The European Cooperative Study Group trial of intravenous recombinant tissue-type plasminogen activator (rt-PA) and conservative therapy versus rt-PA and immediate coronary angioplasty.

This report describes the organization and results of the European Cooperative Study Group trial of intravenous recombinant tissue-type plasminogen activator (rt-PA) plus conservative therapy versus intravenous rt-PA plus immediate intervention (coronary angiography with a view to angioplasty) in patients with acute myocardial infarction. One hundred eighty-four patients were allocated to noninvasive treatment and 183 to an invasive/intervention policy. Immediate angioplasty was attempted in 168 patients (92%) of the latter group. The trial was terminated after a data review by the ethical monitoring committee showed no benefit in the "invasive" group in terms of enzymatic infarct size or left ventricular function, and a trend (although not statistically significant) toward increased mortality in the intervention group. Analysis of coronary patency and residual stenosis at the time of discharge showed no difference in patency rate, but less residual stenosis in the intervention group. The study differed from the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) and the Thrombolysis in Myocardial Infarction Phase-IIB (TIMI-IIB) trials in that the philosophy of intervention to produce the earliest and most complete reperfusion resulted in a high incidence of angioplasty procedures in vessels not yet reperfused. The reasons for the failure of this philosophy to show benefit are uncertain, but may include an increased risk of reocclusion after angioplasty or reperfusion damage, or both.

Thrombolysis with intravenous human recombinant tissue-type plasminogen activator in acute myocardial infarction: the European experience.

The initial studies in Europe with tissue-type plasminogen activator (rt-PA) have been coordinated by a European Cooperative Study Group. By February 1987, 258 patients had been entered into comparative coronary patency trials of rt-PA versus streptokinase and rt-PA versus placebo (trials completed and published); 123 patients had entered a coronary patency trial of prolonged rt-PA infusion versus short-term rt-PA infusion (trial completed but results not yet published); and greater than 500 patients had been recruited for left ventricular function and infarct size trials comparing rt-PA with placebo and rt-PA alone with rt-PA plus immediate coronary angioplasty (studies still in progress). The first three studies used two chain rt-PA, 0.75 mg/kg, for the rt-PA versus streptokinase and rt-PA versus placebo studies and 40 or 80 mg for the short-term versus long-term study. The current studies are using single chain rt-PA in a dose of 100 mg (20 mg bolus, 40, 20 and 20 mg in succeeding hours). Coronary patency at angiography 90 minutes after the start of treatment was 70% for rt-PA and 55% for streptokinase, 1.5 million units, in the plasminogen activator versus streptokinase study (p = 0.054), 61% for rt-PA and 21% for placebo in the rt-PA versus placebo study (p less than 0.001). In the first three studies (251 patients allocated to rt-PA) there was one case of retroperitoneal hematoma, one of hematemesis and no cases of cerebral hemorrhage; 38 patients (15%) had a hematoma or bleeding related to arterial catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between level of heparinization and patency of the infarct-related coronary artery after treatment of acute myocardial infarction with alteplase (rt-PA).

BACKGROUND AND OBJECTIVES: The conjunctive use of intravenous heparin may influence the efficacy of alteplase for coronary thrombolysis in patients with acute myocardial infarction. In this study we examined the relation between the level of intravenous anticoagulation with heparin and sustained coronary artery patency in a subgroup of patients of the European Cooperative Study Group (ECSG) trial. METHODS: In the ECSG trial, patients treated with alteplase and aspirin were randomized to concomitant fixed doses of intravenous heparin (a bolus dose of 5,000 U followed by a continuous infusion of 1,000 U/h or placebo). The current study group comprised 149 of 324 ECSG patients allocated to heparin therapy and 132 of 320 ECSG patients allocated to placebo administration who had both an interpretable coronary angiogram obtained within 6 days of treatment and sufficient plasma samples to assess the level of anticoagulation. Activated partial thromboplastin times, fibrinogen and D-dimer levels were determined on plasma samples at baseline and at 45 min and 3, 12, 24 and 36 h after the start of alteplase administration. RESULTS: The coronary artery patency rate was higher in patients allocated to heparin therapy than in those allocated to placebo (80% and 71%, respectively, p = 0.05). Patients allocated to heparin were classified into three subgroups: 48 patients (32%) with all activated partial thromboplastin times at least twice their own baseline value (optimal anticoagulation), 40 patients (27%) with the lowest activated partial thromboplastin time at 3, 12, 24 or 36 h between 130% and 200% of the baseline value (suboptimal anticoagulation) and 61 patients with at least one activated partial thromboplastin time less than 130% of baseline (inadequate anticoagulation). In the heparin group, coronary artery patency correlated with the level of anticoagulation: 90%, 80% and 72%, respectively, in patients with optimal, suboptimal and inadequate anticoagulation (p = 0.02, optimal vs. inadequate anticoagulation). Heparin administration was associated with a smaller reduction in fibrinogen and a smaller increase in D-dimer level during and after alteplase administration. No correlation was found between fibrinogen or D-dimer levels and coronary artery patency. No intracerebral hemorrhage occurred in these patients; however, bleeding was more frequent in the subgroup with optimal anticoagulation (p = 0.05). CONCLUSIONS: Intense anticoagulation with intravenous heparin enhances coronary artery patency after alteplase treatment of acute myocardial infarction.

Reasons for the lack of benefit of immediate angioplasty during recombinant tissue plasminogen activator therapy for acute myocardial infarction: a regional wall motion analysis. European Cooperative Study Group.

Regional ventricular wall motion analysis utilizing three different methods was performed on predischarge left ventriculograms from 291 of 367 patients enrolled in a randomized trial of single chain recombinant tissue-type plasminogen activator (rt-PA), aspirin and heparin with and without immediate angioplasty in patients with acute myocardial infarction. With univariate analysis, no difference in regional wall motion variables between the two treatment groups was observed. However, with individual baseline risk assessment by multivariate linear regression analysis using baseline characteristics known to be related to left ventricular function after thrombolytic therapy or outcome of coronary angioplasty, or both, an excess of high risk patients in the invasive treatment group was detected. To adjust for this unequal distribution of baseline risk, multivariate linear regression analysis was performed. No benefit of immediate coronary angioplasty was observed after adjustment. Reocclusion or reinfarction, or both, occurred more frequently in the invasive than in the noninvasive treatment group (18% versus 13%, respectively). Among patients with a patent infarct-related vessel on angiography between days 10 and 22 and without reinfarction before angiography, there was a trend toward benefit from the invasive strategy, indicating that reocclusion and reinfarction might be responsible for the lack of benefit of the invasive strategy. This implies that immediate coronary angioplasty may be beneficial in selected patients, provided that these complications can be prevented.

Increased fibrinolytic activity in the intima of atheromatous coronary arteries: protection at a price.

OBJECTIVE: The aim was to quantify and compare the fibrinolytic activity of normal blood vessels (saphenous vein, internal mammary artery, and aorta) and atheromatous arteries (coronary endarterectomy specimens). METHODS: Fibrinolytic activity was measured by fibrin plate and colorimetric assays on fresh samples of coronary endarterectomy core, internal mammary artery, human aorta, and saphenous vein from patients undergoing coronary artery bypass surgery. RESULTS: Fibrinolytic activity on fibrin plates ranked in the order endarterectomy cores > internal mammary artery > saphenous vein. The increased activity of endarterectomy cores was associated with an increased content of extractable tissue plasminogen activator and was suppressed by monoclonal antibody to tissue plasmogen activator. Paired comparisons of tissues from the same patients confirmed this increased activity in endarterectomy specimens relative to normal artery or vein. Urokinase activity was also increased in some endarterectomy specimens, but was more variable than tissue plasmogen activator. CONCLUSIONS: The increased fibrinolytic activity of endarterectomy cores may help preserve patency in atheromatous vessels, but at the possible price of increased intimal instability and fibrous proliferation.

Inhibition of vascular smooth muscle cell adhesion and migration by c7E3 Fab (abciximab): a possible mechanism for influencing restenosis.

OBJECTIVES: Brief intravenous administration of chimeric antibody c7E3 Fab during coronary angioplasty has been shown in some studies to provide long term protection against coronary events. Smooth muscle cell (SMC) adhesion and migration are key initial steps in the development of restenosis. The purpose of this study was to investigate the effect of c7E3 Fab on adhesion and migration of SMC to the extracellular matrix (ECM) proteins osteopontin (Opn) and vitronectin (Vn). METHODS: Adhesion of human vascular SMCs to ECM proteins was quantified using a CyQUANT assay kit. Migration of SMCs to Vn, Opn and PDGF was studied using a modified Boyden's chamber migration assay. Integrin expression was determined by immunoprecipitation. RESULTS: c7E3 Fab reduced SMC adhesion on Vn and Opn to 69.2+/-3.3% (P<0.001) and 52.5+/-4.8% (P<0.001) respectively, compared to adhesion without antibody present. This reduction was the same as that for anti-alpha(v)beta(3) integrin antibody LM609 (P=0.5). The combination of anti-alpha(v)beta(5) integrin antibody and c7E3 Fab had a greater effect than either antibody alone (P<0.001). c7E3 Fab reduced SMC migration to Vn and Opn to 51.6+/-8.9% (P<0.001) and 20.3+/-6.1% (P<0.001) respectively, compared to migration in the absence of antibodies. Again, similar results were seen with LM609. PDGF-induced SMC migration was also inhibited by c7E3 Fab (P=0.004) and LM609 (P=0.001), but to much less an extent. The migration SMCs from a culture found not to express the alpha(v)beta(3) integrin was unaffected by these antibodies, strengthening the argument that c7E3 Fab inhibits SMC function via this integrin. CONCLUSIONS: c7E3 Fab inhibits the adhesion and migration of SMCs via the alpha(v)beta(3) integrin. The inhibition, however, is partial, and varied depending on type of ECM protein and alpha(v)beta(3) integrin expression. Some of the clinical benefits of c7E3 Fab may be due to its effect on SMCs.

Changes in vessel wall plasminogen activator activity and smooth muscle cell proliferation and activation after arterial injury.

OBJECTIVES: The aim was to examine changes in vessel wall fibrinolytic activity following angioplasty and to assess any relationship to changes in smooth muscle cell proliferation and activation. METHODS: Balloon angioplasty was performed to the iliac arteries of New Zealand White rabbits and vessel wall changes assessed at 2 h, 1 d, 7 d, 14 d, and 1 month postprocedure. Tissue-type (tPA) and urokinase-type (uPA) plasminogen activator activity was assessed using chromogenic substrate assays, while smooth muscle cell proliferation and activation was monitored using expression of proliferating cell nuclear antigen (PCNA) and of basic fibroblast growth factor (bFGF) respectively. RESULTS: Intimal thickening progressively increased up to 1 month. uPA activity increased at 2 h [1.94(SEM 0.19) v 1.59(0.05) U.mg-1 tissue for control vessels, P = 0.03], remained increased at 24 h, but by 7 d had decreased to below control levels and remained low. In contrast, tPA activity fell significantly at 2 h [0.9(0.3) v 1.96(0.13) micrograms.mg-1 tissue for control vessels, P = 0.03], remained low at 24 h, but by 7 d had reverted back to control levels [2.19(0.39) micrograms.mg-1]. PCNA positivity of the media increased at day 1, reached maximum on day 7 [16.9(5.1)% positively staining cells] before returning to baseline by 1 month. PCNA positivity of the intima first evident at day 7 [0.7(0.3)%], reached a maximum at day 14 [4.1(0.4)%]. bFGF expression increased early at 2 h [mean(SE) positively staining cells: 15.7(5.3)% v 11.2(4.8)% for control vessels] and continued to increase, reaching a maximum in the media at day 7 [59(8.6)%] and in the intima at day 14 [57.5(5.7)%]. CONCLUSIONS: Balloon injury produced an initial fall in tPA and rise in uPA activity. tPA increased back to control levels by 7 d, while uPA fell to below control levels at 7 d and 1 month. This would be compatible with a mechanism whereby acute injury suppressed tPA and upregulated uPA activity, with increased tPA activity acting as a marker for vessel repair.

Effect of locally applied tissue-type plasminogen activator on venous fibrinolytic activity: in vitro and in vivo investigations.

OBJECTIVES: The aim was to see if topically applied tissue-type plasminogen activator (tPA) would enhance the fibrinolytic activity of saphenous vein prepared before coronary artery surgery, persist in the vessel wall after perfusion, and reduce thrombus formation after vascular injury. METHODS: Varying doses of tPA were applied to the intimal surface of the saphenous vein obtained from patients before coronary artery surgery. After flushing, biopsies were incubated on fibrin plates and areas of lysis quantified. Samples treated with tPA (1 mg.ml-1) were perfused in vitro for 30 minutes. Fibrinolytic activity was assessed on fibrin plates and tPA activity (in tissue extract) measured with chromogenic assays. The effect of locally applied tPA on thrombus formation was quantified with a rat vena cava model based on vascular injury and stasis. RESULTS: Local application of 1 mg.ml-1 tPA enhanced fibrinolysis under static conditions [median (interquartile range) of diameter of lysis.mm-1 (n = 8 both groups), treated vein 16.5 (14.1-17.9), control 8.5 (5.75-10.37) (p < 0.05)]. This enhanced activity was retained after in vitro perfusion [median (interquartile range) of areas of lysis.mm-2 (n = 8 all groups), treated vein 170.8 (132.8-205.1), control (unperfused) 69.5 (45.2-87.6), perfused (untreated) 76.7 (58.3-98.9) (p < 0.01)]. Specific tPA activity in these samples was also increased (p < 0.05). Local application of tPA (1 mg.ml-1) to damaged rat vena cava reduced subsequent thrombus formation [median thrombus weight.mg-1 (interquartile range) (n = 8), tPA treated 2.5 (0.25-5.75), control 38.5 (32-43) (p < 0.001)]. CONCLUSIONS: Locally applied tPA enhances the fibrinolytic activity of damaged vessel wall, persists after perfusion, and reduces thrombus formation after vascular injury. This method of treating conduits before their use as vascular grafts merits further study to see if it is effective in reducing early graft thrombosis while maintaining systemic haemostasis.

Effect of intraluminal application of tissue-type plasminogen activator on the fibrinolytic activity of experimental vein grafts.

OBJECTIVE: The aim was to quantify the effect of intraluminally applied tissue-type plasminogen activator (tPA) on the fibrinolytic activity of experimental vein grafts and assess the effect of pretreatment of the vein on early platelet and thrombus formation using histological techniques. METHODS: A pig model of bilateral saphenous venin-carotid artery grafts was used. In each animal one side of the neck was grafted using vein distended to 230 mm Hg and pretreated with tPA (1 mg.ml-1) for a period of 15 min before grafting (treated graft). The perfused in situ for 2 h after implantation and before analysis. Changes in local fibrinolytic activity were quantified using fibrin plate techniques and specific chromogenic assays for tPA and urokinase (uPA) in tissue extract (n = 6 animals). Histological assessment was made using light and scanning microscopy (n = 4 animals). RESULTS: Surgical preparation and distention significantly reduced the fibrinolytic activity of pig saphenous vein in terms of areas of lysis produced on fibrin plates (P < 0.05), tPA activity (P < 0.05), and uPA activity (P < 0.05). Pretreatment of distended vein with tPA before grafting significantly enhanced its fibrinolytic activity after 2 h perfusion compared to control (untreated) grafts, as assessed by areas of lysis on fibrin plates (P < 0.05) and specific tPA activity (P < 0.05). Treated grafts also showed qualitatively less platelet and thrombus formation on histological examination. CONCLUSIONS: Pretreatment of surgically harvested vein by intraluminal application of tPA before grafting enhances its fibrinolytic activity after exposure to 2 h perfusion in vivo. This technique requires further investigation to validate its potential as a means of providing local anticoagulation to veins implanted as arterial grafts thereby reducing the incidence of early graft thrombosis.

Galectin 1 is involved in vascular smooth muscle cell proliferation.

OBJECTIVE: Smooth muscle cell (SMC) migration and proliferation are the key steps in the development of atherosclerosis and restenosis. Matricellular proteins have been implicated in cell adhesion, migration and proliferation. Here we investigated the role of the matricellular protein galectin-1 (Gal-1), a beta-galactoside-binding lectin, in SMC proliferation in atheroma and DNA synthesis in cell culture. METHODS: Protein expression was visualised by tissue section immunostaining. RNA expression was analysed using Northern blot analysis. DNA synthesis of human vascular SMCs was determined by 3H-thymidine incorporation. Recombinant glutathione S-transferase-galectin-1 fusion protein (Gal FP) binding to extracellular matrix (ECM) proteins was measured by ELISA. Gal-1 binding to cells and ECM was estimated using 125I-labelled Gal FP. RESULTS: Prominent Gal-1 staining coincided with SMC proliferation in human coronary endarterectomy samples in organoid culture. In cell culture, Gal-1 mRNA was upregulated in growing SMCs. Gal FP increased serum-induced DNA synthesis of human SMCs on plastic or endogenous ECM, but not of a rat PAC1 SM cell line. Also, Gal FP slightly increased SMC adhesion to ECM. SMCs exhibited a complex pattern of receptor-ligand interactions with Gal FP. The Gal-1 binding to SMCs was much stronger than to ECM, produced by these SMCs. We identified new ECM proteins: thrombospondin, vitronectin and osteopontin, which bound to Gal FP in a dose- and beta-galactoside-dependent manner in ELISA. CONCLUSIONS: Gal-1 binding to SMCs was stronger than to ECM, although ECM of atherosclerotic blood vessels contained additional ECM proteins which bound to Gal-1. Gal-1 was upregulated during SMC growth and Gal FP enhanced serum-induced DNA synthesis in SMCs. Overall, Gal-1 upregulation is likely to provide a reinforcement of serum-induced events during vascular injury.

Effects of N-methyl hexanoylhydroxamic acid (NMHH) and myoglobin on endothelial damage by hydrogen peroxide.

OBJECTIVE: The aim was to investigate the interaction of the novel antioxidant N-methyl hexanoylhydroxamic acid (NMHH) with myoglobin in protecting endothelial cells against H2O2 mediated damage. METHODS: Cultured bovine aortic endothelial cells were exposed to 50-100 microM H2O2 for 10-60 min with and without NMHH and/or myoglobin, and immediate or delayed damage was assessed by lactate dehydrogenase release, 3H adenine uptake, a tetrazolium reduction assay, and microscopy. RESULTS: Brief exposure to low concentrations of H2O2 caused cell damage, for which the tetrazolium reduction assay was the most sensitive assay, and inhibited subsequent cell division. NMHH in concentrations from 50 to 200 microM protected against damage provided it was present at the time of adding H2O2, and the effect was markedly potentiated by 10 microM oxymyoglobin, which had little protective effect alone. CONCLUSIONS: NMHH is an effective antioxidant which is markedly potentiated by low concentrations of oxymyoglobin. Oxymyoglobin may potentiate NMHH by scavenging H2O2 through the rapid formation of ferrylmyoglobin, which is then reduced by NMHH. This synergism may be particularly relevant to the protection of myoglobin-rich cells such as myocytes.

A targeted antithrombotic conjugate with antiplatelet and fibrinolytic properties which reduces in vivo thrombus formation.

OBJECTIVE: Potent therapy that could be locally delivered to inhibit blood factor-vessel wall interaction and which would remain localised to the site of damage may avoid the side effects of systemic drugs in the treatment of disorders such as subacute thrombosis of saphenous vein grafts and intravascular stents. We therefore assessed the feasibility of developing a targeted antithrombotic conjugate by covalently cross-linking urokinase to a monoclonal antibody to platelet glycoprotein IIb/IIIa (M735) and a monoclonal antibody against damaged endothelium (P14G11). METHODS: Conjugation was carried out using N-succinimidyl-3-(2-pyridyldithio) propionate as the cross-linking reagent. The conjugate was assessed in vitro and in an in vivo model of thrombosis and local delivery. RESULTS: The conjugate formed, ATC(3), retained specificity for damaged endothelial cells and platelets and had urokinase activity of approximately 10,000 IU.mg-1 protein. Persistence of urokinase activity on binding to intact platelets and scratch damaged endothelial monolayer preparations was confirmed. Platelet aggregation studies (using ADP and collagen) revealed complete inhibition by ATC(3) at a dose of 5 micrograms.ml-1 while an unconjugated mixture of M735 (20 micrograms.ml-1), P14G11 (20 micrograms.ml-1), and urokinase (200 IU.ml-1) failed to inhibit completely platelet aggregation induced by ADP. In an in vivo model of thrombosis and vascular injury, local delivery of ATC(3) significantly reduced the weight of thrombus formed [median 13 mg (interquartile range 9-20)] compared to an unconjugated mixture of M735, P14G11 and urokinase [35 mg (28-45)] and urokinase alone [41 mg (33-55)]. CONCLUSIONS: It is possible to produce a targeted antithrombotic conjugate which retains activity of all its individual components.

In vitro evaluation of c7E3-Fab (ReoPro) eluting polymer-coated coronary stents.

OBJECTIVE: Stent thrombosis and in-stent restenosis remain problematic in certain patient sub-groups. c7E3-Fab (ReoPro, abciximab) inhibits the platelet glycoprotein IIb/IIIa receptor as well as the smooth muscle cell alpha(v)beta3 receptor, and thus may influence both processes, especially if high local concentrations could be achieved. We have studied the adsorption and elution characteristics of c7E3-Fab on commercially available polymer-coated stents. We have also investigated the effect of such antibody binding on platelet deposition in vitro, and on antibody deposition into ex vivo human saphenous vein wall to assess whether such stents may influence stent thrombosis and restenosis. METHODS AND RESULTS: Adsorption was measured using a radioisotope technique after immersing segments of polymer-coated stents in c7E3-Fab solutions. Uptake was dependent on antibody concentration and duration of immersion of wire in the solution. After 22 h (at 5 mg ml(-1)), 1146+/-101 ng cm(-1) wire was adsorbed. In an in vitro perfusion circuit, the antibody eluted slowly, with 53% remaining after 12 days washing. To determine the value that such stents might have in clinical practise, adsorption to balloon-mounted stents was assessed at room temperature, using commercially available c7E3-Fab (2 mg ml(-1)). Efficacy of eluting c7E3-Fab was determined by measuring deposition of 111-Indium platelets. Immersing stents in c7E3-Fab for 20 min inhibited platelet deposition by 82.3% compared to controls (P=0.018). Deployment of treated stents in ex vivo saphenous vein resulted in the deposition of c7E3-Fab in the intima and media. CONCLUSIONS: c7E3-Fab can be passively adsorbed onto polymer-coated stents. It elutes slowly and in a predictable manner, significantly inhibiting platelet deposition in vitro. These studies pave the way to developing stent-based delivery of a potent anti-platelet agent that may additionally affect smooth muscle cell activity.

Myoglobin protects against endothelial cell membrane damage associated with hydrogen peroxide or xanthine/xanthine oxidase.

Oxymyoglobin at 'physiological' concentrations of 20-100 micromolar protected cultured endothelial cells from damage by xanthine/xanthine oxidase or by hydrogen peroxide. Metmyoglobin also provided a degree of protection, but apomyoglobin was ineffective. Protection was enhanced in the presence of ascorbate (0.01-1 mM). Myoglobin may have a physiological role in the protection of muscular tissue from ischaemia/reperfusion-induced damage.

A new role for vascular endothelial growth factor and fibroblast growth factors: increasing endothelial resistance to oxidative stress.

Intracellular oxidative stress was measured in cultured human umbilical vein or bovine aortic endothelial cells exposed to hydrogen peroxide using an oxidation-sensitive vital dye, 2',7'-dichlorofluorescein, and flow cytometry. Vascular endothelial growth factor (VEGF), acidic fibroblast growth factor (aFGF) or basic fibroblast growth factor (bFGF) caused both a 5-10-fold increase in resistance to hydrogen peroxide induced fluorescence and an increase in intracellular reduced glutathione concentration. Increased resistance to oxidative stress mediated by growth factors is likely to be biologically relevant, and may open new avenues for therapeutic protection against oxidative stress.

Exposure to low concentrations of hydrogen peroxide causes delayed endothelial cell death and inhibits proliferation of surviving cells.

Cultured bovine aortic endothelial cells were briefly exposed to low concentrations of hydrogen peroxide (0.005 to 0.05 mmol/l). At these concentrations cells do not suffer immediate lysis, but a high proportion underwent delayed cell death over the next 24 h, with changes in nuclear morphology, the appearance of nucleosomal fragments in extracted nuclear DNA, and the appearance of numerous DNA strand breaks demonstrated by 3'OH in situ end-labelling compatible with apoptotic cell death. At the same time, there was marked inhibition of [3H]thymidine uptake, and inhibition of the incorporation of the thymidine analogue 5-bromo-2'deoxy-uridine into nuclear DNA. Cells which survived apoptosis showed inhibition of cell division on subsequent culture for up to 15 days, and there were striking morphological changes, with the formation of uninucleate or multinucleate giant cells. These effects may be relevant to the mechanisms by which brief exposure to oxidative stress causes progressive vessel wall damage.

Apolipoprotein E polymorphism does not predict risk of restenosis after coronary angioplasty.

A recent report has suggested that the E4 allele of apolipoprotein (apo) E increases the risk of restenosis after percutaneous transluminal coronary angioplasty (PTCA) and also that it interacts synergistically with the deletion (D) allele of the angiotensin-converting enzyme (ACE) to increase the risk sixteen-fold. To investigate this further, we genotyped 231 subjects with successful PTCA who underwent planned repeat angiography at 4 months to assess the degree of restenosis. Subjects carrying the apo E4 allele (n = 71) were well matched with non-carriers (n = 160) for clinical and pre- and post-PTCA angiographic features. We found no increase in either apo E4 allele frequency (18.4% versus 15.6%, P = 0.42) or apo E4 homozygosity (2/106 versus 5/125, P = 0.30) in those with restenosis compared with those without. The relative risk of restenosis for apo E4 carriers was 1.11 (95% CI = 0.87-1.42). In apo E4 carriers, restenosis frequency was similar in those also carrying the ACE D allele and those without (28/55 (50.9%) versus 9/16 (56.2%), P = 0.71) and there was no significant increase in restenosis risk in carriers of both the apo E4 and ACE D alleles compared to the rest (odds ratio 1.30, 95% CI 0.68-2.50, P = 0.39). We conclude that in our cohort, the apo E4 allele does not either independently or acting synergistically with the ACE D allele increase the risk of restenosis after PTCA, and that apo E genotyping will not be a useful predictor of risk before the procedure.

Inhibition of platelet thrombosis using an activated protein C-loaded stent: in vitro and in vivo results.

In high-risk and complicated coronary intervention, the risk of acute closure is unpredictable. Thrombus and platelet deposition at the intervention site may also have further effects on subsequent restenosis. In vivo infusion of activated protein C has previously been shown to achieve potent anticoagulation without any haemostatic side effects. We now evaluated the in vitro and in vivo efficacy of polymer-coated coronary stents loaded with purified rabbit Activated Protein C (APC). By measuring 125I-fibrinogen/fibrin deposition APC-loaded stent-wires were antithrombotic compared to albumin-loaded, inhibited-APC-loaded, plain polymer-coated and stainless steel stent-wires. In a balloon injury rabbit iliac artery model, APC-loaded stents did not occlude (0/14) compared to plain stents (9/15) and BSA-loaded stents (2/4). Relative 111In-labelled platelet deposition showed a similarly significant degree of inhibition. In conclusion, APC-loading could render stents significantly less thrombotic. Whether an effective antithrombogenic stent like this effectively reduces restenosis rates warrants further evaluation.

Need for improved treatment for unstable coronary artery disease.

There is a pressing need for improved diagnosis and treatment of unstable coronary artery disease (UCAD). The limitations of the 12-lead electrocardiogram for diagnosing the disease are outlined in this article and additional diagnostic methods are discussed. Available treatments for UCAD are reviewed, including coronary bypass surgery, coronary angioplasty, and medical therapy. Finally, the issue of optimizing healthcare resources is discussed. It is concluded that preventing atheroma from entering an unstable phase may be the most cost-effective way of managing UCAD.

Acute coronary thrombolysis with recombinant human tissue-type plasminogen activator: initial patency and influence of maintained infusion on reocclusion rate.

An intravenous infusion of 40 mg of recombinant tissue-type plasminogen activator (rt-PA) was given intravenously over 90 minutes to 123 patients with acute myocardial infarction (AMI) of less than 4 hours' duration. A coronary angiogram was recorded at the end of the infusion in 119 patients. Central assessment of the angiograms revealed a patent infarct-related artery in 78 patients (patency rate 66%, 95% confidence limits 57 to 74%). Patients with a patent infarct-related artery at the first angiogram were randomized in a double-blind manner to receive a subsequent 6-hour infusion of either 30 mg of rt-PA or placebo. All patients had received an initial bolus of 5,000 IU of heparin and then 1,000 IU/hour until a second angiogram was recorded 6 to 24 hours after the start of the second perfusion. At central assessment of the second coronary angiogram the reocclusion rate was 2 of 36 patients who received rt-PA at the second infusion and 3 of 37 patients not receiving this drug (or the 2 groups combined 7%, 95% confidence limits 2 to 15%). Three of 60 patients (5%, 95% confidence limits 1 to 14%) with patent arteries on both previous angiograms had a later occlusion as judged on the angiogram recorded at hospital discharge. No difference in late reocclusion rates between the 2 treatment groups was observed.