Efficacy of percutaneous transluminal coronary recanalization utilizing streptokinase thrombolysis in patients with acute myocardial infarction

Analytic Review: Thrombolytic Therapy in Acute Myocardial Infarction

The salvage of myocardium in the setting of acute myocardial infarction has long been a goal of physicians involved in the care of patients with coronary artery disease. Understanding the role of thrombosis in the pathogenesis of acute myocardial infarction has led the way to an entirely new approach to the treatment of this entity. Thrombolytic therapy has now become a widely used form of treatment with encouraging results. Both intravenous and intracoronary administration of thrombolytic agents have been shown to promote recanalization of acutely occluded coronary arteries. Results of studies using the clot-specific agent, tissue plasminogen activator, intravenously have been most encouraging; successful reperfusion has been obtained in approximately 70% of patients treated. In addition, a recent large-scale trial has shown a reduction in morbidity and mortality with the early use of thrombolytic agents.

Ongoing trials should help delineate the precise role and timing of these agents as the initial form of therapy for acute myocardial infarction. Other issues that remain unresolved are the frequency of restenosis and the role of percutaneous transluminal coronary angioplasty in addition to thrombolytic therapy in the treatment of acute myocardial infarction.

An evaluation of streptokinase therapy in early coronary reperfusion in a primate model

Efficacy of streptokinase (SK) administered beyond the period of coronary occlusion with regard to ultimate infarct size and the extent of hemorrhagic infarction was assessed in primates. Eleven macaques underwent coronary occlusion for two hours and were then reperfused. Five of them were given a 2,000 U IV bolus of SK followed by a 10,000 U IV infusion over ninety minutes. The remaining 6 served as controls. Macaques were sacrificed seven days postocclusion. The left ventricle was sectioned parallel to the minor axis, and these were examined histologically for infarct size and hemorrhage. Multiplying the planimetric values by the thickness of the sections yielded the total volumes of left ventricle, infarction, and hemorrhage. The mean percentage of left ventricle involved in infarction in the treated group was not significantly different from the controls (14.06 +/- 6.35 versus 16.50 +/- 4.67, P > 0.10). SK-treated animals had a significantly greater volume of infarct involved with hemorrhage as compared with controls (27.1 +/- 10.8 versus 4.0 +/- 1.4, P < 0.05). SK infusions done concurrently with reperfusion following a two-hour occlusion did not result in a significant reduction or increase in the size of infarct. However, SK infusions resulted in a significant increase in the amount of hemorrhagic infarction.

Early T wave inversion after thrombolytic therapy predicts better coronary perfusion: clinical and angiographic study

OBJECTIVES

This study was undertaken to test the hypothesis that early inversion of T waves after thrombolytic therapy for acute myocardial infarction predicts patency of the infarct-related artery with high Thrombolysis in Myocardial Infarction (TIMI) perfusion flow and better in-hospital outcome.

BACKGROUND

Although numerous studies have demonstrated a strong association between early resolution of ST segment elevation after acute myocardial infarction and successful thrombolysis, little is known about early changes in T waves after thrombolytic therapy.

METHODS

Ninety-four consecutive patients with acute myocardial infarction treated with recombinant tissue-type plasminogen activator (rt-PA) were studied with admission and predischarge radionuclide ventriculography and with coronary angiography within 72 h of admission. Patient stratification was based on the presence or absence of early (within 24 h) T wave inversion.

RESULTS

Early T wave inversion was associated with a higher patency rate of the infarct-related artery (90% vs. 65%, p < 0.02) and less severe residual stenosis ([mean +/- SD] 73 +/- 27 vs. 83 +/- 22, p = 0.06), and when only TIMI perfusion grade 3 was considered, the difference was even greater (77% vs. 41%, p < 0.001). Patients with early inversion of T waves had a lower peak creatine kinase value ([mean +/- SD] 678 +/- 480 vs. 1,076 +/- 620, p < 0.01), and although a similar percent of patients with and without early T wave inversion had a normal ejection fraction (> or = 55%) on admission, a higher percent of patients with early inversion had a normal ejection fraction at hospital discharge (71% vs. 44%, p < 0.03). Early T wave inversion anticipated a more benign in-hospital clinical course with a lower incidence of adverse cardiac events (10% vs. 33%, p < 0.02).

CONCLUSIONS

Early inversion of T waves in patients with acute myocardial infarction treated with thrombolytic therapy suggests patency of the infarct-related artery, better perfusion grade and left ventricular function and a more benign in-hospital course.

Additional ST segment elevation during the first hour of thrombolytic therapy: an electrocardiographic sign predicting a favorable clinical outcome

OBJECTIVES

The aim of this study was to investigate the significance of further ST elevation that occurs during the 1st h of thrombolytic therapy before the expected resolution.

BACKGROUND

Early resolution of ST segment elevation is commonly accepted as a marker of clinical reperfusion during thrombolytic therapy for acute myocardial infarction. Using frequent electrocardiographic recordings, we observed in some patients further ST elevation that occurred during hour 1 of thrombolysis before the expected resolution.

METHODS

To investigate the significance of this pattern, we classified 177 consecutive patients with a first acute myocardial infarction into two groups: Group A, 98 patients with ST elevation > or = 1 mm above the initial ST elevation during the 1st h of thrombolytic therapy, and Group B, 79 patients without this finding.

RESULTS

Although the presence or absence of additional ST elevation was not associated with a clinical or prognostic difference in patients with a first inferior or posterior acute myocardial infarction, its presence indicated a more favorable clinical outcome and prognosis in patients with anterior infarction. Among the patients with anterior infarction the 65 patients in Group A had a higher ejection fraction (44 +/- 9% vs. 35 +/- 11%, p < 0.01), less heart failure (15% vs. 35%, p = 0.02) and a lower in-hospital mortality rate (0% vs. 8%, p = 0.04) than did the 37 patients from Group B.

CONCLUSIONS

Additional ST elevation early during thrombolytic therapy in patients with anterior infarction suggests a favorable clinical outcome and thus may be indicative of successful reperfusion.

Are enzymatic tests good indicators of coronary reperfusion?

OBJECTIVE

To assess the accuracy of four enzymatic tests, including early release rates of creatine kinase and alpha-hydroxybutyrate dehydrogenase, in assessing coronary reperfusion after thrombolytic therapy.

DESIGN

A prospective clinical trial identifying patients with a successful thrombolytic treatment.

PATIENTS

Eighty nine patients with acute myocardial infarction were studied. Arteriography showed a closed infarct related artery in all of them. Reperfusion due to thrombolysis occurred in 74 patients and there was no reperfusion in 15 patients.

RESULTS

The 74 patients showing coronary reperfusion had a significantly shorter time to peak creatine kinase activity, higher early release rates for creatine kinase and alpha-hydroxybutyrate dehydrogenase, and a more rapid release of alpha-hydroxybutyrate dehydrogenase (ratio of cumulative release of alpha-hydroxybutyrate dehydrogenase during the first 24 hours to that 72 hours after infarction). All these differences were statistically significant (p less than 0.001). Optimum cut off levels were determined with decision level plots and the accuracy of the four enzymatic tests was calculated. Accuracy was low for all four tests (73%, 70%, 70%, and 82%).

CONCLUSION

None of the four enzymatic tests accurately predicted the perfusion state of the infarct related coronary artery after thrombolysis. These tests cannot be used reliably in routine clinical practice as non-angiographic markers of coronary reperfusion.

Reduction in ST segment elevation after thrombolysis predicts either coronary reperfusion or preservation of left ventricular function

The usefulness of a reduction in ST segment elevation to predict coronary reperfusion in myocardial infarction remains uncertain. ST segment changes and angiographic findings were compared in 45 patients soon after thrombolysis. The percentage ST segment change 3 hours after treatment (in the lead showing the greatest initial ST elevation) was compared with the TIMI perfusion grade (thrombolysis in myocardial infarction trial) obtained between 90 minutes and 3 hours after treatment. Global ejection fraction and regional wall motion were assessed by cineventriculography (11 (5) days (mean (SD))) and by gated blood pool imaging (44 (11) days). Prediction of coronary patency by a reduction of greater than 25% in ST segment elevation 3 hours after thrombolytic treatment had a sensitivity of 97% but a specificity of only 43%. Where the ST segment elevation was reduced by greater than 25% the global ejection fraction was well maintained whether or not the infarct vessel was patent. In patients with a reduction of less than 25% in ST elevation, the ejection fraction was significantly lower and regional wall motion abnormality more severe. Reduction in ST elevation of greater than 25% within 3 hours of thrombolysis indicates either a patent infarct artery or preservation of left ventricular function. When the ST segment elevation does not fall by greater than 25% persistent coronary occlusion is likely (predictive accuracy 86%) and is associated with a lower ejection fraction. These patients may benefit from further treatment or additional interventions.

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.

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.

Myocardial thallium-201 kinetics and regional flow alterations with 3 hours of coronary occlusion and either rapid reperfusion through a totally patent vessel or slow reperfusion through a critical stenosis

Myocardial thallium-201 kinetics and regional blood flow alterations were examined in a canine model using 3 hours of coronary occlusion and different methods of reperfusion. Group I comprised 10 dogs undergoing a 3 hour left anterior descending artery occlusion and no reperfusion. Group II comprised seven dogs undergoing 3 hours of left anterior descending artery occlusion and rapid reperfusion through a totally patent vessel. Group III comprised 10 dogs undergoing 3 hours of left anterior descending artery occlusion and slow reperfusion through a residual stenosis. All dogs received 1.5 mCi of thallium-201 after 40 minutes of coronary occlusion. During occlusion and 2 hours of reperfusion, serial hemodynamic, blood flow and myocardial thallium-201 activity measurements were made. The relative thallium-201 gradient (normal zone minus ischemic zone activity when initial normal activity is expressed as 100%) during left anterior descending coronary occlusion was similar in all groups. Group I, 87 +/- 3%; Group II, 78 +/- 6%; Group III, 83 +/- 6% (p = NS). After 2 hours of either method of reperfusion, the final relative gradient had decreased to a similar level (Group II, 51 +/- 9%; Group III, 42 +/- 6%). These values were not significantly different from the final relative thallium-201 gradient seen in dogs undergoing a sustained 3 hour occlusion (Group I, 55 +/- 5%). After 2 hours of reperfusion, both methods of reflow were associated with similar degrees of "no reflow." Transmural flows in the central ischemic zone were 89 +/- 10% of normal in Group II and 71 +/- 6% of normal in Group III after reperfusion, with both flows substantially higher than the relative thallium-201 activities in these dogs. Infarct size (percent of left ventricle) determined with triphenyltetrazolium chloride was similar in all groups (Group I, 24 +/- 4%; Group II, 29 +/- 4%; Group III, 25 +/- 4%). Thus, in this experimental canine model, 3 hours of coronary occlusion followed by either rapid reperfusion through a totally patent vessel or slow reperfusion through a critical stenosis resulted in little delayed thallium-201 redistribution or myocardial salvage as assessed histologically, despite significant recovery of regional flow.

[Primary dissection of the left coronary artery with rupture of the ventricle in a 27-year-old patient]

This report of a 27-year-old patient describes an extensive infarction of the anterior wall due to primary dissection of the left coronary artery in the absence of the circumflex artery followed by rupture of the left ventricle. In earlier reports an aortocoronary bypass operation was usually performed in similar situations. Although the final outcome was lethal, this case report shows recanalization by methods of "interventional cardiology" to be a potentially successful alternative which may be of value when bypass operation is not available or contraindicated, as in developing cardiogenic shock. This case report demonstrates an initially successful treatment, which after a stable interval was followed by a lethal complication, namely, rupture of the ventricle due to hemorrhagic infarction.

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 randomized controlled trial of intravenous streptokinase in evolving acute myocardial infarction

To determine the efficacy of intravenous streptokinase in acute myocardial infarction, 52 patients were randomized to intravenous streptokinase or control groups. Time from onset of infarction to randomization was similar in the streptokinase group and control group, 4.9 +/- 2.1 hours vs 5.4 +/- 2.4 hours, respectively. The 28 streptokinase patients received an intravenous infusion of 700,000 units of streptokinase followed by full-dose anticoagulation. The 24 control patients received normal saline solution followed by full-dose anticoagulation. Of 28 streptokinase patients, 12 (43%) had noninvasive evidence of reperfusion by early peaking of serum creatine kinase (peak creatine kinase less than 16 hours after onset of infarction) vs 3 of 24 control patients (13%), p less than 0.02. Two streptokinase patients (7%) had reperfusion arrhythmias during streptokinase infusion. One streptokinase patient (4%) and two control patients (8%) died during hospitalization. At angiography (16 +/- 5 days after infarction) 22 of 26 streptokinase patients (85%) had a patent infarct-related coronary artery compared to 8 of 20 control patients (40%), p less than 0.01. Comparison of radionuclide left ventricular ejection fraction assessed acutely (28 +/- 10 hours after infarction) with left ventricular ejection fraction at hospital discharge (15 +/- 3 days after infarction) showed no significant improvement in either the streptokinase or control group, 0% and +1%, respectively. At follow-up 13 +/- 7 months after infarction, total mortality rate was similar in the streptokinase group and control group, 17.8% (5 of 28 streptokinase patients) and 20.8% (5 of 24 control patients), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined thrombolytic therapy and coronary angioplasty for acute myocardial infarction

From September, 1983, to August, 1984, combined thrombolytic therapy and percutaneous transluminal coronary angioplasty was used to treat 22 cases of acute myocardial infarction. Initial coronary angiograms showed total obstruction in 13 and severe stenosis in 9. Intracoronary infusion of urokinase reopened 7 of 13 totally occluded lesions but left a residual severe stenosis. Coronary angioplasty opened all of the remaining totally obstructed lesions and decreased the stenosis in 14 of 16 stenosed lesions. These procedures were performed 0.5 to 24 hours after the onset of chest pain. Lesions were not successfully dilated in two patients, because of arterial dissection in one and rethrombus formation in the other. One patient died from progressive hypotension beginning during the procedure, despite technically successful coronary angioplasty. Eighteen of the 20 successfully dilated lesions were patent at repeat angiography performed 1 to 3 weeks later. One successfully dilated lesion occluded 8 days after the procedure and was redilated by a larger sized balloon.

Percutaneous transluminal coronary angioplasty, alone or in combination with streptokinase therapy, during acute myocardial infarction

The treatment strategy in 66 consecutive patients who underwent invasive therapy for acute myocardial infarction was analyzed, and specific attention was focused on the role of percutaneous transluminal coronary angioplasty. The following four treatment regimens were used: angioplasty alone (11 patients), angioplasty followed immediately by administration of streptokinase (15), streptokinase therapy alone (11), and streptokinase therapy followed by angioplasty (29). Reperfusion was achieved in 91%, 80%, 82%, and 72% of these subgroups, respectively. Angioplasty was particularly helpful in patients with severe residual stenoses after intracoronary administration of streptokinase and in patients in whom streptokinase therapy failed to reopen the occluded artery. Angioplasty further reduced the residual stenosis in 11 of 15 patients (73%) with successful thrombolysis, and it restored blood flow in 10 of 14 patients (71%) in whom thrombolysis had failed to do so. The incidence of reinfarction after therapy was similar in all four treatment groups. Patients in whom angioplasty was used either alone or in combination with streptokinase therapy had a significantly decreased incidence of subsequent revascularization (less than 30% compared with 82%). Angioplasty is of considerable value in patients undergoing invasive therapy for acute infarction. In some patients, it may be used as the only treatment; in others, it may be used to treat severe residual stenosis after initial streptokinase therapy. Finally, angioplasty achieves reperfusion in most patients in whom streptokinase therapy has failed.

Intravenous streptokinase in acute myocardial infarction

Intravenous (IV) fibrinolytic therapy, a recent area of research, has a great deal of applicability in emergency medicine. We report our experience with 30 patients treated with this method. Thirty consecutive patients in the early stages of acute evolving myocardial infarction (AMI) were assigned to receive high-dose IV streptokinase, 1.5 million units over a 30-minute period. Patients presented to the treating hospital at a mean time of 1.21 +/- 1.08 hours, and treatment commenced at a mean time of 2.77 +/- 1.31 hours after the onset of symptoms. Using standard clinical criteria, 86.7% (n = 26) of the patients reperfused initially. Two, however, reoccluded within the first 48 hours, and their clinical symptoms of myocardial infarction reappeared. By clinical observation 80% (n = 24) of the patients reperfused, and myocardial salvage was observed. Twenty-four patients with clinical reperfusion and one additional patient had patency of the affected artery, yielding a reperfusion rate of 83.3% (n = 25) as judged by angiography within one week of AMI. Both patients who had reoccluded clinically also were found to be occluded on angiography. Clinical and angiographic methods yield very similar results for the judgment of reperfusion (80% vs 83%, respectively, with no significant difference, P not significant). The results of our study tend to confirm the efficacy of IV streptokinase as a valuable management tool for early myocardial infarction.

Relationship of the lytic state to successful reperfusion with standard- and low-dose intracoronary streptokinase

The influence of a systemic lytic state on reperfusion obtained after intracoronary streptokinase (SK) therapy has been evaluated in 15 patients with acute myocardial infarction and complete coronary occlusion. Coronary angiographic studies and measurements of blood fibrinolytic parameters were repeated at 15 min intervals during the infusion of a standard dose of SK and were compared with the results with approximately one-tenth the standard dose. Successful reperfusion was obtained in only 20% (2/10) of patients receiving the low dose, compared with a 75% to 80% success rate in patients receiving the standard dose as initial treatment (4/5) or as follow-up treatment of patients in whom low-dose therapy failed (6/8). There was a striking association between reperfusion and development of the lytic state in that all 12 treatments resulting in reperfusion also caused a lytic state and all seven treatments that failed to produce a lytic state also failed to induce reperfusion (p less than .001). Among the successfully treated patients, the dose of SK that induced a lytic state was relatively constant. However, coronary arterial thrombi differed in susceptibility to treatment. Sensitive thrombi (5/12) dissolved before the lytic state occurred and at a lower SK dose than that needed to cause a lytic state; more resistant thrombi (7/12) required a longer time and a significantly larger SK dose to dissolve. These results indicate that intrinsic properties of the thrombus influence the rate and outcome of treatment and that a minimal dose of SK (about 200,000 U) is required to ensure lasting reperfusion in susceptible patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracoronary thrombolytic therapy in acute myocardial infarction: a prospective, randomized, controlled trial

A prospective, randomized trial was designed to assess the efficacy of intracoronary thrombolytic therapy with streptokinase (STK) in acute myocardial infarction. Sixty-four patients with acute myocardial infarction were randomized within 6 hours of onset of symptoms to 1 of 3 groups. Sixteen patients were treated by conventional means (control group). Nineteen patients underwent coronary arteriography and received corticosteroids and intracoronary and intravenous nitroglycerin (NTG group). Twenty-nine patients received management identical to that of the NTG group, with the addition of intracoronary STK therapy (STK group). Recanalization was demonstrated in 21 of 29 patients (72%) in the STK group. Global and regional ejection fraction (EF) was determined by radionuclide ventriculography before any intervention and 7 to 10 days later. No significant improvement in global EF was achieved in the control and NTG groups. In STK patients as a group, global EF did not increase significantly; however, in patients recanalized with STK, EF improved from 42 +/- 17% to 49 +/- 16% (p = 0.023). All groups showed wide variability of response. Improvement in global EF of more than 5% was noted in 44% of patients recanalized with STK. When subgrouped on the basis of initial global EF of 45% or less or more than 45%, only patients recanalized with STK with an initial EF of 45% or less had an improved global EF (from 30 +/- 10% to 42 +/- 10%, p = 0.015).(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing probability of reperfusion with intracoronary ostial infusion of thrombolytic agent in patients with acute myocardial infarction

A multivariate logistic regression equation was used to evaluate variables related to successful intracoronary thrombolytic therapy. One hundred seventeen patients with a totally occluded infarct-related artery were randomly given ostial infusions of urokinase or streptokinase in a blinded study. The opening rate was 57%. The agent used and time from onset of symptoms to beginning of treatment did not significantly influence opening rate (p greater than .25). The site of occlusion was a strong predictor of opening rate (p = .0004). The anterior descending coronary artery was successfully opened more frequently than the left circumflex or right coronary artery (p = .012). Presence of collaterals adversely affected the recanalization rate in all groups (p = .0004). These variables had an additive effect on the probability of opening. Patients with proximal anterior descending occlusion and no collaterals had a 90% recanalization rate, while those with distal occlusions in vessels other than the anterior descending and with collaterals had only a 24% chance for reperfusion. Thus location of occlusion and presence or absence of collaterals may strongly influence opening rates.

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.

Global and regional left ventricular function and tomographic radionuclide perfusion: the Western Washington Intracoronary Streptokinase In Myocardial Infarction Trial

The Western Washington Intracoronary Streptokinase In Myocardial Infarction Trial enrolled 250 patients with acute myocardial infarction. After the coronary angiographic diagnosis of thrombosis, patients were randomly assigned to receive either conventional therapy with heparin or intracoronary streptokinase followed by heparin. Of the 232 patients who survived at least 60 days, 207 (89%) underwent radionuclide ventriculographic determination of global and regional ejection fraction at a single institution at 62 +/- 35 days after infarction. In the first 100 patients, infarct size was also determined by quantitative single-photon emission tomographic imaging with thallium-201 (201Tl) and expressed as a percentage of the left ventricle with a perfusion defect. Overall, global ejection fraction did not differ between patients treated with streptokinase (45.9 +/- 13.9%; n = 115) and control patients (46.1 +/- 14.4%; n = 92, p = NS). Similarly, the regional posterolateral, inferior, and anteroseptal ejection fraction did not differ between the two groups. Infarct size as measured by 201Tl tomography was 19.4 +/- 12.8% (n = 52) of the left ventricle for the streptokinase group and 19.6 +/- 11.8% (n = 48; p = NS) for the control group. When patients were compared within groups by electrocardiographic location of infarction, time to treatment, or the presence or absence of vessel opening, there were no significant differences between streptokinase and control patients. Statistical inclusion of the 18 patients who died early and were unavailable for study also failed to modify the results, except for a possible reduction in inferior infarct size as measured by 201Tl tomography.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Thrombolytic therapy for acute transmural myocardial infarction. Intracoronary versus intravenous

The application of coronary angiography in coordination with streptokinase administration directly into the occluded coronary artery has served to focus attention on the clinical potential of such therapy. About 75 percent of patients with acute transmural myocardial infarction have been shown to have reperfusion after intracoronary administration of streptokinase. However, the data do not prove that the beneficial effect required regional perfusion. Analysis of biochemical data suggests that the active agent was not confined to the locale of the thrombus, but in fact circulated in significant concentration; furthermore, systemic (intravenous) treatment resulted in reperfusion of a significant proportion (50 percent) of coronary arteries as well. Comparative studies are needed to critically compare angiographic results after regional or systemic therapy and also to assess the impact of reperfusion on possible reduction in long-term morbidity and mortality. Although intracoronary therapy appears to be more effective for inducing reperfusion, intravenous therapy has the potential for greater clinical impact, since it can be instituted more quickly after the onset of symptoms and does not require specialized cardiac catheterization facilities.

Hemorrhage and the products of fibrinogen digestion after intracoronary administration of streptokinase

Hemorrhage was prospectively identified in 26 of 116 consecutive patients (23%) who were receiving intracoronary streptokinase for occlusive coronary thrombi producing infarction. Bleeding was not influenced by the dose of streptokinase or the method of cardiac catheterization. Before treatment, prothrombin time and partial thromboplastin time were normal in both bleeders and nonbleeders. Fibrinogen levels measured by bioassay after streptokinase (mean +/- SEM) were 62 +/- 29 mg/dl in patients with major bleeding, 111 +/- 26 mg/dl in patients with minor bleeding, and 109 +/- 13 mg/dl in nonbleeders (p = NS). The regression slope b calculated from poststreptokinase fibrinogen time-concentration data in 71 patients was 4.7 mg/dl/hr. However, mean fibrinogen concentrations calculated at sequential 5 hr intervals revealed no net regeneration for the first 20 hr after thrombolysis. The apparent fibrinogen regeneration rate was less than normal (31 mg/kg/day) for more than 10 hr but subsequently increased to 94 +/- 10 mg/kg/day by the second day. The initial apparent latency of fibrinogen regeneration paralleled the sharp rise in fibrinogen degradation products, which began to decline after 20 hr of treatment but remained elevated well into the second day. Because of their anticoagulant effects, these products may interfere with the fibrinogen assay, causing spuriously low results. Thus, whether the early delay in fibrinogen regeneration is real or simply a reflection of the effects of fibrinogen degradation products on the bioassay, it signals the time for caution in initiating systemic heparin therapy.

Thrombosis and acute coronary-artery lesions in sudden cardiac ischemic death

The nature of the pathologic lesion in sudden cardiac ischemic death is in dispute. Among 100 subjects who died of ischemic heart disease in less than six hours, coronary thrombi were found in 74. There was no difference in incidence between those who died in less than 15 minutes, those who died in 15 to 60 minutes, and those who died after one hour. Among 26 cases without an intraluminal thrombus, plaque fissuring was found in 21; thus, in only 5 cases was no acute arterial lesion demonstrated. No intraluminal thrombi were found in age-matched controls. Forty-eight of the 74 thrombi were found at sites of preexisting high-grade stenosis; 14 were found at points of previous stenosis of less than 50 per cent of the diameter of the lumen. Forty-seven per cent of the thrombi were found in the right coronary artery. Only 30 per cent were found in the left anterior descending coronary artery. The pathologic process in sudden ischemic death involves a rapidly evolving coronary-artery lesion in which plaque fissuring and resultant thrombus formation are present. These findings have implications for the prevention of sudden cardiac death by antithrombotic therapy.

Intravenous streptokinase in evolving acute myocardial infarction

Eighty-one consecutive patients presenting within 3 hours of the onset of acute myocardial infarction (AMI) and without contraindications to thrombolytic or anticoagulant therapy received a 15- to 30-minute intravenous infusion of 750,000 or 1.5 million units of streptokinase (STK) followed by anticoagulation. Treatment was instituted 130 +/- 41 minutes after the onset of symptoms and reperfusion was achieved 36 +/- 26 minutes later. Reperfusion of the "infarct artery" was recognized by indirect clinical criteria in 78 patients (96%). In all 66 patients who underwent coronary angiography 3 to 7 days later, there was complete concordance between indirect and angiographic evidence of reperfusion. In 6 patients there was early reocclusion within 24 hours of treatment; in 4 of these patients, the artery was reopened with an additional dose of STK. Two elderly patients suffered an intracranial hemorrhage and there were 8 other major hemorrhagic complications, of which 7 were related to procedural trauma. Five patients (6.2%) died in the hospital. The results of intravenous STK thrombolytic therapy are compared with those of our previous study using intracoronary STK.

Effects of percutaneous transluminal coronary angioplasty: intracoronary thrombolysis with urokinase in acute myocardial infarction

Coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) were performed in 32 patients with evolving acute myocardial infarction. Of the 25 patients with complete occlusion of an infarct-related coronary artery, in 18 (72%) the occluded vessel was successfully opened by an intracoronary infusion of urokinase. With a small dose of urokinase the successful recanalization was achieved in only 25%; with a larger dose it was achieved in 94%. After PTCA, all patients received glucose-insulin-potassium solution for 76 hours. Repeat angiography 42 days later showed a patent coronary artery in 12 (group A) of 18 patients with successful PTCA. In group A, left ventricular ejection fraction increased from 51 +/- 13% to 72 +/- 10% (p less than 0.01) and regional wall shortening from 4.5 +/- 9.5% to 29 +/- 19% (p less than 0.01). In contrast, these variables did not change significantly in patients with unsuccessful PTCA or late reocclusion of an infarct-related vessel (group B). These data suggest that successful PTCA with sustained patency of an infarct-related coronary artery has a beneficial effect on the salvage of the jeopardized myocardium, and glucose-insulin-potassium therapy may enhance the beneficial effect of PTCA.

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.

The fibrinolytic system in man

The existence of a system in the human body capable of inducing the dissolution of endogenous pathologically formed thrombi was appreciated in ancient times. Considered in detail in this article are the data that have elucidated the physiologic regulation of which plasmin formation is dependent on, the plasma concentration of plasminogen, availability of activators of plasminogen in the plasma and surrounding tissue environment, the concentration of naturally present inhibitors, and the existence of fibrin in the circulation. Important in this rapidly progressive scientific discipline is consideration of the factors which control the synthesis of the components of this proteolytic enzyme system. Recently abundant information has indicated that this plasminogen-plasmin proteolytic enzyme system can be utilized therapeutically. Knowledge of the mechanisms of this system has permitted identification of agents that can be exogenously administered to releave thrombotic obstruction to blood flow in the venous (pulmonary emboli, deep vein thrombosis) and arterial (peripheral and central vessels) circulatory systems. Particularly important is the demonstration that thrombolytic agents can directly attack and alleviate the immediate cause of acute myocardial infarction. As a result of the innovations in the present decade, it is evident that the plasminogen system can be advantageously employed to reverse the pathologic effects of all thrombotic diseases.

Unusual nodular pulmonary lesions associated with thrombolytic therapy

The occurrence of solitary nodular pulmonary lesions associated with thrombolytic therapy is reported in two patients. Resolution was spontaneous in each patient. Multiple thin needle aspiration biopsies in one case revealed only red blood cells. This unusual entity should be included as one of the potential complications associated with the use of thrombolytic agents.

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.

Evaluating the medical literature, Part III: Results and discussion

This series has addressed the basic segments of a research publication and discussed critical considerations that a reader should make as he progresses through the segments. The questions listed in Figure 3 may be helpful to guide the reader through the evaluation process.

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.

Intracoronary thrombolysis in evolving myocardial infarction. Sequential angiographic analysis of left ventricular performance

Since November 1979 left ventricular angiography and coronary arteriography have been performed in 80 patients with evolving acute myocardial infarction in order to attempt coronary recanalisation by local streptokinase infusion. The average delay between the onset of symptoms and streptokinase infusion was 3.6 hours. Thrombolysis was successful in 64% of cases. No serious complications related to the procedure were noted. Of the 12 patients in cardiogenic shock, recanalisation was achieved in only four, of whom two survived. To evaluate the left ventricular salvage resulting from early recanalisation the last 58 patients had a second left ventricular angiogram and further coronary arteriograms 21 +/- 10 days later and 16 patients had a third study three months later. From the left ventricular angiogram in the right anterior oblique projection the ejection fraction and two graphic variables of regional wall motion were computed quantifying the hypokinetic zone. Patients were divided into two groups, according to the patency of the infarct related artery at the second control: group 1 consisted of 28 patients with successful recanalisation confirmed, and group 2 of 30 patients in whom no recanalisation was achieved or secondary reocclusion had occurred. At the second study the ejection fraction was unchanged in group 1 but had significantly decreased in group 2. Regional wall motion improved in group 1 and worsened in group 2, more so in patients without recanalisation than in those in whom secondary reocclusion had occurred. The third study showed a further decrease in ejection fraction in group 2. A progressive decrease in percentage residual stenosis was observed in group 1. This sequential angiographic study confirms the partial myocardial salvage resulting from early coronary recanalisation during acute myocardial infarction.

Effect of interventions in salvaging left ventricular function in acute myocardial infarction: a study of intracoronary streptokinase

The ability of intracoronary streptokinase (STK) infused early in acute myocardial infarction (MI) to salvage left ventricular (LV) function was studied in 52 patients who underwent contrast angiography immediately after STK and 6 +/- 7 weeks later. Ten nonrevascularized patients had no lysis or reocclusion. Of 42 patients with thrombolysis, 22 with optimal reperfusion underwent coronary artery bypass grafting (CABG) to prevent rethrombosis (STK + CABG group) and 20 did not (STK group). Motion was measured at 100 chords around the left ventricle and expressed in standard deviations (SD) from the normal mean. Hypokinesia was computed as the mean motion of chords in the infarct artery territory and hyperkinesia on the opposite wall was similarly computed. Hypokinesia improved greater than or equal to 1 SD/chord in 9 STK + CABG patients (41%), 8 STK patients (30%) (p = not significant versus STK + CABG) and 0 nonrevascularized patients. However, the ejection fraction did not change because it was normal in acute MI despite severe hypokinesia due to hyperkinesia on the opposite wall, and a subsequent decrease in hyperkinesia masked significant improvement in hypokinesia. It is concluded that regional wall motion must be measured to adequately assess the effect of therapeutic interventions on LV function. Early thrombolysis in acute MI results in improved LV function. The main benefit of CABG is to prevent rethrombosis.

Intracoronary thrombolysis in acute myocardial infarction

Forty-seven patients with acute myocardial infarction (MI) underwent intracoronary infusion of Thrombolysin or streptokinase. In 41, a completely reoccluded artery was reopened. Patency was associated with appearance of arrhythmias, relief of pain, gradual return of the ST-segment to the baseline and appearance of abnormal Q waves. Creatine kinase (CK) and MB-CK enzyme levels peaked earlier. Serial thallium scintigrams showed reduction in defect size after reperfusion, and the ejection fraction was higher compared with control. Eighteen patients were recommended for coronary bypass surgery for recurrent pain or severe multivessel disease.

Functional improvement of jeopardized myocardium following intracoronary streptokinase infusion in acute myocardial infarction

The effect of reperfusion on regional left ventricular performance following acute myocardial infarction in man was determined. Intracoronary streptokinase was administered in 24 patients within 6 h of the onset of symptoms. 15 patients (62%) were successfully recanalized during the initial study. Mean percent radial shortening (%RS) in both the jeopardized and compensatory regions were determined using 23 radii from the centroid of diastolic and systolic angiographic silhouettes. Sequential measurements were obtained during repeat cardiac catheterization studies at 24 h in 19 patients and before discharge from the hospital (16 +/- 11 d) in 15 patients. At the time of the predischarge study, each acutely reperfused patient showed improvement in %RS in the jeopardized region (P = 0.01) with 56% returning to the normal range. Despite the uniform improvement in the contractile function of the jeopardized region in each reperfused patient, the global ejection fraction showed no improvement or a decrease at the time of the chronic study in 44%. This was due to a decrease in the compensatory wall motion in the uninvolved segments between the acute and chronic study in each case. Neither the %RS nor the ejection fraction changed significantly at the time of the chronic study in the patients who could not be acutely recanalized. These data indicate (a) significant salvage of jeopardized myocardium associated with recovery of contractile function in patients reperfused during the first 6 h of chest pain following acute myocardial infarction; (b) no improvement in regional or global left ventricular performance in patients who could not be reperfused acutely; and (c) the ejection fraction is strongly influenced by changes in the compensatory wall motion of the uninvolved segments and does not accurately reflect changes in the contractile function of the jeopardized myocardium.

Nonsurgical reperfusion in evolving myocardial infarction

Nonsurgical recanalization of the occluded coronary artery has been performed in patients with evolving myocardial infarction since the late 1970s by intracoronary administration of thrombolytic agents at the ostium of the occluded artery or directly to the site of occlusion. The authors review the basic concepts underlying intracoronary thrombolysis, the method applied at their institution and the clinical results. Reperfusion of totally occluded arteries or termination of the ischemic state in subtotally occluded arteries was achieved in 71 (87.7%) of 81 patients. Reocclusion occurred in four patients, in three of these at a time when anticoagulation became temporarily ineffective, emphasizing the need for uninterrupted anticoagulation with a partial thromboplastin time longer than 80 seconds. Thallium scintigraphic studies before and after reperfusion showed a decrease in defect, indicating myocardial salvage, in the successful cases but not in failures or untreated control subjects. A decrease in thallium-201 defect was followed by improvement of regional wall motion and usually also left ventricular ejection fraction. Three of the patients with an unsuccessful result and one patient with a successful result died. Bypass surgery was performed electively in 18 patients because of multiple vessel involvement. Intracoronary thrombolysis appears to be a relatively safe and promising procedure. A large controlled study will be needed for definitive assessment of its role in the management of acute myocardial infarction.

Fibrinolytic effects of intracoronary streptokinase administration in patients with acute myocardial infarction and coronary insufficiency

Serial coagulation studies were obtained in 25 patients treated with intracoronary streptokinase infusion for myocardial infarction (23 patients) or coronary insufficiency (two patients) to determine the frequency of systemic fibrinolytic activity. Clotting studies were obtained before and after infusion and at 4-hour intervals until normalization. Intracoronary thrombolysis was successful in 20 of 23 patients (87%) with myocardial infarction. Streptokinase dosage in this study was 201,000 +/- 74,000 IU (+/- SD). Systemic fibrinolytic activity, defined as greater than 70% reduction of fibrinogen using a functional assay (Claus method), occurred in 22 of 25 patients (88%) and was present at a mean streptokinase dosage of 119,000 +/- 52,000 IU. Fibrinogen in the total population decreased from 342 +/- 80 to 87 +/- 94 mg% (p less than 0.0001). In patients with systemic effect, the mean fibrinogen level after infusion was 17% of baseline, increased to 43% at 24 hours, and returned to normal at 30 hours. Plasminogen decreased to 7% of baseline activity after infusion (p less than 0.0001), was 44% of baseline at 24 hours, and returned to normal at 48 hours. Intraprocedural sampling during infusion showed reduction of fibrinogen by 25% after 30,000 IU (p less than 0.0005) and by 71% at 120,000 IU (p less than 0.0001); plasminogen decreased by 50% after 30,000 IU (p less than 0.0001) and by 84% at 120,000 IU (p less than 0.0001). Prothrombin time increased from 11.5 +/- 0.8 seconds to 22.0 +/- 7.8 seconds after infusion (p less than 0.0001) and returned to normal at a mean of 18 +/- 11 hours after infusion. Partial thromboplastin time was markedly prolonged (greater than 100 seconds) after infusion, returned to less than or equal to 2 times control at 5 +/- 2 hours, and returned to normal at 9 +/- 4 hours after infusion. Fibrinogen degradation products were less than 10 micrograms/ml before infusion, increased to greater than 40 micrograms/ml after infusion, and remained greater than 40 micrograms/ml in 40% of patients at 24 hours after infusion. These data indicate that systemic fibrinolytic activity occurs in a high percentage of patients with "low-dose" intracoronary streptokinase infusion and that coagulation variables may be altered for 24-48 hours after infusion.

Systemic versus intracoronary streptokinase infusion in the treatment of acute myocardial infarction

Clinically encouraging results can be obtained with an intravenous high dose short-time infusion of streptokinase in patients with evolving myocardial infarction. The feasibility and efficacy of the intracoronary and the systemic approach of streptokinase therapy in acute myocardial infarction are discussed in this report and include topics such as infarct artery recanalization success rate, coronary thrombus lysis time, benefit for patients with subtotal coronary occlusion, reocclusion rate, the necessity of additional surgical interventions, salvage of ischemic myocardium and side effects. The value of high dose intravenous short-time streptokinase infusion needs to be assessed with properly designed clinical trials against the background afforded by the results observed with direct intracoronary streptokinase infusion.

Intravenous short-term infusion of streptokinase in acute myocardial infarction

Short-term i.v. infusion of streptokinase was performed in 93 patients within 6 hours after the onset of acute myocardial infarction. Twenty-six patients underwent angiography in the acute phase (group A) and 52 underwent angiography in the fourth week only (group B); 15 patients had no angiography. Seven patients died during the hospital stay and six suffered nonfatal reinfarctions. There were no bleeding complications. In 11 of 21 group A patients, occluded coronary arteries were opened within 1 hour after the streptokinase infusion was started. In 84% of groups A and B, the infarct-related coronary artery was patent in the fourth week. In 75% of the patent arteries, the residual luminal diameter stenosis was less than 70%. According to serial serum CK-MB curves, recanalization was achieved mostly within 1-2 hours. Myocardial salvage was indicated by improvement in local contraction disorders in the recanalized group A patients and by the significant relationship between infarct size and time from symptom onset to treatment in group B. These data suggest that a high-dose, short-term, i.v. infusion of streptokinase is a safe and efficient method of restoring coronary blood flow. Expeditious initiation of i.v. streptokinase infusion is a critical determinant for early recanalization and salvage of myocardium. Patients with thrombotically subtotal occlusion probably receive the most benefit. Evaluation of the true impact on survival and myocardial function will require controlled clinical trials.

Quantitative coronary angiography during intracoronary streptokinase in acute myocardial infarction: how long to continue thrombolytic therapy?

An intracoronary infusion of streptokinase is often administered in patients with acute myocardial infarction. To address the question of how long intracoronary streptokinase should be infused, we studied 13 patients with symptoms and electrocardiographic findings suggesting an evolving myocardial infarction. We used subselective catheterization techniques and made quantitative angiographic measurements of the percentage of reduction of coronary artery (CA) diameter before intracoronary streptokinase therapy, immediately after reperfusion was established, and at the completion of streptokinase infusion. Before intracoronary streptokinase and after intracoronary nitroglycerin, nine patients had 100% obstruction of the CA in the "infarct-related vessel." In seven patients reperfusion was established (25 +/- 21 min, mean +/- SD) at which time CA diameter was reduced by 77 +/- 22%. The streptokinase infusion was then continued until repeated films (every 10 to 15 min) suggested no further change at the site of CA obstruction (93 +/- 68 min). The percentage of CA diameter reduction when streptokinase infusion was discontinued was 55 +/- 32%; this value was less (P less than 0.05) than that observed early after reperfusion. These data show that after initial reperfusion was achieved by the use of intracoronary streptokinase, additional streptokinase lessened the reduction of CA diameter. Residual thrombus may be present at the narrowed CA site early after reperfusion, and further "cleanup" can be achieved by prolonging streptokinase infusion.