Deaths associated with platelet glycoprotein IIb/IIIa inhibitor treatment

Endogenous Nitric Oxide-Releasing Microgel Coating Prevents Clot Formation on Oxygenator Fibers Exposed to In Vitro Blood Flow

Background: Clot formation on foreign surfaces of extracorporeal membrane oxygenation systems is a frequent event. Herein, we show an approach that mimics the enzymatic process of endogenous nitric oxide (NO) release on the oxygenator membrane via a biomimetic, non-fouling microgel coating to spatiotemporally inhibit the platelet (PLT) activation and improve antithrombotic properties. This study aims to evaluate the potential of this biomimetic coating towards NO-mediated PLT inhibition and thereby the reduction of clot formation under flow conditions. Methods: Microgel-coated (NOrel) or bare (Control) poly(4-methyl pentene) (PMP) fibers were inserted into a test channel and exposed to a short-term continuous flow of human blood. The analysis included high-resolution PLT count, pooled PLT activation via β-Thromboglobulin (β-TG) and the visualization of remnants and clots on the fibers using scanning electron microscopy (SEM). Results: In the Control group, PLT count was significantly decreased, and β-TG concentration was significantly elevated in comparison to the NOrel group. Macroscopic and microscopic visualization showed dense layers of stable clots on the bare PMP fibers, in contrast to minimal deposition of fibrin networks on the coated fibers. Conclusion: Endogenously NO-releasing microgel coating inhibits the PLT activation and reduces the clot formation on PMP fibers under dynamic flow.

Glycoprotein IIb/IIIa inhibitors use and outcome after percutaneous coronary intervention for non-ST elevation myocardial infarction

AIMS

We investigate the effect of glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitors on long-term outcomes following percutaneous coronary intervention (PCI) after non-ST elevation myocardial infarction (NSTEMI). Meta-analyses indicate that these agents are associated with improved short-term outcomes. However, many trials were undertaken before the routine use of P2Y12 inhibitors. Recent studies yield conflicting results and registry data have suggested that GP IIb/IIIa inhibitors may cause more bleeding than what trials indicate.

METHODS AND RESULTS

This retrospective observational study involves 3047 patients receiving dual-antiplatelet therapy who underwent PCI for NSTEMI. Primary outcome was all-cause mortality. Major adverse cardiac events (MACE) were a secondary outcome. Mean follow-up was 4.6 years. Patients treated with GP IIb/IIIa inhibitors were younger with fewer comorbidities. Although the unadjusted Kaplan-Meier analysis suggested that GP IIb/IIIa inhibitor use was associated with improved outcomes, multivariate analysis (including propensity scoring) showed no benefit for either survival (P = 0.136) or MACE (P = 0.614). GP IIb/IIIa inhibitor use was associated with an increased risk of major bleeding (P = 0.021).

CONCLUSION

Although GP IIb/IIIa inhibitor use appeared to improve outcomes after PCI for NSTEMI, patients who received GP IIb/IIIa inhibitors tended to be at lower risk. After multivariate adjustment we observed no improvement in MACE or survival and an increased risk of major bleeding.

Concordance of preclinical and clinical pharmacology and toxicology of therapeutic monoclonal antibodies and fusion proteins: cell surface targets

Monoclonal antibodies (mAbs) and fusion proteins directed towards cell surface targets make an important contribution to the treatment of disease. The purpose of this review was to correlate the clinical and preclinical data on the 15 currently approved mAbs and fusion proteins targeted to the cell surface. The principal sources used to gather data were: the peer reviewed Literature; European Medicines Agency 'Scientific Discussions'; and the US Food and Drug Administration 'Pharmacology/Toxicology Reviews' and package inserts (United States Prescribing Information). Data on the 15 approved biopharmaceuticals were included: abatacept; abciximab; alefacept; alemtuzumab; basiliximab; cetuximab; daclizumab; efalizumab; ipilimumab; muromonab; natalizumab; panitumumab; rituximab; tocilizumab; and trastuzumab. For statistical analysis of concordance, data from these 15 were combined with data on the approved mAbs and fusion proteins directed towards soluble targets. Good concordance with human pharmacodynamics was found for mice receiving surrogates or non-human primates (NHPs) receiving the human pharmaceutical. In contrast, there was poor concordance for human pharmacodynamics in genetically deficient mice and for human adverse effects in all three test systems. No evidence that NHPs have superior predictive value was found.

Age related issues in reperfusion of myocardial infarction

Advances in pharmacological treatment and effective early myocardial revascularization have led to improved clinical outcomes in patients with acute myocardial infarction (AMI). However, it has been suggested that compared to younger subjects, elderly AMI patients are less likely to receive evidence-based treatment. Several reasons have been postulated to explain this trend, including uncertainty regarding the benefits of the commonly used interventions in the older age group as well as increased risk associated with comorbidities. The diagnosis, management, and post-hospitalization care of elderly patients presenting with an acute coronary syndrome (ACS) pose many difficulties at present due, at least in part, to the fact that trial data are scanty as elderly patients have been poorly represented in most clinical trials. Thus it appears that these high-risk individuals are often managed with more conservative strategies, compared to younger patients. This article reviews current evidence regarding management of AMI in the elderly.

Comparison of outcomes of patients ≥ 80 years of age having percutaneous coronary intervention according to presentation (stable vs unstable angina pectoris/non-ST-segment elevation myocardial infarction vs ST-segment elevation myocardial infarction)

Patients ≥ 80 years old with coronary artery disease constitute a particular risk group in relation to percutaneous coronary intervention (PCI). From 2002 through 2008 we examined the annual proportion of patients ≥ 80 years old undergoing PCI in western Denmark, their indications for PCI, and prognosis. From 2002 through 2009 all elderly patients treated with PCI were identified in a population of 3.0 million based on the Western Denmark Heart Registry. Cox regression analysis was used to compare mortality rates according to clinical indications controlling for potential confounding. In total 3,792 elderly patients (≥ 80 years old) were treated with PCI and the annual proportion increased from 224 (5.4%) in 2002 to 588 (10.2%) in 2009. The clinical indication was stable angina pectoris (SAP) in 30.2%, ST-segment elevation myocardial infarction (STEMI) in 35.0%, UAP/non-STEMI in 29.7%, and "ventricular arrhythmia or congestive heart failure" in 5.1%. Overall 30-day and 1-year mortality rates were 9.2% and 18.1%, respectively. Compared to patients with SAP the adjusted 1-year mortality risk was significantly higher for patients presenting with STEMI (hazard ratio 3.86, 95% confidence interval 3.08 to 4.85), UAP/non-STEMI (hazard ratio 1.95, 95% confidence interval 1.53 to 2.50), and ventricular arrhythmia or congestive heart failure (hazard ratio 2.75, 95% confidence interval 1.92 to 3.92). In patients with SAP target vessel revascularization decreased from 7.1% in 2002 to 2.5% in 2008. In conclusion, the proportion of patients ≥ 80 years old treated with PCI increased significantly over an 8-year period. Patients with SAP had the lowest mortality rates and rates of clinically driven target vessel revascularization decreased over time.

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.

Myocardial infarction in the elderly

Advances in pharmacological treatment and effective early myocardial revascularization have -in recent years- led to improved clinical outcomes in patients with acute myocardial infarction (AMI). However, it has been suggested that compared to younger subjects, elderly AMI patients are less likely to receive evidence-based treatment, including myocardial revascularization therapy. Several reasons have been postulated to explain this trend, including uncertainty regarding the true benefits of the interventions commonly used in this setting as well as increased risk mainly associated with comorbidities. The diagnosis, management, and post-hospitalization care of elderly patients presenting with an acute coronary syndrome pose many difficulties at present. A complex interplay of variables such as comorbidities, functional and socioeconomic status, side effects associated with multiple drug administration, and individual biologic variability, all contribute to creating a complex clinical scenario. In this complex setting, clinicians are often required to extrapolate evidence-based results obtained in cardiovascular trials from which older patients are often, implicitly or explicitly, excluded. This article reviews current recommendations regarding management of AMI in the elderly.

Vanishing platelets: rapid and extreme tirofiban-induced thrombocytopenia after percutaneous coronary intervention for acute myocardial infarction

Glycoprotein IIb/IIIa inhibitors are established treatment for patients who develop acute coronary syndromes. Thrombocytopenia is known to occur following the administration of various drugs, including heparin and glycoprotein IIb/IIIa inhibitors. In the case of glycoprotein IIb/IIIa inhibitors, the mechanism is thought to be drug-dependent antibodies. In most cases, the thrombocytopenia is mild or moderate in severity. Severe thrombocytopenia (platelet count, <50 x 10(9)/L) is distinctly rare. Herein, we report a case of tirofiban-induced thrombocytopenia in which the overall platelet count dropped precipitously to <1 x 10(9)/L within 12 hours of administration; recovery was relatively prolonged, possibly owing to concomitant renal insufficiency. The severity and the rapidity of onset emphasize the need to routinely check platelet counts early after tirofiban administration, in order to prevent sequelae.

Hospital performance and differences by kidney function in the use of recommended therapies after non-ST-elevation acute coronary syndromes

BACKGROUND

Chronic kidney disease (CKD) is associated with an increased risk of cardiac events and death; however, underuse of guideline-recommended therapies is widespread. The extent to which hospital performance affects the care of patients with CKD and non-ST-segment elevation acute coronary syndromes (NSTE ACSs) is unknown.

STUDY DESIGN

Observational cohort.

SETTING & PARTICIPANTS

81,374 patients with NSTE ACSs treated at 327 US hospitals.

PREDICTOR

Hospital performance, measured by quartiles of composite adherence to American Heart Association class I guidelines for therapy acutely (aspirin, beta-blockers, clopidogrel, heparin, and glycoprotein IIb/IIIa inhibitors) and at discharge (aspirin, clopidogrel, angiotensin-converting enzyme inhibitors, and lipid-lowering agents) in eligible patients.

OUTCOMES & MEASUREMENTS

Use of each American Heart Association class I acute and discharge therapy stratified by continuous estimated glomerular filtration rate (eGFR). Multivariable models were adjusted for demographics, clinical factors, and hospital features.

RESULTS

Better-performing hospitals had lower prescribing rates for most therapies (5 of 9) with lower levels of kidney function, whereas lower-performing hospitals were more likely to have similar prescribing rates across the eGFR spectrum, suggesting that prescribing patterns at these hospitals were insensitive to differences in eGFR.

LIMITATIONS

Observational design, selection bias of study cohort.

CONCLUSION

Patients with lower levels of kidney function admitted with NSTE ACSs are less likely to receive evidence-based therapies. Treatment disparities related to CKD are most evident at top-performing hospitals.

Evolution of anticoagulant and antiplatelet therapy: benefits and risks of contemporary pharmacologic agents and their implications for myonecrosis and bleeding in percutaneous coronary intervention

Periprocedural myonecrosis, as evidenced by elevated creatine kinase-myocardial bound (CK-MB) levels, occurs in up to 25% of patients undergoing percutaneous coronary intervention (PCI) and has been linked with an increased risk of adverse short- and long-term clinical outcomes. Such myonecrosis arises from three main pathophysiological mechanisms: procedure-related complications, lesion-specific characteristics (e.g., large thrombus burden, plaque volume), and patient-specific characteristics (e.g., genetic predisposition, arterial inflammation). Periprocedural myonecrosis has not been definitively identified as the cause of postprocedural ischemic events, although agents that reduce or prevent thrombosis--including aspirin, thienopyridines, heparin, low-molecular-weight heparins, glycoprotein IIb/IIIa inhibitors, and direct thrombin inhibitors--have been shown to reduce the incidence of ischemic outcomes in this population, as have agents that reduce inflammation (aspirin, statins). At the same time, antithrombotic agents are known to increase the risk of bleeding and the use of transfusions, which have likewise been associated with worse outcomes in these patients. Thus, optimal management of patients undergoing PCI represents a balance between minimizing the risk of ischemic outcomes and simultaneously minimizing the risk of major bleeding. It may be that patients who have only minor, untreated postprocedural elevations in CK-MB level (with no clinical or angiographic signs of ischemia) might have a better prognosis than patients who have normal CK-MB levels but who suffer major bleeding complications.

A retrospective study of the management of retro-peritoneal bleeding after percutaneous coronary intervention in the era of combination anti-platelet therapy

BACKGROUND

Combination anti-platelet therapy is mandatory in patients undergoing percutaneous coronary intervention (PCI) to reduce coronary events and stent thrombosis but increases the risk of bleeding. In particular, the management of retroperitoneal haemorrhage (RPH) after PCI is uncertain and made more complex as multiple anti-platelet agents are given routinely. We audited the outcome of patients who experienced RPH and sought to determine whether operative management was required.

METHODS

We conducted a retrospective observational audit of all patients undergoing PCI at a single institution over a 5-year period.

RESULTS

RPH occurred in 12 patients. Nine patients were managed without surgery. Patients with RPH needed prolonged admissions (mean length of stay 9.5 days), and were transfused with a mean of 4.5 units of packed red cells. Although there were no deaths, one patient had a spinal infarction.

CONCLUSION

Management of RPH may be conservative unless there is ongoing bleeding. RPH has resource implications in terms of transfusions, prolonged length of stay and morbidity.

Prognostic modelling in ischaemic stroke study, additional value of genetic characteristics. Rationale and design

BACKGROUND AND AIM

The prediction of prognosis after cerebral infarction might be improved by genetic information. The aim of the Prognostic Modelling in Ischaemic Stroke study is to develop 2 different prognostic models on the basis of traditional vascular risk factors and genetic information in patients who have suffered from cerebral ischaemia of arterial origin, 1 concerning new ischaemic and the other new haemorrhagic events.

METHODS

Polymorphisms and haplotypes describing the haemostatic system and those that influence antithrombotic drug activity will be identified in a cohort of 1,200 patients with cerebral ischaemia of arterial origin who will be followed up for a mean of 6.5 years. In total, 312 ischaemic and 78 haemorrhagic events are anticipated. With a prevalence of a genetic characteristic of 10% a relative risk of 1.4 (95% confidence interval = 1.1-1.8) for ischaemic events and of 1.8 (95% confidence interval = 1.0-3.2) for haemorrhagic events can be estimated with sufficient precision. To determine the additional prognostic value of genetic characteristics the area under the ROC curves of 2 separate models will be compared: 1 based on non-genetic risk factors only, the other also including genetic data.

Acute coronary care in the elderly, part I: Non-ST-segment-elevation acute coronary syndromes: a scientific statement for healthcare professionals from the American Heart Association Council on Clinical Cardiology: in collaboration with the Society of Geriatric Cardiology

BACKGROUND

Age is an important determinant of outcomes for patients with acute coronary syndromes (ACS); however, community practice reveals a disproportionately lower use of cardiovascular medications and invasive treatment even among elderly patients with ACS who would stand to benefit. Reasons include limited trial data to guide the care of older adults and uncertainty about benefits and risks, particularly with newer medications or invasive treatments and in the setting of advanced age or complex health status.

METHODS AND RESULTS

This 2-part American Heart Association scientific statement summarizes evidence on patient heterogeneity, clinical presentation, and treatment of non-ST-elevation ACS in relation to age (< 65, 65 to 74, 75 to 84, and > or = 85 years). In addition, we review methodological issues that influence the acquisition and application of evidence to the elderly patients treated in community practice. A writing group combining international cardiovascular and geriatric perspectives convened to summarize available data from trials (5 combined Virtual Coordinating Center for Global Collaborative Cardiovascular Research [VIGOUR] trials) and 3 registries (Global Registry of Acute Coronary Events, National Registry of Myocardial Infarction, and the Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the American College of Cardiology/American Heart Association guidelines national quality improvement initiative [CRUSADE]) to provide a conceptual framework for future work in the care of the elderly with acute cardiac disease. Treatment for non-ST-segment-elevation ACS (Part I) and ST-segment-elevation myocardial infarction (Part II) are reviewed. In addition, ethical considerations pertaining to acute care and secondary prevention are considered (Part II). The primary goal is to identify the areas in which sufficient evidence is available to guide practice, as well as to determine areas that warrant further study. Although treatment-related benefits should rise in an elderly population with high disease risk, data to assess these benefits are limited, outcomes of importance vary, and heterogeneity among the elderly increases treatment-related risks. Although a uniform approach to care in the oldest of the old is unlikely, understanding the major contributors to benefits and risks from treatment will advance the ability to apply guideline-based care in this subset of patients.

CONCLUSIONS

Although a few recent trials have described treatment effects in older patients, others continue to exclude patients on the basis of age. Going forward, prospective trials should enroll elderly subjects proportionate to their prevalence among the treated population to define risk and benefit. Findings from age subgroup analyses should be reported in a consistent manner across trials, including absolute and relative risks for efficacy and safety. Outcomes of particular relevance to the elderly, such as quality of life, physical function, and independence, should also be considered. Creatinine clearance should be calculated for every elderly patient to enable appropriate dosing. In addition, physicians need an understanding of conditions unique to older patients (eg, frailty, cognitive impairment) that influence treatment goals and outcomes. With these efforts, treatment risks can be minimized, and benefits can be placed in the health context of the elderly patient with ACS.

Abciximab and fatal pulmonary hemorrhage

Abciximab, a platelet glycoprotein IIb/IIIa receptor blocker, is a well-known agent in percutaneous coronary intervention because of its antiplatelet, antithrombotic effects, which allow for good outcome. Major bleeding is a well-recognized complication of abciximab therapy, and pulmonary hemorrhage, although infrequent, is a serious, under-recognized, and often fatal complication. We describe a case of fatal pulmonary hemorrhage in a young woman who presented with acute myocardial infarction and cardiogenic shock and was treated with abciximab in conjunction with percutaneous coronary intervention. The possibility of diffuse pulmonary hemorrhage should be strongly suspected in the presence of hypoxemia, infiltrates on chest radiography, and a decrease in hemoglobin. Awareness about this complication of abciximab therapy on the part of physicians and health care professionals is strongly warranted. Therapy that may be used if diagnosis is promptly made includes bronchoscopic-guided balloon tamponade or iced saline lavage. These therapeutic interventions are still in the developmental stage, and to date there are no trials to document their efficacy and survival benefit.

Gender Differences in Acute Coronary Syndrome

Acute coronary syndrome (ACS) is common in women, yet we have less sex-specific data in women than in men as a result of lower enrollment in clinical trials and low rates of sex-specific reporting. Women are generally older with more comorbidities when diagnosed with ACS. Women with ACS are less likely than men to be referred for invasive evaluation and procedures and are more likely to have normal coronary arteries when they are referred for coronary angiography. For reasons that are not well understood, women have higher rates of bleeding complications compared with men. This higher bleeding rate is consistently seen in many trials. There are 3 major randomized, controlled trials that compared early invasive therapy with conservative strategy for ACS. Two of these trials found higher rates of myocardial infarction (MI) and death at 1 year in women treated with early invasive strategy, whereas the third trial found a reduction in the composite end point of rehospitalization, MI, and death at 180 days in women treated with early invasive strategy. Sex differences have also been seen in glycoprotein (GP) IIb/IIIa use in women with an increase in death and MI noted for GP use in women with ACS. Continued and increased numbers of women in clinical studies of ACS as well as increased rates of sex-specific reporting will allow us to offer optimal quality care for women and men with ACS.

Use of drotrecogin alfa (activated) in older patients with severe sepsis

Drotrecogin alfa (activated) has been approved by the United States Food and Drug Administration for treatment of patients at high risk of death from severe sepsis. Severe sepsis is common, and its occurrence increases dramatically with age. Clinical use data, however, suggest that drotrecogin alfa (activated) may be underused in older patients, possibly due to concern over the drug's anticoagulant effects and perceived high cost. In addition, clinicians often treat older patients less aggressively than younger patients. We reviewed a subgroup analysis of patients aged 75 years and older from a large clinical trial evaluating efficacy and safety of drotrecogin alfa (activated), as well as cost-effectiveness data from real-world clinical use of the drug in older patients. We also explored ethical dilemmas of treating older patients with sepsis. Drotrecogin alfa (activated) is safe, effective, and cost-effective in older patients with severe sepsis and should be considered for elderly intensive care patients who are high risk of death and who have no contraindications to treatment.

Sex Differences in Major Bleeding With Glycoprotein IIb/IIIa Inhibitors

Background— Glycoprotein (GP) IIb/IIIa inhibitors are beneficial in patients with non–ST-segment elevation acute coronary syndromes (NSTE ACS); their safe use in women, however, remains a concern. The contribution of dosing to the observed sex-related differences in bleeding is unknown.

Methods and Results— We explored the relationship between patient sex, GP IIb/IIIa inhibitor use, dose, and bleeding in 32 601 patients with NSTE ACS across 400 CRUSADE (Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines) hospitals, of whom 18 436 were treated. GP IIb/IIIa inhibitor dose was defined as excessive if not reduced when creatinine clearance was <50 mL/min for eptifibatide or <30 mL/min for tirofiban. Major bleeding was defined as a hematocrit drop ≥0.12, need for transfusion, or intracranial bleeding. Major bleeding was adjusted for clinical factors and antithrombotic dose. The risk for bleeding attributable to excess GP IIb/IIIa dose was determined by sex using prevalence and adjusted odds ratios (ORs). Women had higher rates of major bleeding than men among those treated with GP IIb/IIIa inhibitors (15.7% versus 7.3%, P <0.0001) and among those not treated (8.5% versus 5.4%, P <0.0001). Despite similar serum creatinine levels, creatinine clearance averaged 20 points lower among treated women than men. Treated women were also more likely to receive excess GP IIb/IIIa doses than men (46.4% versus 17.2%, P <0.0001; adjusted OR 3.81, 95% confidence interval [CI] 3.39 to 4.27). Excess dosing was associated with increased risk of bleeding in women (OR 1.72, 95% CI 1.30 to 2.28) and men (OR 1.27, 95% CI 0.97 to 1.66); however, bleeding risk attributable to dosing was much higher in women (25.0% versus 4.4%).

Conclusions— Women experience more bleeding than men whether or not they are treated with GP IIb/IIIa inhibitors; however, because of frequent excessive dosing in women, up to one fourth of this sex-related risk difference in bleeding is avoidable. Appropriate dosing will improve care of all patients with NSTE ACS, with a particular benefit for women.

Platelet function monitoring with the Sonoclot analyzer after in vitro tirofiban and heparin administration

OBJECTIVE

Reliable platelet function monitoring is desirable in patients treated with glycoprotein IIb/IIIa receptor inhibitors. The aim of the present laboratory-based study was to assess platelet function after administration of clinically relevant doses of the glycoprotein IIb/IIIa antagonist tirofiban with or without heparin by using Sonoclot (Sienco Inc) and platelet aggregometry.

METHODS

Tirofiban (0-100 ng x mL(-1)) and heparin (0 or 1 U x mL(-1)) were added to blood samples obtained from 20 healthy volunteers. Coagulation analysis was performed on citrated whole blood by using the Sonoclot analyzer. The glass bead-activated test and the new glass bead test with heparinase were used. The results were compared with adenosine-5'-diphosphate-activated platelet aggregometry.

RESULTS

Administration of tirofiban showed a similar increase of platelet inhibition detected with the Sonoclot glass bead-activated test and glass bead test with heparinase, as well as by means of aggregometry. Bias between the different techniques was comparable; Spearman rank correlation was strong (glass bead-activated test vs aggregometry: rho = 0.823, P < .001; glass bead test with heparinase vs aggregometry: rho = 0.856, P < .001). After additional administration of heparin, platelet inhibition was only comparable for the glass bead test with heparinase and aggregometry, and the correlation coefficient remained unchanged for the glass bead test with heparinase versus aggregometry (rho = 0.878, P < .001). By contrast, the glass bead-activated test showed a nearly complete platelet inhibition with a significant bias compared with the glass bead test with heparinase and aggregometry. Correlation was weak for the glass bead-activated test versus aggregometry (rho = 0.407, P = .004).

CONCLUSIONS

When compared with platelet aggregometry, the glass bead-activated test from Sonoclot reliably detects glycoprotein IIb/IIIa receptor inhibition with tirofiban in unheparinized whole blood. However, in heparinized blood the glass bead test with heparinase is essential to accurately assess platelet function.

Eptifibatide

Eptifibatide (Integrilin) is a highly specific, reversible, intravenously administered glycoprotein (GP) IIb/IIIa receptor antagonist that acts at the final common step of the platelet aggregation pathway. Data from large clinical trials indicate that intravenous eptifibatide as adjunctive therapy to standard care is effective in patients with non-ST-segment elevation (NSTE) acute coronary syndromes (ACS) and/or undergoing percutaneous coronary intervention (PCI). In the ESPRIT (Enhanced Suppression of the Platelet glycoprotein IIb/IIIa Receptor with Integrilin Therapy) trial in patients undergoing PCI with stenting, eptifibatide, compared with placebo, achieved significant reductions in death and ischaemic complications and was better than a strategy of reserving treatment for the bailout situation. In the large PURSUIT (Platelet IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy) trial in patients with NSTE ACS, eptifibatide was associated with a significant reduction in the incidence of death or myocardial infarction (MI) compared with placebo. Eptifibatide is well tolerated in these trials. Ongoing trials are currently investigating the efficacy and tolerability of regimens that include this agent in other indications, including ST-segment elevation MI (STEMI).

Evaluation of Bleeding Complications Associated with Glycoprotein IIb/IIIa Inhibitors

BACKGROUND

Platelet glycoprotein IIb/IIIa inhibitors are used with aspirin and heparin to decrease rates of death, myocardial infarction, and urgent revascularization in patients with acute coronary syndromes.

OBJECTIVE

To determine whether bleeding event rates differed among 3 glycoprotein IIb/IIIa inhibitors prescribed in a high-risk, elderly veteran population and identify risk factors for bleeding.

METHODS

A retrospective chart analysis of patients who received abciximab, eptifibatide, or tirofiban was conducted. χ2 Analysis evaluated the incidence of bleeding complications, and stepwise regression analysis was utilized to identify bleeding risk factors. Parameters evaluated as possible risk factors for bleeding included age, renal function, weight, heparin and glycoprotein IIb/IIIa inhibitor dosing and infusion duration, concomitant antiplatelet and/or anticoagulant medications or disease states, and baseline hemoglobin, hematocrit, or platelet counts.

RESULTS

Of 348 patients whose charts were reviewed, 79 patients were included. There were 37.9% who received abciximab (n = 30), 30.3% who received eptifibatide (n = 24), and 31.6% who received tirofiban (n = 25). Twenty-one bleeding events not related to coronary artery bypass grafting occurred: only 1 major bleed (tirofiban) and 20 minor bleeds. Bleeding rates were not significantly different between groups: abciximab 30% (n = 9), eptifibatide 21% (n = 5), and tirofiban 28% (n = 7). Significant risk factors for bleeding included patient weight, infusion duration, and baseline platelet count (p = 0.024). Patients who bled received significantly more transfusions of packed red blood cells and platelets than patients with no bleeding (p = 0.047).

CONCLUSIONS

Although bleeding complications did not differ significantly between the 3 drugs, several risk factors for bleeding events were identified. A considerable rate of bleeding events occurred in this high-risk patient population.

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.

Meta-analysis of survival with platelet glycoprotein IIb/IIIa antagonists for percutaneous coronary interventions

We performed a cumulative meta-analysis of available studies to evaluate the effect of intravenous platelet glycoprotein (GP) IIb/IIIa antagonists on survival at 30 days and 6 months after percutaneous coronary intervention (PCI). Compounds that block the GP IIb/IIIa receptor substantially reduce myocardial infarctions (MIs) and repeat revascularization. We included 12 trials, which enrolled 20,186 patients in all, in the analysis. Overall, 30-day mortality was significantly reduced with GP IIb/IIIa inhibition (odds ratio 0.73, 95% confidence interval 0.55 to 0.96, p = 0.024). Although 10 of the 12 trials showed a beneficial effect of GP IIb/IIIa inhibitor treatment on mortality, no individual trial detected a statistically significant mortality benefit. The 30-day mortality benefit became significant at the p <0.05 level with addition of the ADMIRAL trial and was further enhanced by the CADILLAC trial. No significant heterogeneity was detected in the collection of trials. At 6 months, the odds ratio was 0.84 (95% confidence interval 0.69 to 1.03, p = 0.087). This survival benefit amounts to preventing approximately 1 of every 3 deaths that occur within 30 days after PCI, saving 2.8 lives/1,000 patients treated (number needed to treat, 357). Thus, patients who undergo PCI can expect significantly lower 30-day mortality, in addition to known reductions in nonfatal MI and repeat procedures, with GP IIb/IIa inhibition. There also is increasing evidence that mortality reductions are preserved at 6 months.