High-dose, brief intravenous streptokinase early in acute myocardial infarction

Pharmacological modulation of vascular inflammation in atherothrombosis

Vascular inflammation, especially at the level of endothelial cells, has been shown to play a pivotal role in the inception, progression, and clinical complications of atherosclerosis. The common denominators for the activation of inflammatory genes appear to be a small subset of transcription factors--among which include nuclear factor-κB, activator protein-1 (AP-1), and GATA--that function as the central hub of vascular inflammation. Strategies directed to inhibit both the secondary mediators and the primary triggers (atherosclerosis risk factors) appear viable to inhibit atherosclerosis. However, attempts have now been made to address the central hub of vascular inflammation. "Old" drugs, such as dipyridamole, can also now be revisited for properties related to inhibition of vascular inflammation, probably by acting on the common hub of inflammation.

Effect of very early intravenous streptokinase infusion in patients with evolving myocardial infarction

The effect of very early infusion of 1.5 X 10(6) U of streptokinase intravenously was studied in 29 patients with nitroglycerin-resistant chest pain and ST-segment elevation. Infarct size was estimated from maximal LD1 isoenzyme levels, and the diagnosis confirmed by CK-MB determination. Thrombolytic therapy was started within 1 hour of pain onset in 11 patients (group A), between 1 and 2 hours in 10 (group B), and later than 2 hours in eight patients (group C). Marked differences appeared between the groups. Thus, three patients in group A and one patient in group B did not develop infarction, all had critical LAD stenoses. Three patients in group C died in shock without bleeding. Further, the average maximal LD1 values in the 22 patients who survived their infarction differed significantly between the groups, and were 12.6, 19.1 and 36.2 mu kat/l in groups A, B and C, respectively. In conclusion, very early intravenous streptokinase infusion probably reduces myocardial necrosis, and possible prevents infarction in some patients.

Changes in Fibrinogen After rt-PA Administration

Among patients participating in the TIMI-II protocol, there was a variability in the fibrinolytic re sponse to recombinant tissue plasminogen activator (rt- PA). A cohort of 20 TIMI-II patients was selected for detailed study because their responses to rt-PA varied widely in the degree of fibrin(ogen)olysis. Patient plasmas were analyzed by immunoblotting for changes in fibrino gen and plasminogen. Measurements of fibrinogen, fibrin ogen degradation product (FDP), D-dimer, Bβ 1-42, plas minogen, and t-PA were also correlated. Three patterns of response to rt-PA were identified: Group A ( n = 4) had fibrinogenolysis without fibrinolysis; Group B ( n = 11) had fibrinolysis and mild fibrinogenolysis; and Group C ( n = 5) had fibrinolysis with intense fibrinogenolysis. Group C patients also demonstrated qualitative changes in high- molecular-weight (HMW) and low-molecular-weight (LMW) fibrinogens, whereas Group A and B patients demonstrated only mild alterations in fibrinogen compo sition. Plasmin-inhibitor complexes were identified in all three groups. All patients had both plasmin-α2-anti plasmin and plasmin-α2-macroglobulin complexes at the 50-min time point. The concentration of pretreatment plasminogen correlated with the degree of fibrinogenoly sis.

Newer agents for coronary thrombolysis. Perspectives from clinical studies

Myocardial infarction (MI) is a major cause of morbidity and mortality in western countries and the formation of intracoronary thrombi is recognized as a critical determinant of this ischaemic event. Since streptokinase and urokinase cause in vitro lysis of clots, it was though that these drugs were also effective in vivo in dissolving coronary thrombi. Clinical studies supported this concept. However, the beneficial effects of these drugs were, to some extent, offset by their inherent adverse reactions. Therefore new thrombolytic agents were developed, and for three of them (APSAC, tPA and proUK) there are enough clinical studies to allow for a comparison with 'old' agents. The data show that none of the new agents is safer or better than old agents with respect to easy handling, incidence of reperfusion of occluded coronary arteries, frequency of reocclusions, thrombus specificity, and bleeding complications. Thus, several directions are currently pursued to develop newer thrombolytic drugs with risk/benefit ratios better than those of 'old' agents. In this respect, it has been shown recently that the combination of aspirin with streptokinase is significantly better than streptokinase alone as far as mortality and incidence of rethrombosis is concerned. These data suggest that thrombolytic approaches safer and better than those currently available are possible and indicate that some of such new strategies are already available to enter the 'thrombolytic era' of acute MI.

A cost-effectiveness model for coronary thrombolysis/reperfusion therapy

A model was designed to examine the relations between incremental costs and benefits of coronary thrombolysis/reperfusion therapy. The model allows for the study of intravenous and intracoronary streptokinase, intravenous tissue plasminogen activator and primary angioplasty. Three strategies for the management of reocclusion are also compared. It was found that each of the following four variables can be responsible for a 2- to 15-fold variation in the costs per additional survivor: 1) the quantity of jeopardized myocardium, 2) the duration of coronary occlusion before the onset of therapy, 3) the time required from the onset of therapy until reperfusion is achieved, and 4) the reocclusion management strategy. Therapeutic strategies involving intravenous administration of thrombolytic agents were found to be consistently more cost effective than were strategies involving intracoronary administration of thrombolytic agents and primary angioplasty. In patients with a large or moderate-sized infarct, proper selection of intravenous protocols and reocclusion management strategies leads to costs of $7,000 to $100,000/additional survivor, costs that are similar to those of many generally accepted medical practices. Substantially higher costs per additional survivor are incurred with the routine use of thrombolytic therapy in patients with a small infarct or the routine use of coronary artery bypass surgery to reduce the risk of reocclusion after successful thrombolytic therapy. Decisions regarding which patients should receive thrombolysis/reperfusion therapy depend on society's willingness to pay for its incremental benefits.

Effects of early high-dose streptokinase intravenously on left ventricular function in acute myocardial infarction

One hundred seven patients who recently had acute myocardial infarction were randomly assigned either to standard heparin therapy or to intravenous streptokinase within 5 hours after the onset of symptoms in 7 hospitals without catheterization facilities. In the third week, the patients were referred to a university hospital, where the patency rate of the infarct-related artery was studied by selective coronary arteriography and left ventricular function by radionuclide angiography. Fifty-five patients received heparin and 52 streptokinase within a mean period of 190 minutes after the onset of symptoms. Seven patients in the heparin group and 4 in the streptokinase group died in hospital. The patency rate of the infarct-related artery was identical in both groups (69% in the heparin group vs 68% in the streptokinase group). Left ventricular ejection fraction was not statistically different (0.44 +/- 0.13 in the heparin group vs 0.45 +/- 0.12 in the streptokinase group). Left ventricular ejection fraction was significantly higher in patients with a patent infarct-related artery than in patients with an obstructed infarct-related artery (0.49 +/- 0.12 vs 0.41 +/- 0.15, p less than 0.01). In patients with inferior wall infarction, left ventricular ejection fraction was identical (0.50 +/- 0.10 in the heparin group vs 0.52 +/- 0.09, in the streptokinase group). In patients with anterior wall infarction, left ventricular ejection fraction was significantly higher in the streptokinase group than in heparin group (0.40 +/- 0.10 vs 0.33 +/- 0.09, p less than 0.05). Analysis of regional wall motion revealed that improvement occurred in the lateral wall of the left ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of thrombolytic therapy for acute myocardial infarction in rural and urban settings

In this study, a tertiary care hospital served as a registry and information source to rural hospitals in northwestern Ohio where thrombolytic therapy had not previously been used. The study was designed to compare the safety and efficacy of intravenous thrombolytic therapy for acute myocardial infarction in the two settings. Fifty-five patients in eight rural hospitals and 36 patients in the urban tertiary care center received intravenous streptokinase. Of the 87 patients whose symptoms first occurred out of the hospital, 63 percent were treated within three hours. There were no significant differences in rates of clinically determined coronary artery recanalization (63 percent versus 69 percent for rural and tertiary hospitals, respectively), in-hospital mortality (5.4 percent versus 11 percent), bleeding complications (3.6 percent versus 5.5 percent), or time from the onset of pain to infusion of streptokinase (3.4 hours versus 2.9 hours). There were also no differences in the completeness of collection of serial coagulation data and cardiac enzyme values, or in the documentation of chest pain onset and cessation. Major differences between rural centers and the tertiary care center involved the use of serial electrocardiography (58 percent versus 89 percent, respectively), subsequent cardiac catheterization (49 percent versus 86 percent), and the timing of catheterization, when performed (30.4 days versus 4.6 days) (p less than 0.005 for all values). Thrombolytic therapy for acute myocardial infarction can be administered quickly, safely, and effectively in rural hospital settings even by physicians previously unfamiliar with this form of treatment.

MM-CK subtypes diagnose reperfusion early after myocardial infarction

Isoelectric focusing (IEF) was used to analyze the serum MM-CK isoenzyme subtypes in 16 patients receiving streptokinase (SK) for attempted coronary thrombolysis early after acute myocardial infarction. Twelve patients had revascularization documented by serial coronary angiograms (Group I); in four patients, angiography documented no such reperfusion (Group II). The data also were compared with a previously reported group of 8 patients who did not receive streptokinase (Group III). Total and MB-CK activity, as well as the MM-CK isoenzyme subtypes MM3-CK, MM2-CK, and MM1-CK tended to rise earlier and peak earlier in Group I compared with Group II; serum MM3-CK, the predominant subtype in myocardium, however, definitely peaked earlier in Group I (8.65 +/- 2.07 hr) compared with Group II (18.50 +/- 6.67 hr) (p less than 0.001). Soon after its release from myocardium, MM3-CK is converted in the serum to MM2-CK and eventually to MM1-CK; thus, the MM3-CK:MM1-CK ratio amplifies the time course of subtype conversion. The MM3-CK:MM1-CK activity ratio peaked earlier in Group I (5.51 +/- 0.97 H) compared to Group II (10.74 +/- 3.28 hr) (p less than 0.01), and peaked even earlier than MM3-CK (p less than 0.007) in both Groups I and II. Thus, the time course of the MM3-CK:MM1-CK ratio separates those patients who reperfuse when early SK is used after acute myocardial infarction from those who do not, and does it significantly earlier than the other enzymatic parameters of cellular necrosis, total CK, and MB-CK.

[Echocardiographic evaluation of intravenous streptokinase in myocardial infarction in the acute phase]

The effects of intravenous fibrinolysis on left ventricular function in acute myocardial infarction were investigated by two-dimensional echocardiography in patients aged less than 70 for whom fibrinolysis was not contra-indicated and who were admitted less than 6 hours after the onset of a first myocardial infarction without heart failure. The 12 patients thus recruited were male; their mean age was 55 years and the infarct was anterior in 6 cases and posterior in 6 cases. Streptokinase was administered first by bolus intravenous injection (250,000 IU over 20 min), then by intravenous infusion (100,000 IU over 12 hours); this was followed by heparin. No other medication was given, except for intravenous lidocaine and oral nifedipine. Two-dimensional echocardiography was performed after 24 hours and on the 21st day, using the apical, two-cavities projection. The ejection fraction and the percentage of shortening in 16 ventricular segments (8 in the anterior and 8 in the inferior territories) were evaluated from systolic and diastolic ventricular contours. Ventricular angiography and coronary arteriography were performed concomitantly with echocardiography. No significant improvement in ejection fraction was observed. On both day 1 and day 21, the kinetics of the lower segments was improved and that of the anterior segments was distinctly reduced in inferior infarcts. The kinetics of all segments, irrespective of their territory, was significantly improved in anterior infarcts.

Thrombolytic therapy in acute myocardial infarction. A perspective

This paper deals with the history of thrombolytic therapy from its inception to its application in acute myocardial infarction. It describes the discovery of streptococcal fibrinolysin, followed by the elucidation of the plasma proteolytic enzyme system concerned with fibrinolysis. An outline is given of the therapeutic basis for the decision to concentrate on the development of activators of the enzyme, rather than the enzyme itself. Early attempts to demonstrate the value of streptokinase and urokinase in the treatment of myocardial infarction are examined. Finally, the more encouraging approaches in current use, especially the early application of thrombolytic therapy after the onset of the morbid event, are discussed.

Activation of the fibrinolytic system during intracoronary streptokinase administration

Serial biochemical studies were performed in 12 patients treated with intracoronary streptokinase infusion for acute myocardial infarction, in order to study the method of activation of the fibrinolytic system during local administration of a relatively low dose of this drug and to determine correlations between systemic effects and reperfusion. Plasma samples were obtained before and every 15 minutes during the infusion of streptokinase and after completion of the therapy. Streptokinase dosage in this study was 211,000 +/- 88,000 IU (+/- SD). The average time from the onset of symptoms to the start of infusion was 2 hours 50 minutes (range 1 hour 10 minutes to 3 hours 30 minutes). Reperfusion occurred in six patients and temporary recanalization in three; in three patients no recanalization was achieved. Fibrinolytic assays of pretreatment plasma samples revealed elevated levels of plasminogen activators, presumably caused by the release of tissue-type plasminogen activator after a condition of stress. Plasminogen concentrations decreased from 94 +/- 17% to 44 +/- 30%. Alpha 2-antiplasmin fell from 84 +/- 27% to 12 +/- 19%; in seven patients no plasmin inhibitor activity was measurable at the completion of the infusion. Free plasmin occurred in samples only when this inhibitor had disappeared. This resulted in a lytic state leading to degradation of fibrinogen, the levels of which fell from 2.9 +/- 0.7% to 1.5 +/- 1.1%. Fibrinogen degradation products, measured in plasma with monoclonal antibodies, increased exponentially during streptokinase infusion in at least four patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum enzymes in acute myocardial infarction after intracoronary thrombolysis

Serum kinetics of total creatine kinase (CK), CK-MB isoenzyme, aspartate aminotransferase (AST), lactate dehydrogenase (LD) and alpha-hydroxybutyrate dehydrogenase (HBD) activities were studied in twenty patients with acute myocardial infarction randomly assigned to receive either intracoronary urokinase (group A) or conventional (control) therapy (group B). The temporal characteristics of enzyme changes described were the time lag from onset of chest pain until maximum catalytic concentration value, the rate at which enzymes are released into blood, the peak value of the serum enzyme curves and (d) the fractional disappearance rate (Kd) for each enzyme considered. Thrombolytic treatment induced earlier peak times in group A: for CK, 10.8 vs 27.0 h, for CK-MB, 10.4 vs 23.1, for AST, 13.9 vs 31.3, for LD, 24.4 vs 49.1, and for HBD, 20.5 vs 48.5 (for all enzymes, p less than 0.001). The maximal rate of release for the enzymes was at least twofold greater in group A. Enzyme peak activities and Kd were not significantly different between the groups. The most significant discrimination between the two groups was obtained with AST peak time (Hartz overlap index (Oi) = 0.11) and CK-MB peak time (Oi = 0.12).

Percutaneous transluminal coronary angioplasty after thrombolytic therapy: a prospective controlled randomized trial

In 162 patients with acute transmural myocardial infarction, combined intravenous and intracoronary thrombolytic therapy with streptokinase was initiated. In vessels that remained occluded, mechanical recanalization was performed with a 3F recanalization catheter (group I, n = 79) or a 4F Grüntzig balloon catheter (group II, n = 83). After reperfusion, intracoronary streptokinase was administered superselectively. After termination of streptokinase infusion, angioplasty was performed only in patients in group II. There was no difference between the groups in relation to sex, age, infarct location, creatine kinase levels and time between onset of symptoms and start of treatment. Initial coronary angiography showed an open vessel in 27 (34%) of 79 patients in group I and 21 (25%) of 83 patients in group II. The final reperfusion rate was 90% (71 of 79) in group I and 86% (71 of 83) in group II. Angioplasty was attempted in 69 of the 71 patients in group II with a success rate of 65% and an occlusion rate of 3%. During the hospital stay, reocclusion occurred in 14 (20%) of 71 patients in group I. After thrombolytic therapy, coronary luminal narrowing in group I was 75 +/- 17% in patients without and 87 +/- 6% in patients with reocclusion (p less than 0.05). In group II, reocclusion was found in 10 (14%) of 71 patients. After angioplasty, the degree of coronary stenosis in group II was reduced from 82 +/- 12 to 51 +/- 30% (p less than 0.001). Reocclusion was found in 3 (7%) of the 45 patients with successful angioplasty and in 7 (32%) of the 22 patients with unsuccessful angioplasty (p less than 0.01). Improvement in regional left ventricular function was observed only in patients from group II with anterior myocardial infarction. In conclusion, by combined medical and mechanical recanalization, the rate of coronary reperfusion can be increased and infarct time shortened, providing the possibility of full revascularization by angioplasty, with improvement of regional wall motion and reduction of the rate of reocclusion.

A prospective randomized clinical trial of intracoronary streptokinase versus coronary angioplasty for acute myocardial infarction

We randomly assigned 56 patients who presented within 12 hours of their first symptoms of acute myocardial infarction to treatment with either intracoronary streptokinase or coronary angioplasty. The mean (+/- SD) duration of symptoms (3.0 +/- 1.2 hours in the group treated with angioplasty vs. 3.6 +/- 1.8 in the group treated with streptokinase; P not significant) and time to recanalization (4.1 +/- 1.4 hours vs. 4.8 +/- 1.7 hours; P not significant) were similar in both groups. Coronary recanalization was achieved in 83 percent of the patients treated with angioplasty and in 85 percent of those treated with streptokinase (P not significant). Residual luminal stenosis in the coronary artery was significantly decreased after angioplasty, as compared with streptokinase therapy (43 +/- 31 percent of patients vs. 83 +/- 17; P less than 0.001). Residual stenosis of 70 percent or more was present in 4 percent of the angioplasty-treated patients and in 83 percent of the streptokinase-treated patients (P less than 0.01). Ventricular function after therapy was assessed by serial contrast ventriculograms. Increases in both global ejection fraction (8 +/- 7 percent vs. 1 +/- 6; P less than 0.001) and regional wall motion (+1.32 +/- 1.32 SD vs. +0.59 +/- 0.79 SD; P less than 0.05) were greater for the angioplasty group. We conclude that angioplasty and streptokinase produce similar rates of early coronary reperfusion during evolving transmural myocardial infarction. However, angioplasty is significantly more effective in alleviating the underlying coronary stenoses, and this may result in more effective preservation of ventricular function after therapy.

The fibrinolytic system in man

The fibrinolytic system comprises a proenzyme, plasminogen, which can be activated to the active enzyme plasmin, that will degrade fibrin by different types of plasminogen activators. Inhibition of fibrinolysis may occur at the level of plasmin or at the level of the activators. Fibrinolysis in human blood seems to be regulated by specific molecular interactions between these components. In plasma, normally no systemic plasminogen activation occurs. When fibrin is formed, small amounts of plasminogen activator and plasminogen adsorb to the fibrin, and plasmin is generated in situ. The formed plasmin, which remains transiently complexed to fibrin, is only slowly inactivated by alpha 2-antiplasmin, while plasmin, which is released from digested fibrin, is rapidly and irreversibly neutralized. The fibrinolytic process, thus, seems to be triggered by and confined to fibrin. Thrombus formation may occur as the result of insufficient activation of the fibrinolytic system and (or) the presence of excess inhibitors, while excessive activation and/or deficiency of inhibitors might cause excessive plasmin formation and a bleeding tendency. Evidence obtained in animal models suggests that tissue-type plasminogen activator, obtained by recombinant DNA technology, may constitute a specific clot-selective thrombolytic agent with higher specific activity and fewer side effects than those currently in use.

High dose intravenous streptokinase for acute myocardial infarction: preliminary results of a multicenter trial

To assess the efficacy of intravenous streptokinase in patients with acute myocardial infarction, 40 patients (30 men and 10 women, mean age 54 years) with acute myocardial infarction were given 1.5 million U of streptokinase intravenously in 1 hour, and coronary arteriography was performed repeatedly to assess reperfusion. Streptokinase treatment was begun 270 +/- 86 (mean +/- SD) minutes after the onset of chest pain. Of the 40 patients, 34 had total or near total coronary occlusion before streptokinase administration. In 14 (41%) of these 34 patients, some reperfusion occurred during the 90 minutes after the administration of streptokinase, but in only 11 of the 14 was reperfusion present at 90 minutes. After streptokinase administration, all patients received heparin for 8 to 10 days; they were subsequently administered aspirin and dipyridamole. Clinical evidence of reocclusion during the first 24 hours of heparin therapy occurred in one patient. Thus, when given to patients with acute myocardial infarction and total coronary occlusion an average of 4 1/2 hours after the onset of chest pain, high dose intravenous streptokinase achieves reperfusion in only about 40% and results in sustained reperfusion in only about 30%.

Intravenous urokinase in acute myocardial infarction

To achieve reperfusion early, an intravenous bolus of 2 million units of urokinase was administered in 50 patients with transmural acute myocardial infarction (AMI) 1.8 +/- 2.5 hours after the onset of symptoms. Coronary angiography performed 1.1 +/- 0.6 hours after urokinase therapy revealed patent coronary arteries in 30 patients (60%), with no significant difference between those with anterior and those with inferior AMI. Reocclusion occurred in only 1 of 24 patients restudied. Failure to achieve reperfusion was not related to the degree of systemic fibrinolytic activity, which was equally high in patients who did and those who did not achieve reperfusion, as evident from serially obtained fibrinogen measurements (77 +/- 52 vs 84 +/- 24 mg/dl, difference not significant). Plasmin activity, measured serially from 15 minutes to 24 hours after urokinase in 7 patients, was maximal at 15 minutes and undetectable after 3 hours. Wall motion at the infarct site measured from contrast ventriculograms was significantly better at follow-up only in patients in whom reperfusion was achieved and who received urokinase within 2 hours after the onset of symptoms as compared with patients in whom reperfusion was not achieved (-1.2 +/- 1.4 vs -2.4 +/- 0.9 standard deviations from normal, p less than 0.05). Peak serum creatine kinase level was significantly lower in patients in whom reperfusion was achieved than in those in whom it was not or those who had rethrombosis (802 +/- 763 vs 1,973 +/- 1,071 U/liter, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Plaque fissuring--the cause of acute myocardial infarction, sudden ischaemic death, and crescendo angina

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Acute myocardial infarction treated with intracoronary streptokinase: a report of the Society for Cardiac Angiography

The Society for Cardiac Angiography maintains a registry of intracoronary streptokinase therapy (IC-SK) in patients with acute myocardial infarction. Between July 1981 and August 1984, 1,029 patients were entered into the registry. The baseline and clinical characteristics of patients were determined, the early results of therapy were evaluated, and baseline characteristics of those in whom reperfusion was achieved were compared with those in whom it was not. Multivariate discriminant analysis was used to identify the predictors of reperfusion and hospital mortality. The overall rate of reperfusion was 71.2%. Reperfusion was positively associated with hypotension, absence of cardiogenic shock and early treatment. The hospital mortality rate for all patients was 8.2% and was higher for women and the elderly. The hospital mortality was significantly lower among patients in whom reperfusion was achieved compared with those in whom it was not (5.5% vs 14.7%, p less than 0.0001) and for several high-risk subgroups. Thus, coronary artery reperfusion induced by IC-SK significantly reduces hospital mortality in high-risk patients with acute myocardial infarction. High-risk patients in whom reperfusion fails with IC-SK therapy should be considered for early coronary angioplasty or coronary artery bypass surgery.

Arteriographic predictors of spontaneous improvement in left ventricular function after myocardial infarction

To better characterize the changes in left ventricular ejection fraction after myocardial infarction, we compared radionuclide ventriculograms obtained acutely and 2 weeks after acute myocardial infarction in 40 patients. These patients underwent angiography within a mean of 4 hr and 20 min after the onset of symptoms of infarction and either received no therapy (32 patients who were control subjects in a thrombolysis trial) or did not experience reperfusion (eight patients) despite receiving streptokinase infusions. In all 40 patients, the change in left ventricular ejection fraction over 2 weeks was small (+2.6%). Patients were then grouped according to the presence or absence of residual flow on their angiograms. Residual flow was considered to be present in 21 patients, in 12 by virtue of subtotal occlusion of the artery supplying the area of infarct and in nine because of well-developed coronary collaterals to the distal infarct artery. Mean change in ejection fraction for patients with residual flow was +6.9 +/- 2.3% vs -2.2 +/- 1.7% for patients without residual flow (p less than .01). Fourteen of 21 (67%) patients with residual flow had a spontaneous rise in ejection fraction of greater than 5%, as compared with two of 19 (11%) patients without residual flow (p less than .01). Time to peak level of creatine kinase (CK) was significantly shorter in the residual flow group (15 vs 23 hr, p less than .01), while the peak level of CK was lower (1550 vs 2220 IU) in these patients. This latter difference did not reach statistical significance (p = .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Combined medical and mechanical recanalization in acute myocardial infarction

A technique of combined medical and mechanical recanalization was employed in 96 patients with acute transmural myocardial infarction. The mean time between onset of symptoms and admission to hospital was 170 +/- 65 min (X +/- SD). After 10 +/- 16 min, 250,000 U streptokinase was administered intravenously for 20 min. Intracoronary thrombolysis was commenced within 38 +/- 14 min. First coronary angiograms demonstrated reperfusion, an open vessel in 25/96 patients (26%). In 15/71 patients (21%) reperfusion occurred during thrombolysis therapy, before mechanical recanalization could be performed. Recanalization was achieved mechanically in 37/71 patients (52%) with occluded coronary vessels. In 8/71 patients (11%) mechanical recanalization failed but the vessel opened during thrombolysis. In 12/96 patients (12%), the coronary vessel remained occluded. Thus, reperfusion could be achieved in 88% of the patients. Reperfusion rate was 76% in the first 38 patients and 95% subsequently. After reperfusion, coronary thrombi were found in 25/96 patients (26%) but dissolved during thrombolysis in 16/25 patients (64%). Peripheral coronary embolism was observed in 3/25 patients (12%). For the whole group, reocclusion occurred in 8/84 patients (10%). By combined medical and mechanical recanalization, the recanalization rate could be increased with low reocclusion rate. Trends showed an improvement in regional and global left ventricular function in patients with anterior myocardial infarction.

Mechanisms contributing to precipitation of unstable angina and acute myocardial infarction: implications regarding therapy

Clinical and autopsy studies indicate that most patients who present with unstable angina or an acute myocardial infarction (AMI) have significant underlying coronary atherosclerosis. This review discusses 4 mechanisms that may contribute to the precipitation of these acute ischemic clinical syndromes: progression of atherosclerosis, acute coronary thrombosis, coronary artery spasm, and platelet aggregation. Numerous clinical trials using thrombolytic agents early during AMI have shown the incidence of thrombosis to be at least 60%. Other studies suggest that platelet aggregation frequently contributes to the evolution of AMI from unstable angina and that spasm may occasionally play a similar role. The therapeutic implications of these mechanisms are also considered in light of their potential to restore coronary artery blood flow (vs conventional methods thought mainly to reduce myocardial oxygen demand) and thereby limit the infarct process. The role of vasodilators, thrombolytic agents, antiplatelet drugs and beta-adrenergic blocking drugs are discussed. Finally, therapeutic guidelines for the treatment of acutely ill patients are constructed that emphasize the need for a comprehensive yet time-efficient treatment strategy that uses nitrates, calcium channel-blocking drugs, streptokinase, heparin, aspirin and, in selected patients in an unstable condition, emergency percutaneous transluminal coronary angioplasty and coronary artery bypass grafting.

Streptokinase thrombolysis in experimental coronary artery thrombosis: pattern of reflow and effect of a stenosis

We studied recanalization of an obstructed left circumflex coronary artery by streptokinase in open-chest anesthetized dogs. Thrombotic occlusion was induced by a 100 microA anodal current selectively delivered to the intimal surface of the vessel. Intracoronary streptokinase (50,000 U) or saline was infused over a 50-min period beginning at either 30 min or 90 min after occlusion. Continuous recordings were made of antegrade circumflex flow and regional myocardial function, which was quantitated using sonomicrometer crystals in the regions of the left anterior descending and circumflex coronary arteries. In some experiments a fixed stenosis, having no effect on mean circumflex coronary artery blood flow, was placed at the site of subsequent thrombus formation. The presence of a stenosis decreased the weight of occlusive thrombi obtained from nonreperfused saline controls by 40% and increased the proportion of animals successfully reperfused by streptokinase from 13 to 76%. Streptokinase reduced thrombus mass by 44% in animals recanalized in the presence of the stenosis. On the average, reflow was established after 26 min of streptokinase infusion, was less in magnitude than pre-occlusion flow, and was unstable and intermittent, being marked by frequent reocclusions. Initiating treatment at 30 min or 90 min post-occlusion did not influence characteristics of the reflow. Return of myocardial contractility in the ischemic bed was not detected during the immediate reperfusion period in the majority of these experiments.

Intracoronary streptokinase therapy in the coronary care unit for acute myocardial infarction

Intracoronary streptokinase was offered and preliminary coronary angiography performed in 14 patients who were seen with the clinical diagnosis of acute myocardial infarction within 4 h of onset of symptoms. The procedure was performed in the Coronary Care Unit (CCU) of St. Peter's Medical Center with the use of a portable C-arm fluoroscope. Angiography was recorded on video tape. Service was provided by an "on-call" team consisting of two physicians, a CCU nurse, and a radiology technician, on a 24-h service basis. Adequate visualization of coronary anatomy was obtained in all patients. Patency of occluded vessels was achieved in 10 of 11 patients who received intracoronary streptokinase. The initial streptokinase bolus was administered at a mean interval of 4.1 h from onset of symptoms. It is concluded that speedy and effective coronary thrombolytic therapy can be provided in the CCU on a 24-h service basis by an on-call team. The use of CCU for this purpose will make this therapy widely available across the country, without the need for Cardiac Catheterization Laboratory.

Intravenous streptokinase therapy in acute myocardial infarction: assessment of therapy effects by quantitative 201Tl myocardial imaging (including SPECT) and radionuclide ventriculography

To evaluate a potential beneficial effect of systemic streptokinase therapy in acute myocardial infarction, 36 patients treated with streptokinase intravenously were assessed by radionuclide ventriculography and quantitative 201Tl myocardial imaging (including SPECT) in comparison with 18 conventionally treated patients. Patients after thrombolysis had significantly higher EF, PFR, and PER as well as fewer wall motion abnormalities compared with controls. These differences were also observed in the subset of patients with anterior wall infarction (AMI), but not in patients with inferior wall infarction (IMI). Quantitative 201Tl imaging demonstrated significantly smaller percent myocardial defects and fewer pathological stress segments in patients with thrombolysis compared with controls. The same differences were also found in both AMI and IMI patients. Our data suggest a favorable effect of intravenous streptokinase on recovery of left ventricular function and myocardial salvage. Radionuclide ventriculography and quantitative 201Tl myocardial imaging seem to be reliable tools for objective assessment of therapy effects.

A comparison of intravenous and intracoronary streptokinase in acute myocardial infarction

A randomised study of intravenous and intracoronary streptokinase therapy was carried out in 20 subjects with acute myocardial infarction and angiographically confirmed complete obstruction of the associated coronary artery. Two dose levels of therapy were used. Although more recanalisations occurred with intracoronary than intravenous therapy at the low dose levels, overall there was not a significant difference between the two groups; one million IU intravenously over 20 minutes recanalised four of five arteries. While seven of nine recanalisations with intracoronary therapy occurred within an hour, only two of five with intravenous therapy did so. Hence prolonged angiographic observation is necessary to document recanalisation with intravenous therapy adequately. Nevertheless, the time disadvantage of large dose intravenous therapy is not great and it may yet prove as effective as, and more practical than, intracoronary therapy.

Intravenous versus intracoronary streptokinase therapy for acute myocardial infarction in community hospitals

A consecutive series of 184 patients with acute myocardial infarction (AMI) received thrombolytic therapy. The first 63 were treated in the catheterization laboratory with intracoronary streptokinase (IC-STK), and 44 (70%) had successful thrombolysis. One hundred twenty-one patients received intravenous (IV) STK immediately after diagnosis of AMI, and 99 (82%) were found to have an open infarct artery. Only 58% of patients (14 of 24) who required transfer from out-of-town hospitals for IC-STK treatment had successful thrombolysis; in contrast, IV-STK given in the local hospital resulted in an 85% (72 of 85) rate of thrombolysis (p = 0.005). IV-STK thus appears at least as effective as IC-STK for AMI and is more effective for patients treated in hospitals without catheterization facilities.

Thrombolysis in acute myocardial infarction: effect of intravenous followed by intracoronary streptokinase application on estimates of infarct size

The effect of pretreatment with intravenous infusion of streptokinase (SK) (16,700 U/min for 90 minutes), started after diagnosis and followed by intracoronary application (2000 U/min) (protocol 1), was assessed retrospectively in 55 consecutive patients with acute transmural myocardial infarction (MI). Another 46 patients with acute MI treated previously by intracoronary thrombolysis served as control subjects (protocol 2). Reperfusion at first coronary injection was observed after pretreatment in 25 patients (45%), but in no control patient (p less than 0.001). Fifteen patients with successful pretreatment (group A), 20 patients with successful treatment according to protocol 2 (group B) and 9 patients with unsuccessful thrombolysis (group C) were restudied after 4 weeks. Data from patients with reinfarction, coronary bypass surgery or percutaneous transluminal coronary angioplasty before restudy were excluded. Thallium-201 scintigraphy was performed before and 24 hours after treatment, serum creatine kinase activity was measured every 8 hours for 3 days and regional ejection fraction (EF) of acute MI was determined before and 4 weeks after treatment. The scintigraphic, enzymatic and hemodynamic data before treatment indicated severe and comparable ischemia among the 3 groups. The thallium-201 perfusion defect decreased in group A (from 41 to 21%, p less than 0.01) and in group B (from 38 to 26%, p less than 0.01), but did not change in group C (from 37 to 31%, difference not significant). Peak serum creatine kinase levels normalized by the perfusion area of acute MI was 20, 33 and 58 U/liter unit in groups A, B and C. The mean values of groups A and C were significantly different (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous streptokinase infusion in acute myocardial infarction with electrocardiographic monitoring for myocardial reperfusion

We present a case of thrombolytic therapy for acute myocardial infarction with high-dose intravenous streptokinase infusion in the emergency department. Resolution of ST segment elevation and relief of chest pain occurred within one hour of the infusion, and coronary angiographic study six days later showed a significant proximal obstruction (80%) of the right coronary artery. The patient underwent coronary artery bypass surgery eight weeks after his initial hospital presentation.

Recent advances using streptokinase for acute coronary thrombosis

Most important in comparison to earlier European trials, streptokinase (STK) is administered now at the earliest time possible after acute coronary thrombosis. In this series, STK was started 2.5 (+/- 1.5) h after onset of chest pain, with reperfusion achieved approximately 1 h later in 6 (55%) of 11 patients treated. Posttreatment angiograms will not be required to identify thrombolysis if noninvasive indicators will provide this information correctly. Early creatine kinase enzyme peaking 8 to 15 h after chest pain appears to be the most accurate marker available. Among untreated and unsuccessfully treated patients, creatine kinase peaking usually occurs 18-36 h after chest pain. A large intravenous STK loading dose of 1,500,000 IU produces a plasma concentration of approximately 500 IU/ml, equal to that concentration employed originally by intracoronary infusions. Such large doses have been employed in 60 patients thus far, without an unusual incidence or severity of hemorrhages. High dose, ultrashort-term treatment for only 1 h is being investigated now. Systemic STK penetrates most "blind coronary pouches" and gains access to acute thrombi, as identified by radiocontrast material washout during angiography in patients with severe coronary occlusions. Streptokinase exerts a significant anticoagulant effect, not previous considered, which may be beneficial in the prevention of new clot formation and the rapid dissolution of acute coronary thrombi.

Coronary thrombolysis by intravenous streptokinase in acute myocardial infarction: acute and follow-up studies

Coronary arteriography was performed before, immediately after, and 9 to 14 days after administering i.v. streptokinase (850,000 to 1,500,000 IU) to 43 patients within 6 hours of myocardial infarction. Ventricular function was determined by contrast ventriculography before and 9 to 14 days later and by radionuclide studies at clinical follow-up 8 months later. Early reperfusion occurred in 49% of patients, but in only 35% was it sustained. In patients with sustained reperfusion, early ventricular dysfunction was significantly reduced 9 to 14 days and 10 months later, and frequency of infarction, sudden death, and angina pectoris was not increased at follow-up. No serious bleeding occurred.

Percutaneous transluminal angioplasty. The radiologist's contribution to the treatment of vascular disease

Percutaneous transluminal angioplasty is a nonsurgical treatment for vascular disease. It is relatively safe and economical and may be an alternative, or an adjunct, to surgery, or may be helpful where no surgical alternative exists. Percutaneous transluminal angioplasty is applicable to nearly every system, except the carotid bifurcation plaque.

Return of left ventricular function after reperfusion in patients with myocardial infarction: importance of subtotal stenoses or intact collaterals

To determine whether subsequent improvement in left ventricular ejection fraction can be predicted from preintervention coronary arteriograms, we divided 63 patients with acute myocardial infarction into two groups based on findings at emergency coronary arteriography at a mean of 7 hr after onset of symptoms: (1) a "no-flow" group with an occluded infarct-related artery and no easily visible collaterals (n = 36) and (2) a "limited-flow" group with either subtotal stenosis or total occlusion of the infarct-related vessel with intact collaterals (n = 27). Of the 63 patients, 61 underwent emergency procedures to establish reperfusion. At follow-up angiography (contrast or radionuclide) performed 12 +/- 7 days after infarction, global ejection fraction had increased significantly in patients with limited flow to the infarct zone and "successful" early reperfusion intervention due primarily to a significant increase in the regional ejection fraction in the infarct zone. Global ejection fraction fell significantly between baseline and follow-up in patients with no flow to the infarct zone and "unsuccessful" early reperfusion intervention due primarily to a fall in the regional ejection fraction of the noninfarct zone. Global and regional ejection fractions did not change significantly in patients with no flow to the infarct zone and successful early reperfusion or in patients with limited flow to the infarct zone and unsuccessful early reperfusion intervention. The elapsed time before reperfusion did not relate significantly to the change in either regional or global ejection fraction. However, the magnitude of improvement in both global and regional ejection fraction at follow-up was greater among patients with anterior infarcts than among those with inferior infarcts, possibly because baseline ejection fraction was lower in patients with anterior infarcts. These data indicate that among patients with acute myocardial infarction undergoing emergency coronary arteriography at a mean of 7 hr after onset of symptoms, improvement in global ejection fraction is unlikely to occur even after a successful early reperfusion intervention in the absence of preserved flow to the infarct area. However, among patients with subtotally occluded infarct-related arteries or significant collateral blood flow to the infarct zone, subsequent improvement in global and regional ejection fraction in the zone of myocardial infarction frequently occurs. Improvement in both global and regional ejection fraction may be more readily demonstrated in patients initially having more severe depression of these parameters.

Intravenous versus intracoronary streptokinase for acute transmural myocardial infarction

In order to compare the thrombolytic efficacy of selective versus systemic administration of streptokinase, we gave this drug by either the intracoronary or intravenous routes to 25 patients during the first 6 hours of acute myocardial infarction. All patients had total occlusion of the infarct-related vessel, unresponsive to intracoronary nitroglycerin. Twelve patients received intravenous streptokinase and 13 received intracoronary administration of the drug. Angiograms were taken prior to and during streptokinase administration. Reopening was achieved in 11 of 13 intracoronary patients and 8 of 12 intravenous patients (P = Ns). Time to reopening was longer (54 minutes) in the intravenous patients than in the intracoronary patients (26 minutes) (P less than 0.05). In this study, intravenous streptokinase reopened infarct-related vessels nearly as often as intracoronary streptokinase, but it took longer. Given the limited access and time to prepare for intracoronary infusion and the ease of intravenous administration, further study of intravenous streptokinase is justified.

Prospective randomized trial of intravenous and intracoronary streptokinase in acute myocardial infarction

To evaluate the relative thrombolytic efficacy and complications of intracoronary vs high-dose, short-term intravenous streptokinase infusion in patients with acute myocardial infarction, we performed baseline coronary arteriography and then randomly allocated 51 patients with acute myocardial infarction to receive either intracoronary (n = 25) or intravenous (n = 26) streptokinase. Patients getting the drug by the intracoronary route received 240,000 IU of streptokinase into the infarct-related artery over 1 hr, whereas those getting the drug by the intravenous route received either 500,000 IU of streptokinase over 15 min (n = 10) or 1 million IU of streptokinase over 45 min (n = 16). Angiographically observed thrombolysis occurred in 76% (19/25) of the patients receiving intracoronary streptokinase, in 10% (1/10) of the patients receiving 500,000 IU of streptokinase intravenously, and in 44% (7/16) of the patients receiving 1 million IU of streptokinase intravenously. Among patients in whom thrombolysis was observed, mean elapsed time from onset of streptokinase infusion until lysis was 31 +/- 18 min in patients receiving intracoronary streptokinase and 38 +/- 20 min in those receiving intravenous streptokinase (p = NS). Among patients in whom intravenous streptokinase "failed," intracoronary streptokinase in combination with intracoronary guidewire manipulation recanalized only 7% (1/15). Fibrinogen levels within 6 hr after streptokinase were significantly lower in the patients receiving intravenous streptokinase (39 +/- 17 mg/dl) than the levels in those receiving intracoronary streptokinase (88 +/- 70 mg/dl) (p less than .05) but were similar 24 hr after streptokinase in the two groups. Bleeding requiring transfusion occurred in one patient in each group. Thus, in this prospective randomized trial of intracoronary vs intravenous streptokinase, hemorrhagic complications were few, although both regimens produced a systemic lytic state. Although the thrombolytic efficacy of intracoronary streptokinase was superior to that of high-dose, short-term intravenous streptokinase, the higher-dose intravenous regimen (1 million IU over 45 min) achieved thrombolysis in a significant minority (44%) of patients and might be useful therapy for patients not having access to emergency catheterization.

High dose intravenous streptokinase in acute myocardial infarction

Early recanalization of infarct-related coronary arteries has been attempted in 40 patients with acute myocardial infarction (AMI) and angiographically proven total occlusion by brief high dose intravenous streptokinase infusion (IVSK). In 24 patients (60%) recanalization was achieved after 48 +/- 14 min of IVSK at an infusion rate of 30,000 to 40,000 IU/min (group A), in 16 patients there was a late (greater than 2 h) or no recanalization (group B). The total dose of SK was 1.7 +/- 0.48 Mio IU in group A and 1.74 +/- 0.41 Mio IU in group B, the time from the onset of symptoms to peak myocardial enzyme of creatine phosphokinase (CKMB) 11 +/- 3 h in group A and 22 +/- 6 h in group B (p less than 0.001). Biplane left ventricular ejection fraction increased from 55 +/- 9% at the time of acute angiography to 58 +/- 10% after 14 to 24 days in group A (p less than 0.1) and decreased from 49 +/- 11 to 41 +/- 11% in group B (p less than 0.005). There were four reocclusions in group A, two could be reopened by i.v. urokinase (1 Mio IU over 30 min). During a follow-up period of 18 +/- 8 months one patient in group A died from an early ventricular rupture 2 hours after recanalization, and one patient in group B from heart failure 7 months after IVSK. There was no serious bleeding or other complication related to IVSK. We conclude that IVSK is an effective and safe means of early recanalization of coronary thrombosis in AMI, and feasible in the majority of patients with AMI.

Intravenous streptokinase in acute myocardial infarction

Intracoronary streptokinase has been reported to be successful in producing coronary recanalization and lowered morbidity and mortality in acute myocardial infarction patients, when administered shortly after the onset of chest pain. However, intracoronary administration of streptokinase is not practical for most hospitals at present, and intravenous administration would enable treatment of larger numbers of patients and enable the drug to be administered earlier than by the intracoronary route. Available studies have suggested benefits of the intravenous route and results of randomized clinical trials indicate an approximately 20-percent decrease in mortality after intravenous use. Intravenous streptokinase after acute myocardial infarction warrants further investigation.

Changing concepts of pathophysiology, prognosis, and therapy in acute myocardial infarction

Recent research findings regarding the pathophysiology of acute myocardial infarction, newer concepts of treatment, and better means of identifying high- and low-risk patients after acute myocardial infarction are presented, along with practical clinical considerations.