Outcomes at 6 months for the direct comparison of tirofiban and abciximab during percutaneous coronary revascularisation with stent placement: the TARGET follow-up study

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet agents may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the benefits and harms of antiplatelet agents in people with any form of CKD, including those with CKD not receiving renal replacement therapy, patients receiving any form of dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 13 July 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet agents versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data were pooled using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 113 studies, enrolling 51,959 participants; 90 studies (40,597 CKD participants) compared an antiplatelet agent with placebo or no treatment, and 29 studies (11,805 CKD participants) directly compared one antiplatelet agent with another. Fifty-six new studies were added to this 2021 update. Seven studies originally excluded from the 2013 review were included, although they had a follow-up lower than two months. Random sequence generation and allocation concealment were at low risk of bias in 16 and 22 studies, respectively. Sixty-four studies reported low-risk methods for blinding of participants and investigators; outcome assessment was blinded in 41 studies. Forty-one studies were at low risk of attrition bias, 50 studies were at low risk of selective reporting bias, and 57 studies were at low risk of other potential sources of bias. Compared to placebo or no treatment, antiplatelet agents probably reduces myocardial infarction (18 studies, 15,289 participants: RR 0.88, 95% CI 0.79 to 0.99, I² = 0%; moderate certainty). Antiplatelet agents has uncertain effects on fatal or nonfatal stroke (12 studies, 10.382 participants: RR 1.01, 95% CI 0.64 to 1.59, I² = 37%; very low certainty) and may have little or no effect on death from any cause (35 studies, 18,241 participants: RR 0.94, 95 % CI 0.84 to 1.06, I² = 14%; low certainty). Antiplatelet therapy probably increases major bleeding in people with CKD and those treated with haemodialysis (HD) (29 studies, 16,194 participants: RR 1.35, 95% CI 1.10 to 1.65, I² = 12%; moderate certainty). In addition, antiplatelet therapy may increase minor bleeding in people with CKD and those treated with HD (21 studies, 13,218 participants: RR 1.55, 95% CI 1.27 to 1.90, I² = 58%; low certainty). Antiplatelet treatment may reduce early dialysis vascular access thrombosis (8 studies, 1525 participants) RR 0.52, 95% CI 0.38 to 0.70; low certainty). Antiplatelet agents may reduce doubling of serum creatinine in CKD (3 studies, 217 participants: RR 0.39, 95% CI 0.17 to 0.86, I² = 8%; low certainty). The treatment effects of antiplatelet agents on stroke, cardiovascular death, kidney failure, kidney transplant graft loss, transplant rejection, creatinine clearance, proteinuria, dialysis access failure, loss of primary unassisted patency, failure to attain suitability for dialysis, need of intervention and cardiovascular hospitalisation were uncertain. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, including prasugrel, ticagrelor, different doses of clopidogrel, abciximab, defibrotide, sarpogrelate and beraprost.

AUTHORS' CONCLUSIONS

Antiplatelet agents probably reduced myocardial infarction and increased major bleeding, but do not appear to reduce all-cause and cardiovascular death among people with CKD and those treated with dialysis. The treatment effects of antiplatelet agents compared with each other are uncertain.

GPIIb/IIIa inhibitors: From bench to bedside and back to bench again

From the discovery of the platelet glycoprotein (GP) IIb/IIIa and identification of its central role in haemostasis, the integrin GPIIb/IIIa (αIIbβ3, CD41/CD61) was destined to be an anti-thrombotic target. The subsequent successful development of intravenous ligand-mimetic inhibitors occurred during a time of limited understanding of integrin physiology. Although efficient inhibitors of ligand binding, they also mimic ligand function. In the case of GPIIb/IIIa inhibitors, despite strongly inhibiting platelet aggregation, paradoxical fibrinogen binding and platelet activation can occur. The quick progression to development of small-molecule orally available inhibitors meant that this approach inherited many potential flaws, which together with a short half-life resulted in an increase in mortality and a halt to the numerous pharmaceutical development programs. Limited clinical benefits, together with the success of other anti-thrombotic drugs, in particular P2Y12 ADP receptor blockers, have also led to a restrictive use of intravenous GPIIb/ IIIa inhibitors. However, with a greater understanding of this key platelet-specific integrin, GPIIb/IIIa remains a potentially attractive target and future drug developments will be better informed by the lessons learnt from taking the current inhibitors back to the bench. This overview will review the physiology behind the inherent problems of a ligand-based integrin inhibitor design and discuss novel promising approaches for GPIIb/IIIa inhibition.

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.

A comparative study of restenosis rates in bare metal and drug-eluting stents

BACKGROUND

Various studies have been performed throughout the world on the rate of restenosis using bare metal stents (BMS) and drug-eluting stents (DES). The prohibitive costs associated with DES generally dictate the type of stent used, especially in developing countries. Therefore, there was a need for a study to assess the effect of various risk factors on restenosis in BMS and DES in the Indian context. A study was performed in the premier institution of the Indian Armed Forces, the Army Hospital (Research and Referral), New Delhi, India, under the aegis of the Indian Council of Medical Research (New Delhi). The profile of patients in the armed forces is inherently diverse in terms of demography, ethnicity, genetics, etc, which reflects the diverse and varied nature of the population in India.

METHODS AND RESULTS

A total of 130 patients were included in the present study. Follow-up after stent implantation was scheduled for six to nine months following the procedure to assess symptoms, drug compliance, and treadmill test and coronary angiography results, and to ascertain the incidence of restenosis. However, only 80 patients returned for follow-up and, therefore, the final analysis was based on these patients. They were segregated into BMS (n=41) and DES (n=39) groups. Restenosis occurred in 29 patients (36.3%). Nine of 39 patients with DES (23.1%) and 20 of 41 patients with BMS (48.8%) developed restenosis. There was a statistically significant relationship between restenosis and female sex, clinical presentation before intervention and at the time of follow-up evaluation (unstable angina), hypertension, positive stress test and compliance with medical therapy (P<0.05). No statistically significant relationship was observed between restenosis and age, diabetes, smoking, obesity and diet (P>0.05).

CONCLUSIONS

DES appear to reduce the restenosis rate and clinical end points, and appear to be more cost effective than BMS. Patient-related factors (eg, sex, hypertension and unstable angina) are important variables that affect the restenosis rate. Noninvasive stress testing had high positive and negative predictive values. Therefore, based on the present study, noninvasive stress testing is suggested before routine angiography at follow-up, which will reduce the need for repeat coronary angiography.

Antiplatelet drugs: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

The article describes the mechanisms of action, pharmacokinetics, and pharmacodynamics of aspirin, dipyridamole, cilostazol, the thienopyridines, and the glycoprotein IIb/IIIa antagonists. The relationships among dose, efficacy, and safety are discussed along with a mechanistic overview of results of randomized clinical trials. The article does not provide specific management recommendations but highlights important practical aspects of antiplatelet therapy, including optimal dosing, the variable balance between benefits and risks when antiplatelet therapies are used alone or in combination with other antiplatelet drugs in different clinical settings, and the implications of persistently high platelet reactivity despite such treatment.

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.

The Role of Glycoprotein IIb/IIIa Inhibitors- A Promise Not Kept?

For over one decade Glycoproteins IIb/IIIa inhibitors (GPI) have been administered to prevent coronary artery thrombosis. Initially these agents were used for acute coronary syndromes and subsequently as adjunctive pharmacotherapy for percutaneous coronary interventions (PCIs).

Most benefit of GPI emerged from reduction of ischemic events: mostly non-q-wave myocardial infarctions (NQWMIs) during PCI. However, individual randomized clinical trials could not demonstrate that any of these agents could significantly reduce mortality in any clinical subset of patients. Studies of employing prolonged oral GPI administration resulted in excessive death. The non-homogenous statistically-significant reduction of ischemic endpoints was accompanied by an excess of bleeding, vascular complications, and thrombocytopenia. The clinical and ecomomic burden of major bleeding and thrombocytopenia is substantial. The ACUITY trial has initiate a new debate regarding the efficacy and safety of GPI.

Selective “patient-tailored” use of GPI limited to moderate-high risk PCI patients with low bleeding propensity is suggested. Research of new algorithms emphasizing abbreviated GPI administration, careful access site and bleeding surveillance, in conjunction with lower doses of unfractionated heparin or new and safer anti-thrombins may further enhance patient safety.

New antiplatelet drugs: beyond aspirin and clopidogrel

Antiplatelet therapy remains a cornerstone of modern management of atherothrombotic vascular disease. For many years, aspirin has been the mainstay of initial antiplatelet drug management in coronary heart disease, while the need for inhibition of other platelet activation pathways has led to the development of various other antiplatelet drugs, such as clopidogrel. An improved understanding of the underlying mechanisms involved in thrombogenesis has paved the way for further development of newer antiplatelet drug therapies. Various clinical studies have probed the effectiveness and risk profile of the newer antiplatelet drugs, such as prasugrel, in comparison with currently available drugs. Some newer agents such as prasugrel are close to being approved for clinical use, whereas other agents such as cangrelor and AZD6140 are in phase 3 clinical trials. New drug classes, such as the thromboxane receptor antagonists (such as NCX-4016 and S18886), as well as platelet adhesion antagonists and thrombin receptor antagonists are similarly being evaluated for their efficacy and risk profile in phase I and II trials.

Antiplatelet drugs: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article about currently available antiplatelet drugs is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). It describes the mechanism of action, pharmacokinetics, and pharmacodynamics of aspirin, reversible cyclooxygenase inhibitors, thienopyridines, and integrin alphaIIbbeta3 receptor antagonists. The relationships among dose, efficacy, and safety are thoroughly discussed, with a mechanistic overview of randomized clinical trials. The article does not provide specific management recommendations; however, it does highlight important practical aspects related to antiplatelet therapy, including the optimal dose of aspirin, the variable balance of benefits and hazards in different clinical settings, and the issue of interindividual variability in response to antiplatelet drugs.

Implementing Consultant Recommendations in Percutaneous Coronary Interventions: Look before you Leap

Purpose

To determine if hospital consultant recommendations were clinically applicable to the cardiac catheterization laboratory and to compare medication usage in percutaneous coronary intervention (PCI) to those goals.

Methods

The medical records of 96 adults on whom PCI had been performed over a 6-month period were reviewed retrospectively. Only PCIs that included intracoronary stent placement were considered. The primary end point was to determine if abciximab usage was 15% or less in all PCI cases. Secondary end points evaluated the use of abciximab, eptifibatide, and bivalirudin based on the acuity of the clinical syndrome.

Results

Abciximab, eptifibatide, and bivalirudin monotherapy were used in 16.7%, 40.6%, and 42.7% of all cases, respectively. The total consumption of abciximab exceeded the primary end point by 1.7%. Eptifibatide usage was 71% of all glycoprotein (GP) IIb/IIIa inhibitors, less than the 85% target proposed by the hospital consultants. Bivalirudin monotherapy surpassed eptifibatide as the antithrombotic of choice across all PCI cases. The use of provisional GP IIb/IIIa inhibitors in conjunction with bivalirudin was 8.3%, more than the 5% target specified by the consultants. Emergent PCIs comprised 41% of all cases sampled.

Conclusion

This 6-month retrospective survey demonstrated that the use of abciximab exceeded the percentage recommended by consultants. However, given the large percentage of emergent PCIs during the time period and the literature supporting the use of abciximab in emergent PCIs, a change in GP IIb/IIIa inhibitor usage patterns was not considered necessary.

Glycoprotein IIb/IIIa inhibitors: questioning indications and treatment algorithms

Glycoprotein inhibitors (GPI) are viewed as beneficial adjunctive pharmacotherapy agents for percutaneous coronary interventions (PCIs). The major benefit of GPI is derived from the reduction of ischemic events (mostly non-Q-wave myocardial infarctions) during PCI. There is no single randomized clinical trial demonstrating that any of these agents significantly reduces mortality in any clinical subset of patients. Studies of sustained oral GPI resulted in excessive death and myocardial infarctions. Reduction of ischemic end points was counteracted by excessive bleeding, vascular complications, and thrombocytopenia. These complications bear considerable medical and economic impact. The Acute Catheterization and Early Intervention Triage Strategy trial demonstrated that GPI, when added to heparin, enoxaparine, or bivalirudin, do not reduce mortality or ischemic events but significantly increase bleeding complications. Major bleeding resulted in threefold mortality at 1 year. In view of available data, the use of GPI should be limited to moderate-risk to high-risk PCI patients with low bleeding propensity. Protocols of abbreviated GPI administration and careful bleeding surveillance, in conjunction with lower doses of unfractionated heparin or new and possibly safer antithrombins, can potentially improve patient safety.

Pharmacological antithrombotic adjuncts to percutaneous coronary intervention

Stent thrombosis is the major cause of early adverse events during percutaneous coronary intervention. Its incidence has fallen considerably in recent years, principally due to the introduction of effective antithrombotic therapies. The selection of an appropriate antithrombotic regimen is critical in achieving a balance between reducing ischaemic events and minimising bleeding complications in patients undergoing percutaneous coronary intervention. In this article, evidence for the role of antiplatelet and anticoagulant therapies is discussed, including the thienopyridines, glycoprotein IIb/IIIa receptor antagonists, direct thrombin inhibitors and pentasaccharides.

Newer Pharmacotherapy in Patients Undergoing Percutaneous Coronary Interventions: A Guide for Pharmacists and Other Health Care Professionals

Significant advances in pharmacotherapy for patients undergoing percutaneous coronary intervention (PCI) have occurred during the past decade, including the introduction and approval of new antithrombin and antiplatelet therapies, as well as modifications in dosing, administration, and/or duration of older pharmacotherapy regimens. Also, off-label (i.e., not approved by the United States Food and Drug Administration) use of certain agents has become common. Given the novel nature of these agents and the nuances of therapy, the pharmacist and other health care professionals should play an integral role in collaboration with interventional cardiologists in development of hospital protocols, determination of appropriate agent selection, assessment of patient renal function and hematologic status, dosing, and monitoring for adverse effects. In this guide, the newer antiplatelet and antithrombin drugs that may be used during PCI are reviewed, and recommendations regarding the proper administration of these agents are provided.

Outcome of multivessel coronary intervention in the contemporary percutaneous revascularization era

Clinical outcomes after multivessel versus single-vessel percutaneous coronary intervention (PCI) in the era of stents, glycoprotein IIb/IIIa inhibitors, and clopidogrel pretreatment have not been well studied. Thus, we compared outcomes from the Do Tirofiban and ReoPro Give Similar Efficacy Outcome Trial (TARGET) for patients who underwent multivessel versus single-vessel PCI and separately considered the effect of acute coronary syndromes on the results. Composite clinical outcomes (death, myocardial infarction, and target vessel revascularization) were evaluated at 30 days and 6 months and mortality at 1 year. Safety analysis included in-patient major and minor bleeding. Despite similar baseline characteristics, patients who underwent multivessel PCI (n = 775) had significantly higher 30-day and 6-month composite event rates than did those who were treated in a single coronary artery territory (n = 3,969). This association remained significant at 30 days (hazard ratio 1.57, 95% confidence interval 1.06 to 2.33, p = 0.025) after using propensity matching to minimize confounding factors. The higher event rate was primarily due to an increase in periprocedural myocardial infarction. However, there were no significant differences in propensity-matched ischemic outcomes at 6 months and 1 year or in bleeding. In addition, in a propensity-matched analysis that included 810 patients with acute coronary syndrome, multivessel stenting resulted in numerically more ischemic events than did single-vessel stenting, although this did not reach statistical significance (hazard ratio 1.32, 95% confidence interval 0.85 to 2.05, p = 0.221). In conclusion, multivessel PCI was more often associated with periprocedural myocardial infarction than single-vessel intervention, although this did not translate into higher 1-year mortality. A randomized trial comparing multivessel PCI with staged or surgical revascularization is warranted.

Percutaneous coronary intervention: recommendations for good practice and training

Cardiologists undertaking percutaneous coronary intervention (PCI) are excited by the combination of patient and physician satisfaction and technological advance occurring on the background of the necessary manual dexterity. Progress and applicability of percutaneous techniques since their inception in 1977 have been remarkable; a sound evidence base coupled with the enthusiasm and ingenuity of the medical device industry has resulted in a sea change in the treatment of coronary heart disease (CHD), which continues to evolve at breakneck speed. This is the third set of guidelines produced by the British Cardiovascular Intervention Society and the British Cardiac Society. Following the last set of guidelines published in 2000, we have seen PCI activity in the UK increase from 33,652 to 62,780 (87% in four years) such that the PCI to coronary artery bypass grafting ratio has increased to 2.5:1. The impact of drug eluting stents has been profound, and the Department of Health is investigating the feasibility of primary PCI for acute myocardial infarction. Nevertheless, the changes in the structure of National Health Service funding are likely to focus our attention on cost effective treatments and will require physician engagement and sensitive handling if we are to continue the rapid and appropriate growth in our chosen field. It is important with this burgeoning development now occurring on a broad front (in both regional centres and district general hospitals) that we maintain our vigilance on audit and outcome measures so that standards are maintained for both operators and institutions alike. This set of guidelines includes new sections on training, informed consent, and a core evidence base, which we hope you will find useful and informative.

Drug-Eluting Coronary Stents

The introduction and widespread use of coronary stents have been the most important advancement in the percutaneous treatment of coronary artery disease since the introduction of balloon angioplasty. Coronary artery stents reduce the rate of angiographic and clinical restenosis compared to balloon angioplasty. This angiographic restenosis was further reduced with the introduction of drug-eluting stents and hence further reduction in the frequency of major adverse cardiac events. Herein we present a comprehensive and up-to-date review about the use of drug-eluting stents in the treatment of coronary artery disease.

Tirofiban for the treatment of ischaemic stroke

Tirofiban is one of three glycoprotein IIb/IIIa receptor antagonists approved by the US FDA, beside abciximab and eptifibatide. The approval of tirofiban covers conservative treatment of myocardial infarction and unstable angina, as well as percutaneous coronary intervention, for which treatment with tirofiban is recommended in moderate-to-high-risk patients. The efficacy of glycoprotein IIb/IIIa antagonists in myocardial infarction indicated that these agents may also be helpful in the treatment of acute ischaemic stroke. Although experimental data are lacking, observational studies are promising. In recent years, increasing effort in studying glycoprotein IIb/IIIa antagonists has been made, mostly for treatment with abciximab. However, there is one Phase II trial that investigated treatment with tirofiban.

Mortality at 1 year for the direct comparison of tirofiban and abciximab during percutaneous coronary revascularization: do tirofiban and ReoPro give similar efficacy outcomes at trial 1-year follow-up

AIMS

Compared with placebo, abciximab has been associated with mortality reduction at late follow-up. The TARGET trial was performed to test whether tirofiban and abciximab provide similar efficacy outcomes among patients undergoing non-emergent, stent-based percutaneous coronary intervention. We report here the 1-year mortality of the study population.

METHODS AND RESULTS

In 18 countries at 149 hospitals, 4,809 patients undergoing elective or urgent stent implantation were randomly assigned a bolus and infusion of tirofiban or abciximab. Ischaemic events were assessed at 30 days and 6 months and mortality was assessed at 1 year. We previously reported that abciximab was superior to tirofiban considering the composite rate of death or myocardial infarction at 30 days among all patients and at 6 months among those with an acute coronary syndrome (ACS). At 1-year follow-up death occurred in 46 (1.9%) patients who received tirofiban and 42 (1.7%) patients who received abciximab (hazard ratio 1.10, 95% CI 0.72-1.67; P=0.660). Mortality rates for patients with ACS were 2.3% with tirofiban vs. 2.2% with abciximab (hazard ratio 1.03, 95% CI 0.64-1.67; P=0.897) and those without ACS were 1.4 vs. 1.0% (hazard ratio 1.32, 95% CI 0.56-3.13; P=0.530).

CONCLUSION

At 1 year, tirofiban provided a similar level of survival benefit compared with abciximab.

Medical decision making with incomplete evidence--choosing a platelet glycoprotein IIbIIIa receptor inhibitor for percutaneous coronary interventions

BACKGROUND

Medical decision making must often be performed despite incomplete evidence. An example is the choice of a glycoprotein IIb/IIIa (GP2b3a) inhibitor, a class of potent antiplatelet medications, as adjunctive therapy during percutaneous coronary interventions (PCIs). GP2b3a inhibitor efficacy in reducing adverse outcomes has been well documented with multiple placebo-controlled randomized trials, but there is a paucity of comparative data about their individual equivalency. Substantial cost differentials are also present between the drugs.

METHODS

A systematic review of the literature was performed to identify all randomized placebo-controlled trials of GP2b3a inhibitors as adjunctive therapy for PCI. Three complimentary methods were used to assist in decision making regarding drug equivalency. First, the data from the single direct comparative trial are analyzed from a Bayesian perspective. Next, prior information from other GP2b3a inhibitor trials in similar but not identical patient populations is incorporated. In the 3rd method, indirect comparisons of GP2b3a inhibitors are carried out using a hierarchical meta-analytic model of the placebo-controlled trials identified by the systematic review.

RESULTS

A total of 12 randomized trials were identified involving 3 agents (abciximab, eptifibatide, tirofiban), but only 1 involved a direct comparison of 2 drugs (abciximab v. tirofiban). In contradiction to the original publication, the authors' Bayesian analysis both without (method 1) and with (method 2) the inclusion of some prior information suggests a reasonable probability of equivalency. The indirect comparisons from all randomized placebo-controlled trials (method 3) also failed to provide support for superiority of any agent over the others.

CONCLUSION

Decision making with incomplete evidence is a difficult but frequently occurring medical dilemma. The authors propose 3 methods that may elucidate the process and illustrate them in the context of the choice of GP2b3a inhibitor for adjunctive therapy during PCI. Further data may or may not eventually lead to a different conclusion, but based on the evidence available to date, the authors' 3 methods suggest clinical equivalency between GP2b3a inhibitors, in contrast to the initial conclusions from the single comparative randomized trial.

Choice of GPIIb/IIIa antagonist in percutaneous coronary intervention: how should economic criteria be factored in?

OBJECTIVE

Three GPIIb/IIIa antagonists are available in the market. In France, as in many countries, their acquisition costs strongly differ. The objective of this study was to analyze how economic criteria-beyond the acquisition cost-should be factored in, when choosing a GPIIb/IIIa antagonist.

METHOD

Both clinical and economic papers on the use of GPIIb/IIIa antagonists in percutaneous coronary interventions published in peer-review journals from 1994 to 2002 were reviewed and analyzed.

RESULTS

Cost differentials between products strongly vary from one 'cost concept' to another, i.e., acquisition cost, administration cost, hospital cost, net treatment cost. The comparison of efficacy is even more complicated, as most of the time only indirect comparisons are available, based on different clinical studies, with different durations and definitions of outcomes. Finally, cost-effectiveness ratios range from US dollar 10,695 per avoided event for eptifibatide (IMPACT II study) to US dollar 74,047 for tirofiban (RESTORE study).

CONCLUSION

The concept of cost, inevitably entering into the choice of a medicinal strategy, must be used with caution. The amplitude of the difference between products, and the product favored by the difference, vary according to the cost concept retained.

Guidelines for percutaneous coronary interventions. The Task Force for Percutaneous Coronary Interventions of the European Society of Cardiology

In patients with stable CAD, PCI can be considered a valuable initial mode of revascularization in all patients with objective large ischaemia in the presence of almost every lesion subset, with only one exception: chronic total occlusions that cannot be crossed. In early studies, there was a small survival advantage with CABG surgery compared with PCI without stenting. The addition of stents and newer adjunctive medications improved the outcome for PCI. The decision to recommend PCI or CABG surgery will be guided by technical improvements in cardiology or surgery, local expertise, and patients' preference. However, until proved otherwise, PCI should be used only with reservation in diabetics with multi-vessel disease and in patients with unprotected left main stenosis. The use of drug-eluting stents might change this situation. Patients presenting with NSTE-ACS (UA or NSTEMI) have to be stratified first for their risk of acute thrombotic complications. A clear benefit from early angiography (<48 h) and, when needed, PCI or CABG surgery has been reported only in the high-risk groups. Deferral of intervention does not improve outcome. Routine stenting is recommended on the basis of the predictability of the result and its immediate safety. In patients with STEMI, primary PCI should be the treatment of choice in patients presenting in a hospital with PCI facility and an experienced team. Patients with contra-indications to thrombolysis should be immediately transferred for primary PCI, because this might be their only chance for quickly opening the coronary artery. In cardiogenic shock, emergency PCI for complete revascularization may be life-saving and should be considered at an early stage. Compared with thrombolysis, randomized trials that transferred the patients for primary PCI to a 'heart attack centre' observed a better clinical outcome, despite transport times leading to a significantly longer delay between randomization and start of the treatment. The superiority of primary PCI over thrombolysis seems to be especially clinically relevant for the time interval between 3 and 12 h after onset of chest pain or other symptoms on the basis of its superior preservation of myocardium. Furthermore, with increasing time to presentation, major-adverse-cardiac-event rates increase after thrombolysis, but appear to remain relatively stable after primary PCI. Within the first 3 h after onset of chest pain or other symptoms, both reperfusion strategies seem equally effective in reducing infarct size and mortality. Therefore, thrombolysis is still a viable alternative to primary PCI, if it can be delivered within 3 h after onset of chest pain or other symptoms. Primary PCI compared with thrombolysis significantly reduced stroke. Overall, we prefer primary PCI over thrombolysis in the first 3 h of chest pain to prevent stroke, and in patients presenting 3-12 h after the onset of chest pain, to salvage myocardium and also to prevent stroke. At the moment, there is no evidence to recommend facilitated PCI. Rescue PCI is recommended, if thrombolysis failed within 45-60 min after starting the administration. After successful thrombolysis, the use of routine coronary angiography within 24 h and PCI, if applicable, is recommended even in asymptomatic patients without demonstrable ischaemia to improve patients' outcome. If a PCI centre is not available within 24 h, patients who have received successful thrombolysis with evidence of spontaneous or inducible ischaemia before discharge should be referred to coronary angiography and revascularized accordingly--independent of 'maximal' medical therapy.

Percutaneous coronary intervention and adjunctive pharmacotherapy in women: a statement for healthcare professionals from the American Heart Association

More than 1.2 million percutaneous coronary interventions are performed annually in the United States, with only an estimated 33% performed in women, despite the established benefits of percutaneous coronary intervention and adjunctive pharmacotherapy in reducing fatal and nonfatal ischemic complications in acute myocardial infarction and high-risk acute coronary syndromes. This statement reviews sex-specific data on the safety and efficacy of contemporary interventional therapies in women.

Prevention of restenosis after coronary angioplasty

PURPOSE OF REVIEW

Despite numerous advances in coronary interventional techniques, the frequent occurrence of restenosis continues to plague interventional cardiology. With the widespread use of drug-eluting stents, there is a need to reexamine critically the roles of the various interventional techniques currently available.

RECENT FINDINGS

Drug-eluting stents have dramatically reduced the rates of restenosis and target vessel revascularization in a wide spectrum of patients with varying lesion morphologies. However, when restenosis does occur, it still tends to be dependent on the same factors that predict restenosis with bare metal stenting. The routine use of drug-eluting stents entails high initial costs to the health care system. Debulking as a means to improve outcomes after angioplasty has not lived up to expectations. Gene therapy is rapidly evolving into a viable means to reduce neointimal proliferation after angioplasty.

SUMMARY

Careful patient selection and attention to the procedure of stent deployment optimize the results of angioplasty with drug-eluting stents. Because of cost considerations, drug-eluting stents should be used in patients who are expected to have the greatest absolute benefit. In this context, when judiciously used, conventional balloon angioplasty and bare metal stenting still have a definite role in the management of patients with obstructive coronary artery disease.

Platelet-Active Drugs: The Relationships Among Dose, Effectiveness, and Side Effects

This article discusses platelet active drugs as part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. New data on antiplatelet agents include the following: (1) the role of aspirin in primary prevention has been the subject of recommendations based on the assessment of cardiovascular risk; (2) an increasing number of reports suggest a substantial interindividual variability in the response to antiplatelet agents, and various phenomena of "resistance" to the antiplatelet effects of aspirin and clopidogrel; (3) the benefit/risk profile of currently available glycoprotein IIb/IIIa antagonists is substantially uncertain for patients with acute coronary syndromes who are not routinely scheduled for early revascularization; (4) there is an expanding role for the combination of aspirin and clopidogrel in the long-term management of high-risk patients; and (5) the cardiovascular effects of selective and nonselective cyclooxygenase-2 inhibitors have been the subject of increasing attention.

Modulating thrombotic potential in catheter-based percutaneous coronary and peripheral vascular interventions

Thrombosis is an obligatory consequence of all percutaneous vascular interventions. Balloon angioplasty, intravascular stents and other devices routinely used to facilitate dilatation of critical vascular stenoses result in fracture of the intima and exposure of the thrombogenic subendothelium with initiation and perpetuation of platelet activation and aggregation. This not uncommonly results in thrombus formation that may lead to abrupt vessel closure, distal ischemia and tissue infarction, and target organ dysfunction. Fortunately, advances in our understanding of the mechanisms that underlie vascular thrombosis have led to advances in the use of adjunctive pharmacological agents that modulate this pathophysiological response and have led to important reductions in the incidence and severity of thrombotic complications of percutaneous transluminal interventions.

A comparison of coronary artery stenting with angioplasty for isolated stenosis of the proximal left anterior descending coronary artery: five year clinical follow up

BACKGROUND

Stent implantation for isolated stenosis of the proximal left anterior descending coronary artery (LAD) with preserved left ventricular function has been found to have a better clinical and angiographic outcome at one year than balloon angioplasty (PTCA).

OBJECTIVE

To establish whether those results are maintained at five year follow up.

METHODS

Patients were followed at least every six months. For those who died during follow up, data were obtained from medical records.

MAIN OUTCOME MEASURES

Freedom from death, non-fatal myocardial infarction, cerebrovascular accident, and repeated target lesion revascularisation. Secondary end points were revascularisation in a remote region and freedom from angina.

RESULTS

Follow up was complete in all patients. At five years, the primary end point was reached more often by patients randomised to stent implantation than to PTCA (80% v 53%; odds ratio (OR) 0.29 (95% confidence interval (CI) 0.13 to 0.69); p = 0.0034). In the PTCA group, 35% of patients underwent target lesion revascularisation v 15% in the stent group (OR 0.33, 95% CI 0.13 to 0.80; p = 0.014). There was a trend towards increased mortality in the PTCA group than in the stent group (17% v 7%; OR 0.36, 95% CI 0.10 to 1.21; p = 0.098). No significant differences were found between PTCA and stent groups for non-fatal myocardial infarction (8% v 5%; OR 0.58, 95% CI 0.13 to 2.54; p = 0.46) or cerebrovascular accident (2% v 0%).

CONCLUSIONS

In patients with isolated stenosis of the proximal LAD, a five year clinical follow up confirmed a better outcome in those treated with stenting than with PTCA.

Use of GPIIb/IIIa inhibitors in cardiovascular medicine

The GPIIb/IIIa inhibitors were the first clinically used anti-integrin therapeutics. They opened the gate to a rapidly developing area of anti-integrin targeting as a therapeutic approach to many diseases. The use of GPIIb/IIIa inhibitors in interventional cardiology is widespread and still increasing, as is the number of percutaneous coronary interventions. There seems to be a class effect of GPIIb/IIIa inhibitors in percutaneous coronary intervention, but there are major differences in the pharmacokinetics and pharmacodynamics of these agents. Currently clinically approved for parenteral use are the Fab fragment abciximab (ReoPro, Lilly) and the small-molecule GPIIb/IIIa inhibitors eptifibatide (Integrilin, Millennium/Schering-Plough) and tirofiban (Aggrastat, Merck). This review focuses on the different pharmacological properties of these agents and summarizes present and future therapeutic use of GPIIb/IIIa inhibitors in cardiovascular and other vascular diseases.

Platelet glycoprotein IIb/IIIa inhibitors

Glycoprotein (GP) IIb/IIIa inhibitors including abciximab, eptifibatide and tirofiban have been studied extensively as short-term adjuncts to short-term heparin and indefinite aspirin in patients with acute coronary syndrome or undergoing percutaneous coronary interventions on native vessels. The drugs provide a small advantage in the composite endpoint of death, myocardial infarction, and need for revascularization at 30 days (1-2% of treated patients) at the expense of an increase in major and potentially fatal bleeding complications (1% of treated patients over heparin plus aspirin alone). Highest-risk patients appear to benefit the most; clopidogrel should also be considered in these patients. Patients undergoing percutaneous interventions on bypass grafts do not benefit. Whether one GP IIb/IIIa inhibitor is superior to another is incompletely clarified. Abciximab causes severe immune-mediated thrombocytopenia (<20,000/microl) in 0.7% of cases; this is more often than eptifibatide or tirofiban (0.2%). Pseudothrombocytopenia should be differentiated. Effective use of GP IIb/IIIa inhibitors for acute coronary syndrome and percutaneous coronary interventions requires discerning clinical judgment. The value of GP IIb/IIIa inhibitors is not established in other forms of vascular disease.

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.

Percutaneous coronary intervention: historical perspectives, current status, and future directions

In the twenty-six years since Gruntzig introduced a simple balloon angioplasty technique, percutaneous coronary intervention has undergone extraordinary growth and has now surpassed bypass surgery in frequency of performance. Several critical breakthrough technologies account for this remarkable progress: intracoronary stents have increased success rates and reduced restenosis, adjunctive antiplatelet therapy has reduced periprocedural complications, and restenosis after stent placement has been effectively treated with local radiation. Most recently, drug-eluting stents coated with cell-cycle inhibitors have shown great promise for further reducing restenosis, possibly to negligible levels.

Peripheral vascular disease and one-year mortality following percutaneous coronary revascularization

The association between peripheral vascular disease and outcomes after percutaneous coronary intervention was examined in the Do Tirofiban and Reopro Give Similar Efficacy Outcome Trial (TARGET). After adjustments in a multivariate model, a history of peripheral vascular disease was found to be associated with a two- to threefold increase in mortality at 1 year after coronary stent placement.

Different effects of various anti-GPIIb-IIIa agents on shear-induced platelet activation and expression of procoagulant activity

Inhibitors of the platelet glycoprotein (GP)IIb-IIIa receptor (integrin alphaIIbbeta3) reduce acute thrombotic events in patients with coronary artery disease. To characterize the mechanism of action of these drugs, we evaluated the effects of different GPIIb-IIIa antagonists on shear-induced platelet aggregation, activation, and the expression of procoagulant activity. Samples of platelet-rich plasma from 16 volunteers were exposed to the shear rate of 10 800 s-1 for 6 min in an optically modified cone-plate viscometer. Abciximab, tirofiban and eptifibatide inhibited aggregation to a similar extent (mean +/- SD: 74.1 +/- 8.5%, 69.5 +/- 13.6%, 65.6 +/- 17.0%, respectively), but only abciximab inhibited significantly microparticle release associated with shear-induced platelet activation (64.4 +/- 13.6%, P = 2.2 x 10-7; tirofiban = 20.0 +/- 23.4%; eptifibatide = 23.9 +/- 17.4%). P-selectin platelet surface translocation was also strongly inhibited by abciximab, weakly by eptifibatide, but not by tirofiban. The addition of anti-alphavbeta3 to tirofiban enhanced the inhibiting effects on shear-induced P-selectin translocation and microparticle release. Shearing of platelet-rich plasma shortened the re-calcification clotting time after addition of kaolin from 106.9 +/- 14.3 to 94.2 +/- 10.7 s (mean +/- SD; P = 0.0013). This effect, which is mediated by the appearance of procoagulant phospholipids on the surface of sheared platelets and microparticles, was prevented by abciximab and by the combination of tirofiban and anti-alphavbeta3, but not by tirofiban alone or eptifibatide. The ability to inhibit shear-induced platelet activation, as evidenced by microparticle release and P-selectin surface translocation as well as the expression of procoagulant activity, differentiates the effects of anti-GPIIb-IIIa agents, which may explain the distinct antithrombotic efficacy of the agents.

Glycoprotein IIb/IIIa receptor inhibitors in percutaneous coronary intervention and acute coronary syndrome

OBJECTIVE

To review the contemporary role of the glycoprotein (GYP) IIb/IIIa receptor inhibitors abciximab, eptifibatide, and tirofiban in patients undergoing percutaneous coronary intervention (PCI) and those with an acute coronary syndrome (ACS), and to provide an algorithm based on currently available evidence for specific agents.

DATA SOURCES

Primary articles were identified by a MEDLINE search (1966-January 2003); references cited in these articles provided additional resources.

STUDY SELECTION AND DATA EXTRACTION

All of the articles identified from data sources were considered for relevant information; this article primarily addresses large, controlled or comparative studies, and meta-analyses.

DATA SYNTHESIS

The role of GYP IIb/IIIa inhibitors in patients undergoing PCI and those with ACS has progressed markedly. To date, abciximab has the most robust data in patients undergoing PCI, particularly high-risk individuals. In PCI patients with lower risk (e.g., elective stenting), eptifibatide is a reasonable first-line option. Data do not support tirofiban for routine use in patients undergoing PCI. For individuals with signs and symptoms of ACS, specifically unstable angina or non-ST-segment elevation myocardial infarction (MI), eptifibatide or tirofiban is recommended in high-risk patients when a conservative approach is used (PCI is not planned). Abciximab is not recommended in this situation. In patients with ST-segment elevation MI (STEMI), abciximab is the only GYP IIb/IIIa inhibitor evaluated in large, well-designed investigations. For medical management in combination with a fibrinolytic agent, the role of abciximab remains unclear. For patients undergoing primary PCI for the management of STEMI, the available evidence supports the use of abciximab, albeit further investigation is warranted.

CONCLUSIONS

The role of GYP IIb/IIIa inhibitors in clinical cardiology continues to evolve. Choice of the agent depends on situation of use, patient-specific characteristics and risk stratification, and, in the case of ACS, chosen management strategy (medical management or intervention).

Adjunctive platelet glycoprotein IIb/IIIa receptor inhibition with tirofiban before primary angioplasty improves angiographic outcomes: results of the TIrofiban Given in the Emergency Room before Primary Angioplasty (TIGER-PA) pilot trial

BACKGROUND

Previous work has suggested that platelet glycoprotein IIb/IIIa receptor blockade may confer benefit in the treatment of acute myocardial infarction. The TIGER-PA pilot trial was a single-center randomized study to evaluate the safety, feasibility, and utility of early tirofiban administration before planned primary angioplasty in patients presenting with acute myocardial infarction.

METHODS AND RESULTS

A total of 100 patients presenting with acute myocardial infarction were randomized to either early administration of tirofiban in the emergency room or later administration in the catheterization laboratory. The primary outcome measures were initial TIMI grade flow, corrected TIMI frame counts, and TIMI grade myocardial perfusion ("blush"). Thirty-day major adverse cardiac events were also assessed. Angiographic outcomes demonstrate a significant improvement in initial TIMI grade flow, corrected TIMI frame counts, and TIMI grade myocardial perfusion when patients are given tirofiban in the emergency room before primary angioplasty. The rate of 30-day major adverse cardiac events suggests that early administration may be beneficial.

CONCLUSIONS

This pilot study suggests that early administration of tirofiban improves angiographic outcomes and is safe and feasible in patients undergoing primary angioplasty for acute myocardial infarction.

Effects of Enoxaparin and Nadroparin on Major Cardiac Events in High-risk Unstable Angina Treated With a Glycoprotein IIb/IIIa Inhibitor

Clinical trials have reported the beneficial effects of platelet glycoprotein (GP) IIb/IIIa receptor antagonists and low-molecular-weight heparins (LMWH) on major cardiac events (MACE) in patients presenting with unstable angina or non-ST elevation myocardial infarction. A number of studies have documented the significant superiority of low-molecular-weight heparins, especially enoxaparin, over unfractionated heparin in the treatment of acute coronary syndromes. The purpose of this study was to compare the effects of two different LMWHs, enoxaparin and nadroparin, accompanied by platelet GP IIb/IIIa inhibition on MACE in high-risk unstable angina. The study was designed as an open-label and observational study. Sixty-eight patients presenting with unstable angina associated with high-risk criteria were randomly assigned to treatment with enoxaparin plus tirofiban (36 patients, mean age 57 +/- 11) or nadroparin plus tirofiban (32 patients, mean age: 58 +/- 8). In-hospital MACE including acute myocardial infarction (AMI), recurrent refractory angina, death, stroke, and urgent revascularization were compared between the study groups. Patient characteristics and durations of LMWH and tirofiban treatments were not different between the study groups. Coronary artery risk factors, except family history (which was observed more frequently in the enoxaparin group, P = 0.02), were also similar. MACE between the enoxaparin and nadroparin groups including AMI (5.5%, 6%), recurrent refractory angina (19%, 12%), death (0%, 3%), stroke (was not observed in either group), urgent revascularization (14%, 12%) and total MACE (19%, 15%) were not different. Enoxaparin and nadroparin, accompanied by GP IIb/IIIa inhibitor therapy, have similar effects on the development of major cardiac events in patients presenting with unstable angina and high-risk characteristics.