Multicenter trial of intravenous anisoylated plasminogen streptokinase activator complex (APSAC) in acute myocardial infarction: effects on infarct size and left ventricular function

Two hundred thirty-one patients with a first acute myocardial infarction were randomly allocated within 5 h after the onset of symptoms either to treatment with anisoylated plasminogen streptokinase activator complex (APSAC), 30 U over 5 min, or to conventional heparin therapy, 5,000 IU in a bolus injection. Heparin was reintroduced in both groups 4 h after initial therapy at a dosage of 500 IU/kg per day. One hundred twelve patients received APSAC and 119 received heparin within a mean period of 188 +/- 62 min after the onset of symptoms. Both groups were similar in age, location of the acute myocardial infarction, Killip functional class and time of randomization. Elective coronary arteriography was performed on an average of 4 +/- 1.2 days after initial therapy. Follow-up radionuclide angiography and thallium-201 single photon emission computed tomography were performed before hospital discharge. Infarct size was estimated from single photon emission computed tomography and expressed as a percent of total myocardial volume. The patency rate of the infarct-related artery was 77% in the APSAC group and 36% in the heparin group (p less than 0.001). Left ventricular ejection fraction determined from contrast angiography was significantly higher in the APSAC group than in the heparin group. This was true for the entire study group (0.53 +/- 0.13 versus 0.47 +/- 0.12; p = 0.002) as well as for the subgroups of patients with anterior and inferior wall infarction (0.47 +/- 0.13 versus 0.40 +/- 0.11; p = 0.04 and 0.56 +/- 0.10 versus 0.51 +/- 0.11; p = 0.02, respectively). At 3 weeks, the difference remained significant for the anterior myocardial infarction subgroup. A significant 31% reduction in infarct size was found in the APSAC group (33% for the anterior infarction subgroup [p less than 0.05] and 16% for the inferior infarction subgroup [p = NS]). A close inverse relation was found between the values of left ventricular ejection fraction and infarct size (r = -0.73, p less than 0.01). By the end of a 3 week follow-up period, seven APSAC-treated patients and six heparin-treated patients had died. In conclusion, the early infusion of APSAC in acute myocardial infarction produced a high early patency rate, significant limitation of infarct size and significant preservation of left ventricular systolic function, mainly in anterior wall infarction.

Influence of fibrinolysis and percutaneous transluminal coronary angioplasty on the frequency of ventricular premature complexes

This study evaluated the aggressive management of acute myocardial infarction to determine how it modifies the incidence of ventricular arrhythmias and of other determinants of prognosis during recovery. The population consisted of 344 consecutive survivors of acute myocardial infarction admitted to the hospital with chest pain and ST-segment elevation on the electrocardiogram. Three groups constituted the study population: 168 control patients treated conservatively or in whom fibrinolysis was unsuccessful, 73 patients successfully reperfused with intravenous streptokinase and 103 patients with both successful fibrinolysis and successful percutaneous transluminal coronary angioplasty (PTCA) of the artery responsible for the infarct. Early spontaneous angina occurred in 47 control patients (28%), 25 streptokinase patients, (34%) and, in significantly fewer number, 20 PTCA patients (19%, p less than 0.05). Similarly, exercise-induced ST-segment depression on the predischarge exercise treadmill test was less frequent with PTCA (p less than 0.05). The number of ventricular premature complexes (VPCs) on a 24-hour Holter recording was 40 +/- 123/hr in the control group and significantly less in the streptokinase (21 +/- 64, p less than 0.05) and PTCA groups (17 +/- 61, p less than 0.05). Three or more VPCs/hr were observed in 50% of the control patients, compared with 29% of the streptokinase and 27% of the PTCA patients (p less than 0.005). Mean radionuclide ejection fraction was greater than 40% and similar in the 3 study groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intravenous streptokinase as compared with that of tissue plasminogen activator on left ventricular function after first myocardial infarction

In a double-blind trial comparing two thrombolytic agents as treatment for acute myocardial infarction, we randomized 270 consecutive patients an average (+/- SD) of 2.5 +/- 0.6 hours after the onset of chest pain from a first myocardial infarction--135 to receive intravenous streptokinase (1.5 million units over 30 minutes) and 135 to receive intravenous recombinant tissue plasminogen activator (rt-PA) (100 mg over three hours). The primary end point was left ventricular function as assessed by cineangiography performed three weeks after infarction. The effects of the two agents on left ventricular function were similar. The ejection fraction was identical (58 +/- 12 percent) in both groups. The end-systolic volume was 61 +/- 29 ml in the streptokinase group and 66 +/- 31 ml in the rt-PA group (P not significant). Patency rates at three weeks for the infarct-related artery were also similar (75 percent in the streptokinase group and 76 percent in the rt-PA group). Reinfarction rates at 30 days were the same (5 percent) in both groups. One patient had a fatal intracerebral hemorrhage 13 hours after receiving rt-PA, and another had a fatal cerebellar hemorrhage 21 hours after receiving rt-PA for reinfarction nine days after treatment with streptokinase. An intention-to-treat analysis revealed that mortality at 30 days was 3.7 percent in the rt-PA group as compared with 7.4 percent in the streptokinase group (P greater than 0.2). Follow-up for a mean of 9.0 months revealed no significant difference in survival; we observed 12 deaths (8.9 percent) in the streptokinase group and 8 deaths (5.9 percent) in the rt-PA group (P = 0.34). We conclude that rt-PA and streptokinase, in the doses given, have similar effects on left ventricular function after a first myocardial infarction. Because of the small number of deaths, it is not possible to determine whether their effects on mortality are similar.

Lower-extremity in situ saphenous vein grafts: angiographic interventions

In 16 consecutive patients, thrombosis, anastomotic and intragraft stenoses, and residual venous communications (arteriovenous fistulas [AVFs]), after in situ saphenous vein bypass of femoropopliteal and infrapopliteal arteries, were treated with interventional angiographic techniques. Streptokinase infusion for graft thrombosis was performed in four patients, with long-term clinical improvement in two; in the other two, early rethrombosis was treated with surgical thrombectomy. Delayed rethrombosis occurred at 13 months in another patient. Anastomotic (six occasions) and intragraft (four occasions) stenoses in six patients were dilated with percutaneous transluminal angioplasty (PTA). Two grafts subsequently occluded, one 3 weeks and one 3 months after PTA. Residual AVFs were occluded in ten patients. Ten of 16 patients remained clinically improved without further therapy. One complication occurred: A graft stenosis developed at the site where a coil, protruding from the AVF into the graft lumen, was successfully removed and replaced.

Thrombolytic therapy in acute myocardial infarction: an overview (continuing education credit)

An understanding of the pathophysiology of acute MI helps the emergency nurse to appreciate the value of thrombolytic therapy for these patients. Knowledge of the mechanisms of action, benefits, and side effects of these agents will help the nurse to manage optimally the care of patients undergoing thrombolytic therapy.

Clinical experience with thrombolytic agents

It is now possible through the administration of thrombolytic therapy to dissolve an obstructive thrombus in the coronary artery. On the basis of the pathophysiology of acute MI, this should translate into interruption of the ischemic process and benefit to the patient. Clinical trials with t-PA and SK have supported this concept by demonstrating preservation of LVF, reduction in congestive heart failure, and reduction in mortality. All clinical data point to the importance of early intervention and treatment in attaining maximal patient benefit. Studies have shown the safety and feasibility of early treatment in the emergency setting. In the era of thrombolytic therapy, there is an opportunity for the emergency physician and nurse to play a significant role in the treatment of the patient with acute MI. Prompt intervention with thrombolytic therapy in the emergency department will offer the patient the greatest opportunity for benefit.

Streptokinase treatment versus calcium overload blockade in experimental thromboembolic stroke

Thromboembolic brain ischemia was produced in dogs using an autologous blood clot model. The effect of postembolic treatment with flunarizine and streptokinase on hemispheric cerebral metabolic rate for oxygen (CMRO2), oxygen extraction ratio (OER), and cerebral blood flow (CBF) was studied by positron emission tomography (oxygen-15 technique) 24 hours after the insult. We studied five groups of experimental dogs and compared them with a control group of nonembolized dogs. Group I received no treatment, Group II was treated locally with 500,000 IU streptokinase starting 30 minutes after the insult, Group III received streptokinase locally 30 minutes after the insult and 0.1 mg/kg i.v. flunarizine immediately after the insult and 2 hours later, Group IV received flunarizine as Group III, and Group V was orally pretreated with 0.5 mg/kg/day flunarizine during 2 weeks preceding embolization. Compared with the contralateral hemisphere, in the embolized hemisphere a significant reduction of CMRO2 (-25% to -40%) and CBF in normocapnia (-35%) and hypercapnia (-50%) was observed in Groups I, II, and V. In Groups III and IV, CMRO2, OER, and CBF of the embolized hemisphere were within the normal range during normocapnia and hypercapnia; the extent of the ischemic lesions was markedly less than in the other groups of experimental dogs. We conclude that flunarizine treatment after experimental thromboembolic stroke had a favorable influence on brain tissue. Chronic preventive flunarizine treatment failed to have a beneficial effect.

Doppler echocardiography: application to the assessment of successful thrombolysis of prosthetic valve thrombosis

Prosthetic valve thrombosis remains a significant problem despite anticoagulation therapy and advances in valve design. Thrombolytic therapy offers an alternative approach to valve replacement in patients with high surgical risk. In this article we discuss three cases in which Doppler echocardiography was used to confirm the diagnosis of prosthetic mitral valve obstruction and serially monitor the response of valvular hemodynamic measurements to thrombolysis with intravenous streptokinase. These cases illustrate how the Doppler technique, in addition to allowing the noninvasive diagnosis of prosthetic valve obstruction, is presently the ideal tool to follow serially the effect of thrombolytic therapy on prosthetic valve function.

Thrombolytic therapy

The accepted role for thrombolytic therapy has until recently been limited because of its complexity and side-effects. It has generally been reserved for use systemically in a limited number of patients with acute, major pulmonary embolism or iliofemoral venous thrombosis, and locally in some patients with acute, peripheral arterial occlusion. Its indications have now been greatly expanded by the confirmation from large, multicentre trials completed within the last year that it is also effective in acute myocardial infarction, with a reduction in acute mortality of 20-25%. Moreover, administration has become greatly simplified as dosage regimens have been standardised and the need for laboratory monitoring eliminated. The standard thrombolytic agent used for nearly 3 decades has been streptokinase but within the last year recombinant, human, tissue-type plasminogen activator (the first 'third generation' thrombolytic agent) has become clinically available. This protein is the body's own chief plasminogen activator and has been produced by recombinant DNA technology. Compared with streptokinase, it appears to be both somewhat more effective and also safer (less bleeding and probably no allergic reactions). Other new thrombolytic agents are also being developed but the cost-effectiveness of the newer agents in relation to streptokinase will be for many the main practical issue.

Salvage of occluded arterial bypass grafts by means of thrombolysis

Seventy-two thrombosed peripheral arterial bypass grafts in 62 patients were treated by local intraarterial thrombolytic infusion. The initial success rate was 69% (50 of 72 grafts). Graft material and location had no significant effect on the initial results. Urokinase was used in 43 cases with a 84% success rate, and streptokinase was used in 29 cases with a 48% success rate. After a follow-up period that ranged from 2 to 58 months, 27 grafts remained patent, with an average patency duration of 15 months (median 8 months). Overall graft patency at the end of 1 year was 60% applying life-table analysis. Factors that were evaluated to determine their effect on long-term patency included graft age and material, graft location, and the presence or absence of an underlying correctable lesion. The most significant factor in long-term patency was the presence of a lesion that was correctable by surgical revision or balloon angioplasty. In 25 grafts with underlying stenotic lesions, the 1-year patency was 86% after successful treatment. Twenty-five grafts without detectable lesions had 37% 1-year patency.

[Socioeconomic implications of the practice of thrombolysis in the acute stage of myocardial infarction]

The use of variegated and costly thrombolytic agents for the treatment of myocardial infarction in its acute phase may have medico-social advantages. In the present study, these advantages were evaluated after one year from two age and sex matched populations: 40 patients who underwent thrombolysis and 38 patients who did not. Compared with the first hospitalizations, the difference was + 4,000 francs, rising to + 11.000 francs with the drug Eminase. A questionnaire including medical, social and economic data was sent to the 78 patients and was filled by 63 of them, remaining unanswered by one patient who had thrombolysis and 10 patients who did not. Readmission to hospital showed a 44.000 francs difference to the benefit of patients who underwent thrombolysis. Ancillary care and return to work were similar in both groups. Cost expectancy was 119.500 francs for patients who had thrombolysis and 122.000 francs for those who did not. Thrombolysis therefore is a cost reduction factor, but its influence on costs is less pronounced when it is performed soon after the onset of myocardial infarction. Thrombolysis is more expensive when carried out at home than in hospital. In this study, the excess cost (+ 5.000 francs) was due to the relatively small number of patients and to the loss of professional activity which may be an uncertain factor. Mortality at one year was nil when thrombolysis was performed within the first two hours (12 patients) and rose to 16.6 percent between 2 and 3 hours (18 patients) and 30 percent after 3 hours (10 patients). Conducted on a necessarily limited number of patients, this multiple criteria study was also aimed at establishing a method to evaluate the health expenditures imposed by the introduction of new and costly treatment in the management of myocardial infarction.

Evolution of left ventricular function after intracoronary thrombolysis for acute myocardial infarction

The temporal evolution of left ventricular (LV) function after intracoronary streptokinase therapy for acute myocardial infarction (AMI) was assessed from the data of 264 patients who had complete occlusion of either the left anterior descending or the right coronary artery before treatment. Angiography was performed immediately, and at 3 days and 6 months after AMI in 91%, 71% and 47% of the study group, respectively. Wall motion was measured by the centerline method. In patients with sustained reperfusion, the ejection fraction decreased at 3 days (delta = -2.0 +/- 9.9%, n = 134, p = 0.02) and recovered later (from 54 +/- 12% acutely to 57 +/- 12% at 6 months, n = 82, p less than 0.05). These changes in global function were associated with a marked regression in hyperkinesis in the noninfarcted wall by 3 days, and delayed recovery of wall motion in the infarct region (delta = 0.2 +/- 0.9 at 3 days, p = 0.055; 1.0 +/- 1.2 at 6 months, p less than 0.001). Patients without reperfusion or with reocclusion had a more severe decrease in ejection fraction at 3 days, and little or no subsequent functional recovery. The length of the hypokinetic segment increased significantly by 3 days but subsequently diminished to slightly less than the acute value. It is concluded that full recovery of ischemically impaired myocardium takes greater than 3 days, but compensatory hyperkinesis regresses earlier so that global LV function deteriorates by the third day. Variability or deterioration of LV function early after AMI need not be due to infarct extension; it can reflect regression of hyperkinesis in the noninfarcted region.

Fibrinolytic therapy in peripheral arterial grafts utilizing the "crossed two catheter" technique

Direct puncture of a thrombosed lower extremity bypass graft may be the only angiographic access to the graft when it cannot be opacified or cannulated by conventional angiographic techniques. In 1 patient, fibrinolytic therapy was performed from this approach using the "crossed two catheter" technique previously described for thrombosed dialysis grafts.

[Streptokinase treatment in acute myocardial infarction]

Myocardial necrosis develops gradually after coronary artery occlusion, and in man is completed after several hours. Most infarctions are precipitated by thrombi, and early fibrinolytic treatment should therefore be the rational therapy. Recanalization is achieved in three of four patients whether streptokinase is applied intracoronary or intravenously. Early treatment limits the size of the infarct, and he myocardial function is preserved better in patients treated with streptokinase than in others. Very early treatment, started within one hour from the onset of nitroglycerin-resistant chest pain, may prevent infarction in some patients. Streptokinase reduces mortality after infarction, in total by as much as 25 per cent, and even considerably more when infusion is started early. There is some risk of bleeding, but serious bleeding episodes are rare. Intracoronary application has no advantages as compared with intravenous infusion. Unless there are strong contra-indications, patients with nitroglycerin-resistant chest pain and abnormal ECG should receive streptokinase intravenously in a dose of 1.5 x 10(6) units. Most patients treated with streptokinase should be given acetylsalicylic acid.

Massive pulmonary embolism: triple-armed therapy

Many patients who suffer a massive pulmonary embolus die despite emergent therapy. In these desperately ill patients an aggressive, combined method of management was initiated to improve their chances and quality of survival. During a 5-year period 10 patients were treated with (1) low-dose topical, intrapulmonary thrombolytic therapy to dissolve thrombus, (streptokinase or urokinase); (2) anticoagulation to prevent thrombus propagation (heparin); and (3) the simultaneous insertion of a Greenfield filter to prevent the early, recurrent, and therefore potentially fatal pulmonary embolus--"triple-armed therapy." Thrombolytic therapy was administered through a Swan-Ganz catheter wedged against the pulmonary embolus. During the same interval 10 other patients also sustained massive pulmonary emboli but were treated only with systemic heparin. Serial pulmonary arteriography was performed daily. The patients treated by triple-armed therapy responded favorably with a rapid (less than 6 hours), significant improvement in PaO2, pulmonary artery pressure, cardiac output, pulmonary vascular resistance, and blood pressure, compared with patients treated with continuous heparin alone. Nine patients in the triple-armed therapy group survived whereas only six in the heparin group survived. Two additional patients were treated by triple-armed therapy and had thrombolysis with triple-armed therapy with tissue plasminogen activator; these patients demonstrated the most rapid improvement in cardiorespiratory dynamics and arteriographic clearance of emboli. This management protocol shows promise for patients who sustain a massive pulmonary embolus, because it reduces the morbidity associated with pulmonary embolectomy while avoiding the hazards associated with systemic thrombolytic therapy.

Streptokinase used in general practice

Over a six-month study in general practice 43 patients were identified whose presenting symptom was chest pain thought to be cardiac in origin. The median time from the onset of pain to the general practitioner attending was 60 minutes. On the basis of history, examination and initial electrocardiogram these patients were assessed as unlikely or likely to be infarcting. Of this latter group 15 fulfilled the inclusion criteria for intravenous streptokinase, four commencing treatment at home and 11 on admission to the local general practitioner medical ward. Each received 1.5 mega units over 60 minutes. The median time from the onset of pain to the start of therapy was 120 minutes. Of the 28 patients clinically suspected of having sustained a myocardial infarct 24 proved positive--an over-diagnosis rate of 14%. No major problems were encountered following streptokinase.