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

Thrombolysis with recombinant human tissue-type plasminogen activator during instability in coronary artery disease: effect on myocardial ischemia and need for coronary revascularization. TRIC Study Group

Two hundred five men, 40 to 70 years of age, admitted to the coronary care unit with unstable coronary artery disease (unstable angina or non-Q wave myocardial infarction), were randomized to double-blind placebo-controlled treatment with an intravenous infusion of recombinant tissue-type plasminogen activator (rTPA), 1 mg/kg body weight (maximum 100 mg) during 4 hours, in addition to aspirin, heparin, and beta-blockade. No severe complications occurred. Myocardial ischemia, defined as myocardial infarction, incapacitating angina despite medication, or signs of ischemia at the exercise test, was reduced by treatment with rTPA compared with placebo both at discharge, 53% compared with 70% (p = 0.02), and at 1 month, 61% compared with 80% (p = 0.005). Signs of myocardial ischemia during the exercise test were reduced at discharge 51.0% compared with 68% (p = 0.03) and at 1 month 48% compared with 62% (p = 0.09). Coronary angiography after 1 month showed no difference in major coronary lesions between the groups, nor was there any reduction in the number of performed coronary revascularization procedures. In conclusion, treatment with rTPA in unstable coronary artery disease in men reduced myocardial ischemia but did not significantly reduce the need for revascularization in long-term follow-up.

The impact of thrombolytic therapy on hospital mortality from acute myocardial infarction in the Chinese in Hong Kong

Thrombolytic therapy using recombinant-tissue plasminogen activator, urokinase and streptokinase for acute myocardial infarction was instituted in the coronary care unit of the Prince of Wales Hospital in Hong Kong in 1988. To evaluate its impact on hospital mortality of acute myocardial infarction, the database of 465 patients (mean age 65.2 +/- 12.6 yr) admitted into the coronary care unit in the period between 1985-1990 was collected prospectively and their clinical course reviewed. Three hundred and thirty-five patients were males and 130 were females. Patients in the prethrombolytic era (1985-87) and the thrombolytic era (1988-90) were matched for age, proportion of females and clinical severity. One hundred and two patients (39.5%) received thrombolytic therapy. The overall hospital mortality (18.6%) in the thrombolytic era and that for each sex (18.2% in the males; 19.5% in the females) were significantly lower than those of prethrombolytic era (27.1%, 23.4% and 37.7%, respectively). No death was due to bleeding complication. The benefit of thrombolytic therapies in the Chinese was confirmed. More effort is needed to popularize this concept in the Chinese communities, to shorten the prehospital delay of patients and to extend its utilisation to the elderly patients.

Enhancement of fibrinolysis in vitro by ultrasound

The effect of ultrasound on the rate of fibrinolysis has been investigated using an in vitro system. Plasma or blood clots containing a trace label of 125I fibrin were suspended in plasma containing plasminogen activator and intermittently exposed to continuous wave 1-MHz ultrasound at intensities up to 8 W/cm2. Plasma clot lysis at 1 h with 1 microgram/ml recombinant tissue plasminogen activator (rt-PA) was 12.8 +/- 1.2% without ultrasound and was significantly (P = 0.0001) increased by exposure to ultrasound with greater lysis at 1 W/cm2 (18.0 +/- 1.4%), 2 W/cm2 (19.3 +/- 0.7%), 4 W/cm2 (22.8 +/- 1.8%), and 8 W/cm2 (58.7 +/- 7.1%). Significant increases in lysis were also seen with urokinase at ultrasound intensities of 2 W/cm2 and above. Exposure of clots to ultrasound in the absence of plasminogen activator did not increase lysis. Ultrasound exposure resulted in a marked reduction in the rt-PA concentration required to achieve an equivalent degree of lysis to that seen without ultrasound. For example, 15% lysis occurred in 1 h at 1 microgram/ml rt-PA without ultrasound or with 0.2 microgram/ml with ultrasound, a five-fold reduction in concentration. Ultrasound at 1 W/cm2 and above also potentiated lysis of retracted whole blood clots mediated by rt-PA or urokinase. The maximum temperature increase of plasma clots exposed to 4 W/cm2 ultrasound was only 1.7 degrees C, which could not explain the enhancement of fibrinolysis. Ultrasound exposure did not cause mechanical fragmentation of the clot into sedimentable fragments, nor did it alter the sizes of plasmic derivatives as demonstrated by SDS polyacrylamide gel electrophoresis. We conclude that ultrasound at 1 MHz potentiates enzymatic fibrinolysis by a nonthermal mechanism at energies that can potentially be applied and tolerated in vivo to accelerate therapeutic fibrinolysis.

Oesophageal dissection after thrombolytic treatment for myocardial infarction

A 62 year old woman admitted with a history suggesting acute myocardial infarction had thrombolytic treatment with anisoylated plasminogen-streptokinase activator complex, which resulted in submucosal haemorrhage in the oesophagus; this caused dissection of the wall of the oesophagus and complete dysphagia. The haematoma resolved spontaneously, leaving behind a diverticulum, with reduced peristalsis and delayed emptying but no obstruction.

When to stop a clinical trial

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Cumulative meta-analysis of therapeutic trials for myocardial infarction

BACKGROUND

The large volume of published randomized, controlled trials has led to a need for meta-analyses to track therapeutic advances. Performing a new meta-analysis whenever the results of a new trial of a particular therapy are published permits the study of trends in efficacy and makes it possible to determine when a new treatment appears to be significantly effective or deleterious. We describe the use of such a procedure, cumulative meta-analysis, to assess therapeutic trials among patients with myocardial infarction.

METHODS

We performed cumulative meta-analyses of clinical trials that evaluated 15 treatments and preventive measures for acute myocardial infarction.

RESULTS

An example of this method is its application to the use of intravenous streptokinase as thrombolytic therapy for acute infarction. Thirty-three trials evaluating this therapy were performed between 1959 and 1988. We found that a consistent, statistically significant reduction in total mortality (odds ratios, 0.74; 95 percent confidence interval, 0.59 to 0.92) was achieved in 1973, after only eight trials involving 2432 patients had been completed. The results of the 25 subsequent trials, which enrolled an additional 34,542 patients through 1988, had little or no effect on the odds ratio establishing efficacy, but simply narrowed the 95 percent confidence interval. In particular, two very large trials, the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico trial in 1986 (11,712 patients) and the Second International Study of Infarct Survival trial in 1988 (17,187 patients) did not modify the already established evidence of efficacy. We used a similar approach to study the accumulating evidence of efficacy (or lack of efficacy) of 14 other therapies and preventive measures for myocardial infarction.

CONCLUSIONS

Cumulative meta-analysis of therapeutic trials facilitates the determination of clinical efficacy and harm and may be helpful in tracking trials, planning future trials, and making clinical recommendations for therapy.

Acute myocardial infarction. An updated protocol for thrombolytic therapy

Only a small percentage of patients who have acute myocardial infarction receive the benefit of intravenous thrombolytic therapy, often because logistics result in unnecessary pre-hospital and in-hospital delays. Dr Selig therefore recommends that a streamlined protocol be available and that it be updated at regular intervals to ensure that this time-dependent therapy is more routinely utilized.

Thrombolytic therapy: a state of the art review

The plasminogen-plasmin enzyme system and its therapeutic manipulation provide the substrate for an assessment of the clinical use of thrombolytic agents. Proven effective in acute MI and its complications, such agents have other potential applications--e.g., in stroke or pulmonary embolism--and are being investigated in those contexts.

The diagnosis of acute myocardial infarction

Changes in the economic and therapeutic environment have altered the time frame in which an accurate diagnosis of acute myocardial infarction (AMI) must be made. The advent of effective reperfusion therapies and the increasing emphasis on reducing cost produce an environment in which rapid diagnosis can reduce morbidity and mortality while simultaneously reducing overall cost by avoiding unnecessary hospitalization and intervention. The first element of a diagnostic strategy remains a brief, directed history and physical examination. The orientation of this phase is to identify important causes of symptoms other than AMI, while rapidly leading to more definitive evaluation for myocardial ischemia when another diagnosis is not found. The ECG provides the most rapid definitive diagnosis, but the diagnosis remains equivocal in many patients with nondiagnostic ECGs. In this group, the use of cardiac enzyme measurements early in the course holds promise in directing intensive care at high-risk patients while avoiding unnecessary intervention in low-risk patients. A protocolized approach to patient evaluation should become a part of standard practice patterns in every hospital.

Frequency of complications of cardiopulmonary resuscitation after thrombolysis during acute myocardial infarction

Prolonged external cardiac massage is often regarded as a contraindication for thrombolytic therapy because of the risk of fatal hemorrhage. The influence of cardiopulmonary resuscitation on complications of thrombolytic bleeding was assessed analyzing data of all patients with myocardial infarction admitted to our clinic during the 10-year period between 1978 and 1987. From the total of 2,147 patients with acute myocardial infarction, 590 received thrombolytic therapy (intracoronary in 229, intravenous in 400). Of these, 43 patients underwent prolonged cardiopulmonary resuscitation and received thrombolysis within a time interval of less than 24 hours. In 21 patients, resuscitation was performed within a short period of time (5 minutes to 20 hours) after thrombolysis (10 intracoronary, 10 intravenous, 1 intravenous + intracoronary) had been initiated; 9 of these patients survived (43%). In the other 22 patients, thrombolytic therapy was initiated during ongoing resuscitation (n = 6: intravenous in 5, intravenous + intracoronary in 1) or in the early phase (10 to 120 minutes) after successful resuscitation (n = 16: intracoronary in 10, intravenous in 4, intravenous + intracoronary in 2). From this group, 14 patients survived (in-hospital mortality 36%). The mean duration of cardiopulmonary resuscitation was 36 +/- 32 minutes (range 4 to 120). Autopsy studies were performed in 16 of 20 decreased patients. Bleeding complications occurred in 8 of 43 patients. No case of bleeding was directly related to cardiocompression despite the often traumatic procedure with rib fractures verified in 17 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Prehospital Thrombolysis in Acute Myocardial Infarction

Introduction:

The effectiveness and safety of thrombolytic treatment (TT) for acute myocardial infarction (AMI) in the prehospital setting have not been defined. Therefore, its use on a mobile coronary care unit (MCCU) was studied.

Methods:

A MCCU was provided with the equipment and supplies necessary for the administration TT and its personnel were trained in the indications for TT and in its administration. When an emergency medical team physician suspected the diagnosis from the presence of chest pain typical of an AMI, the patient's ECG was transmitted to the Cardiological Consulting Center. If the S-T segments were elevated and the patient met all of the screening criteria, the cardiologist ordered the MCCU personnel to carry out TT. Streptokinase (Avelyzin, Germed, GDR) was administered intravenously at a dose of 500,000 UE.

Results:

Sixty-seven patients with AMI were included in the trial. The mean interval between the onset of the symptoms and the beginning of the TT was 156±77 minutes; it was less than 3 hours for 54 patients. Thirty-four patients (50.7%) had non-invasive markers of successful reperfusion, while 33 (49.3%) did not. Three patients had non-fatal ventricular fibrillation (VF), ventricular tachycardia (VT) and/or ventricular premature beats of high grades (Lown classes 3–5) developed in six and 22 patients respectively. Five patients had conduction disturbances, and 40 had symptomatic hypotension. None of the patients died before arrival at the hospital. Four suffered reinfarction, and one died of VF during the in-hospital phase of care. Post-discharge follow-up (17.5±5.0 months) demonstrated a positive exercise test in 23 (43%), and a left ventricular ejection fraction >80% in 29 (85.2%) and <40% in five (14.8%) of the patients. The in-hospital and post-discharge mortalities were 1.5 and 4.8% respectively. There was not a single case of bleeding sufficient to require a transfusion.

Conclusions:

The study indicates that the administration of TT for AMI in the prehospital setting is both safe and effective.

Clinical benefits of thrombolytic therapy in acute myocardial infarction

The value of coronary artery reperfusion resulting from pharmacologically induced fibrinolysis in patients with evolving myocardial infarction has been rigorously evaluated. Improved left ventricular function and even more impressive improvements in survival rates have been demonstrated consistently in controlled studies. Benefit is related to the restoration of myocardial blood flow. Maximal benefit is achieved with early and sustained restoration of coronary artery patency. Benefits observed during initial hospitalization are sustained for at least 1 year in the majority of patients, even without subsequent mechanical revascularization. To date, analysis of subgroups has not identified a population of patients with evolving infarction that should routinely be excluded from consideration for thrombolysis. As with many potent pharmacologic agents, activators of the fibrinolytic system are associated with a degree of risk whenever they are administered to a patient. Therefore, patients must be assessed carefully prior to initiating treatment, especially for potential bleeding hazards, and appropriate follow-up evaluation and concomitant therapy needs to be planned. However, given the overwhelming body of data now available regarding its benefits and relative safety, thrombolysis should be considered as conventional therapy for patients with acute evolving myocardial infarction (AMI).

Comparative analysis of long-term mortality after thrombolytic therapy

In patients with acute myocardial infarction, thrombolytic therapy has a demonstrable and favorable impact on a range of clinical indicators, including left ventricular function, infarct size, coronary arterial patency, and symptom relief. However, these indicators have not provided a reliable basis for the comparison of thrombolytic regimens; mortality provides the "gold standard." One-year mortality obviates the differences in the timing of short-term comparisons (in-hospital, 30-day, or 5-week). In addition, late effects of differences in patency, including the impact of reocclusion, infarct healing, and remodeling, will be evident by 1 year. Meta-analysis of data from previous major mortality studies shows that differences in design and the overlap of confidence intervals of mortality studies suggest that no thrombolytic agent is superior in terms of short-term mortality. Long-term survival may provide a more meaningful basis for comparison of efficacy of the thrombolytic regimens. Long-term mortality has been evaluated for anistreplase in acute myocardial infarction in a composite analysis, similar to a meta-analysis. From the pooled life table analysis of all anistreplase studies, the odds reduction in mortality at 1 year was approximately 48%.

Antithrombotic effects of combining activated protein C and urokinase in nonhuman primates

BACKGROUND

We have determined in vivo the relative antithrombotic efficacy and hemostatic safety of combining low-dose activated protein C (APC) and urokinase (urinary plasminogen activator, u-PA), two natural proteins that regulate thrombogenesis.

METHODS AND RESULTS

To model acute thrombotic responses of native blood under conditions of arterial flow, thrombogenic segments of Dacron vascular graft (VG) were incorporated into chronic exteriorized femoral arteriovenous (AV) access shunts in baboons. Thrombus formation on VG was determined by measuring 1) the deposition of autologous 111In platelets using real-time scintillation camera imaging, 2) the accumulation of 125I fibrin, 3) segment patency by Doppler flow analysis, and 4) blood tests for thrombosis, including plasma concentrations of platelet factor 4, beta-thromboglobulin, fibrinopeptide A (FPA), and D-dimer. Treatments consisting of low-dose and intermediate-dose APC (0.07 or 0.25 mg/kg.hr), u-PA (25,000 or 50,000 IU/kg.hr), or the combination were administered for 1 hour by continuous intravenous infusion. In untreated controls, platelets and fibrin accumulated rapidly, reaching plateau values at 1 hour of 15.1 +/- 3.8 x 10(9) platelets and 7.8 +/- 2.2 mg fibrin. Although the low-dose APC or u-PA alone did not decrease either platelet or fibrin deposition significantly, this combination moderately reduced both platelet and fibrin accumulation (7.3 +/- 2.6 x 10(9) platelets, p less than 0.05; 3.9 +/- 0.6 mg fibrin, p less than 0.05). Furthermore, intermediate-dose APC or u-PA reduced thrombus formation by half when administered alone (p less than 0.001 for both platelet and fibrin deposition), and the combination markedly interrupted the accumulation of platelets (3.0 +/- 1.0 x 10(9) platelets, p less than 0.001) and fibrin (1.3 +/- 0.6 mg fibrin, p less than 0.001). During active treatments, all VG segments remained patent. Hemostatic plug forming capability, as measured by template bleeding times, remained normal during all experiments (p greater than 0.05). The T50 clearance time for APC activity was not affected by the concurrent administration of u-PA. u-PA alone increased the plasma levels of D-dimer, FPA, and, interestingly, APC, implying that during pharmacological activation of the fibrinolytic system, thrombin activity was released, and the protein C pathway was activated.

CONCLUSIONS

A combination of intermediate-dose APC and u-PA produce substantial and efficient antithrombotic effects without impairing hemostatic function.

Patency of the infarct-related coronary artery and ventricular geometry

The pathogenesis of acute myocardial infarction (AMI) involves a sudden thrombotic occlusion of a coronary artery. Spontaneous or pharmacologic thrombolysis may lead to myocardial salvage if patency is achieved within a narrow time window. However, patients in whom thrombolysis occurs late seem to demonstrate improved left ventricular (LV) function and prognosis, which may be independent of myocardial salvage. Preservation of normal LV geometry by reducing expansion of the infarcted segment is a likely mechanism for this benefit. Infarct expansion is most pronounced in patients with anterior wall AMI who have a persistently occluded infarct-related vessel. This process of expansion leads to early increases in LV volume and distortions of LV contour (abnormal LV geometry). Patients whose infarct segment is largest, patients who have manifested infarct expansion, and patients with a persistently occluded infarct-related artery are at highest risk for progressive LV dilation. Experimental data support the concept that reperfusion of occluded vessels that occurs too late for myocardial salvage will preserve LV geometry by limiting infarct expansion. Prospective clinical trials should address whether there is a late, "second time window" during which infarct expansion and distortions of LV geometry may be reduced by (1) therapy with thrombolytic agents applied late after infarction, (2) late mechanical reperfusion with percutaneous transluminal coronary angioplasty (PTCA) or related methods, and (3) load-reducing agents to decrease remodeling, such as angiotensin-converting enzyme inhibitors or nitroglycerin.

Usefulness of electrocardiographic findings and creatine kinase levels on admission in predicting the accuracy of the interval between onset of chest pain of acute myocardial infarction and initiation of thrombolytic therapy

Patients with chest pain lasting greater than 6 hours and suggesting acute myocardial infarction (AMI) are often excluded from thrombolytic therapy, because myocardial necrosis is believed to be largely irreversible beyond that time. To evaluate the relation between time of onset of chest pain and enzymatic evidence of myocardial necrosis, enzymes on admission were analyzed in 221 consecutive patients with greater than or equal to 2 mm ST-segment elevation by electrocardiography on admission and no contraindications to thrombolytic therapy. Patients with symptoms within 6 hours (n = 170, early) received thrombolytic therapy, but those with symptoms after 6 hours did not (n = 51, late). Eventually, 219 (168 early, 51 late) patients had enzymatically proven AMI within 24 hours. Creatine kinase levels on admission less than twice the upper normal limit were found in 155 (91%) early patients, but surprisingly, also in 30 (59%) late patients. By electrocardiography on admission, ST-segment elevation per lead was 2.1 +/- 1.1 mm in late patients with low initial enzymes versus 1.1 +/- 0.3 mm in those with elevated initial enzymes (p less than 0.0001). Concomitantly, Q waves in leads with ST-segment elevation were present in 17 (57%) late patients with low enzymes on admission versus 17 (81%) with elevated enzymes on admission (p = 0.06). Eventually, maximal creatine kinase levels were similar in all late patients irrespective of enzyme levels on admission. Therefore, many patients with symptoms of AMI after 6 hours have low enzymes on admission and may still be eligible for thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency of use of thrombolytic therapy in acute myocardial infarction in Israel

Thrombolysis is now generally accepted as the initial treatment for patients with acute myocardial infarction (AMI). The extent to which this therapy is implemented in daily practice and the reasons for exclusion from thrombolytic therapy among 413 consecutive patients with AMI hospitalized in 18 coronary care units in Israel during a 1-month survey were prospectively investigated. Thrombolytic therapy administered to 145 patients (35%) was given to 38% of men versus 29% of women (p = not significant), to 38% of patients less than 75 years old compared with 18% of the very elderly (p less than 0.005), and more often to patients with a first or anterior AMI (40 and 48%) than to counterparts with recurrent or inferior AMI (23 and 31%, respectively, p less than 0.005 for both). The 2 most frequent reasons for excluding patients from thrombolysis were late arrivals to coronary care units (33%) and lack of ST elevation on the admission electrocardiogram (28%). Hospital mortality was 6% in the thrombolytic group versus 20% in patients found ineligible for thrombolysis. The significance of this difference is not clear as treatment was not randomized.

Limitations of thrombolytic therapy for acute myocardial infarction complicated by congestive heart failure and cardiogenic shock

As many as one quarter of patients treated with thrombolytic therapy present with congestive heart failure or cardiogenic shock. Although thrombolytic therapy has been shown to limit infarct size, preserve left ventricular ejection fraction and decrease mortality in most subgroups of patients, no apparent benefit has been demonstrated in patients with clinical left ventricular dysfunction. The lack of correlation between ejection fraction and other measurements of left ventricular dysfunction such as exercise time, cardiac output, filling pressures, activation of the neurohumoral system and regional perfusion bed abnormalities may partly explain this paradox. Alternatively, lower perfusion rates, higher reocclusion rates, associated mechanical complications or completed infarction may explain these findings. Preliminary data indicate that emergency coronary angioplasty or bypass graft surgery improves survival in selected patients with cardiogenic shock. Because these findings suggest that restoration of infarct artery patency is especially important in patients with clinical left ventricular dysfunction, additional studies are needed in these patients to investigate the potential benefit that new thrombolytic strategies, inotropic or vasodilator agents or intraaortic balloon counterpulsation might offer by augmenting coronary blood flow and improving reperfusion rates. Currently, acute mechanical revascularization should be considered for patients who present with congestive heart failure associated with hypotension or tachycardia and for patients with cardiogenic shock.

Can meta-analysis help uncertainty in surgery for otitis media in children

While otitis media is perhaps the most common disease of childhood that receives medical attention, there is little agreement concerning the efficacy of the medical and surgical therapies employed to try to alleviate its symptoms or hasten its natural resolution. Because various surgeries including adenoidectomy, myringotomy, and insertion of tympanostomy tubes are frequently involved in the treatment of otitis media with effusion (OME), it is likely the most expensive condition being managed in national terms. In an attempt to elucidate the most appropriate management of this condition, a meta-analysis was attempted to the 12 randomized control trials of surgical treatments for OME in children, published between 1966 and 1990. Heterogeneity both in the populations and comparisons studied and in the outcomes presented made meta-analysis an inappropriate method for clarifying this area of clinical uncertainty. Important elements in the design of randomized control trials that should be included in future studies of treatment for OME are therefore discussed.

British Heart Foundation surveys (1987 and 1989) of United Kingdom treatment policies for acute myocardial infarction

Consultant physicians and cardiologists were surveyed early in 1987 and 1989 to document the management policies for the treatment of acute myocardial infarction in United Kingdom hospitals and to assess the influence of major clinical trials on these policies. The response rate to both these surveys was high (84% (1178 physicians) in 1987 and 76% (982 physicians) in 1989). The percentage of physicians that reported using antiplatelet therapy "routinely" in acute myocardial infarction rose from 9% in 1987 to 84% in 1989 while those who reported using it "rarely or never" fell from 42% to 3%. Similarly, "routine" use of fibrinolytic therapy rose from 2% to 68%, and use "rarely or never" fell from 53% to 3%. This increase in the reported use of fibrinolytic therapy was accompanied by greater certainty about its efficacy and relative safety and by a general widening of the indications for its use. The use of other treatments in acute myocardial infarction (for example, the general use of anticoagulants, beta blockers, nitrates, calcium antagonists, or prophylactic antiarrhythmic agents) seemed to change little during this period, although the routine use of coronary angiography and oral anticoagulants after fibrinolytic therapy fell substantially between 1987 and 1989 (from 23% to 4%, and from 24% to 7% respectively). Fibrinolytic and antiplatelet therapy were accepted into the routine management of myocardial infarction during a relatively short period that coincided with the reporting of several positive controlled trial results. Clinical trials have rarely been seen to have had such a great impact on practice. In this case the rapid acceptance of the trial results may have been due to the consistency and reliability of the estimates of the size of the benefits (and risks) of therapy seen in these unusually large studies.

Cerebrovascular events after myocardial infarction: analysis of the GISSI trial. Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico (GISSI)

OBJECTIVES

To describe the epidemiology of cerebrovascular events in patients given or not given fibrinolytic treatment and to assess the prognostic implications and risk factors.

DESIGN

Case series derived from the GISSI randomised trial.

SETTING

176 coronary care units in Italy giving various levels of care.

PATIENTS

5860 patients with acute myocardial infarction treated with 1.5 million units of intravenous streptokinase and 5852 patients not given fibrinolytic treatment.

MAIN OUTCOME MEASURES

Cerebrovascular event, sex, age, blood pressure, history of previous infarct, site of infarction, and Killip class.

RESULTS

99 of 11,712 patients (0.84%) had a cerebrovascular event. Older age, worse Killip class, and anterior location of infarction seemed to be risk factors for cerebrovascular events (40/3201 aged 65-75 v 42/7295 aged less than 65, odds ratio 2.18; 9/437 class 3 v 55/8277 class 1, 1.81; and 57/4878 anterior v 24/4013 posterior, 1.96). No significant difference was found in the rate of cerebrovascular events between patients treated with streptokinase and controls (45/5852 (0.92%) streptokinase v 54/5860 (0.77) control). More patients in the streptokinase group than in the control group had cerebrovascular events (especially haemorrhagic strokes) on day 0-1 after randomisation (27 streptokinase v 7, control), although this was balanced by late events in control patients (54 streptokinase v 45 control at one year). The mortality of patients who had a cerebrovascular event was higher than that of those who did not (47% (47/99) v 11.6% (1350/11,613].

CONCLUSIONS

Although the incidence of cerebrovascular events complicating myocardial infarction was low, they increased morbidity and mortality. Treatment with streptokinase did not significantly alter the incidence, but age and poor haemodynamic state were associated with an increased risk.

Long-term effect of thrombolytic therapy on left ventricular ejection fraction after acute myocardial infarction

To assess the long-term effect of thrombolytic therapy on left ventricular (LV) systolic function, 222 patients with acute myocardial infarction treated with intravenous tissue plasminogen activator within 4 hours of symptom onset underwent assessment of LV ejection fraction (EF) by radionuclide equilibrium angiography at hospital discharge and 1 year later. Mean EF at hospital discharge (46 +/- 12) was similar to that at 1 year (45 +/- 13). Stepwise multivariate linear regression analysis identified EF at discharge and patency of the infarct-related artery before discharge as independent predictors of EF change at 1 year (p = 0.0002 and 0.003, respectively). Random assignments to invasive versus conservative treatment strategies or to early versus delayed beta-blocker therapy did not affect EF change during follow-up. No significant deterioration of EF was observed in patients with larger infarcts. However, EF decreased from 45 +/- 10 at hospital discharge to 39 +/- 12 (p = 0.005) at 1-year follow-up in a subgroup of patients with history of prior infarction. Thus, patients with acute myocardial infarction, treated with intravenous tissue plasminogen activator early after onset of symptoms, appear to have stable LV function between hospital discharge and 1 year follow-up. The change in EF between hospital discharge and 1 year can be predicted from the EF value at discharge, patency of the infarct-related artery before discharge and history of previous myocardial infarction.

A randomized comparison of intravenous heparin with oral aspirin and dipyridamole 24 hours after recombinant tissue-type plasminogen activator for acute myocardial infarction. National Heart Foundation of Australia Coronary Thrombolysis Group

BACKGROUND

This study addressed the need for heparin administration to be continued for more than 24 hours after coronary thrombolysis with recombinant tissue-type plasminogen activator (rt-PA).

METHODS AND RESULTS

A total of 241 patients with acute myocardial infarction were treated with 100 mg rt-PA and a bolus of 5,000 units i.v. heparin followed by 1,000 units/hr i.v. heparin for 24 hours. At 24 hours, 202 patients were randomized to continue intravenous heparin therapy (n = 99) in full dosage or to discontinue heparin therapy and begin an oral antiplatelet regimen of aspirin (300 mg/day) and dipyridamole (300 mg/day) (n = 103). On prospective recording, there were no differences in the pattern of chest pain, reinfarction, or bleeding complications. Coronary angiography on cardiac catheterization at 7-10 days showed no differences in patency of the infarct-related artery. The proportion of patients with total occlusion (TIMI grade 0-1) of the infarct-related artery was 18.9% in the heparin group and 19.8% in the aspirin and dipyridamole group. In the patients with an incompletely occluded infarct-related artery, the lumen was reduced by 69 +/- 2% of normal in the heparin group and 67 +/- 2% in the aspirin and dipyridamole group. Left ventricular function assessed on cardiac catheterization and radionuclide study at day 2 and at 1 month showed no differences between the two groups. Left ventricular ejection fraction on radionuclide ventriculography at 1 month was 52.4 +/- 1.2% in the heparin group and 51.9 +/- 1.2% in the aspirin and dipyridamole group.

CONCLUSIONS

We conclude that heparin therapy can be discontinued 24 hours after rt-PA therapy and replaced with an oral antiplatelet regimen without any adverse effects on chest pain, reinfarction, coronary patency, or left ventricular function.

Evaluation of combination thrombolytic therapy and timing of cardiac catheterization in acute myocardial infarction. Results of thrombolysis and angioplasty in myocardial infarction--phase 5 randomized trial. TAMI Study Group

Recent trials of myocardial reperfusion using single-agent thrombolytic therapy and sequential cardiac catheterization have supported a conservative approach to the patient with acute myocardial infarction. To evaluate combination thrombolytic therapy and the role of a previously untested strategy for the aggressive use of cardiac catheterization, we performed a multicenter clinical trial with a 3 x 2 factorial design in which 575 patients were randomly allocated to one of three drug regimens--tissue-type plasminogen activator (t-PA) (n = 191), urokinase (n = 190), or both (n = 194) - and one of two catheterization strategies--immediate catheterization with angioplasty for failed thrombolysis (n = 287) or deferred predischarge catheterization on days 5-10 (n = 288). Patients with contraindications to thrombolytic therapy, cardiogenic shock, or age of more than 75 years were excluded. Global left ventricular ejection fraction was well preserved and almost identical at predischarge catheterization (54%), regardless of the catheterization or thrombolytic strategy used (p = 0.98). Combination thrombolytic therapy was associated with a less complicated clinical course, most clearly documented by a lower rate of reocclusion (2%) compared with urokinase (7%) and t-PA (12%) (p = 0.04) and a lower rate of recurrent ischemia (25%) compared with urokinase (35%) and t-PA (31%). When a composite clinical end point (e.g., death, stroke, reinfarction, reocclusion, heart failure, or recurrent ischemia) was examined, combination thrombolytic therapy was associated with greater freedom from any adverse event (68%) compared with either single agent (urokinase, 55%; t-PA, 60%) (p = 0.04) and with a less complicated clinical course when the composite clinical end points were ranked according to clinical severity (p = 0.024). Early patency rates were greater with combination therapy, although predischarge patency rates after considering interventions to maintain patency were similar among drug regimens. No difference in bleeding complication rates was observed with any thrombolytic regimen. The aggressive catheterization strategy led to an overall early patency rate of 96% and a predischarge patency rate of 94% compared with a 90% predischarge patency in the conservative strategy (p = 0.065). The aggressive strategy improved regional wall motion in the infarct region (-2.16 SDs/chord) compared with deferred catheterization (-2.49 SDs/chord) (p = 0.004). More patients treated with the aggressive strategy were free from adverse outcomes (67% versus 55% in the conservative strategy, p = 0.004), and the clinical course was less complicated when the adverse outcomes were ranked according to severity (p = 0.016). No significant increase in use of blood products resulted from the aggressive strategy.(ABSTRACT TRUNCATED AT 400 WORDS)

Significance of a negative exercise thallium test in the presence of a critical residual stenosis after thrombolysis for acute myocardial infarction

BACKGROUND

After thrombolytic therapy for acute myocardial infarction, increasing emphasis is placed on early submaximal exercise testing, with further intervention advocated only for demonstrable ischemia. Although significant residual coronary artery lesions after successful thrombolysis are common, many patients paradoxically have no corresponding provokable ischemia.

METHODS AND RESULTS

The relation between significant postthrombolytic residual coronary artery disease and a negative early, submaximal exercise thallium-201 tomogram was studied among 101 consecutive patients with uncomplicated myocardial infarction and at least 70% residual stenosis of the infarct artery. A negative test occurred in 49 (48.5%) patients with a mean 88% residual infarct artery stenosis. Further characteristics of the group were as follows: mean time to treatment was 3.1 hours; mean age was 54 +/- 10 years; 80% were male; 47% had anterior infarction; 39% had multivessel disease; mean left ventricular ejection fraction was 53 +/- 14%; and mean peak creatine kinase level was 3,820 +/- 3,123 IU/ml. A similar group of 52 (51.5%) patients, treated within 3.3 hours from symptom onset, with a mean postthrombolysis stenosis of 90%, had a positive exercise test. Characteristics of this group were as follows: age was 58 +/- 10 years; 92% were male; 56% had anterior infarction; 40% had multivessel disease; and mean left ventricular ejection fraction was 54 +/- 15%. The peak creatine kinase level associated with the infarction, however, was lower: 2,605 +/- 1,805 IU/ml (p = 0.04). There was no difference in performance at exercise testing with respect to peak systolic pressure, peak heart rate, or time tolerated on the treadmill between the two groups. By multivariate logistic regression, only peak creatine kinase level predicted a negative stress result in the presence of a significant residual stenosis (odds ratio, 4.2; 95% confidence interval, 1.1-16.3).

CONCLUSIONS

The explanation for the relatively frequent finding of a negative early stress 201Tl tomogram after apparently successful reperfusion appears to be more extensive myocardial necrosis and not delay in therapy or inadequate exercise performance.

Reduction in the frequency of ventricular late potentials after acute myocardial infarction by early thrombolytic therapy

Ventricular late potentials are strong predictors of arrhythmic events after acute myocardial infarction (AMI). To assess the effect of intravenous thrombolysis on the incidence of ventricular late potentials, 223 consecutive patients surviving a first AMI were included in the present study: 59 patients (53 men, 6 women, mean age +/- standard deviation 55 +/- 10 years) received intravenous recombinant tissue-type plasminogen activator (100 mg over 3 hours, group A) and 164 patients (123 men, 41 women, mean age 61 +/- 11 years) received conventional medical treatment (group B). A time-domain signal-averaged electrocardiogram and a high-resolution beat-to-beat recording (gain 10(6), filters 100 to 300 Hz) were performed at 10 +/- 3 days after AMI. There was no difference between group A and B patients in terms of AMI location (anterior in 28 of 59 vs 80 of 164, difference not significant [NS]), mean left ventricular ejection fraction (55 +/- 10 vs 55 +/- 13%, NS), or presence of heart failure (New York Heart Association class III or IV in 12 of 59 vs 40 of 164, NS). The incidence of ventricular late potentials was 10% (6 of 59) in group A and 24% (39 of 164) in group B (p less than 0.05). Among the 146 patients who underwent coronary arteriography, the incidence of ventricular late potentials was 13% (10 of 80) in patients with a patent infarct-related artery and 26% (17 of 66) in patients with an occluded infarct-related artery (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The occurrence of oxidative stress during reperfusion in experimental animals and men

Reperfusion is the prerequisite for the ischemic myocardium to recover its metabolic and mechanical function. However, reperfusion after a prolonged period of ischemia in the experimental animal may exacerbate, or at least accelerate, the occurrence of ischemic injury, whilst in humans at the least it is not beneficial. This entity has been called reperfusion damage, since much of the damage is believed to be caused by events occurring at the moment of reperfusion rather than by changes occurring during ischemia. The existence of reperfusion damage, however, has been questioned, and evidence in favour of the concept is sparse. At the moment the molecular events occurring at the time of reperfusion are not completely understood, and the relative importance of several proposed deleterious mechanisms is not yet established. One of the most fashionable ideas for the cause of reperfusion damage is that the function of cell membrane is modified by oxygen radicals generated at the moment of reperfusion. Evidence in favour of and against this hypothesis is described in detail in the present article.

Cardiac tamponade early after thrombolysis for acute myocardial infarction: a rare but not reported hemorrhagic complication

Among 392 consecutive patients admitted for acute myocardial infarction and treated with thrombolytic drugs, 4 patients (1%) developed an early hemorrhagic pericardial effusion (without ventricular wall rupture) evolving within 24 h to cardiogenic shock consequent to cardiac tamponade. They all suffered from a large anterior myocardial infarction treated within 4 h after onset of symptoms with intravenous anisoylated plasminogen streptokinase activator complex (one case), recombinant tissue-type plasminogen activator (rt-PA) (two cases) or streptokinase (one case), anticoagulation with heparin (all cases) and aspirin (three cases). As soon as pericardial effusion was established by echocardiography, emergency percutaneous pericardiocentesis was performed at the bedside 20 +/- 6 h after thrombolytic therapy was started. This corrected immediately the clinical and hemodynamic status of each patient and a catheter was left in the pericardial space for 34 +/- 18 h. Thus, in the presence of unexplained clinical and hemodynamic deterioration occurring during the first 24 h after thrombolytic treatment of a large myocardial infarction, cardiac tamponade should be suspected. Immediate percutaneous pericardiocentesis followed by continuous drainage is a simple and definitive treatment for this complication.

Trends in mortality from coronary heart and cerebrovascular disease in Switzerland, 1969-87

Trends in age-specific and age-standardized death certification rates from all ischaemic heart disease and cerebrovascular disease in Switzerland have been analysed for the period 1969-87, i.e. since the introduction of the Eighth Revision of the International Classification of Diseases for coding causes of death. For coronary heart disease, overall age-standardized rates of males in the mid-late 1980's were similar to those in the late 1960's, although some upward trend was evident up to the mid 1970's (with a peak rate of 120.4/100,000, World standard, in 1978) followed by steady declines in more recent years (103.8/100,000 in 1987). These falls were larger in truncated (35 to 64 years) rates. For females, overall age-standardized rates were stable around a value of 40/100,000, while truncated rates tended to decrease, particularly over most recent years, with an overall decline of over 25%. Examination of age-specific trends showed that in both sexes declines at younger ages were already evident in the earlier calendar period, while above age 50 some fall became evident only in most recent years. Thus, in a formal log-linear age/period/cohort model, both a period and a cohort component emerged. In relation to cerebrovascular diseases, the overall declines were around 40% in males (from 67.4 to 41.2/100,000, World standard) and 45% for females (from 56.6 to 31.7/100,000), and were proportionally comparable across subsequent age groups above age 45. The estimates for the age/period/cohort model were thus downwards both for the period and the cohort component although, in such a situation, it is difficult to disentangle the major underlying component.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin and fibrinolysis in acute myocardial infarction: meta-analytic evidence for synergy

A meta-analysis of randomized clinical trials of fibrinolysis was performed, examining the interaction between aspirin and fibrinolysis in treating patients with acute myocardial infarction. Reductions in the odds of death up to 35 days were assessed for patients receiving tissue plasminogen activator or streptokinase up to 6 hours after the onset of symptoms. No significant difference in effectiveness between tissue plasminogen activator and streptokinase was demonstrated. The overall reduction in odds of death due to fibrinolytic therapy was 28%. However, there was a significant difference between the odds reduction of 24% when fibrinolysis is compared to placebo, and 40% when fibrinolysis and aspirin combined are compared to aspirin alone (p = 0.02). This difference indicates that there exists a synergistic interaction between coronary fibrinolysis and aspirin rather than independence of their beneficial effects, as is generally believed. These results illustrate the perils of assessing drug efficacy, even in an overview of all relevant trials, without consideration of identifiable sources of heterogeneity such as the interaction between the treatment of interest and co-interventions. They also demonstrate the potential application of logistic regression diagnostic techniques to meta-analyses.

Holter monitoring of ventricular arrhythmias in a randomised, controlled study of intravenous streptokinase in acute myocardial infarction

The occurrence of ventricular arrhythmias attributed to streptokinase treatment in acute myocardial infarction is not well defined. Holter monitoring was performed for 24 hours in 81 patients with suspected acute myocardial infarction randomised in a ratio of 2:1 to intravenous streptokinase 1.5 x 10(6) IU (n = 55) or placebo infusion (n = 26) 6.7 hours (mean) after the onset of symptoms. No episodes of ventricular fibrillation were recorded. For the whole 24 hour period and during the first three hours after the start of treatment the incidence and frequency of ventricular arrhythmias were similar in the patients randomised to streptokinase and to placebo. But when the results in patients randomised "early" after the onset of symptoms of suspected acute myocardial infarction were analysed separately the frequency of abnormal complexes, pairs, runs, and repetitive arrhythmias seemed to be higher in patients allocated to streptokinase. This may reflect arrhythmias associated with reperfusion.

Reduction in incidence of inducible ventricular tachycardia after myocardial infarction by treatment with streptokinase during infarct evolution

The aim of this study was to determine whether intravenous streptokinase administered with or without oral aspirin to patients with evolving myocardial infarction reduces the inducibility of ventricular tachycardia at electrophysiologic study and thus the risk of sudden death in infarct survivors. Of 159 patients randomized at Westmead Hospital to the multicenter Second International Study of Infarct Survival (ISIS-2) after streptokinase and aspirin in acute myocardial infarction, 87 underwent electrophysiologic testing 6 to 28 days after infarction to determine their risk of subsequent ventricular arrhythmias (streptokinase 20 patients; aspirin 25 patients; streptokinase and aspirin 21 patients; both placebos 21 patients). Patients who underwent electrophysiologic testing had similar clinical characteristics to those of patients who did not. The stimulation protocol comprised up to and including four extrastimuli applied to the right ventricular apex at twice diastolic threshold. An abnormal result was defined as ventricular tachycardia with a cycle length greater than or equal to 230 ms lasting greater than or equal to 10 s. Ventricular tachycardia was inducible at electrophysiologic study in 8 patients who received placebo streptokinase, but in no patient who received active streptokinase (8 of 46 versus 0 of 41; p = 0.005, Fischer's exact test). Ventricular tachycardia was inducible in 4 patients who received aspirin therapy and 4 who did not (4 of 41 versus 4 of 46; p = NS). During a mean follow-up period of 39 +/- 9 months, there were no spontaneous episodes of ventricular tachycardia, ventricular fibrillation or witnessed sudden death in the streptokinase-treated group compared with three such events in the placebo-treated group (p = 0.13). When compared with placebo therapy, intravenous streptokinase substantially reduced the incidence of inducible ventricular tachycardia in infarct survivors. No similar benefit was attributable to aspirin therapy.