Recurrent ischemic events after successful thrombolysis in acute myocardial infarction. The Achilles' heel of thrombolytic therapy

Direct interactions of plasminogen activators with human aortic and pulmonary artery endothelial cells in vitro: implications for thrombolytic therapy

Direct interactions of plasminogen activators with arterial endothelial cells are important in the pathogenesis of vascular complications associated with thrombolytic therapy. We investigated the direct effects of various plasminogen activators on human aortic and pulmonary artery endothelial cell functions in vitro. The effects of plasminogen activators on endothelial cells were not caused by generation of plasmin, as shown by the absence of plasminogen and alpha(2)-plasmin inhibitor-plasmin complex both before and after addition of plasminogen activators to endothelial cells. High concentrations of plasminogen activators increased the permeability of aortic endothelial cells to albumin. Alteplase (50 x 10(3) IU/ml), a recombinant tissue-type plasminogen activator (t-PA), increased prostaglandin I(2) (PGI(2)) production by aortic endothelial cells from 175.5 +/- 13.8 to 870.8 +/- 131.0 pg/mg cellular protein during a 2-h incubation; other plasminogen activators increased PGI(2) production to a lesser extent. Alteplase (100 x 10(3) IU/ml) also increased PGI(2) production from 152.0 +/- 16.2 to 1,080 +/- 95.1 pg/mg cellular protein in human pulmonary artery endothelial cells. High concentrations of urokinases decreased the amount of endothelin-1 in the medium of aortic or pulmonary artery endothelial cells by as much as 93%; part of this decrease was attributable to degradation of endothelin-l by urokinases. Other plasminogen activators either had no effect on or slightly increased the production of endothelin-1. These changes in the function of human arterial endothelial cells induced by plasminogen activators may affect regional vascular tone, endothelial permeability, and platelet aggregability, all of which are important in the efficacy of thrombolysis and in the pathogenesis of such vascular complications as rethrombosis and hemorrhage.

Frequency, significance, and cost of recurrent ischemia after thrombolytic therapy for acute myocardial infarction. TAMI Study Group

Early postinfarction angina implies an unfavorable prognosis. Most published information on this outcome represents data collected in the prethrombolytic era, in which definitions and populations differed considerably. Our purpose was to evaluate the incidence and importance of recurrent ischemia after administration of thrombolytic therapy. We studied patients enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction studies. Patients were enrolled into 5 studies with similar entry criteria; 552 patients were treated with tissue plasminogen activator (t-PA), 293 were treated with urokinase, and 385 received both thrombolytic agents. Recurrent ischemia was defined as symptoms in association with electrocardiographic changes; reinfarction was defined as a reelevation of creatine kinase myocardial band isoenzyme in an appropriate clinical setting. Both recurrent ischemia and reinfarction occurred in 42 patients (3.4%), recurrent ischemia alone occurred in 226 (18%), whereas neither occurred in 964 (78%). Although baseline characteristics were similar among the 3 groups, in-hospital cardiac events (total 73 deaths, 253 heart failure episodes) were not: in-hospital mortality in patients with reinfarction was 21%; with recurrent ischemia, 11%; and with neither event, 4% (p < 0.0001). The in-hospital heart failure rate of patients with reinfarction was 50%; with recurrent ischemia alone, 31%; and with neither event, 17% (p < 0.0001). As expected, median in-hospital costs were highest in patients with reinfarction ($26,802), intermediate for those with recurrent ischemia alone ($18,422), and lowest in patients with neither event ($15,623). Recurrent myocardial ischemia after thrombolytic therapy is a frequent, important, and expensive adverse clinical outcome, making it a critical target for therapeutic intervention.

Implications of recurrent ischemia after reperfusion therapy in acute myocardial infarction: a comparison of thrombolytic therapy and primary angioplasty

OBJECTIVES

The purpose of this study was to examine the incidence and implications of recurrent ischemia after different reperfusion strategies in acute myocardial infarction.

BACKGROUND

The rates and effects of recurrent ischemia after reperfusion with thrombolytic therapy and with primary percutaneous transluminal coronary angioplasty have not been compared.

METHODS

At 12 centers 395 patients presenting within 12 h of the onset of acute myocardial infarction were prospectively randomized to receive recombinant tissue-type plasminogen activator (rt-PA) or primary coronary angioplasty. Sixteen clinical variables were examined by using univariate and multiple logistic regression analysis to identify the predictors of recurrent ischemia. The relation of recurrent ischemic events to patient outcome was analyzed.

RESULTS

Recurrent ischemia developed in 76 patients (19.2%) before hospital discharge, resulting in reinfarction in 18 patients (4.6%) and death in 5 (2.6%). Recurrent ischemia occurred in 56 patients (28.0%) after rt-PA but in only 20 patients (10.3%) after coronary angioplasty (p < 0.0001), directly contributing to a higher rate of death or reinfarction (7.5% vs. 3.1%, p = 0.05), catheterization and revascularization procedures and prolonged hospital stay after thrombolysis. By multivariate analysis, treatment with coronary angioplasty rather than rt-PA was the strongest predictor of freedom from recurrent ischemia. Although the incidence of recurrent ischemia after angioplasty and after rt-PA was similar within the 1st 2 days of admission (9.2% vs. 14.5%, p = 0.11), after hospital day 2 recurrent ischemia occurred in only 2 patients who received primary angioplasty compared with 27 patients who received rt-PA (1.1% vs. 13.5%, p < 0.0001).

CONCLUSIONS

The development of recurrent ischemia adversely affects patient outcome, increasing morbidity, mortality and resource utilization. The much lower rate of recurrent ischemia after primary coronary angioplasty than after rt-PA results in improved survival without reinfarction and allows a shorter, less complicated hospital stay. Given the extremely low rate of recurrent ischemia after hospital day 2, safe early discharge on day 3 after primary coronary angioplasty should be feasible in selected patients with acute myocardial infarction.

Culprit lesion morphology and stenosis severity in the prediction of reocclusion after coronary thrombolysis: angiographic results of the APRICOT study. Antithrombotics in the Prevention of Reocclusion in Coronary Thrombolysis

OBJECTIVES

In the APRICOT study (Antithrombotics in the Prevention of Reocclusion In Coronary Thrombolysis), we sought to determine whether angiographic characteristics of the culprit lesion could predict reocclusion after successful thrombolysis and to analyze the influence of three antithrombotic treatment regimens.

BACKGROUND

After successful thrombolysis, reocclusion is a major problem. Prediction of reocclusion by angiographic data and choice of antithrombotic treatment would be important for clinical management.

METHODS

After thrombolysis, patients were treated with intravenous heparin until initial angiography was performed within 48 h. Patients with a patent infarct-related artery were eligible. Three hundred patients were randomly selected for treatment with coumadin, aspirin (300 mg once daily) or placebo. Patency on a second angiographic study after 3 months was the primary end point of the study.

RESULTS

Reocclusion rate was 25% with aspirin, 30% with coumadin and 32% with placebo (p = NS). Lesions with > 90% stenosis reoccluded more frequently (42%) than did those with < 90% stenosis (23%) (p < 0.01). Reocclusion rate of smooth lesions was higher (34%) than that of complex lesions (23%) (p < 0.05). In lesions with < 90% stenosis, the reocclusion rate was lower with aspirin (17%) than with coumadin (25%) or placebo (30%) (p < 0.01). In complex lesions, the reocclusion rate was lower with aspirin (14%) than with coumadin (32%) or placebo (25%) (p < 0.02). Multivariate analysis showed only stenosis severity > 90% to be an independent predictor of reocclusion (odds ratio 2.31, 95% confidence interval 1.28 to 4.18, p = 0.006).

CONCLUSIONS

Angiographic features of the culprit lesion after successful coronary thrombolysis significantly predict the risk of reocclusion: high grade (> 90%) stenoses reoccluded more frequently. Aspirin was effective only in complex and less severe lesions (< 90% stenosis). These findings should prompt investigation of the effects of an aggressive approach to patients with severe residual stenosis.

Impact of tissue plasminogen activator and heparin versus heparin alone on quantitative coronary angiographic findings in myocardial infarction. The Toronto Tissue Plasminogen Activator Trial Study Group

The influence of tissue plasminogen activator (t-PA) and heparin versus heparin alone on anatomic characteristics of patent infarct-related coronary arteries and the development of these angiographic descriptors in coronary arteries that remain patent during the hospital course was examined in 108 patients who participated in a placebo-controlled trial of recombinant tissue-type plasminogen activator in acute myocardial infarction. Coronary angiography was performed 18 +/- 6 hours after treatment in 47 patients (group A) and at 10 days in 61 patients (group B). Quantitative coronary angiography of the infarct-related lesion was performed, and luminal irregularity was quantitated with an ulceration index. Of the 47 patients in group A, 7 (29%) treated with placebo had Thrombolysis in Myocardial Infarction grade 2 or 3 perfusion, whereas 18 (78%) treated with t-PA had grade 2 or 3 (p < 0.001); there was no difference between patients who had grade 2 or 3 perfusion in group B (placebo 59% vs t-PA 75%). In group A, at 10 days, the luminal area of the infarct artery had increased from 0.59 +/- 0.11 to 0.9 +/- 0.24 mm2 and from 0.75 +/- 0.16 to 1.31 +/- 0.39 mm2 for placebo- and t-PA-treated patients, respectively (p < 0.04). There was no change in the ulcerative index over time in either placebo- or t-PA-treated patients. It is concluded that early after infarction, t-PA produces marked and rapid improvement in overall patency as compared with heparin, although this difference was attenuated at 10 days because of spontaneous recanalization in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic significance of early ischemia after acute myocardial infarction in low-risk patients. IRES (Ischemia Residua) Study Group

Early postinfarction angina is generally believed to imply an unfavorable prognosis. However, most of the published information devices from data collected in the prethrombolytic era, with widely differing populations and definitions of early angina, and very little data pertinent to low-risk patients are available. This collaborative study prospectively assessed the incidence of early recurrent ischemia after thrombolysis, as well as its prognostic significance, in 453 consecutive patients aged < or = 70 years with an uncomplicated course in the first 24 hours of a first myocardial infarction participating in the second Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI-2) trial. Early recurrent ischemia (spontaneous, transient ST depression or elevation of > 1 mm and/or T-wave inversion), assessed in the coronary care unit with continuous clinical and electrocardiographic monitoring, was documented in 35 of 453 patients (8%) and was unrelated to sex, age, electrocardiographic location, Q-wave or non-Q-wave infarction, thrombolytic agent and time to its administration. In-hospital cardiac events (7 deaths, 19 nonfatal reinfarctions and 8 urgent revascularizations) occurred in 15 of 35 patients (43%) with versus 19 of 418 without (4.5%) recurrent ischemia (p < 0.001). At the 6-month follow-up of 352 medically treated patients who did not have in-hospital events, the incidence of death, reinfarction and recurrent angina was comparable between patients with (2 of 18, 11%) and without (62 of 334, 19%) early ischemia (p = NS). With use of stepwise multivariate analysis, early ischemia was the only significant predictor of in-hospital cardiac events (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Improved coronary thrombolysis by tissue-type plasminogen activator in the presence of BAY U 3405

The effect of BAY U 3405 (3 mg/kg i.v.) was tested on recombinant tissue-type plasminogen activator (rt-PA)-induced thrombolysis of an experimentally induced coronary thrombosis in anaesthetized dogs. BAY U 3405, given immediately before an rt-PA infusion, reduced time to reperfusion by more than 50% compared with vehicle-treated controls (P less than 0.01). After cessation of the rt-PA infusion, BAY U 3405 reduced the reocclusion rate compared to controls (P less than 0.05). These results show that BAY U 3405 improves rt-PA-induced coronary thrombolysis in a canine model.

Possible mechanism of vascular reocclusion after initially successful thrombolysis with recombinant tissue-type plasminogen activator

We studied the effects of urokinase (UK), pro-urokinase (pro-UK), and recombinant tissue-type plasminogen activator (rt-PA) on platelet aggregation and the production of thromboxane A2 (TXA2) in vitro. Both UK and pro-UK inhibited the platelet aggregation induced by adenosine 5'-diphosphate (ADP), collagen, or thrombin in a concentration-dependent manner. In contrast, although a low dose of rt-PA (5 to 10 x 10(4) U/ml) blunted platelet aggregability, a high dose (40 to 60 x 10(4) U/ml) led to platelet hyperaggregation. UK and pro-UK markedly inhibited TXA2 synthesis during ADP-induced platelet aggregation. Despite the significant reduction of TXA2 synthesis by 10 x 10(4) U/ml rt-PA, a concentration of 60 x 10(4) U/ml rt-PA had no effect on synthesis. These results indicate that UK and pro-UK each inhibit platelet function, but a high concentration of rt-PA enhances platelet aggregability. This finding may at least in part contribute to the high incidence of reocclusion after initially successful thrombolysis with rt-PA.

The use of intraaortic balloon pumping as an adjunct to reperfusion therapy in acute myocardial infarction. The Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) Study Group

To assess the risk and possible benefits of use of the percutaneous IABP in patients given thrombolytic therapy as treatment for acute myocardial infarction, we prospectively evaluated 810 consecutive patients entered into the TAMI trials. During hospitalization the 85 patients treated with the IABP had more cardiac risk factors, were slightly older (58 vs 56 years), and more often had anterior infarction (62% vs 38%). At acute cardiac catheterization, patients treated with the IABP also had more multivessel coronary disease (67% vs 43%), more frequent TIMI grade 0 or 1 flow (44% vs 28%), lower global ejection fraction (40% vs 52%), and worse regional infarct (-3.2 vs -2.5 SD/chord) and noninfarct (-0.67 vs +0.36 SD/chord) zone function. Although mortality rates (32% vs 4%) and in-hospital complications were greater in patients treated with the IABP, a greater improvement in global (delta ejection fraction: +1.9% vs +0.7%) and noninfarct zone (delta SD/chord: +0.11 vs -0.09) left ventricular function was observed in patients treated with the IABP at 1-week follow-up angiography. In addition, no reinfarction or reocclusion of the infarct-related artery occurred while patients were being treated with the IABP. These results suggest that the IABP may have a specific role after thrombolytic therapy in treating patients at high risk for reocclusion or at high risk for hemodynamic deterioration because of large infarction or critical stenoses in coronary vessels supplying the noninfarct zone.

Intravascular ultrasound as a guiding modality for mechanical atherectomy and laser ablation

One of the most compelling practical applications for intravascular ultrasound imaging is in enhancing the safety and efficacy of the second-generation catheter devices designed to ablate or remove plaque. Initial studies have shown that intravascular ultrasound is well suited to demonstrate the amount of atheroma present in a vessel, and the distribution within the vessel wall at any given point. Further clinical studies are required to determine whether more complete debulking of atheroma, guided by ultrasound imaging, has a favorable impact in reducing the rates of acute closure and restenosis following the procedure.