Thrombolytic therapy. A new strategy for the treatment of acute myocardial infarction (1)

Thrombosis and Thrombolysis: Platelet Membrane Glycoproteins

Over the last quarter of a century, therapy for acute coronary syndromes has rapidly evolved. The major causative factor for acute coronary syndromes, particularly acute myocardial infarction, is now recognised to be coronary thrombosis and therapies using thrombolytic agents to dissolve thrombus or percutaneous coronary interventions (angioplasty and stenting) to mechanically disrupt thrombus and restore vessel patency are now routine. The precipitant for coronary thrombus is believed to be atherosclerotic plaque rupture. Plaque rupture has been demonstrated at autopsy in humans and in vivo in an experimental animal model for atherosclerosis. Thrombus formed at these sites is platelet rich and anti-platelet therapy has an established role in the treatment of cardiovascular disease. The study of platelet membrane glycoproteins, which mediate platelet adhesion and aggregation, has resulted in specific therapies. Future directions for research with clinical relevance include the development of markers for plaque instability.

Effects of reperfusion on arrhythmias and death after coronary artery occlusion in the rat: increased electrical stability independent of myocardial salvage

OBJECTIVES

This study sought to delineate salvage-dependent from salvage-independent coronary reperfusion in acute myocardial infarction and the effects on spontaneously occurring arrhythmias and arrhythmic death in rats.

BACKGROUND

Reperfusion of the infarct-related artery might increase electrical stability independently of salvage of ischemic myocardium.

METHODS

In 98 conscious rats the electrocardiogram was monitored by telemetry for 48 h after MI, and all episodes of ventricular tachycardia (VT) and ventricular fibrillation (VF) were analyzed. Reperfusion at 45 min (RP45) (n = 15), 90 min (RP90) (n = 18) and 180 min (RP180) (n = 30) min was compared with permanent coronary artery occlusion (CAO) (n = 35) with respect to the post-reperfusion periods.

RESULTS

RP45, RP90 and RP180 reduced the incidence of VT by 93%, 98% and 88% and VF by 89%, 97% and 92%, respectively (all p < 0.01 vs. CAO). The all-cause mortality rate was reduced from 47% (CAO) to 8% (RP45, p < 0.05) and 0% (RP90, p < 0.01); after RP180 it was 17% (CAO 42%, p = 0.08). All reperfusion regimens reduced arrhythmic deaths: 47% to 8% (RP45, p < 0.05), 47% to 0% (RP90, p < 0.01) and 42% to 8% (RP180, p < 0.05). Infarct size was identical to that during CAO (49 +/- 10% [mean +/- SD]) and RP180 (49 +/- 10%), whereas preferentially epicardial salvage occurred at RP45 (36 +/- 8%, p < 0.001) and RP90 (38 < 10%, p < 0.001).

CONCLUSIONS

Early and late reperfusion reduce the incidence and duration of VT and VF in conscious rats with acute MI. Thereby, arrhythmia-related mortality is improved through the prevention of fatal VF episodes. Thus, reperfusion increases the electrical stability of the heart independently of myocyte salvage, as proposed by the open artery hypothesis.

Bisaramil and antiarrhythmics as inhibitors of free radical generation

The aim of this study was to investigate the effect of bisaramil--an antiarrhythmic drug under clinical trials-on free radical generation of isolated polymorph neutrophil granulocytes (PMN) and furthermore to compare its activity to that of well-known antiarrhythmics which have different modes of action. PMNs were isolated from healthy beagle dogs, and superoxide radical generation was induced by phorbol-myristate-acetate. Stimulated free radical generation capacity of PMNs and the time lag necessary for the initiation of free radical production were measured. All compounds were used at the concentrations of 10, 25, 50, 75, 100 micrograms ml-1. None of the antiarrhythmics stimulated by itself the free radical generation. Bisaramil exerted concentration dependent inhibitory effect on PMA-stimulated free radical generation and prolonged the time lag concentration dependently. At the investigated concentration range of antiarrhythmics only propafenon, mexiletine and diltiazem showed similar activity to bisaramil, but clear concentration dependency could not be seen in any of the cases. According to the results of this study inhibition of the stimulated free radical production of isolated PMNs cannot be closely connected merely to either membrane stabilizing or Ca-antagonistic activity of drugs. In vitro and earlier measured in vivo inhibitory action of bisaramil on free radical generation indicate a possible cardioprotective effect existing independently from its antiarrhythmic one. This observation may be important in outlining of the clinical indication field of bisaramil, and may be useful in the treatment of reperfusional damage.

Metaanalysis of five reported studies on the relation of early coronary patency grades with mortality and outcomes after acute myocardial infarction

Coronary patency has been used as a measure of thrombolysis success after acute myocardial infarction (AMI). The Thrombolysis in Myocardial Infarction (TIMI) study grading scale for coronary perfusion has gained wide acceptance, but the significance of individual grades on clinical outcome has not been adequately tested. We hypothesized that optimal outcomes would be achieved only with early (and maintained) TIMI grade 3 (complete) perfusion compared with TIMI grade 2 (partial perfusion, previously classified as a reperfusion success) or grades 0 or 1 (occluded arteries). Five recent, angiographically controlled, prospectively performed studies of thrombolysis in AMI were identified, representing 3,969 patients. Odds ratios for mortality by early perfusion grades were calculated using the Mantel-Haenszel test and combined in a weighted fashion. Results for selected clinical and laboratory outcomes by patency grade were also assessed. Overall, mortality averaged 8.8% for TIMI grade 0/1, 7.0% for grade 2, and 3.7% for grade 3 perfusion. The odds ratio (OR) for early mortality was substantially reduced for grade 3 versus <3 perfusion (OR = 0.45, confidence interval [CI] 0.34 to 0.61, p <0.0001). In pairwise comparisons, grade 3 was clearly superior to grade 2 (OR = 0.54, CI) 0.37 to 0.78, p = 0.001) as well as grades 0/1 (OR = 0.41, CI 0.30 to 0.56, p <0.0001). Acute and convalescent ejection fraction, regional wall motion, time to enzyme peaks (creatine kinase [CK], creatine kinase myocardial bond [CK-MB]), peak enzyme levels [CK, lactate dehydrogenase [LDH], LDH-1), and risk of heart failure were each significantly less in patients achieving grade 3 than grade 2 (or lower grades) perfusion. Results were observed despite the frequent use of interventions after angiography. This meta-analysis demonstrates that early and complete (grade 3) flow is associated with superior survival and clinical outcome; grade 2 perfusion results in an inferior outcome, closer to that of an occluded than an open artery. The goal of reperfusion strategies should be early and maintained TIMI grade 3 perfusion.

Prognostic significance of ST-T segment alterations in patients with non-Q wave myocardial infarction

OBJECTIVE

To determine whether, among patients with non-Q wave myocardial infarction, the characteristics of the segment ST-T shifts at presentation in the diagnostic electrocardiogram can identify those with more severe coronary artery disease and predict a poor clinical outcome.

DESIGN

Prospective controlled clinical trial.

SETTING

Primary referral medical centre.

PATIENTS

93 patients (mean (SD) 62.0 (7.5) years) were studied: 41 with non-Q wave myocardial infarction and T wave inversion and 52 with ST segment depression. Cardiac events and mortality rates were assessed over 42 months. Age, sex, risk factors, creatinine kinase MB isoenzyme peak, and left ventricular function were comparable.

RESULTS

31 patients with T wave inversion myocardial infarction (94.6%) had total occlusion of the infarct related artery, compared with 12 patients with ST segment depression myocardial infarction (26.7%) (P < 0.05). When compared with patients with T wave inversion, patients with ST segment depression had a higher incidence of cardiac events during the first month and in the 41 subsequent months: 9.6% and 30.8% v 0% (P < 0.01) and 9.8% (P < 0.02), respectively. For the same observation periods, the mortality rates in patients with T wave inversion were 4.9% and 7.3%, and in patients with ST segment depression they were 5.8% and 9.6%, respectively.

CONCLUSION

These data suggest that during a non-Q wave myocardial infarction the presence of ST segment depression is related to higher rates of short and long term cardiac events when compared with T wave inversion--possibly because of a higher incidence of residual stenosis of the infarct related artery.

Early remodelling of coronary stenoses after thrombolytic treatment in patients with acute myocardial infarction

OBJECTIVE

To assess the frequency of early remodelling of coronary stenosis morphology after thrombolytic treatment in patients with acute myocardial infarction.

DESIGN

Coronary angiograms were analysed by a computerised edge detection analysis system. Coronary stenosis severity was measured and morphology classified as smooth or complex.

PATIENTS

Coronary arteriograms were obtained approximately 90 min and 24 h after thrombolytic treatment from 40 patients with acute myocardial infarction.

MAIN RESULTS

Stenosis morphology was complex in 22 patients (65%) and smooth in 11 (32%) 90 min after thrombolysis. The morphology of 11 (50%) complex coronary stenoses and three (27%) smooth stenoses had changed at 24 h (P < 0.05). The transition from complex to smooth was associated with a reduction in stenosis severity from 65 (4)% to 51 (5)% (P < 0.05). The stenosis severity was 63 (4)% and 60 (5)% in those with persistently complex morphology, and 56 (7)% and 50 (5)% in those with persistently smooth morphology at 90 min and 24 h respectively (NS).

CONCLUSIONS

Transition of morphology from complex to smooth within 24 h is common. This transition is associated with a reduction in stenosis severity of a degree greater than that found in persistently smooth stenoses over the same interval. 50% of stenoses are smooth at 24 h.

MYOCARDIAL REVASCULARIZATION

Atherosclerotic coronary artery disease causes more morbidity, mortality and loss of economic capacity than any other group of diseases. The modalities of revascularization of the myocardium have undergone rapid advances with emphasis shifting alternately from medical methods to surgical. Lately interventional cardiology armed with laser technology stands at par with coronary artery bypass grafts.

Coronary artery spasm. Multiple causes and multiple roles in heart disease

Myocardial infarction and sudden cardiac death may be initiated by a sudden intense localized contraction of coronary artery smooth muscle. When this event occurs around a vulnerable eccentric lipid-filled plaque, rupture and extrusion of plaque contents and exposure of collagen occur. This may sometimes be a silent and self-limiting event; other times it leads to thrombus formation. A second wave of spasm due to accumulated platelet and inflammatory mediators may compound the contractile consequences of the initiating event. Spasm involves intrinsic smooth muscle cell electrical mechanisms, hyper-responsive cells, and multiple agonists that synergize their actions, and the involvement of each mechanism varies at different times in the sequence of vascular occlusion. Study of spasm requires vascular systems that adequately model coronary artery responses of the ageing human heart. As previously emphasized, tissues obtained postmortem, and when possible from recipients during heart transplants, must be integral to theory building, alongside animal models, despite the experimental limitations such tissues impose. A multidisciplinary approach, at all levels of vascular physiology and pharmacology, will be necessary to understand coronary motor activity and human heart disease.

Urgent therapy for acute stroke. Effects of a stroke trial on untreated patients

BACKGROUND AND PURPOSE

As part of the recruitment efforts for the National Institutes of Health Tissue Plasminogen Activator Pilot Study, public education and awareness campaigns were conducted to encourage early hospital arrival. We evaluated the change in arrival times during the course of the study for all stroke patients, including those who were not entered into study.

METHODS

Data were gathered on all patients presenting within 24 hours of stroke onset to all of the study hospitals. Coincident with the start of the study, educational and promotional programs, which stressed signs and symptoms of stroke and the need to call 911, were presented to physicians, paramedical personnel, and the public. The study was divided into four quartiles to analyze differences in time to hospital arrival and use of 911.

RESULTS

Of 2099 patients screened, time data were available on 1116. During the course of the study, the mean time from symptom onset to hospital arrival declined significantly (3.2 hours versus 1.5 hours). Patients arrived for treatment sooner at community hospitals than at university/teaching hospitals. The use of 911 increased from 39% in the first quartile of the study to 60% in the fourth quartile. This was a consistent finding in all study sites. Increased use of 911 was seen almost exclusively in patients with nonhemorrhagic stroke.

CONCLUSIONS

Times from stroke onset to hospital arrival decreased significantly during the course of the National Institutes of Health Tissue Plasminogen Activator Pilot Study. Significantly increased use of 911 was the likely major explanation for the shortened arrival times. The decrease in arrival times may be a consequence of the public and professional education programs conducted at all study sites.

Difference in plasminogen activator inhibitor activity between non-Q-wave infarction and Q-wave infarction

We examined the plasma levels of tissue plasminogen activator antigen and plasminogen activator inhibitor activity in 14 patients with non-Q-wave infarction and in 27 patients with Q-wave infarction before the start of thrombolytic therapy and in 34 control subjects. The mean level of plasma tissue plasminogen activator antigen (ng/ml) was higher (P < 0.01) both in the patients with non-Q-wave infarction and in those with Q-wave infarction than in the control subjects (10.3 +/- 1.9, 9.5 +/- 0.8 vs. 5.8 +/- 0.3), and there was no difference in the level between the patients with non-Q-wave infarction and those with Q-wave infarction. The mean level of plasma plasminogen activator inhibitor activity (IU/ml) was lower (P < 0.01) in the patients with non-Q-wave infarction than in those with Q-wave infarction (7.3 +/- 2.0 vs. 17.1 +/- 2.2), and there was no difference in the level between the patients with non-Q-wave infarction and the control subjects (7.3 +/- 2.0 vs. 4.1 +/- 2.6). The patency rate of infarct-related coronary artery before thrombolytic therapy was higher (P < 0.01) in the patients with non-Q-wave infarction than in those with Q-wave infarction (54% vs. 15%). We conclude that plasminogen activator inhibitor activity was lower in non-Q-wave infarction than in Q-wave infarction and this may be related to the higher patency rate of infarct-related coronary artery in non-Q-wave infarction.

Anistreplase versus alteplase in acute myocardial infarction: comparative effects on left ventricular function, morbidity and 1-day coronary artery patency. The TEAM-3 Investigators

OBJECTIVES

This double-blind, randomized, multicenter trial was designed to compare the effects of treatment with anistreplase (APSAC) and alteplase (rt-PA) on convalescent left ventricular function, morbidity and coronary artery patency at 1 day in patients with acute myocardial infarction.

BACKGROUND

Anistreplase (APSAC) is a new, easily administered thrombolytic agent recently approved for treatment of acute myocardial infarction. Alteplase (rt-PA) is a rapidly acting, relatively fibrin-specific thrombolytic agent that is currently the most widely used agent in the United States.

METHODS

Study entry requirements were age less than or equal to 75 years, symptom duration less than or equal to 4 h, ST segment elevation and no contraindications. The two study drugs, APSAC, 30 U/2 to 5 min, and rt-PA, 100 mg/3 h, were each given with aspirin (160 mg/day) and intravenous heparin. Prespecified end points were convalescent left ventricular function (rest/exercise), clinical morbidity and coronary artery patency at 1 day. A total of 325 patients were entered, stratified into groups with anterior (37%) or inferior or other (63%) acute myocardial infarction, randomized to receive APSAC or rt-PA and followed up for 1 month.

RESULTS

At entry, patient characteristics in the two groups were balanced. Convalescent ejection fraction at the predischarge study averaged 51.3% in the APSAC group and 54.2% in the rt-PA group (p less than 0.05); at 1 month, ejection fraction averaged 50.2% versus 54.8%, respectively (p less than 0.01). In contrast, ejection fraction showed similar augmentation with exercise at 1 month after APSAC (+4.3% points) and rt-PA (+4.6% points), and exercise times were comparable. Coronary artery patency at 1 day was high and similar in both groups (APSAC 89%, rt-PA 86%). Mortality (APSAC 6.2%, rt-PA 7.9%) and the incidence of other serious clinical events, including stroke, ventricular tachycardia, ventricular fibrillation, heart failure within 1 month, recurrent ischemia and reinfarction were comparable in the two groups; and mechanical interventions were applied with equal frequency. A combined clinical morbidity index was determined and showed a comparable overall outcome for the two treatments.

CONCLUSIONS

Convalescent rest ejection fraction was high after both therapies but higher after rt-PA; other clinical outcomes, including exercise function, morbidity index, and 1-day coronary artery patency, were favorable and comparable after APSAC and rt-PA.

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.

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.

Percutaneous transluminal coronary angioplasty for unstable angina

Coronary angioplasty is an effective treatment for patients with angina at rest, either refractory or initially stabilized but returning despite pharmacologic treatment, and with early postinfarction angina. The procedure has a high initial success rate, but there is an increased risk of major complications resulting from a higher incidence of acute closure, which may be related to preexisting thrombus. Resolution of this problem may be achieved by the use of more potent antiplatelet treatment, pretreatment with thrombolytic agents, or treatment that can be applied locally (e.g., laser energy, atherectomy) at the site of the unstable plaque. Results in this study have been obtained from selected groups of patients: those with predominantly single-vessel disease and well-preserved left ventricular function. It remains to be determined whether the same benefits can be achieved in patients with multivessel disease or in those who have severely reduced left ventricular function.

Tissue plasminogen activator-associated lingual artery hemorrhage

Reported is the case of a patient with vertebrobasilar artery ischemia who received tissue plasminogen activator with resulting hemorrhage into the tongue and nearly exsanguinating hemorrhage from a branch of the lingual artery. Suggestions for immediate management of the hemorrhage as well as prevention are presented. As the use of thrombolytic agents increases and the list of their indications expands, unusual life-threatening hemorrhagic problems other than gastrointestinal or intracranial bleeding will be seen, and management decisions may be life saving.

Incidence and prognosis of secondary ventricular fibrillation in acute myocardial infarction. Evidence for a protective effect of thrombolytic therapy. GISSI Investigators

The multicenter randomized study of the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico has provided the opportunity to analyze the impact of thrombolytic treatment on secondary ventricular fibrillation incidence in a large population of patients (11,712) with acute myocardial infarction. A reduction of about 20% in the frequency of secondary ventricular fibrillation was observed among patients allocated to thrombolytic treatment (streptokinase, 2.4% versus control, 2.9%; relative risk, 0.80; 95% confidence interval, 0.64-1.00). Streptokinase appeared to exert its protective effect specifically in patients treated within 3 hours of onset of symptoms (streptokinase, 2.6% versus control, 3.7%; relative risk, 0.71; 95% confidence interval, 0.53-0.95). This protection was essentially due to a reduced incidence of late ventricular fibrillation occurring after the first day of hospitalization. The 311 patients with secondary ventricular fibrillation represented an overall incidence of 2.7%. Such incidence was not related to infarct location or sex but was significantly more common in patients older than 65 years (3.3% versus 2.3% in younger patients). A significant excess of in-hospital deaths was found in patients with secondary ventricular fibrillation compared with those in the reference group (38% versus 24%; relative risk, 1.98; 95% confidence interval, 1.56-2.52). Conversely, secondary ventricular fibrillation was not a predictor of 1-year mortality for hospital survivors. Thrombolytic treatment with intravenous streptokinase affords protection against secondary ventricular fibrillation most probably by a limitation of infarct size. When the arrhythmia complicates the course of infarction, it is associated with an adverse short-term outcome, whereas the long-term prognosis is not influenced.

Conjugation to antifibrin Fab' enhances fibrinolytic potency of single-chain urokinase plasminogen activator

Single-chain urokinase plasminogen activator (scu-PA) that had been modified with N-succinimidyl-3-(2-pyridyldithio)propionate was covalently linked by disulfide bonds to the Fab' of a monoclonal antibody specific for the beta-chain of fibrin (antibody 59D8). scu-PA-59D8 Fab' conjugate was separated from free scu-PA and two-chain urokinase coupled to 59D8 Fab' by two-step affinity chromatography. First, the reaction mixture was chromatographed on a column containing Sepharose linked to the peptide that had been used as immunogen for antibody 59D8; scu-PA-59D8 Fab' conjugate and unconjugated 59D8 Fab' were retained but not unconjugated scu-PA. Then, the eluate from the peptide-Sepharose column was chromatographed on a column containing Sepharose linked to benzamidine, which acts as a ligand for two-chain urokinase. The molecular weight of the scu-PA-59D8 Fab' conjugate was approximately 100 kDa when electrophoresed on a nonreducing sodium dodecylsulfate-polyacrylamide gel. Enzymatic assay after purification revealed that more than 97% of the scu-PA present in the conjugate retained the single-chain form. The Fab' portion of the conjugate functioned in a manner indistinguishable from that of native antibody 59D8. In an in vitro assay for lysis of fibrin monomer, the fibrinolytic potency of scu-PA-59D8 Fab' was 33-fold more than that of tissue plasminogen activator (p less than 0.001), 230-fold more than that of unconjugated scu-PA (p less than 0.0001), and 420-fold more than that of urokinase (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin and infarct coronary artery patency after streptokinase in acute myocardial infarction

Anticoagulant therapy is frequently used after thrombolytic agents in the treatment of acute myocardial infarction (AMI) although it is unclear that such therapy will prevent subsequent infarct vessel reocclusion. The role of duration of heparin therapy in maintaining infarct artery patency was studied retrospectively in 53 consecutive AMI patients who received streptokinase therapy and underwent coronary angiography acutely and at 14 +/- 1 days. Of the 39 patients with initial infarct vessel patency, patency at follow-up angiography was observed in 100% (22 of 22) of those who received greater than or equal to 4 days of intravenous heparin but in only 59% (10 of 17) of those patients who received less than 4 days of heparin (p less than 0.05). Of the 14 patients not initially recanalized after streptokinase, patent infarct-related arteries at follow-up angiography were found in 3 of 8 (38%) treated with greater than or equal to 4 days of heparin therapy but in none of the 6 patients treated for less than 4 days (difference not significant). No significant difference in hemorrhagic complications was noted between the short- and long-term heparin treatment groups. Thus, greater than or equal to 4 days of intravenous heparin therapy after successful streptokinase therapy in AMI is more effective in maintaining short-term infarct vessel patency than a shorter duration of therapy and it may maintain the short-term patency of the infarct vessel in those patients who later spontaneously recanalize.

Value of immediate angioplasty after intravenous streptokinase in acute myocardial infarction

To improve reperfusion, immediate percutaneous transluminal coronary angioplasty (PTCA) was considered after intravenous streptokinase (0.75 to 1.5 million U) was administered to 98 patients with acute myocardial infarction less than 4 hours after the onset of chest pain. Thirty-four culprit arteries were occluded (group A); 42 arteries were patent with residual stenosis of more than 70% (group B). Twenty-two patients had residual stenosis of less than 70% (group C); eight of these had severe disease of the remaining vessels. Group C patients were either treated conservatively or underwent bypass surgery. Immediate PTCA was attempted in 74 patients (32 in group A, 42 in group B) and was successful in 68 (92%). Emergency bypass surgery for acute occlusion after PTCA was required in two patients. Follow-up averaged 23 months (range, 16 to 47 months). Asymptomatic occlusion recurred in three patients. Restenosis occurred in five patients: four had early restenosis (one in group A, three in group B) and one had late restenosis (group B). These arteries were successfully redilated. Late reinfarction occurred in two patients. They were treated with intravenous urokinase and repeat PTCA. Elective bypass surgery was performed in three patients because of recurrent angina. They had severe three-vessel disease as revealed by control angiography. The mortality rate was 2.7% (two patients; one in group B had early reinfarction, and one patient in group A died suddenly after 17 months). Eighty-five percent of patients treated with PTCA alone remain free of symptoms. This approach has a high success rate and low morbidity and mortality rates. Long-term results are superior to thrombolysis alone.

Variability of thrombolytic coronary reperfusion: an angiographic study of streptokinase and anistreplase

A total of 1,615 angiographic readings in 240 patients with acute myocardial infarction were analyzed from a randomized trial of intravenous anistreplase (Eminase), also known as anisoylated plasminogen streptokinase activator complex (APSAC), versus intracoronary streptokinase. Coronary arteriography was performed at baseline and at 15, 30, 45, 60, 75, and 90 minutes after drug infusion. Coronary flow in the infarct-related artery was defined using the TIMI criteria. Some serial change in perfusion was noted in 25% of the total patient population and in 49% of all reperfusion patients. Complete loss of perfusion (grade 2 or 3 to grade 0 or 1) occurred in 35% of all reperfused patients. Half of these patients ultimately developed complete loss of perfusion at the study endpoint. All of these changes in flow were statistically more common for the circumflex coronary artery and early treatment (less than 4 h), but did not differ for anistreplase or streptokinase. We conclude that frequent alterations in coronary blood flow occur early during reperfusion therapy and that these findings may explain reports with varying results of thrombolytic therapy. Any angiographic assessment of thrombolytic drug efficacy should take these variations as well as interobserver variability into account.

Summary of U.S. clinical trials program for evaluation of anistreplase

Because the reestablishment of coronary blood flow is believed to be central to the benefit of thrombolytic therapy, the U.S. evaluation program of anistreplase has focused on reperfusion, patency, and reocclusion comparisons with approved thrombolytic regimens, including (1) intracoronary streptokinase (completed) (TEAM-I), (2) intravenous streptokinase (completed) (TEAM-II), and (3) intravenous tissue plasminogen activator complex or alteplase (tPA, ongoing) (TEAM-III). The TEAM trials have established that anistreplase possesses similar reperfusion efficacy to intracoronary streptokinase, if given within 4 h, but is much easier to administer; comparisons with currently approved intravenous agents, streptokinase, and tissue plasminogen activator (tPA) have been completed and are being analyzed or are underway; reocclusion and reinfarction rates are low; safety is good, and similar to that of streptokinase; and mortality rates have been low with treatment, consistent with beneficial reports from randomized trials. Based on overall efficacy, ease of administration, and safety, anistreplase has been shown to be a promising agent for treatment of acute myocardial infarction.

Intravenous thrombolytic therapy with a combination of single-chain urokinase-type plasminogen activator and recombinant tissue-type plasminogen activator in acute myocardial infarction

The effects of simultaneous intravenous infusions of 12 mg recombinant tissue-type plasminogen activator (rt-PA) over 30 minutes and 48 mg single-chain urokinase-type plasminogen activator (scuPA) over 40 minutes were studied in 38 patients with acute myocardial infarction. Coronary arterial patency was assessed angiographically 60 minutes and 90 minutes after initiation of treatment. Patency was achieved in 19 of 31 patients (61.3%) (95% confidence limits, 42-78%) at 60 minutes and in 27 of 33 patients (81.8%) (95% confidence limits, 65-93%) at 90 minutes. Nonspecific plasminogen activation was monitored by measuring relevant plasma parameters. At 60 minutes and 120 minutes, the fibrinogen concentration decreased slightly to 82.8 +/- 24.3% and 91.2 +/- 17.4% of the preinfusion level, and the plasminogen concentration to 66.3 +/- 15.2% and 65.3 +/- 13.4%, respectively. A greater consumption of alpha 2-antiplasmin was observed, which decreased to 30.7 +/- 22.8% and 32.2 +/- 21.2% of the preinfusion level at 60 and 120 minutes, respectively. No bleeding necessitating transfusion was observed. Two patients (5.3%) died during hospitalization. The findings suggest that the combined intravenous infusion of rt-PA and scuPA at appropriate doses induces highly effective coronary thrombolysis equal to the best results obtained with either rt-PA or scuPA alone. This efficacy is coupled with high specificity. Thus, the data support the potential use of combinations of rt-PA and scuPA in place of monotherapy.

Accelerated thrombolysis and reperfusion in a canine model of myocardial infarction by liposomal encapsulation of streptokinase

The aim of thrombolytic therapy for acute myocardial infarction with plasminogen activators such as streptokinase is to lyse the coronary thrombus and reestablish blood flow as quickly as possible so that heart tissue loss is minimized and mortality rates are improved. Streptokinase has been encapsulated in large unilamellar phospholipid vesicles and tested in an animal model of acute myocardial infarction. The time required to restore vessel patency has been reduced more than 50% when compared with findings for free streptokinase. The total dosage of streptokinase required was lower, and smaller remnant thrombi were observed with the encapsulated agent. Results from this initial unoptimized study may have significant implications for further reduction in mortality from heart attacks by therapy with plasminogen activators.

Role of a nonsteroidal anti-inflammatory agent, ibuprofen, in coronary revascularization after acute myocardial infarction

The efficacy of using a nonsteroidal anti-inflammatory agent such as ibuprofen for the salvage of ischemic and reperfused myocardium was investigated by examining its ability to improve global and regional functions as well as to preserve high-energy phosphate compounds and inhibit creatine kinase release from an isolated in-situ pig heart subjected to 1 h of normothermic regional ischemia followed by 1 h of global hypothermic arrest and 1 h of normothermic reperfusion. Preperfusion of the heart for 15 min prior to ischemic insult with 50 microM ibuprofen failed to mitigate the myocardial reperfusion injury. Ibuprofen, however, functioned as an anti-inflammatory agent, as judged by its ability to inhibit the influx of indium-111-labeled polymorphonuclear leukocytes and chromium-51 (51Cr)-labeled platelets into the ischemic and reperfused heart. It also blocked the cyclooxygenase pathway, as evidenced by the significant reduction of 6-keto-prostaglandin F1 alpha and thromboxane B2 concentrations in the perfusate. Inhibition of cyclooxygenase resulted in increased accumulation of nonesterified fatty acids, particularly arachidonic acid, in the heart. These results suggest that although ibuprofen can inhibit polymorphonuclear leukocyte and platelet influx into the ischemic and reperfused heart, it causes further damage to the already ischemic heart by reducing prostacyclin concentration and increasing free fatty acids in the heart.

[Antibody mediated thrombolysis. A new therapeutic principle]

Thrombosis of a coronary artery is the most common cause of myocardial infarction. Thrombolytic therapy, when instituted timely, has been shown capable of reducing morbidity and mortality. However, the use of presently available thrombolytic agents is associated with a bleeding tendency and efficacy is not optimal. This article reviews one of several lines of investigation that are presently being pursued in order to improve efficacy and specificity of thrombolytic therapy. The chemical conjugation of a fibrin specific monoclonal antibody and urokinase or tissue plasminogen activator results in markedly enhanced thrombolytic potency, both in vitro and in vivo. Specificity of the conjugates is greater than that of the parent plasminogen activators as reflected by conservation of fibrinogen, plasminogen and alpha-2 antiplasmin. A bispecific antibody, with specificity for both, fibrin and tissue plasminogen activator, has the potential of concentrating endogenous tissue plasminogen activator at the site of a thrombus. In the presence of the bispecific antibody, efficacy and specificity of tissue plasminogen activator are markedly enhanced in vitro and in vivo. The tools of molecular biology are presently being applied in order to translate these findings into better thrombolytic therapy.

Low dose urokinase preactivated natural prourokinase for thrombolysis in acute myocardial infarction

By inducing minimal free-fibrinolytic activity with low dose urokinase, the lag phase of prourokinase can be overcome, and the rate of thrombolysis with this substance can be strongly enhanced. The thrombolytic potency of a combination of 250,000 IU of urokinase and 2 doses of prourokinase (4.5 or 6.5 megaunits) was evaluated in an open-label, nonrandomized dose-finding study. Thirty-one patients participated. With 4.5 megaunits of prourokinase (group 1, 15 patients) patency was demonstrated angiographically at 60 minutes in 33% while with 6.5 megaunits (group II, 16 patients) 75% patency was achieved (p less than 0.01). A second angiogram recorded 24 to 36 hours after thrombolysis revealed reocclusion in 60 versus 8% of primarily patent coronary arteries (p less than 0.05). Hemostatic monitoring in both groups revealed only slight to moderate consumption of fibrinogen (-9 vs -13%), plasminogen (-29 vs -34%) and alpha 2-antiplasmin (-59 vs -63%), and an increase in D-dimers, the split products of cross-linked fibrin, to a maximum of 1.008 +/- 1.211 vs 0.547 +/- 0.684 micrograms/liter. None of these differences was significant. Bleeding complications were more frequently observed in group II (13 vs 37%) (difference not significant), but were mild and related to puncture sites, except in 1 patient with mild oozing from the gum. No major hemorrhage was observed. These results suggest that low dose urokinase preactivation enhances the thrombolytic potency of prourokinase, without affecting its high fibrin specificity. Compared to previous studies using only prourokinase, low dose urokinase preactivation reduces by 50% the prourokinase dose as required for effective thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Implications for patient triage from survival and left ventricular functional recovery analyses in 500 patients treated with coronary angioplasty for acute myocardial infarction

The in-hospital course of 500 consecutive patients treated with coronary angioplasty for acute myocardial infarction was reviewed in relation to their clinical and angiographic presentation and angioplasty outcome to determine which patients benefit most from successful angioplasty in this setting. Patient age was 56 +/- 11 years (mean +/- SD) and 78% were men; 46% had anterior myocardial infarction, 49% received concomitant intravenous thrombolytic therapy, left ventricular ejection fraction was 47 +/- 11% and median time to angioplasty was 4.7 h (range 1 to 24). Angioplasty was successful in 78% of patients and partially successful in 7% of patients; the overall in-hospital mortality rate was 10.2%. Multivariate analysis found six independent correlates (p less than 0.05) of in-hospital mortality: left ventricular ejection fraction less than or equal to 30%, lack of postangioplasty infarct artery patency, age greater than 65 years, recurrent ischemia after successful angioplasty, emergency bypass surgery and arterial pressure on admission to the catheterization laboratory less than 100 mm Hg. After consideration of these predictors of survival in multivariate analyses, angioplasty success still was independently correlated with improved in-hospital survival for patients with cardiogenic shock (p = 0.002) and anterior myocardial infarction (p = 0.007). A trend toward an independent beneficial effect of successful angioplasty on survival was also noted in patients with inferior wall infarction and precordial ST segment depression (p = 0.063) and for all patients who were hypotensive on admission to the catheterization laboratory, regardless of the infarct site (p = 0.057).(ABSTRACT TRUNCATED AT 250 WORDS)

Clot-selective coronary thrombolysis with pro-urokinase

Recognition that myocardial infarction is caused by coronary thrombosis has stimulated a search for a safe, rapidly acting, and effective thrombolytic regimen. Tissue plasminogen activator (t-PA) can provide relatively clot-selective thrombolysis, but one quarter of patients fail to achieve reperfusion, lysis speed is not optimal, and higher doses have been associated with an increased incidence of hemorrhagic stroke. We report the results of a multicenter study of pro-urokinase, a second naturally occurring plasminogen activator that has structural similarities to t-PA but has a different mechanism of action. Pro-urokinase was administered 3.9 +/- 1.1 hours after the onset of chest pain to 40 patients with acute myocardial infarction with angiographically confirmed complete coronary occlusion (TIMI grade 0). After a 90-minute intravenous infusion of pro-urokinase (4.7-9 million units, 36-69 mg) 51% (20 of 39) of the patients demonstrated reperfusion (TIMI grade 2 or 3) occurring 64.8 +/- 22.3 minutes after initiation of therapy. Fibrinogen levels fell only 10 +/- 17% from baseline, confirming the fibrin specificity of pro-urokinase. As with t-PA, however, this specificity was only relative. alpha 2-Antiplasmin decreased to 39% and plasminogen decreased to 64% of initial values. Fibrinogen degradation products increased 63% and the fibrin-specific D-dimer increased 8.7-fold. Thus, pro-urokinase produces relatively clot-selective coronary thrombolysis similar to that produced by t-PA, but the use of either pro-urokinase or t-PA alone in higher doses would be likely to produce more nonspecific effects.

Coronary angioplasty as primary therapy for acute myocardial infarction 6 to 48 hours after symptom onset: report of an initial experience

Recent randomized trials in acute myocardial infarction suggest that infarct size reduction need not be achieved for intravenous streptokinase to improve patient survival. If this is the case, attempts to achieve late revascularization may be justified. To assess the results of late primary coronary angioplasty performed in the setting of acute myocardial infarction, the clinical and angiographic data as well as hospital outcome of 139 consecutive patients treated with coronary angioplasty without prior thrombolytic therapy 6 to 48 h after the onset of chest pain (late group) were compared with those of 117 patients treated with primary angioplasty less than 6 h after the onset of chest pain (early group); time to angioplasty was assessed as a covariate of survival. In the 139 patients treated greater than or equal to 6 h after the onset of chest pain, the mean age (+/- SD) was 57 +/- 12 years and the median time to angioplasty was 15 h; 61% had multivessel disease, 14% were in cardiogenic shock and the mean left ventricular ejection fraction was 44 +/- 12%. Angioplasty was successful (final diameter stenosis less than 70% and Thrombolysis in Myocardial Infarction [TIMI] flow grade greater than or equal to 2) in 78% of patients. Successful angioplasty was associated with a 5.5% in-hospital mortality rate, whereas unsuccessful angioplasty was associated with a 43% hospital mortality rate (p less than 0.001). Multivariate testing in all patients identified four independent predictors of in-hospital death: cardiogenic shock (p less than 0.001), unsuccessful angioplasty (p = 0.001), ejection fraction less than or equal to 30% (p = 0.002) and patient age (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

ST segment shifts are poor predictors of subsequent Q wave evolution in acute myocardial infarction. A natural history study of early non-Q wave infarction

Acute ST segment elevation is regarded generally as the sine qua non of evolving Q wave myocardial infarction (MI) because such electrocardiographic (ECG) injury is believed to be a marker of transmural ischemia and a forerunner of transmural necrosis. Alternatively, ST segment depression with or without T wave inversion is viewed as the dominant ECG feature of non-Q wave MI. However, this hypothesis has not been assessed prospectively in an acute MI population. We analyzed 2,304 serial ECGs at study entry (admission), day 2, day 3, and predischarge (mean, 10.2 +/- 2 days) from 576 patients with creatine kinase MB confirmed acute non-Q wave MI to determine what percentage of patients with early ST segment elevation culminated in subsequent Q wave development. Of this group, 187 patients (32%) exhibited 1 mm or greater ST segment elevation in two or more contiguous entry ECG leads. Of those patients whose non-Q wave MI could be localized on the basis of diagnostic admission ST segment shifts, the prevalence of early ST segment elevation was 43% (187 of 439). The sum total mean (+/- SD) peak ST segment elevation by lead group (anterior, inferior, lateral) was 4.0 +/- 2.4, 4.5 +/- 2.4, and 2.5 +/- 0.6 mm, respectively. Despite this, only 20% of patients with ST segment elevation (37 of 187) developed Q waves. Of 252 patients who exhibited early ST segment depression or T wave inversion or both, 39 (15%) evolved subsequent Q waves. Thus, while the prevalence of early ST segment elevation in acute evolving non-Q wave MI was higher than previously reported, 80% of patients with and 85% of patients without ST segment elevation and absent Q waves on the admission ECG did not develop subsequent Q waves during a 2-week period of observation (p = NS). In addition, when patients with ST segment elevation were compared with patients with ST segment depression or T wave inversions or both, there were no between-group differences in log peak creatine kinase (404 vs. 383 IU), reinfarction (6% vs. 8%), postinfarction angina (50% vs. 42%), or early recurrent ischemia (49% vs. 45%), defined as postinfarction angina with transient ECG changes. Thus, in patients who present with initial acute non-Q wave MI, ST segment shifts on admission are unreliable predictors of subsequent Q wave evolution and do not discriminate significant differences in postinfarction outcome. In particular, ST segment elevation during the early hours of evolving infarction is not an invariable harbinger of subsequent Q wave development.

Time course of thrombolysis induced by intravenous bolus or infusion of tissue plasminogen activator in a rabbit jugular vein thrombosis model

Tissue plasminogen activator is a thrombolytic agent that has been shown to be efficient in patients with myocardial infarction or pulmonary embolus. However, little is known about the time course and the dose dependency of its thrombolytic effect. The goal of our study was to investigate the time course of the thrombolysis induced by increasing doses of tissue plasminogen activator (t-PA) given either as a continuous infusion (0.0625-1 mg/kg) or as a bolus (0.05-0.4 mg/kg). For this purpose, we modified a previously described rabbit jugular vein thrombosis model by using an external gamma counter to follow continuously the thrombolysis. After administration of t-PA as either an infusion or a bolus, the rate and the extent of thrombolysis were dose dependent. The thrombus size decreased regularly following an exponential curve and reached a lower asymptote implicating an unlysable thrombus. As expected, after bolus injection, t-PA was rapidly inhibited resulting in a duration of action of approximately 15 minutes; this was independent of the dose. Surprisingly, during continuous infusion of t-PA for as long as 4 hours, the duration of action was limited to about 2 hours, although the plasma t-PA activity levels remained stable. Although the rate of inhibition was lower and thus the duration of action was longer during continuous infusion of t-PA than after a bolus injection, the extent of thrombolysis was similar when the same dose of t-PA was given as either a bolus or an infusion. These findings could be attributed to the higher initial rate of thrombolysis observed after a bolus injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships between structure and effects of ACE inhibitors: comparative effects in myocardial ischaemic/reperfusion injury

1. Coronary artery reperfusion has become the treatment of choice for evolving myocardial infarction. 2. While there is no question that timely restoration of coronary blood flow is essential for the salvage of ischaemic myocardium, coronary reperfusion has also been associated with potentially deleterious consequences. Specifically, the viable tissue salvaged by reperfusion remains 'stunned'--i.e., exhibits prolonged abnormalities in contractile function--for hours to days following reflow. Furthermore, it has been suggested that reperfusion per se may lethally injure some myocytes that were only reversibly injured prior to restoration of blood flow. 3. ACE inhibitors such as captopril and enalapril have been shown to reduce indices of myocardial injury (infarct size, creatine kinase release) and enhance contractile function of stunned myocardium in experimental models of coronary occlusion followed by reperfusion. These effects of ACE inhibitors have largely been attributed to the reduction in myocardial O2-demand and increase in myocardial blood flow associated with blunting of angiotensin II formation. 4. Recent studies suggest that the effects of some ACE inhibitors--particularly captopril--may not solely be explained on the basis of ACE inhibition. In fact, sulphydryl (-SH) containing ACE inhibitors such as captopril appear to act as scavengers of oxygen-derived free radical species thought to be important in the pathogenesis of both postischaemic contractile dysfunction and ischaemia/reperfusion induced myocyte necrosis. 5. Thus, -SH containing ACE inhibitors--which both inhibit ACE and scavenge cytotoxic free radicals--may offer a suitable form of treatment for myocardial ischaemia/reperfusion injury.

Oxygen-derived free radicals and postischemic myocardial dysfunction ("stunned myocardium")

Experimental studies have demonstrated that myocardium reperfused after reversible ischemia exhibits prolonged depression of contractile function ("stunning"), which is associated with various ultrastructural, biochemical, vascular and other functional abnormalities. Clinical observations suggest that stunning occurs in many situations (for example, rest and exercise-induced angina, myocardial infarction with early reperfusion, open heart surgery, transplantation) and thus may contribute significantly to morbidity among patients with coronary artery disease. In recent years an increasing number of studies have provided indirect evidence that postischemic myocardial dysfunction may be mediated in part by the generation of reactive oxygen species, such as superoxide radical (.O2-), hydrogen peroxide (H2O2) and hydroxyl radical (.OH). Thus, it has been shown that the recovery of the stunned myocardium is enhanced by agents that either scavenge oxygen metabolites, such as superoxide dismutase and catalase, N-2-mercaptopropionylglycine and dimethylthiourea, or prevent their generation, such as allopurinol, oxypurinol and desferrioxamine. More recent experiments utilizing electron paramagnetic resonance spectroscopy have directly demonstrated that reperfusion after a reversible ischemic episode is associated with a burst of free radical production. At present, the evidence supporting the free radical hypothesis is suggestive but not conclusive. Definitive demonstration of the role of oxy-radicals will require careful studies measuring the production of these species in conscious animal models of postischemic dysfunction. If confirmed, the free radical hypothesis will provide not only new important insights into the pathophysiology of ischemic injury, but also a rationale for developing clinically applicable interventions.

Intracarotid urokinase with thromboembolic occlusion of the middle cerebral artery

Intracarotid urokinase infusion therapy was performed on 22 patients with evolving cerebral infarction due to acute thromboembolic occlusion of the middle cerebral artery. Mean time from onset of symptoms to start of infusion and mean dosage of urokinase were 4.5 hours and 927,000 units, respectively. Immediate recanalization was achieved in 10 patients (45%) after urokinase therapy. In patients with successful recanalization, rapid amelioration of symptoms followed the restoration of blood flow. Thrombolytic recanalization was associated with reduction of neurologic deficits and of computed tomography-demonstrable infarction volume. The reduction of infarction volume and functional outcome correlated highly with the degree of reflow. Hemorrhagic transformation of infarction occurred in four patients and controllable extracranial bleeding in three patients. These results support the safety and efficacy of urokinase therapy for acute thromboembolic occlusion of the middle cerebral artery.

Local measurements of thrombus induced vasoconstriction in vivo

No data is available describing the local effect of thrombus formation on the vessel's diameter in vivo. As platelet or thrombus induced vasoconstriction seems to be of clinical importance in various diseases, it is desirable to get insight into the interrelation of thrombus formation and local vasoactivity. With a contactless photochemical process, endothelial cells can be damaged and thrombogenesis may be initiated in vivo. After first platelets stick to endothelial cells, a strong vasoconstriction is observed in arterioles. In venules, no vascular reaction can be observed. Constriction is most pronounced at the site of thrombus formation and decreases at growing distance. The thrombus is squeezed by the vascular constriction and thus mechanically held in place and squeezed out. A slight relaxation follows 30-80 min later, but the vessel remains constricted during the following three hours. Thrombus induced vasoconstrictions can be reduced by papaverine, EP 092 (a thromboxane A2 antagonist) and phentolamine in dose-dependent manner in vivo. Papaverine was most effective followed by EP 092, Phentolamine was less effective, showing the minor importance of alpha-receptor stimulation in this model.

Streptokinase-induced, antibody-mediated platelet aggregation: a potential cause of clot propagation in vivo

The administration of intracoronary streptokinase to a patient with a prior history of rheumatic fever was associated with the retrograde propagation of thrombus from the left anterior descending coronary artery into the left main coronary artery with near catastrophic consequences. The addition of streptokinase to platelet-rich plasma from the patient initiated platelet aggregation and secretion in vitro. Platelet aggregation was also seen in 1 of 15 control subjects after the addition of streptokinase, and the addition of plasma or immunoglobulin G (IgG) from the index patient supported platelet aggregation in the presence of streptokinase in all of the previously nonreactive control subjects. This in vitro platelet aggregation was specific for streptokinase and not initiated by either urokinase or tissue plasminogen activator. Streptokinase-induced platelet aggregation was not inhibited by aprotinin, but was completely attenuated by the addition of an excess of antihuman IgG Fab. These findings suggest that streptokinase can initiate specific antibody-mediated platelet aggregation in vitro and may be more than coincidentally related to clot propagation or thromboembolism in vivo.

Multicenter reperfusion trial of intravenous anisoylated plasminogen streptokinase activator complex (APSAC) in acute myocardial infarction: controlled comparison with intracoronary streptokinase

The recent establishment of a firm therapeutic role for reperfusion in acute myocardial infarction has stimulated interest in the development of more ideal thrombolytic agents. Anisoylated plasminogen streptokinase activator complex (APSAC) is a new plasminogen activator possessing properties that are promising for intravenous thrombolytic application in acute myocardial infarction. To assess the reperfusion potential of intravenous APSAC, a multi-center, angiographically controlled reperfusion trial was performed. An approved thrombolytic regimen of intracoronary streptokinase served as a control. Consenting patients with clinical and electrocardiographic signs of acute myocardial infarction were studied angiographically and 240 qualifying patients with documented coronary occlusion (flow grade 0 or 1) were randomized to treatment in less than 6 h of symptom onset (mean 3.4 h, range 0.4 to 6.0) with either intravenous APSAC (30 U in 2 to 4 min) or intracoronary streptokinase (160,000 U over 60 min). Both groups also received heparin for greater than or equal to 24 h. Reperfusion was evaluated angiographically over 90 min and success was defined as advancement of grade 0 or 1 to grade 2 or 3 flow. Rates of reperfusion for the two treatment regimens were 51% (59 of 115) at 90 min after intravenous APSAC and 60% (67 of 111) after 60 min of intracoronary streptokinase (p less than or equal to 0.18). Reperfusion at any time within the 90 min was observed in 55 and 64%, respectively (p less than or equal to 0.16). Time to reperfusion occurred at 43 +/- 23 min after intravenous and 31 +/- 17 min after intracoronary therapy. The success of intravenous therapy was dependent on the time to treatment: 60% of APSAC patients treated within 4 h exhibited reperfusion compared with 33% of those treated after 4 h (p less than or equal to 0.01). Reperfusion rates were also dependent on initial flow grade (p less than or equal to 0.0001): 48% (81 of 168) for grade 0 (APSAC = 43%, streptokinase = 54%), but 78% for grade 1 (APSAC = 78%, streptokinase = 77%). APSAC given as a rapid injection was generally well tolerated, although the median change in blood pressure at 2 to 4 min was greater after APSAC than after streptokinase (-10 versus -5 mm Hg). Mean plasma fibrogen levels fell more at 90 min after the sixfold higher dose of APSAC than after streptokinase (to 32 versus 64% of control). Reported bleeding events were more frequent after APSAC but occurred primarily at the site of catheter insertion and no event was intracranial.(ABSTRACT TRUNCATED AT 400 WORDS)

What is established in thrombolytic therapy of acute myocardial infarction? Pharmacological approaches

Thrombolytic therapy by early reopening of an occluded coronary vessel, and hence re-establishing oxygen delivery, can significantly reduce infarct size. The result depends both on the duration of ischemia and the presence of collaterals. By early initiation of intravenous thrombolytic therapy and shortening the ischemic period, the functional results may be improved. PTCA has to be considered in order to avoid reocclusion of the infarct vessel, mainly in patients with high-grade residual stenosis and viable myocardium in the poststenotic area. The benefit of early thrombolytic therapy in acute myocardial infarction has been proven in randomized trials. However, to achieve statistical significance, a large number of patients had to be included. It is mainly the patients with previous myocardial infarction with a large area at infarct risk and/or anterior myocardial infarction that derive most benefit from this intervention.

Relation of coronary arterial patency and left ventricular function to electrocardiographic changes after streptokinase treatment during acute myocardial infarction

One hundred and eighty-eight patients with evolving acute myocardial infarction were treated with intravenous streptokinase. Serial 12-lead electrocardiograms were recorded for 3 hours after treatment and inspected for rapid repolarization changes of the ST segment and T wave. Abrupt electrocardiographic repolarization changes were observed in 106 patients (56%) and were strongly predictive for an open infarct-related coronary artery at a mean of 6 days after treatment (predictive value = 0.92, sensitivity = 0.67). Abrupt electrocardiographic changes were not observed in 82 patients (44%). This absence was not a good predictor of an occluded infarct-related coronary artery (predictive value = 0.4). There was no relation between the presence or absence of abrupt electrocardiographic changes and global or regional left ventricular function after streptokinase treatment. Abrupt repolarization changes after thrombolytic treatment indicate a high probability of an open infarct-related artery. When abrupt repolarization changes do not occur, the patency of the infarct-related coronary artery cannot be predicted with accuracy. Serial electrocardiographic recordings do not provide sufficient information about coronary patency to eliminate the need for coronary arteriography.

Efficacy of intravenous prourokinase and a combination of prourokinase and urokinase in acute myocardial infarction

Fifty-four patients with Q-wave acute myocardial infarction (AMI) were treated with heparin combined with intravenous single-chain urokinase-type plasminogen activator (prourokinase). To determine the optimal treatment regimen, prourokinase was applied in 3 different ways: group I received a bolus of 7.5 mg and a subsequent infusion of 40.5 mg over 60 minutes. Patency of the infarct artery was observed in 7 patients (50%) at the end of the infusion time. One hour after the end of the infusion the fibrinogen level had decreased to 87 +/- 12% of the preinfusion level; the plasminogen and alpha-2 antiplasmin levels to 61 +/- 13% and 59 +/- 34%, respectively. In group II prourokinase was administered as a 7.5 mg bolus followed by 66.5 mg over 60 minutes. Eleven patients (55%) had patent infarct-related coronary arteries and fibrinogen, plasminogen and alpha-2 antiplasmin levels had decreased to 58 +/- 29%, 38 +/- 18% and 21 +/- 14%, respectively. Group III was treated with a bolus of 3.7 mg prourokinase and 250,000 IU urokinase followed by 44.3 mg prourokinase, resulting in a patency rate of 65% (13 patients). Fibrinogen, plasminogen and alpha-2 antiplasmin levels decreased to 76 +/- 15%, 67 +/- 15% and 47 +/- 29%, respectively. Fibrin-specific thrombolysis can be achieved with glycosylated prourokinase. At higher dosages considerable systemic activation of the fibrinolytic system with little enhancement of the observed therapeutic effect occurred. The combination of prourokinase and urokinase yielded a higher patency rate than either dosage of prourokinase alone, although the difference was not statistically significant in this pilot trial.