Six-month angiographic and clinical follow-up of patients prospectively randomized to receive either tirofiban or placebo during angioplasty in the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis

Role of Integrins in Modulating Smooth Muscle Cell Plasticity and Vascular Remodeling: From Expression to Therapeutic Implications

Smooth muscle cells (SMCs), present in the media layer of blood vessels, are crucial in maintaining vascular homeostasis. Upon vascular injury, SMCs show a high degree of plasticity, undergo a change from a “contractile” to a “synthetic” phenotype, and play an essential role in the pathophysiology of diseases including atherosclerosis and restenosis. Integrins are cell surface receptors, which are involved in cell-to-cell binding and cell-to-extracellular-matrix interactions. By binding to extracellular matrix components, integrins trigger intracellular signaling and regulate several of the SMC function, including proliferation, migration, and phenotypic switching. Although pharmacological approaches, including antibodies and synthetic peptides, have been effectively utilized to target integrins to limit atherosclerosis and restenosis, none has been commercialized yet. A clear understanding of how integrins modulate SMC biology is essential to facilitate the development of integrin-based interventions to combat atherosclerosis and restenosis. Herein, we highlight the importance of integrins in modulating functional properties of SMCs and their implications for vascular pathology.

Optimal Antiplatelet Therapy in ST-Segment Elevation Myocardial Infarction

Cardiovascular disease is the leading cause of death worldwide. Case-fatality rates for myocardial infarction (MI) in the United States have decreased over the past decades, in large part due to advances in the treatment of acute MI and secondary preventive therapy after MI. Antiplatelet therapy remains the cornerstone of treatment of MI. This article reviews the current state of antiplatelet therapy in ST-segment elevation MI.

Effect of statins on coronary blood flow after percutaneous coronary intervention in patients with stable coronary artery disease

Aims

Statins have favourable effects on the vascular system. However, few data are available regarding the effect of these drugs on patients undergoing percutaneous coronary intervention (PCI). We sought to determine the impact of prior statin use on coronary blood flow after PCI in patients with stable coronary artery disease (CAD) by using the corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC).

Methods

A total of 80 consecutive eligible patients (mean age: 60 ± 7 years, 65 % male) with the diagnosis of stable CAD who were hospitalised for elective PCI were retrospectively enrolled in our study. The study population was divided into two groups according to statin use at least 6 months before PCI. Group 1 comprised of 51 patients (67 % male; mean age: 58 ± 4 years) taking statins and group 2 comprised of 29 patients (62 % male; mean age: 60 ± 3 years) not taking statins. PCI was applied to de novo type A lesions. CTFC was calculated for the treated vessels at baseline and after PCI.

Results

The two groups had similar characteristics in terms of age, sex, concomitant medications, lesion characteristics, pre-procedural CTFC, lipid parameters, and risk factors for CAD. Post-PCI CTFC (16 ± 3 vs. 22 ± 5, p = 0.01) and hs-CRP (2.1 ± 0.7 mg/l vs. 6.1 ± 2 mg/l, p = 0.01) in patients receiving statins before PCI were significantly lower than in patients without statin therapy. Multiple logistic regression analysis showed that statin pre-treatment (OR 2.5, 95 % CI 1.2 to 3.8, p < 0.001) and hs-CRP level (OR 1.8, 95 % CI 1.2 to 2.4, p = 0.001) were independent predictors of post-PCI CTFC.

Conclusions

In patients with stable CAD undergoing PCI, receipt of long-term statin therapy was associated with improvement in epicardial perfusion after PCI.

Tirofiban in acute coronary syndromes

Acute coronary syndromes represent a major health problem in terms of incidence and mortality. Intracoronary platelet-rich thrombi may develop in response to plaque rupture, and are involved in the pathogenesis of all acute coronary syndromes. The glycoprotein IIb/IIIa receptor, a platelet surface integrin, plays a key role in platelet aggregation once it has been activated by specific ligands. The development of glycoprotein IIb/IIIa inhibitors has revolutionized the management of acute coronary syndromes. Tirofiban is one of three parenteral glycoprotein IIb/IIIa inhibitors in clinical use, and many trials have demonstrated its clinical efficacy and low rate of adverse effects in patients with non-ST-segment elevation acute coronary syndrome. This article reviews the data concerning its use in the clinical settings of acute coronary syndromes and percutaneous coronary angioplasty, and discusses its benefits in different treatment strategies and in association with other drugs. In particular, the role of early, upstream tirofiban coupled with early aggressive revascularization in the management of high-risk non-ST-segment elevation acute coronary syndromes is emphasized.

Platelet glycoprotein IIb/IIIa blockers during percutaneous coronary intervention and as the initial medical treatment of non-ST segment elevation acute coronary syndromes

BACKGROUND

During percutaneous coronary intervention (PCI), and in non-ST segment elevation acute coronary syndromes (NSTEACS), the risk of acute vessel occlusion by thrombosis is high. Glycoprotein IIb/IIIa blockers strongly inhibit platelet aggregation and may prevent mortality and myocardial infarction. This is an update of a Cochrane review first published in 2001, and previously updated in 2007 and 2010.

OBJECTIVES

To assess the efficacy and safety effects of glycoprotein IIb/IIIa blockers when administered during PCI, and as initial medical treatment in patients with NSTEACS.

SEARCH METHODS

We updated the searches of the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 12, 2012), MEDLINE (OVID, 1946 to January Week 1 2013) and EMBASE (OVID, 1947 to Week 1 2013) on 11 January 2013.

SELECTION CRITERIA

Randomised controlled trials comparing intravenous IIb/IIIa blockers with placebo or usual care.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, assessed trial quality and extracted data. We collected major bleeding as adverse effect information from the trials. We used odds ratios (OR) and 95% confidence intervals (CI) for effect measures.

MAIN RESULTS

Sixty trials involving 66,689 patients were included. During PCI (48 trials with 33,513 participants) glycoprotein IIb/IIIa blockers decreased all-cause mortality at 30 days (OR 0.79, 95% CI 0.64 to 0.97) but not at six months (OR 0.90, 95% CI 0.77 to 1.05). All-cause death or myocardial infarction was decreased both at 30 days (OR 0.66, 95% CI 0.60 to 0.72) and at six months (OR 0.75, 95% CI 0.64 to 0.86), although severe bleeding was increased (OR 1.39, 95% CI 1.21 to 1.61; absolute risk increase (ARI) 8.0 per 1000). The efficacy results were homogeneous for every endpoint according to the clinical condition of the patients, but were less marked for patients pre-treated with clopidogrel, especially in patients without acute coronary syndromes.As initial medical treatment of NSTEACS (12 trials with 33,176 participants), IIb/IIIa blockers did not decrease mortality at 30 days (OR 0.90, 95% CI 0.79 to 1.02) or at six months (OR 1.00, 95% CI 0.87 to 1.15), but slightly decreased death or myocardial infarction at 30 days (OR 0.91, 95% CI 0.85 to 0.98) and at six months (OR 0.88, 95% CI 0.81 to 0.96), although severe bleeding was increased (OR 1.29, 95% CI 1.14 to 1.45; ARI 1.4 per 1000).

AUTHORS' CONCLUSIONS

When administered during PCI, intravenous glycoprotein IIb/IIIa blockers reduce the risk of all-cause death at 30 days but not at six months, and reduce the risk of death or myocardial infarction at 30 days and at six months, at a price of an increase in the risk of severe bleeding. The efficacy effects are homogeneous but are less marked in patients pre-treated with clopidogrel where they seem to be effective only in patients with acute coronary syndromes. When administered as initial medical treatment in patients with NSTEACS, these agents do not reduce mortality although they slightly reduce the risk of death or myocardial infarction.

Platelet glycoprotein IIb/IIIa blockers during percutaneous coronary intervention and as the initial medical treatment of non-ST segment elevation acute coronary syndromes

BACKGROUND

During percutaneous coronary intervention (PCI), and in non-ST segment elevation acute coronary syndromes (NSTEACS), the risk of acute vessel occlusion by thrombosis is high. Glycoprotein IIb/IIIa blockers strongly inhibit platelet aggregation and may prevent mortality and myocardial infarction. This is an update of a Cochrane review first published in 2001, and previously updated in 2007 and 2010.

OBJECTIVES

To assess the efficacy and safety effects of glycoprotein IIb/IIIa blockers when administered during PCI, and as initial medical treatment in patients with NSTEACS.

SEARCH METHODS

We updated the searches of the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 12, 2012), MEDLINE (OVID, 1946 to January Week 1 2013) and EMBASE (OVID, 1947 to Week 1 2013) on 11 January 2013.

SELECTION CRITERIA

Randomised controlled trials comparing intravenous IIb/IIIa blockers with placebo or usual care.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, assessed trial quality and extracted data. We collected major bleeding as adverse effect information from the trials. We used odds ratios (OR) and 95% confidence intervals (CI) for effect measures.

MAIN RESULTS

Sixty trials involving 66,689 patients were included. During PCI (48 trials with 33,513 participants) glycoprotein IIb/IIIa blockers decreased all-cause mortality at 30 days (OR 0.79, 95% CI 0.64 to 0.97) but not at six months (OR 0.90, 95% CI 0.77 to 1.05). All-cause death or myocardial infarction was decreased both at 30 days (OR 0.66, 95% CI 0.60 to 0.72) and at six months (OR 0.75, 95% CI 0.64 to 0.86), although severe bleeding was increased (OR 1.39, 95% CI 1.21 to 1.61; absolute risk increase (ARI) 8.0 per 1000). The efficacy results were homogeneous for every endpoint according to the clinical condition of the patients, but were less marked for patients pre-treated with clopidogrel, especially in patients without acute coronary syndromes.As initial medical treatment of NSTEACS (12 trials with 33,176 participants), IIb/IIIa blockers did not decrease mortality at 30 days (OR 0.90, 95% CI 0.79 to 1.02) or at six months (OR 1.00, 95% CI 0.87 to 1.15), but slightly decreased death or myocardial infarction at 30 days (OR 0.91, 95% CI 0.85 to 0.98) and at six months (OR 0.88, 95% CI 0.81 to 0.96), although severe bleeding was increased (OR 1.29, 95% CI 1.14 to 1.45; ARI 1.4 per 1000).

AUTHORS' CONCLUSIONS

When administered during PCI, intravenous glycoprotein IIb/IIIa blockers reduce the risk of all-cause death at 30 days but not at six months, and reduce the risk of death or myocardial infarction at 30 days and at six months, at a price of an increase in the risk of severe bleeding. The efficacy effects are homogeneous but are less marked in patients pre-treated with clopidogrel where they seem to be effective only in patients with acute coronary syndromes. When administered as initial medical treatment in patients with NSTEACS, these agents do not reduce mortality although they slightly reduce the risk of death or myocardial infarction.

Treatment with tirofiban for acute coronary syndrome (ACS): a systematic review and network analysis

OBJECTIVE

To assess the efficacy of tirofiban in comparison to usual care or other GPIIb/IIIa antagonists (eptifibatide and abciximab). Results were analysed by drug administration with planned percutaneous coronary intervention (PCI) or as medical management without planned PCI, and separately for STEMI or NSTE ACS patients.

RESEARCH DESIGN AND METHODS

A systematic review was performed of randomized controlled trials of tirofiban, abciximab, eptifibatide or usual care given to patients with acute coronary syndrome. Nine databases were searched up to March 2010. Pair-wise meta-analysis was used to combine all available direct comparisons; indirect comparisons and network analysis were performed when this was not possible. The primary outcome was MACE (major adverse cardiac event).

RESULTS

The search yielded 8, 119 records and 50 trials were included (total number of patients = 52,958). Compared to usual care, high and medium-dose tirofiban (25 and 10 µg/kg/min) administered with planned PCI reduced MACE at 30 days for patients with STEMI (RR 0.67, 95% CI 0.45, 0.99; RR 0.28, 95% CI 0.10, 0.80), but was not effective as a medical management. Medium-dose tirofiban (10 µg/kg/min) administered with planned PCI or low dose (0.4 µg/kg/min) as medical management reduced the risk of MACE for patients with NSTE ACS (RR 0.39, 95% CI 0.21, 0.75; RR 0.58, 95% CI 0.41, 0.83) in comparison to usual care, but at the expense of increased thrombocytopenia (RR 3.26, 95% CI 1.31, 8.13). Evidence from RCTs and network analysis indicated tirofiban and abciximab were equally effective and safe. Comparing tirofiban and eptifibatide treatment by indirect and network analysis produced inconclusive results.

CONCLUSIONS

Tirofiban was more effective than usual care for STEMI and NSTE ACS patients receiving planned PCI, and NSTE ACS patients receiving medical management. Tirofiban and abciximab were equally effective. Comparisons of tirofiban and eptifibatide were inconclusive.

Platelet glycoprotein IIb/IIIa blockers during percutaneous coronary intervention and as the initial medical treatment of non-ST segment elevation acute coronary syndromes

BACKGROUND

During percutaneous coronary intervention (PCI), and in non-ST segment elevation acute coronary syndromes (NSTEACS), the risk of acute vessel occlusion by thrombosis is high. IIb/IIIa blockers strongly inhibit platelet aggregation and may prevent mortality and myocardial infarction (MI). This is an update of a Cochrane review first published in 2001, and previously updated in 2007.

OBJECTIVES

To assess the effects and safety of IIb/IIIa blockers when administered during PCI, and as initial medical treatment in patients with NSTEACS.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 3, 2009), MEDLINE (1966 to October 2009), and EMBASE (1980 to October 2009).

SELECTION CRITERIA

Randomised controlled trials comparing intravenous IIb/IIIa blockers with placebo or usual care.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion, assessed trial quality and extracted data. We collected major bleeding as adverse effect information from the trials. Odds ratios (OR) and 95% confidence intervals (CI) were used for effect measures.

MAIN RESULTS

Forty-eight trials involving 62,417 patients were included. During PCI, IIb/IIIa blockers decreased mortality at 30 days (OR 0.76, 95% CI 0.62 to 0.95) and at six months (OR 0.84, 95% CI 0.71 to 1.00). Death or MI was decreased both at 30 days (OR 0.65, 95% CI 0.60 to 0.72), and at 6 months (OR 0.70, 95% CI 0.61 to 0.81), although severe bleeding was increased (OR 1.38, 95% CI 1.20 to 1.59; absolute risk increase (ARI) 8.0 per 1000). The efficacy results were homogeneous for every endpoint according to the clinical condition of the patients, but were less marked for patients pre-treated with clopidogrel, especially in patients without ACS.As initial medical treatment of NSTEACS, IIb/IIIa blockers did not decrease mortality at 30 days (OR 0.91, 95% CI 0.80 to 1.03) or at six months (OR 1.00, 95% CI 0.87 to 1.15), but slightly decreased death or MI at 30 days (OR 0.92, 95% CI 0.86 to 0.99) and at six months (OR 0.88, 95% CI 0.81 to 0.96), although severe bleeding was increased (OR 1.27, 95% CI 1.12 to 1.43; ARI 1.4 per 1000).

AUTHORS' CONCLUSIONS

When administered during PCI, intravenous IIb/IIIa blockers reduce the risk of death and of death or MI at 30 days and at six months, at a price of an increase in the risk of severe bleeding. The efficacy effects are homogeneous but are less marked in patients pre-treated with clopidogrel where they seem to be effective only in patients with ACS. When administered as initial medical treatment in patients with NSTEACS, these agents do not reduce mortality although they slightly reduce the risk of death or MI.

Intracoronary Eptifibatide Bolus Administration During Percutaneous Coronary Revascularization for Acute Coronary Syndromes With Evaluation of Platelet Glycoprotein IIb/IIIa Receptor Occupancy and Platelet Function

Background— Eptifibatide reduces major adverse cardiac events in patients with acute coronary syndromes undergoing percutaneous coronary intervention (PCI). Intracoronary bolus administration of eptifibatide may result in higher levels of platelet glycoprotein IIb/IIIa receptor occupancy in the local coronary bed, disaggregate thrombus in the epicardial artery and microvasculature, and thereby improve coronary flow.

Methods and Results— Patients undergoing PCI for an acute coronary syndrome were randomized to either intracoronary or intravenous bolus administration of eptifibatide. The primary end point was the local glycoprotein IIb/IIIa receptor occupancy measured in the coronary sinus. There were no angiographic, electrophysiological, or other adverse findings attributable to intracoronary eptifibatide. Platelet glycoprotein IIb/IIIa receptor occupancy was significantly greater with intracoronary versus intravenous administration: first bolus, 94±9% versus 51±15% ( P <0.001); and second bolus, 99±2% versus 91±4% ( P =0.001), respectively. Microvascular perfusion was significantly improved as measured by the corrected thrombolysis in myocardial infarction frame count (cTFC) with intracoronary versus intravenous administration: pre-PCI, 36 (median) (25th and 75th percentiles, 16 and 64) versus 31 (25th and 75th percentiles, 23 and 45; P =0.8); and post-PCI, 18 (25th and 75th percentiles, 10 and 22) versus 25 (25th and 75th percentiles, 22 and 35; P =0.007), respectively. The only multivariate predictor associated with a post-PCI cTFC rank score was the first bolus glycoprotein IIb/IIIa receptor occupancy ( P <0.001).

Conclusions— Intracoronary bolus administration of eptifibatide during PCI in patients with acute coronary syndromes results in higher local platelet glycoprotein IIb/IIIa receptor occupancy, which is associated with improved microvascular perfusion demonstrated by an improved cTFC.

Coronary pressure measurement based decision making for percutaneous coronary intervention

The fractional flow reserve (FFR) is a simple, reliable, and reproducible physiologic index of lesion severity. In patients with intermediate stenosis, FFR≥0.75 can be used to safely defer percutaneous coronary intervention (PCI), and patients with FFR≥0.75 have a very low cardiac event rate. Coronary pressure measurement can determine which lesion should be treated with PCI in patients with tandem lesions, and PCI on the basis of FFR has been demonstrated to result in an acceptably low repeat PCI rate. FFR can identify patients with equivocal left main coronary artery disease who benefit from coronary bypass surgery. Coronary pressure measurement distinguishes patients with an abrupt pressure drop pattern from those with a gradual pressure drop pattern, and the former group of patients benefit from PCI. Coronary pressure measurement is clinically useful in evaluating sufficient recruitable coronary collateral blood flow for prevention of ischemia, which affects future cardiac events. FFR is useful for the prediction of restenosis after PCI. As an end-point of PCI, FFR ≥0.95 and ≥0.90 would be appropriate for coronary stenting and coronary angioplasty, respectively. In summary, if you encounter a coronary stenosis in doubt you should measure pressure rather than dilate it.

Meta-analysis of clinical efficacy and bleeding risk with intravenous glycoprotein IIb/IIIa antagonists for percutaneous coronary intervention

OBJECTIVE

Percutaneous coronary intervention (PCI) has become the most common mode of coronary revascularization. Inhibition of platelet aggregation via glycoprotein (GP) IIb/IIIa receptor blockade significantly reduces the acute ischemic complications associated with PCI, but the risk of bleeding may also be increased with these agents. The purpose of the present study was to provide an up-to-date meta-analysis on the clinical efficacy and safety of intravenous GP IIb/IIIa antagonists in patients undergoing PCI.

METHODS

A comprehensive search was undertaken to identify all randomized trials of GP IIb/IIIa antagonists versus control in patients intended to undergo PCI. Medline, Embase, Biosis, HealthStar and hand searches were performed. The primary outcome was all-cause mortality. Secondary outcomes included myocardial infarction (MI), repeat revascularization, thrombocytopenia and bleeding. OR and their 95% CI were calculated using the random effects model.

RESULTS

Twenty-one randomized trials were identified, which together included 23,941 patients. The mortality rate at seven days was 0.33% in the GP IIb/IIa group compared with 0.50% in the control group (OR 0.70, 95% CI 0.29 to 1.68); at 30 days, the mortality rate was 0.83% versus 1.21%, respectively (OR 0.72, 95% CI 0.56 to 0.94); at six months, the mortality rate was 1.92% versus 2.33%, respectively (OR 0.85, 95% CI 0.68 to 1.07); and at one year, the mortality rate was 2.61% versus 3.32%, respectively (OR 0.80, 95% CI 0.64 to 1.00). The number needed to treat at 30 days to save one life was 296. The mortality benefit appeared to dissipate by six months and was of borderline significance at one year. The incidence of MI in the treatment group compared with the control group was reduced at seven days (4.31% versus 6.97%, respectively; OR 0.59, 95% CI 0.46 to 0.75), at 30 days (4.54% versus 6.46% respectively; OR 0.63, 95% CI 0.54 to 0.74) and at six months (5.73% versus 8.29%; OR 0.65, 95% CI 0.55 to 0.77). Repeat revascularization procedures were also significantly lower in the GP IIb/IIIa group compared with the control group at seven days (2.47% versus 4.44%, respectively; OR 0.43, 95% CI 0.29 to 0.84), at 30 days (3.44% versus 5.19%, respectively; OR 0.66, 95% CI 0.56 to 0.77) and at six months (15.21% versus 17.40%, respectively; OR 0.86, 95% CI 0.78 to 0.94). Overall, the composite of death, MI and repeat revascularization was reduced at all time points. An assessment of risk revealed that the incidence of thrombocytopenia (OR 1.41, 95% CI 1.10 to 1.81) and minor bleeding (OR 1.80, 95% CI 1.47 to 2.21), but not major bleeding (OR 1.29, 95 CI 0.98 to 1.68), was significantly increased in the GP IIb/IIIa group versus the control group.

CONCLUSIONS

Treatment with GP IIb/IIIa inhibitors in the setting of PCI significantly reduces the rates of 30-day mortality, MI and repeat revascularization procedures. These beneficial effects are achieved at an increased risk of thrombocytopenia and minor bleeding, but not major bleeding.

The role of fibrinolytic system in no-reflow after stenting with and without predilation in patients with acute coronary syndromes

BACKGROUND

No-reflow developed after coronary revascularization is an independent predictor of in-hospital mortality and poor clinical outcome. In this study, we investigated the difference between direct stenting and stenting with predilation, regarding to development of no-reflow in patients with acute coronary syndromes (ACS) and the role of fibrinolytic system in that phenomenon.

METHODS

Fifty eight patients with the diagnosis of ACS in whom percutaneous coronary intervention (PCI) was applied were included in study. Patients were divided into two groups according to stent application with and without predilation. Pre- and post-intervention corrected TIMI frame counts (cTFC) were calculated. Post-PCI plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), plasminogen and D-Dimer levels were measured.

RESULTS

Pre-intervention cTFC values were similar between stenting with and without predilation groups (P > 0.05). There was a significant decrease in post-intervention cTFC values in both groups (P < 0.002 and P < 0.05, respectively). But, there was no significant difference between post-intervention cTFC values of the groups, regardless to stent implantation techniques. (P > 0.05). In patients having high cTFC values compared with having low cTFC values; PAI-1 (P = 0.002), tPA (P = 0.015), plasminogen (P = 0.040) and D-dimer (P = 0.049) levels were significantly higher. Also, significant relationship was determined between cTFC and PAI-1, tPA, plasminogen, D-dimer levels (P values 0.003, <0.05, <0.05, and <0.002, respectively).

CONCLUSIONS

Results of this study indicated an important role of increased fibrinolytic activity in development of no-reflow phenomenon after PCI. We didn't observe any differences between direct stenting and stenting with predilation according to the occurrence of no-reflow.

Rationale for intracoronary administration of abciximab

The present review aims to describe the pharmacological aspects as well as the available clinical data supporting the choice of intracoronary route of administration for abciximab, an antiplatelet drug used in patients with acute coronary syndromes undergoing percutaneous coronary interventions (PCI). Abciximab is a glycoprotein (GP) IIb/IIIa receptor antagonist which determines a potent inhibition of platelet aggregation and thrombus formation. These properties seem to prevent not only thrombus formation but also to promote (at higher drug concentration) lysis of fresh thrombus. Moreover, differently from the other GP IIb/IIIa inhibitors, abciximab also binds to the vitronectin receptor on endothelial, smooth muscle, and inflammatory cells and to an activated conformation of the aMb2 receptor on leukocytes. Such cross-reactivity raises the possibility that clinical benefits derived from its use may not be exclusively due to its anti-thrombotic effect, but may also be related to the suppression of inflammatory pathways involving platelets, white blood cells, and the vascular endothelium. On such basis, the local administration of abciximab at the site of coronary thrombosis may enhance, by increasing its local concentration, the binding to both platelet and endothelium receptors. The results of several angiographic studies assessing the effect of intracoronary abciximab administration support on clinical grounds its adoption in patients with fresh coronary thrombosis. Indeed, better post-angioplasty coronary flow, greater degree of myocardial salvage and a better left ventricular function recovery have been achieved as compared to the intravenous, systemic, administration of drug's bolus. Condensed Abstract Several studies have highlighted the benefits of abciximab, a potent antiplatelet agent, in patients with acute coronary syndromes undergoing percutaneous coronary interventions. Moreover, differently from the other glycoprotein IIb/IIIa receptor antagonists, abciximab also has non-IIb/IIIa-related properties raising the possibility that clinical benefits derived from its use may not be exclusively due to its anti-thrombotic effect, but may also be related to the suppression of inflammatory pathways. Several angiographic studies in patients with fresh coronary thrombosis and recent clinical studies in patients with acute coronary syndromes undergoing mechanical revascularization support the hypothesis that local administration of abciximab at the site of the culprit coronary artery may facilitate both the de-thrombotic and the non-GP IIb/IIIa-dependent properties of the drug. On such basis, the present review aims to describe the pharmacological aspects as well as the available clinical data supporting the choice of intracoronary route of administration for abciximab.

Antithrombotic therapy for percutaneous coronary intervention

This article outlines the antiplatelet and antithrombotic therapy used in contemporary percutaneous coronary interventions. It is a comprehensive review of past and present pharmacologic agents and includes a discussion of the more promising potential future therapies. The clinical trials that provide the basis for the current standard of care are provided, as are ongoing trials that will likely shape the future standard. This article is not intended to provide a detailed discussion of precise mechanistic or structural features of each agent but to serve as a practical clinical guide to the interventionalist when choosing specific pharmacotherapies for specific patients in the catheterization laboratory.

The drug-based pipeline against restenosis

More than 1 million percutaneous coronary interventions (PCIs) are performed yearly worldwide. Restenosis is the recurrent narrowing that can occur within 6 months following an initially successful PCI. Although drug-eluting stents have accomplished remarkable success, restenosis has not been eliminated and optimisation of both the polymers and drugs associated with them is desirable. This article reviews the presently available and potential preventive approaches against restenosis, including the sirolimus and paclitaxel drug-eluting stents.

Pharmacological treatment for prevention of restenosis

Coronary artery disease (CAD) is the leading cause of mortality and morbidity among adults in the Western world. Coronary artery bypass grafting and percutaneous coronary interventions (PCI) have gained widespread acceptance for the treatment of symptomatic CAD. There has been an explosive growth worldwide in the utilisation of PCI, such as balloon angioplasty and stenting, which now accounts for over 50% of coronary revascularisation. Despite the popularity of PCI, the problem of recurrent narrowing of the dilated artery (restenosis) continues to vex investigators. In recent years, significant advances have occurred in the understanding of restenosis. Two processes seem to contribute to restenosis: remodelling (vessel size changes) and intimal hyperplasia (vascular smooth muscle cell [VSMC] proliferation and extracellular matrix [ECM] deposition). Despite considerable efforts, pharmacological approaches to decrease restenosis have been largely unsuccessful and the only currently applied modality to reduce the restenosis rate is stenting. However, stenting only prevents remodelling and does not inhibit intimal hyperplasia. Several potential targets for inhibiting restenosis are currently under investigation including platelet activation, the coagulation cascade, VSMC proliferation and migration, and ECM synthesis. In addition, new approaches for local drug therapy, such as drug eluting stents, are currently being evaluated in preclinical and clinical studies. In this article, we critically review the current status of drugs that are being evaluated for restenosis at various stages of development (in vitro, preclinical animal models and human trials).

Local drug delivery in restenosis injury: thermoresponsive co-polymers as potential drug delivery systems

The success of percutaneous transluminal coronary angioplasty in treatment of acute coronary syndromes has been compromised by the incidence of restenosis. The physical insult of balloon insertion can damage or remove the endothelial monolayer, thereby generating a prothrombotic surface. The resulting inappropriate response to injury can also lead to penetration of inflammatory cells, conversion of the underlying media to a synthetic phenotype, deposition of extracellular matrix, constrictive remodeling, and neointimal hyperplasia. While stent implantation at the time of balloon insertion has offset some of these events, inflammatory responses to the implanted biomaterial (stent) and intimal hyperplasia are still prominent features of the procedure, leading in 20-30% of cases to in-stent restenosis within a year. Systemic delivery of drugs designed to offset in-stent restenosis injury has been largely unsuccessful, which has led to the development of strategies for coating stents with drugs for local delivery. Drug-eluting stents constitute an innovative means of further reducing the incidence of restenosis injury and clinical trials have shown encouraging results. This review focuses on properties of a class of environment-sensitive hydrogels, the N-isopropylacrylamide-based thermoresponsive co-polymers, on their potential roles as stent coatings, on their demonstrated ability to incorporate and release drugs that modify vascular endothelial and smooth muscle cell functions, and on issues that still await clarification, prior to their adoption in a clinical setting.

Improved clinical outcomes with abciximab therapy in acute myocardial infarction: a systematic overview of randomized clinical trials

BACKGROUND

Investigations of glycoprotein (GP) IIb/IIIa inhibition in primary percutaneous coronary intervention (PCI) have suggested the efficacy of abciximab in improving clinical and angiographic outcomes, but sample-size limitations and variability in trial design preclude the ability to generalize these results to a broader patient population.

METHODS

Meta-analytic techniques were used to evaluate clinical outcomes from randomized trials comparing GP IIb/IIIa inhibition with placebo or control therapy in primary PCI for acute myocardial infarction (MI).

RESULTS

In 3266 patients, treatment with abciximab significantly reduced the 30-day composite end point of death, reinfarction, or ischemic or urgent target-vessel revascularization (TVR; odds ratio [OR], 0.54; 95% CI, 0.40-0.72), with trends toward reduced 30-day death and death or reinfarction. Abciximab resulted in an increased likelihood of major bleeding (OR, 1.74; 95% CI, 1.11-2.72). By 6 months, abciximab significantly reduced the occurrence of death, reinfarction, or any TVR (OR, 0.80; 95% CI, 0.67-0.97), and there were positive trends favoring a decrease in mortality alone and the composite of death or reinfarction.

CONCLUSIONS

Treatment with abciximab significantly reduces early adverse ischemic events, a clinical benefit that is maintained at 6-month follow-up. These findings support the use of adjunctive GP IIb/IIIa inhibition in primary PCI.

Foundation and sites of action of antithrombotic agents

Thromboembolic disorders are a major cause of morbidity and mortality. As knowledge of the complex interactions between the vessel wall, platelets and coagulation and fibrinolytic enzyme systems increases, new avenues for more effective and safer therapies become evident. In this review, we discuss mechanisms of hemostasis in relation to antithrombotic agents and results of clinical trials using these drugs.

Outcomes with changes in prescribing of glycoprotein IIb/IIIa inhibitors in PCI

BACKGROUND

Glycoprotein IIb/IIIa receptor antagonists have been shown to have an impact on the outcomes of death/myocardial infarction (MI) in patients undergoing percutaneous coronary intervention. At our institution, tirofiban has largely replaced abciximab in an attempt to decrease costs.

OBJECTIVE

To assess the impact of this change on patient outcomes in the absence of head-to-head trials.

METHODS

Medical records were reviewed and telephone follow-ups were conducted on patients receiving tirofiban (n = 83) at our facility between February and November 1999. Death/MI at 30 days and 6 months after infusion were recorded. Safety and length of stay (LOS) were also assessed. These data were compared using chi2 analysis with results obtained from a previous review of abciximab use (n = 83) collected between May 1997 and November 1998.

RESULTS

There was no difference in the baseline incidence of (1) cardiovascular risk factors, (2) prior revascularization, (3) prior MI, (4) the number of vessels with atherosclerotic disease assessed by angiography, and (5) the number of vessels receiving procedures. Death/MI trended to be worse with tirofiban versus abciximab at our institution at 30 days (4.8% abciximab vs. 12% tirofiban; p = 0.163) and 6 months (6% abciximab vs. 18.1% tirofiban; p = 0.032). Bleeding and median LOS (3 d abciximab vs. 3 d tirofiban) were not different. Despite an increase in pharmacy cost, the use of abciximab provided these outcomes without an increase in total hospital cost.

CONCLUSIONS

The perceived economically driven change in medication selection from abciximab to tirofiban may not have been appropriate based on the negative trends seen in this review. To maintain optimal patient outcomes, this change should be reevaluated.

The use of adjunctive GPIIb/IIIa inhibitors in patients with unstable angina/non-Q-wave MI undergoing percutaneous coronary intervention

Glycoprotein IIb/IIIa receptor inhibitors represent a relatively new therapeutic approach in the field of antiplatelet therapy. Following the development of abciximab a number of small molecule GPIIb/IIIa inhibitors have been introduced such as tirofiban and eptifibatide. In this fast-moving field the interventional cardiologist needs a framework to guide decision-making for the individual patient. This review covers the efficacy and safety data from the clinical trials of GPIIb/IIIa inhibitors in the context of patients undergoing percutaneous coronary intervention for unstable angina/non-Q-wave myocardial infarction. There is an increasing body of evidence to support the efficacy of GPIIb/IIIa inhibitors in reducing the risk of adverse ischemic events in high and low risk patients undergoing percutaneous coronary intervention. A number of unresolved efficacy and safety issues remain, including the duration of treatment before and after intervention; whether a reduction in the heparin dose would further decrease the risk of hemorrhage without affecting the periprocedural thrombotic rate in patients undergoing PTCA with adjunctive GPIIb/IIIa inhibitors; and the cost-effectiveness of this therapy. When a thorough analysis of cost-effectiveness has been made, it will be easier to advocate the widespread use of these agents in all patients undergoing coronary intervention.

Intravenous glycoprotein IIb/IIIa receptor antagonists reduce mortality after percutaneous coronary interventions

OBJECTIVES

We sought to evaluate the impact of intravenous antagonists of the platelet IIb/IIIa receptor on the survival of patients undergoing percutaneous coronary interventions (PCIs).

BACKGROUND

Several trials have shown that intravenous antagonists of the platelet glycoprotein (GP) IIb/IIIa receptor reduce the incidence of myocardial infarction (MI) and composite cardiac outcomes (death, MI, or revascularization) in patients undergoing PCI. However, individual studies have not had adequate power to examine differences in mortality.

METHODS

We performed a meta-analysis of 19 randomized, placebo-controlled trials (20 comparisons, n = 20,137). Death was the primary outcome. Secondary outcomes included MI, composite cardiac outcomes, and major bleeding.

RESULTS

Mortality was significantly reduced at 30 days (risk ratio [RR] 0.69 [95% confidence interval [CI] 0.53 to 0.90]), at six months (RR 0.79 [95% CI 0.64 to 0.97]), and including longer follow-up (RR 0.79 [95% CI 0.66 to 0.94]), with no significant between-study heterogeneity. The relative risk reduction was largely similar in trials of patients with or without acute myocardial infarction (AMI), in trials continuing or discontinuing heparin after the procedure, and in trials using stents or another PCI as the intended primary procedure. Myocardial infarction and composite outcomes were significantly reduced (p < 0.001 for all) at 30 days and six months. Major bleeding was significantly increased only in trials where heparin infusion was continued after the procedure (RR 1.70 [95% CI 1.36 to 2.14]), although there was no excess bleeding when heparin was discontinued (RR 1.02 [95% CI 0.85 to 1.24]).

CONCLUSIONS

In patients undergoing PCI, GP IIb/IIIa receptor antagonists confer a significant and sustained decrease (20% to 30%) in the risk of death.

Correlates of coronary blood flow before and after percutaneous coronary intervention and their relationship to angiographic and clinical outcomes in the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis

BACKGROUND AND OBJECTIVES

Slower blood flow in the setting of acute myocardial infarction (MI) has been related to adverse outcomes, but the relationship of coronary blood flow after percutaneous transluminal coronary angioplasty (PTCA) in the setting of acute coronary syndromes to adverse outcomes and restenosis has not been well described. We sought to evaluate the correlates of pre- and post-PTCA coronary blood flow to shed light on potential modifiable determinants.

METHODS

The RESTORE trial (Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis) was a randomized, double-blind, placebo-controlled trial of tirofiban in patients undergoing balloon angioplasty or directional atherectomy within 72 hours of occurrence of either unstable angina pectoris or acute MI. Coronary blood flow was assessed with the corrected TIMI frame count (CTFC), and clinical outcomes were assessed at 30 days.

RESULTS

In addition to tighter and longer minimum lumen diameters (MLDs), the multivariate correlates of slower flow before PTCA also included the presence of thrombus, collaterals, left coronary artery lesion location, acute MI, and >8F catheter size. As well as the above variables, type C and D dissection grades were related to slower post-PTCA CTFC. Death, or the composite of death/MI/coronary artery bypass graft at 30 days, was more frequent among patients with slower post-PTCA CTFCs and those with post-PTCA thrombus. In a multivariate model correcting for reference segment diameter and MLD, the post-PTCA CTFC was an independent predictor of late lumen loss and the follow-up MLD at 6 months. As a single index that integrates functional and anatomical aspects of the post-PTCA results, the ratio of CTFC/MLD was associated with death/MI by 30 days.

CONCLUSIONS

In addition to MLD, variables such as the presence of thrombus, left coronary artery lesion location, and dissection grade also are associated with slower coronary blood flow after PTCA. In turn, post-PTCA CTFCs were an independent predictor of late lumen loss and follow-up MLDs. Furthermore, patients who die or who sustain other adverse cardiac events have slower coronary blood flow and greater thrombus burden after PTCA.

Impact of different platelet glycoprotein IIb/IIIa receptor inhibitors among diabetic patients undergoing percutaneous coronary intervention: : Do Tirofiban and ReoPro Give Similar Efficacy Outcomes Trial (TARGET) 1-year follow-up

BACKGROUND

The platelet glycoprotein IIb/IIIa receptor inhibitor abciximab, a monoclonal antibody, has been shown to improve early and late outcomes among diabetic patients undergoing percutaneous coronary intervention (PCI). It is unknown whether small-molecule agents confer similar benefits.

METHODS AND RESULTS

In 18 countries, 4809 patients undergoing PCI with stent implantation were randomized to tirofiban or abciximab. At the time of enrollment, patients were stratified according to diabetes status. As compared with non-diabetic patients, patients with diabetes (n=1117) showed similar 30-day ischemic outcomes, an increased incidence of any target vessel revascularization (TVR) at 6 months (10.3% versus 7.8%; P= 0.008), and a trend toward higher 1-year mortality (2.5% versus 1.6%; P=0.056). Among diabetic patients randomized to tirofiban (n=560), the incidence of death, myocardial infarction (MI), or urgent TVR at 30 days was 6.2%, and among those randomized to abciximab (n=557) it was 5.4% (hazard ratio [HR] 1.16; P=0.540). At 6 months, the composite of death, MI, or any TVR occurred in 15.7% and in 16.9% of tirofiban and abciximab patients, respectively (HR 0.93; P=0.610). Any TVR occurred in 9.5% and 11.1%, respectively (HR 0.84; P= 0.366). The 1-year mortality was 2.1% in the tirofiban group and 2.9% in the abciximab group (HR 0.74; P= 0.436).

CONCLUSIONS

Among diabetic patients undergoing PCI, tirofiban and abciximab were associated with comparable event rates, including similar rates of 6-month TVR and 1-year mortality. These findings suggest that the non-glycoprotein IIb/IIIa properties of abciximab do not translate into a discernible long-term clinical benefit among diabetic patients.

Overview of therapies for prevention of restenosis after coronary interventions

Coronary artery disease is a leading cause of morbidity and mortality in the United States and across the world. The economic impact of coronary artery disease is staggering and on the rise. Percutaneous transluminal coronary angioplasty is widely used to treat severe, symptomatic coronary stenosis. The Achilles heel of angioplasty is restenosis of those treated arteries. As a result, numerous therapies, including mechanical and pharmacological approaches, to prevent restenosis have been studied. A greater understanding of the pathophysiology of restenosis has enhanced the success of these therapeutic approaches. To date, the most important and successful approach to limit restenosis has been the use of coronary stents. Stents have reduced the rate of restenosis from approximately 50% down to 20-30%. However, in-stent restenosis presents a new and an even more challenging dilemma. The success of adjunctive drug therapy has been promising, but, as of yet, very limited. Antithrombotic agents have reduced acute thrombosis and many of the acute complications of angioplasty. New approaches and therapies are very encouraging, and provide great hope in the treatment of restenosis. Brachytherapy has shown success in the treatment of in-stent restenosis, and recently has been approved by the United States Food and Drug Administration for this indication. Drug-eluting stents using antiproliferative drugs are the most exciting new advance in preventing restenosis, currently in Phase III trials. Gene therapy, targeted drug delivery, and newer antithrombotic agents are also under investigation. We will review the pathophysiology of restenosis, animal models, pharmacological therapies, and mechanical approaches for the treatment of restenosis.

TIMI frame count immediately after primary coronary angioplasty as a predictor of functional recovery in patients with TIMI 3 reperfused acute myocardial infarction

OBJECTIVES

The purpose of this study was to evaluate whether higher coronary blood flow, estimated by the corrected Thrombolysis In Myocardial Infarction (TIMI) frame count (CTFC), is related to better functional and clinical outcome after successful percutaneous transluminal coronary angioplasty (PTCA) in patients with acute myocardial infarction (AMI).

BACKGROUND

Experimental studies have found that functional recovery of the infarcted myocardium was associated with increased blood flow (reactive hyperemia) to the infarcted bed shortly after reperfusion.

METHODS

We measured CTFC immediately after successful (TIMI 3) primary PTCA in 104 consecutive patients with their first AMI. Wall motion score index (WMSI) and the presence of pericardial effusion were assessed by two-dimensional echocardiography before and one month after PTCA.

RESULTS

The patients were divided into two groups according to mean CTFC for corresponding coronary artery of the control group: TIMI 3 slow group (45 patients, 40 > CTFC > or = 23) and TIMI 3 fast group (59 patients, CTFC < 23). There were no significant differences in the baseline characteristics and WMSI before reperfusion between the two groups. Improvement of WMSI in the TIMI 3 fast group was significantly greater than that of the TIMI 3 slow group (1.33 +/- 0.52 vs. 0.60 +/- 0.34, p < 0.001). Pericardial effusion and intractable heart failure were observed more frequently in the TIMI 3 slow group than in the TIMI 3 fast group (27 vs. 10%; p < 0.05, 36 vs. 17%; p < 0.05). Corrected TIMI frame count, assessed as a continuous variable, had a significant correlation with the change in WMSI (r = 0.60, p < 0.001) after adjusting for age, gender, history of hypertension, history of diabetes, elapsed time to PTCA, collateral grade, presence of antegrade flow before PTCA and number of diseased vessels.

CONCLUSIONS

Lower CTFC of the infarct-related artery immediately after PTCA was associated with greater functional recovery; and hence, CTFC can predict clinical and functional outcome in patients with successful PTCA.

Risk stratification in non-ST segment elevation acute coronary syndromes with special focus on recent guidelines

Patients with unstable angina or non-ST segment elevation (non-Q-wave) myocardial infarction are a heterogeneous group with respect to their risk of developing clinically significant adverse events such as subsequent myocardial infarction and death. Recent guidelines promote risk stratification of these patients, targeting high-risk patients for maximal antithrombotic and antiischemic therapy and low-risk patients for early discharge. We reviewed current and future modalities for risk stratification of patients and the predictive value of these methods in context with available pharmacologic agents. Unfortunately, most of the data identifying a particular pharmacologic regimen as beneficial in high-risk patients are retrospectively derived from large trials. Until prospective studies that use markers to guide therapy are available, clinicians should be familiar with the use of these risk markers and their application to the role of a given management strategy, including pharmacologic therapy.

Treatment of Perioperative Myocardial Ischemia

Prevention and treatment of myocardial ischemia re mains a central focus of perioperative care. Myocardial ischemia is best understood in terms of myocardial oxygen supply and demand ratios. Conventional ther apy includes nitrates, β-blockers, and calcium channel blockers. In all 3 drug classes, ischemia is reduced by either improving supply, decreasing demand, or both. More recent investigation evaluates these medications either as prophylactic therapy or as a component of long-term risk reduction for cardiac morbid events. Newer therapies, including anticoagulation, pain ther apy, normothermia, central neuroaxial techniques, and other therapies, are reviewed.

Novel platelet inhibitors

Platelet-inhibitory drugs are of proven benefit to individuals who suffer from atherosclerotic cardiovascular disease. Despite substantial effort to identify more potent platelet-inhibitory agents, aspirin, an irreversible inhibitor of platelet cyclooxygenase activity, remains the standard against which other drugs are judged. Drugs that appear to be at least as efficacious as aspirin in specific clinical settings include the thienopyridines ticlopidine and clopidogrel, specific inhibitors of ADP-stimulated platelet function, and the phosphodiesterase 3 inhibitor cilostazol. Ligand binding to the platelet integrin alphaIIbbeta3 (GPIIb-IIIa), a prerequisite for platelet thrombus formation, has been a prominent target for drug development. Currently, three types of alphaIIbbeta3 antagonists are available: the monoclonal antibody Fab fragment abciximab, cyclic peptides based on the Arg-Gly-Asp (RGD) or related amino acid motifs, and RGD-based peptidomimetics. The efficacy of each type of alphaIIbbeta3 antagonist in the setting of acute coronary artery disease has been confirmed in multicenter clinical trials.

Current approaches to therapy for vascular injury

Vascular injury is a ubiquitous phenomenon which can be both occult (such as with hyperlipidemia) and overt (such as with angioplasty). While the exact pathophysiology differs between acute and chronic atherosclerosis, both lesions can be mechanistically explained by the vasculature's exaggerated response to injury. Pharmacological attempts to treat atherosclerotic cardiovascular disease can be categorised by their role in modifying this inflammatory response. This manuscript reviews current therapy for cardiovascular injury at two levels: the chronic smouldering atheromatous lesion and intimal hyperplasia associated with acute vascular intervention. In addition, future therapeutic strategies, based within this inflammatory paradigm, are discussed.

Platelet glycoprotein IIb/IIIa receptor antagonists and coronary artery disease

The importance of platelets in coronary artery disease has been better elucidated in the past 20 years with the continued understanding of their role in the development of the atherosclerotic lesion and acute coronary syndromes. The most recent therapeutic efforts have focused on blockade of the platelet glycoprotein IIb/IIIa receptor, which represents the final common pathway to platelet aggregation and arterial thrombus formation. This manuscript summarizes platelet function and pathophysiology, currently available glycoprotein IIb/IIIa inhibitors, and the important clinical trials with this new class of drugs.

Cardiac markers protocols in a chest pain observation unit

The use of cardiac markers to identify high-risk patients in the observation unit is undeniable. As the literature reviewed here reveals, the history and ECG miss a significant portion of patients with acute cardiac ischemia. It appears that acute MI and some high-risk "unstable angina" observation unit patients can be identified within 6 hours of hospital presentation using a combination of cardiac markers. Testing these patients soon after symptom onset or on arrival in the ED for myoglobin, CK-MB subforms, or CK-MB delta appears to provide the best diagnostic usefulness. For testing later in the clinical course, CK-MB troponin I, or troponin T are of clear diagnostic and prognostic value. The markers currently used are unable to identify the significant subset of patients with "non-AMI" coronary syndromes, however. These patients require further testing with appropriate noninvasive or invasive diagnostic studies.

Platelet glycoprotein IIb/IIIa blockers for percutaneous coronary revascularization, and unstable angina and non-ST-segment elevation myocardial infarction

BACKGROUND

During percutaneous coronary revascularisation (i.e. coronary angioplasty (PTCA) with or without stent implantation), and in unstable angina/non-ST-segment elevation myocardial infarction, the risk of acute vessel occlusion by thrombosis is high in spite of treatment with aspirin and heparin. GP IIb/IIIa antagonists inhibit platelet aggregation and may prevent mortality and myocardial infarction.

OBJECTIVES

To assess the efficacy and safety of GP IIb/IIIa blockers during percutaneous coronary revascularisation, and in patients with unstable angina/non-ST-segment elevation myocardial infarction.

SEARCH STRATEGY

We searched the Cochrane Library (issue 1, 2000), MEDLINE (1966 to June 2001), EMBASE (1980 to Nov 1999), reference list of articles, medical websites and handsearch among abstracts from cardiology congresses.

SELECTION CRITERIA

Randomized controlled trials comparing intravenous GP IIb/IIIa blockers with standard medical treatment during percutaneous coronary revascularisation, and in patients with unstable angina/non-ST-segment elevation myocardial infarction.

DATA COLLECTION AND ANALYSIS

A list of titles and abstracts was screened separately by two reviewers who assessed trial quality and extracted data.

MAIN RESULTS

Percutaneous coronary revascularisation: Fourteen trials involving 17,788 patients were included. GP IIb/IIIa blockers were associated with decreased mortality at 30 days (OR 0.71 (95% CI 0.52, 0.97)) but not at 6 months (OR 0.85 (0.66, 1.11)). Mortality or infarction was decreased both at 30 days (OR 0.62 (0.55, 0.70); ARR: 31 per 1,000), and at 6 months (OR 0.65 (0.58, 0.73); ARR: 38 per 1,000)), but severe bleeding was increased (10 per 1,000; OR 1.38 (1.04, 1.85)). Unstable angina/non-ST-segment elevation myocardial infarction: Eight trials involving 30,006 patients were included. GP IIb/IIIa blockers were not associated with decreased mortality at 30 days (OR 0.90 (0.80, 1.02)) or at 6 months (OR: 1.01 (0.88, 1.16)). Mortality or infarction was decreased at 30 days (OR 0.91 (0.85, 0.98); ARR: 13 per 1,000)) and at 6 months (OR 0,88 (0.81, 0.95); ARR: 13 per 1,000)), although severe bleeding was increased (1 per 1,000; OR 1.27 (1.12, 1.44)).

REVIEWER'S CONCLUSIONS

Intravenous GP IIb/IIIa blockers reduce the risk of death at 30 days and markedly that of death or MI at 30 days and 6 months in patients submitted to percutaneous coronary revascularisation at a price of a moderate increased risk of severe bleeding. In contrast, in patients with unstable angina/non-ST-segment elevation myocardial infarction, these agents do not reduce mortality, only slightly reduce the risk of death or MI, and slightly increase the risk for severe bleeding.

Global impairment of coronary blood flow in the setting of acute coronary syndromes (a RESTORE substudy). Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis

Acute coronary syndromes result in a global impairment of coronary blood flow with nonculprit artery blood flow being associated with culprit artery flow and vice versa. Improvements in nonculprit artery flow are related to improvements in culprit artery flow after percutaneous intervention; nonculprit arteries with abnormal flow sustain greater improvements in their flow after culprit artery intervention.

The use of glycoprotein IIb/IIIa inhibitors in patients with coronary artery disease

Platelet membrane glycoprotein IIb/IIIa inhibitors, a new class of potent antiplatelet agents, have been used in the treatment of acute coronary syndromes as well as in the prevention of complications after percutaneous coronary interventions. Approximately 50,000 patients with coronary artery disease have been enrolled in randomized studies of glycoprotein IIb/IIIa inhibitors. The purpose of this article is to review the pharmacology of glycoprotein IIb/IIIa inhibitors, the results of the clinical trials using these agents, and their current use in percutaneous coronary interventions and the treatment of acute coronary syndromes.

A randomized comparison of elective high-pressure stenting with balloon angioplasty: six-month angiographic and two-year clinical follow-up. On behalf of AS (Angioplasty or Stent) trial investigators

BACKGROUND

Previous randomized trials have shown beneficial effects of coronary stenting on restenosis and event-free survival rates. However, it has not yet been fully established if routine high-pressure stenting with an antiplatelet regimen can show similar results.

METHODS

We compared the 6-month angiographic restenosis rate and 2-year event-free survival rate in 400 patients randomly assigned to stent or angioplasty. Aspirin and ticlopidine were prescribed in both groups.

RESULTS

The procedural success rate did not significantly differ between the stent and angioplasty groups (97.92% vs 97.45%, P = not significant). No stent thrombosis was found. The 6-month restenosis rate was lower in the stent group (18. 18% vs 24.87%, P =.055). At 2 years target lesion revascularization rate was 17.19% in the stent group and 25.51% in the angioplasty group (P =.02, 33% reduction). No significant differences with regard to death and myocardial infarction were observed. Event-free survival rate at 6, 12, and 24 months was 86.77% vs 78.84%, 84.13% vs 76.70%, and 83.07% vs 73.54% for stent and angioplasty groups, respectively (P =.0172).

CONCLUSIONS

The 6-month angiographic and 2-year clinical outcomes were better in patients who received stent than in those after balloon angioplasty. The difference in 2-year event-free survival rate was explained by a reduction in target lesion revascularization rate in the stent group.

Pronounced benefit of coronary stenting and adjunctive platelet glycoprotein IIb/IIIa inhibition in complex atherosclerotic lesions

BACKGROUND

Previous trials testing stents compared with balloon angioplasty excluded patients with complex lesions and did not assess the effect of adjunctive platelet IIb/IIIa inhibition. This analysis sought to assess the effect of stenting and abciximab specifically for patients with complex lesions.

METHODS AND RESULTS

Patients with complex lesions (long, tandem, severely calcified, restenotic, thrombotic, or ostial; total occlusions; bifurcations; saphenous vein grafts; and multivessel interventions) from the Evaluation of PTCA to Improve Long-Term Outcome by c7E3 GP IIb/IIIa Receptor Blockade (EPILOG) and the Evaluation of Platelet IIb/IIIa Inhibitor for Stenting (EPISTENT) trials were included in the analysis. The 1-year combined death or myocardial infarction rates in the 4 treatment groups were as follows: balloon angioplasty/placebo, 14.2%; stent/placebo, 15.8%; balloon angioplasty/abciximab, 7.6%; and stent/abciximab, 8.0% (P<0.001). Death rates were 3.2%, 3.1%, 2.1%, and 0.5%, respectively (P=0.03). The incidence of target vessel revascularization at 1 year was 30.5%, 18.0%, 24.4%, and 19.7% in the 4 groups, respectively (P<0.001). After adjustment for baseline differences, multivariate analysis demonstrated that the rate of death or myocardial infarction was independently reduced by balloon angioplasty/abciximab (hazard ratio, 0.51; P<0.001) and stent/abciximab (hazard ratio, 0.60; P=0.02) but was not affected by the use of stents alone. Conversely, target vessel revascularization was reduced by stent/placebo (hazard ratio, 0.53; P<0.001), stent/abciximab (hazard ratio, 0.58; P<0.001), and balloon angioplasty/abciximab (hazard ratio, 0.74; P=0.006) compared with balloon angioplasty/placebo, respectively.

CONCLUSIONS

The combination of stenting and abciximab during percutaneous coronary interventions for patients with angiographically complex lesions confers additive long-term benefit with respect to death, myocardial infarction, and target vessel revascularization.

IIb's are not IIb's

Platelet glycoprotein (GP) IIb/IIIa receptor blockade improves clinical outcomes after percutaneous coronary intervention (PCI) and for patients who present with non-ST-segment elevation acute coronary syndromes. Although this class of therapeutic agents has been defined by a common affinity for the platelet GP IIb/IIIa receptor, the 3 currently available agents differ markedly in pharmacodynamic and pharmacokinetic profile as well as receptor affinity. Differential (separate) binding sites on the GP IIb/IIIa receptor explain the observation that abciximab binding to platelets is not influenced by either tirofiban or eptifibatide. Abciximab (ReoPro, chimeric 7E3 Fab) is a low K(d) (high affinity) agent with a very short plasma t(1/2) and a prolonged duration of action at the platelet target receptor. Eptifibatide and tirofiban are high K(d) (low affinity) agents with a relatively long plasma t(1/2) and short duration of action at the platelet target receptor. These pharmacodynamic differences underlie the phenomena of gradual redistribution in abciximab binding and smooth tapering of abciximab antiplatelet effect after discontinuation of therapy. Furthermore, abciximab demonstrates affinity for both the CD11b/18 (alpha(m)beta(2) or MAC 1) and alpha(V)beta(3) (vitronectin) receptors. Although a survival advantage in favor of abciximab has been observed after PCI in both randomized controlled trials and high-volume clinical practice, no survival benefit has been observed to date after eptifibatide or tirofiban therapy for PCI. The mechanism of survival advantage after abciximab therapy has not been defined but may be distinct from the degree of platelet GP IIb/IIIa receptor inhibition during the duration of intravenous treatment. Although this important new "class" of therapeutic agent was simplistically defined by a common affinity for the GP IIb/IIIa receptor, this solitary unifying attribute may not define agent-specific benefit.

Platelet glycoprotein IIb/IIIa receptor blockade in coronary artery disease

New strategies for profound inhibition of platelet activity at the injured coronary plaque focus on blockade of the platelet surface membrane glycoprotein IIb/IIIa receptor, which binds circulating fibrinogen or von Willebrand factor and crosslinks platelets as the final common pathway to platelet aggregation. Intravenous agents directed against this receptor include the chimeric monoclonal antibody fragment abciximab, the peptide inhibitor eptifibatide and nonpeptide mimetics tirofiban and lamifiban. Over 33,000 patients have been evaluated in 11 large-scale, placebo-controlled trials of these agents. During percutaneous coronary intervention, an absolute reduction of 1.5% to 6.5% in the 30-day risk of death, myocardial infarction or repeat urgent revascularization has been observed, with some variability in treatment effect among the agents tested (abciximab, eptifibatide and tirofiban). Treatment effect is achieved early with every modality of revascularization and is maintained over the long-term (up to three years). Increased bleeding risk may be minimized by reduction and weight-adjustment of concomitant heparin dosing. In the acute coronary syndromes without ST segment elevation, absolute 1.5% to 3.2% reductions in 30-day rates of death or myocardial (re-) infarction have been achieved with two to four day courses of eptifibatide or tirofiban. Clinical benefit accrues during the period of drug infusion and is durable. Treatment effect may be enhanced among patients undergoing early coronary revascularization, with evidence of stabilization before intervention and suppression of postprocedural ischemic events. Thus, blockade of the platelet glycoprotein IIb/IIIa receptor reduces ischemic complications when used as an adjunct to percutaneous coronary intervention or the management of acute ischemic syndromes.

Prediction of restenosis after coronary angioplasty by use of a new index: TIMI frame count/minimal luminal diameter ratio

BACKGROUND

It has been shown recently that postangioplasty coronary flow reserve and the degree of residual stenosis have a modest predictive value for short- and long-term clinical outcomes after coronary angioplasty. Corrected TIMI frame count (CTFC) is a simple quantitative index of coronary blood flow. Its relationship with Doppler coronary flow velocity and clinical outcome after coronary angioplasty has not been fully clarified. The aim of this study was to identify clinical, angiographic, and functional predictors of clinical and angiographic restenosis after conventional coronary angioplasty.

METHODS AND RESULTS

We studied 70 consecutive patients in whom intracoronary Doppler flow-velocity measurements were performed before and after angioplasty. Patients were evaluated for restenosis by clinical follow-up, exercise stress test/(201)Tl scintigraphy, and follow-up angiography, which was performed at 10. 5+/-10.3 months in 63 patients. According to the results of univariate analysis, a new index, postangioplasty CTFC/minimal luminal diameter (MLD) ratio, was created. Multivariate analysis revealed that CTFC/MLD ratio was the only independent predictor of angiographic (OR 2.02; 95% CI 1.37 to 2.97; P<0.0004) and clinical (OR 1.60; 95% CI 1.15 to 2.21; P<0.005) restenosis. The receiver operating characteristic curve area of this index was 79% for angiographic and 73% for clinical restenosis. The optimal CTFC/MLD ratio cutoff values were 7.88 for angiographic and 7.94 for clinical restenosis, respectively.

CONCLUSIONS

Our data indicate that postangioplasty CTFC/MLD ratio, which incorporates both the angiographic and functional features of coronary lesions, is a reliable, objective, and inexpensive index for prediction of angiographic and clinical restenosis after conventional coronary angioplasty.