute myocardial infarction (with ST-segment elevation on the electrocardiogram) to primary angioplasty or accelerated thrombolytic therapy with recombinant tissue plasminogen activator (t-PA). We also randomly assigned 1012 patients to heparin or hirudin treatment in a factorial design. The primary study end point was a composite outcome of death, nonfatal reinfarction, and nonfatal disabling stroke at 30 days.

RESULTS

The incidence of the primary end point in the angioplasty and t-PA groups was 9.6 percent and 13.7 percent, respectively (odds ratio, 0.67; 95 percent confidence interval, 0.47 to 0.97; P = 0.033). Death occurred in 5.7 percent of the patients assigned to angioplasty and 7.0 percent of those assigned to t-PA (P=0.37), reinfarction in 4.5 percent and 6.5 percent (P=0.13), and disabling stroke in 0.2 percent and 0.9 percent (P=0.11). At six months, there was no significant difference in the incidence of the composite outcome (13.3 percent vs. 15.7 percent, P not significant) [corrected]. The primary end point was observed in 10.6 percent of the patients in the angioplasty group assigned to heparin and 8.2 percent of those assigned to hirudin (P=0.37).

CONCLUSIONS

This trial suggests that angioplasty provides a small-to-moderate, short-term clinical advantage over thrombolytic therapy with t-PA. Primary angioplasty, when it can be accomplished promptly at experienced centers, should be considered an excellent alternative method for myocardial reperfusion.

Thrombolytic therapy for pulmonary embolism. Frequency of intracranial hemorrhage and associated risk factors

STUDY OBJECTIVES

To determine the risk factors and frequency of intracranial hemorrhage among patients undergoing thrombolysis for pulmonary embolism.

DESIGN

A retrospective descriptive and controlled analysis.

SETTING

Hospitalized patients at centers in the United States, Canada, and Italy.

PATIENTS

All had evidence of pulmonary embolism on perfusion scans or angiography.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Data were analyzed on 312 patients from five previously reported studies of pulmonary embolism thrombolysis. The frequency of intracranial hemorrhage up to 14 days after pulmonary embolism thrombolysis was 6 of 312 or 1.9% (95% confidence interval, 0.7 to 4.1%). Two of six intracranial hemorrhages were fatal. Two of the six patients received thrombolysis in violation of the protocol because they had pre-existing, known intracranial disease. Average diastolic BP at the time of hospital admission was significantly elevated in patients who developed an intracranial hemorrhage (90.3 +/- 15.1 mm Hg) compared with those who did not (77.6 +/- 10.9 mm Hg; p = 0.04). Other baseline characteristics and laboratory data were similar in both groups. Decreased level of consciousness, hemiparesis, and visual field deficits were the most common clinical signs of intracranial hemorrhage.

CONCLUSIONS

Intracranial hemorrhage after pulmonary embolism thrombolysis is an infrequent but often grave complication. Meticulous patient screening before administering thrombolysis is imperative. Diastolic hypertension at the time of hospital admission is a risk factor for intracranial hemorrhage after pulmonary embolism thrombolysis.

Randomized comparison of primary coronary angioplasty with thrombolytic therapy in low risk patients with acute myocardial infarction

OBJECTIVES

We sought to compare primary coronary angioplasty and thrombolysis as treatment for low risk patients with an acute myocardial infarction.

BACKGROUND

Primary coronary angioplasty is the most effective reperfusion therapy for patients with acute myocardial infarction; however, intravenous thrombolysis is easier to apply, more widely available and possibly more appropriate in low risk patients.

METHODS

We stratified 240 patients with acute myocardial infarction at admission according to risk. Low risk patients (n = 95) were randomized to primary angioplasty or thrombolytic therapy. The primary end point was death, nonfatal stroke or reinfarction during 6 months of follow-up. Left ventricular ejection fraction and medical charges were secondary end points. High risk patients (n = 145) were treated with primary angioplasty.

RESULTS

In low risk patients, the incidence of the primary clinical end point (4% vs. 20%, p < 0.02) was lower in the group with primary coronary angioplasty than in the group with thrombolysis, because of a higher rate of reinfarction in the latter group. Mortality and stroke rates were low in both treatment groups. There were no differences in left ventricular ejection fraction or total medical charges. High risk patients had a 14% incidence rate of the primary clinical end point.

CONCLUSIONS

Simple clinical data can be used to risk-stratify patients during the initial admission for myocardial infarction. Even in low risk patients, primary coronary angioplasty results in a better clinical outcome at 6 months than does thrombolysis and does not increase total medical charges.

Amyloid beta peptides stimulate tissue-type plasminogen activator but not recombinant prourokinase

Tissue-type plasminogen activator (rt-PA) and prourokinase (rscu-PA) have been tested with respect to the influence of amyloid beta peptides on plasminogen activation which was monitored by cleavage of the chromogenic plasmin substrate S-2251. It was shown that rt-PA is stimulated by amyloid beta peptides at concentrations of 10 micrograms/ml in contrast to prourokinase, which does not alter its catalytic properties in presence of amyloid beta peptides. The stimulation of rt-PA can be inhibited by tranexamic acid indicating a molecular mode of stimulation similar to the fibrin mediated stimulation of rt-PA.

Implications of the GUSTO trial for thrombolytic therapy

This article discusses the impact of previous clinical observations on the development of the GUSTO-I protocol, particularly the absence of a survival benefit of alteplase (rt-PA) over streptokinase in the GISSI-2/International Study Group and ISIS-3 trials in spite of a higher efficacy for clot lysis. The demonstrated superiority of front-loaded alteplase in this large trial is translated into useful guidelines for the practising clinician. Risk-benefit analysis indicates that, in general, this thrombolytic regimen is most indicated in patients presenting with large amounts of jeopardized ischaemic myocardium in the absence of a particularly increased risk of haemorrhagic stroke. Finally, the impact of this study for future development in the field of acute coronary syndromes is evaluated, more specifically for the design of new trials with new fibrinolytic and antithrombotic agents. These include mutants of alteplase, staphylokinase, direct antithrombins and inhibitors of the glycoprotein IIb/IIIa platelet receptor.

Time from symptom onset to treatment and outcomes after thrombolytic therapy. GUSTO-1 Investigators

OBJECTIVES

This study sought to examine the relations among patient characteristics, time to thrombolysis and outcomes in the international GUSTO-I trial.

BACKGROUND

Studies have shown better left ventricular function and decreased infarct size as well as increased survival with earlier thrombolysis, but the relative benefits of various thrombolytic agents with earlier administration are uncertain.

METHODS

We evaluated the relations of baseline characteristics to three prospectively defined time variables: symptom onset to treatment, symptom onset to hospital arrival (presentation delay) and hospital arrival to treatment (treatment delay). We also examined the relations of delays to clinical outcomes and to the relative 30-day mortality benefit with accelerated tissue-type plasminogen activator (t-PA) versus streptokinase.

RESULTS

Female, elderly, diabetic and hypertensive patients had longer delays at all stages. Previous infarction or bypass surgery was an additional risk factor for treatment delay. Early thrombolysis was associated with lower overall mortality rate (< 2 h, 5.5%; > 4 h, 9.0%), but no additional relative benefit resulted from earlier treatment with accelerated t-PA versus streptokinase (p = 0.38). Longer presentation and treatment delays were both associated with increased mortality rate (presentation delay < 1 h, 5.6% and > 4 h, 8.6%; treatment delay < 1 h, 5.4%, and > 90 min, 8.1%). As time to treatment increased, the incidence of recurrent ischemia or reinfarction decreased, but the rates of shock, heart failure and stroke increased.

CONCLUSIONS

Earlier treatment resulted in better outcomes, regardless of thrombolytic strategy. Elderly, female and diabetic patients were treated later, adding to their already substantial risk.