ESPRIT Investigators. Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy. Novel dosing regimen of eptifibatide in planned coronary stent implantation (ESPRIT): a randomised, placebo-controlled trial

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.

Acute coronary syndrome in the elderly

The spectrum of acute coronary syndrome (ACS) including unstable angina, non-ST-elevation myocardial infarction and ST-elevation myocardial infarction accounts for increasing numbers of deaths among persons age > or = 65 years in the US. This is important given demographic changes involving falling birth rates and increasing life expectancy. Elderly patients are likely to benefit the most from treatment of ACS, even though community practice still demonstrates less use of cardiac medications as an early-invasive approach among this population.

Profound thrombocytopenia after primary exposure to eptifibatide

Eptifibatide is a glycoprotein IIb/IIIa receptor antagonist used to reduce the incidence of ischemic events in patients with acute coronary syndromes and those undergoing percutaneous coronary intervention. A minority of patients given eptifibatide develop acute, profound thrombocytopenia (<20,000 cells/mm(3)) within a few hours of receiving the drug. This case report discusses a patient who developed profound thrombocytopenia within hours of receiving eptifibatide for the first time. The Naranjo algorithm classified the likelihood that this patient's thrombocytopenia was related to eptifibatide as probable. Profound thrombocytopenia is an uncommon but clinically important complication of eptifibatide. This case report emphasizes the importance of monitoring platelet counts routinely at baseline and within 2-6 hours of eptifibatide administration.

Platelet inhibition with cangrelor in patients undergoing PCI

BACKGROUND

Cangrelor, a nonthienopyridine adenosine triphosphate analogue, is an intravenous blocker of the adenosine diphosphate receptor P2Y(12). This agent might have a role in the treatment of patients who require rapid, predictable, and profound but reversible platelet inhibition.

METHODS

We performed a large-scale international trial comparing cangrelor with 600 mg of oral clopidogrel administered before percutaneous coronary intervention (PCI) in patients with acute coronary syndromes. The primary efficacy end point was a composite of death from any cause, myocardial infarction, or ischemia-driven revascularization at 48 hours.

RESULTS

We enrolled 8877 patients, and 8716 underwent PCI. At 48 hours, cangrelor was not superior to clopidogrel with respect to the primary composite end point, which occurred in 7.5% of patients in the cangrelor group and 7.1% of patients in the clopidogrel group (odds ratio, 1.05; 95% confidence interval [CI], 0.88 to 1.24; P=0.59). Likewise, cangrelor was not superior at 30 days. The rate of major bleeding (according to Acute Catheterization and Urgent Intervention Triage Strategy criteria) was higher with cangrelor, a difference that approached statistical significance (3.6% vs. 2.9%; odds ratio, 1.26; 95% CI, 0.99 to 1.60; P=0.06), but this was not the case with major bleeding (according to the Thrombolysis in Myocardial Infarction criteria) or severe or life-threatening bleeding (according to Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries criteria). A secondary exploratory end point of death from any cause, Q-wave myocardial infarction, or ischemia-driven revascularization showed a trend toward a reduction with cangrelor, but it was not significant (0.6% vs. 0.9%; odds ratio, 0.67; 95% CI, 0.39 to 1.14; P=0.14).

CONCLUSIONS

Cangrelor, when administered intravenously 30 minutes before PCI and continued for 2 hours after PCI, was not superior to an oral loading dose of 600 mg of clopidogrel, administered 30 minutes before PCI, in reducing the composite end point of death from any cause, myocardial infarction, or ischemia-driven revascularization at 48 hours. (ClinicalTrials.gov number, NCT00305162.)

Impact of computerized dosing on eptifibatide-associated bleeding and mortality

OBJECTIVE

The study aimed to determine the impact on eptifibatide-associated bleeding by implementing a computerized dosing algorithm in the cardiac catheterization suite.

BACKGROUND

Excessive dosing of eptifibatide is associated with increased bleeding rates and hospital mortality. Although dosing adjustments based on renal function has been recommended, its implementation and clinical impact have not been assessed in daily practice.

METHODS

A computerized algorithm was implemented in January 2006 to calculate appropriate eptifibatide infusion dose (1 microg kg(-1) min(-1) for creatinine clearance <50 mL/min or 2 microg kg(-1) min(-1) for creatinine clearance >or=50 mL/min) using the Cockroft-Gault formula. All patients had hemoglobin measured before and the day after the procedure. Bleeding within 24 hours and mortality during hospitalization were compared in consecutive patients before and after implementation of the algorithm.

RESULTS

A total of 334 patients qualified for inclusion (pre-algorithm n = 91, post-algorithm n = 243). There was an increase in the proportion of patients receiving recommended doses of eptifibatide dosing (74.7% pre-algorithm vs 97.5% post-algorithm, P <or= .0001). Twenty-four-hour bleeding complications as classified using 3 major bleeding classification systems were reduced as was hospital mortality (4.4% vs 0%, P = .005). Packed red blood cell transfusion rates were similar between both groups (4.4% pre-algorithm vs 2.1% post-algorithm, P = .26).

CONCLUSIONS

In patients receiving eptifibatide in the catheterization laboratory before percutaneous coronary intervention, implementation of a computerized algorithm was associated with appropriate dosing and reduced bleeding and mortality.

[Therapeutic approach in patients undergoing percutaneous coronary interventions]

While the performance of percutaneous coronary interventions remains the domain of interventional cardiologists, the management of these patients before, during, and after the procedure is in the domain of general cardiologists, internists and primary care physicians. Therefore, for optimal patient care it is crucial that all engaged physicians should understand the procedural risks, complications and optimal treatment strategy before, during and after the procedure. Before a percutanous coronary intervention, patients with known allergies to iodinated contrast dye should be pretreated with oral corticosteroids and H1-receptor blockers. Diabetic patients as well as patients with renal failure need special care. Hydration is crucial for patients with renal insufficiency in order to minimise the risk of contrast nephropathy. Metformin therapy should be discontinued before the procedure in patients with renal failure in order to avoid lactic acidosis, and it should be reinstituted after the procedure only when normal serum creatine level is confirmed. Double antiplatelet therapy (aspirin plus clopidogrel) should be initiated at least six hours before the procedure. While aspirin therapy after the procedure is life long, the duration of clopidogrel therapy depends on the type of implanted stent (in patients with bare stents implanted clopidogrel should be taken at least 3 - 4 weeks post procedural, and in patients with drug-eluting stents implanted clopidogrel should be taken at least 6 - 12 months after the procedure due to in-stent restenosis prevention). Patients who experience typical anginal pain in a period of one to eight month after percutaneous coronary revascularization are likely to have restenosis, and they should be reevaluated with stress echocardiography and/or repeated coronary angiography.

Design and rationale of the Evaluation of M118 IN pErcutaNeous Coronary intErvention (EMINENCE) trial

BACKGROUND

Currently recommended anticoagulant agents used in the setting of percutaneous coronary intervention (PCI) inhibit, with varying degrees of intensity, 2 critical targets (factor Xa and/or IIa) of the coagulation cascade, yet they carry significant limitations. M118-a novel, rationally engineered heparin-provides consistent anti-Xa and anti-IIa activity with a constant anti-Xa:anti-IIa ratio over time. M118 also combines the desired anticoagulant effects of unfractionated heparin with the beneficial attributes of low-molecular-weight heparin, and may represent the next generation of heparin therapy in patients diagnosed with acute coronary syndrome.

STUDY DESIGN

The EMINENCE trial is a prospective, randomized, open-label, multicenter phase 2 study that will evaluate the safety and feasibility of M118 as an anticoagulant versus unfractionated heparin in subjects with stable coronary artery disease undergoing PCI. The primary end point of the study will be the combined incidence of clinical events defined as the composite of 30-day death, myocardial infarction, repeat revascularization, catheter thrombus, stroke, thrombocytopenia, bailout use of glycoprotein IIb/IIIa inhibitors, and major or minor bleeding.

CONCLUSION

The EMINENCE trial will assess the safety and feasibility of M118 as an anticoagulant in the setting of PCI and will provide important information to determine the appropriate therapeutic range of activated clotting time for M118 and the appropriate dose or doses to be explored in a phase 3 clinical trial.

Effect of operator and institutional volume on clinical outcomes after percutaneous coronary interventions performed in Canada and the United States: a brief report from the Enhanced Suppression of the Platelet glycoprotein IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) study

BACKGROUND

The Enhanced Suppression of the Platelet glycoprotein IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial compared the use of eptifibatide with placebo in 2064 coronary intervention patients. It was previously reported that Canadian patients had reduced rates of 30-day and one-year death, myocardial infarction (MI) or target vessel revascularization (TVR) compared with patients in the United States (US).

OBJECTIVE

To examine whether operator or institutional volume differences explain the regional variation in clinical outcome.

METHODS AND RESULTS

Each site received an operator and institutional volume survey. Fifty-seven sites (62%) returned complete data on 1338 patients. In this smaller cohort, Canadian patients had reduced rates of 30-day and one-year death, MI or TVR compared with US patients (6.3% versus 10.3% and 14.9% versus 20.1%, respectively; P<0.05 for both comparisons). Among 176 physicians with a median of 13 years experience, the median operator volume was 200 cases per year. Operators with fewer than 100 cases per year had higher rates of 30-day death, MI or TVR (13.2% versus 8.7%; P=0.18) and large MI (7.7% versus 3.3%; P=0.06) than those with 100 or more cases per year. The median institutional volume was 1064 cases per year. Canadian and US centres had similar operator and institutional volumes. By multivariate modelling, operator volume was not predictive of adverse clinical events. However, the rates of 30-day and one-year death, MI or TVR fell by 3% for every 100 patients treated by the institution (OR 0.97; P=0.058 and P=0.002, respectively). Enrollment in Canada was associated with improved outcomes at 30 days (OR 0.50; P=0.001) and one year (OR 0.66; P=0.001) despite inclusion of volume variables in the models.

CONCLUSIONS

In the ESPRIT study, institutional volume was associated with a modest reduction in risk of death, MI or TVR over short- and long-term follow-up periods. The Canadian and US investigators and institutions selected in ESPRIT had similar annual procedural volumes. Therefore, volume variables did not explain the differential risk of clinical events observed for patients enrolled in the two countries.

Selecting the optimal antithrombotic regimen for patients with acute coronary syndromes undergoing percutaneous coronary intervention

The wide variety of anticoagulant and antiplatelet agents available for clinical use has made choosing the optimal antithrombotic regimen for patients with acute coronary syndromes undergoing percutaneous coronary intervention a complex task. While there is no single best regimen, from a risk-benefit ratio standpoint, particular regimens may be considered optimal for different patients. We review the mechanisms of action for the commonly prescribed antithrombotic medications, summarize pertinent data from randomized trials on their use in acute coronary syndromes, and provide an algorithm (incorporating data from these trials as well as risk assessment instruments) that will help guide the decision-making process.

Association of cytochrome P450 2C19 genotype with the antiplatelet effect and clinical efficacy of clopidogrel therapy

CONTEXT

Clopidogrel therapy improves cardiovascular outcomes in patients with acute coronary syndromes and following percutaneous coronary intervention by inhibiting adenosine diphosphate (ADP)-dependent platelet activation. However, nonresponsiveness is widely recognized and is related to recurrent ischemic events.

OBJECTIVE

To identify gene variants that influence clopidogrel response.

DESIGN, SETTING, AND PARTICIPANTS

In the Pharmacogenomics of Antiplatelet Intervention (PAPI) Study (2006-2008), we administered clopidogrel for 7 days to 429 healthy Amish persons and measured response by ex vivo platelet aggregometry. A genome-wide association study was performed followed by genotyping the loss-of-function cytochrome P450 (CYP) 2C19*2 variant (rs4244285). Findings in the PAPI Study were extended by examining the relation of CYP2C19*2 genotype to platelet function and cardiovascular outcomes in an independent sample of 227 patients undergoing percutaneous coronary intervention.

MAIN OUTCOME MEASURE

ADP-stimulated platelet aggregation in response to clopidogrel treatment and cardiovascular events.

RESULTS

Platelet response to clopidogrel was highly heritable (h(2) = 0.73; P < .001). Thirteen single-nucleotide polymorphisms on chromosome 10q24 within the CYP2C18-CYP2C19-CYP2C9-CYP2C8 cluster were associated with diminished clopidogrel response, with a high degree of statistical significance (P = 1.5 x 10(-13) for rs12777823, additive model). The rs12777823 polymorphism was in strong linkage disequilibrium with the CYP2C19*2 variant, and was associated with diminished clopidogrel response, accounting for 12% of the variation in platelet aggregation to ADP (P = 4.3 x 10(-11)). The relation between CYP2C19*2 genotype and platelet aggregation was replicated in clopidogrel-treated patients undergoing coronary intervention (P = .02). Furthermore, patients with the CYP2C19*2 variant were more likely (20.9% vs 10.0%) to have a cardiovascular ischemic event or death during 1 year of follow-up (hazard ratio, 2.42; 95% confidence interval, 1.18-4.99; P = .02).

CONCLUSION

CYP2C19*2 genotype was associated with diminished platelet response to clopidogrel treatment and poorer cardiovascular outcomes.

A comparison of the radial and the femoral approaches in primary or rescue percutaneous coronary intervention for acute myocardial infarction in the elderly

BACKGROUND

Access site complications are reduced using radial percutaneous coronary intervention (PCI). There is concern that technical difficulties using this approach can delay achievement of reperfusion during primary or rescue PCI for acute myocardial infarction (AMI) especially in elderly patients.

METHODS AND RESULTS

We studied 155 patients (pts) > or = 70 years who underwent primary or rescue PCI for AMI; radial (Group1; 87 pts) or femoral (Group2; 68 pts). Baseline characteristics, the amount of IIB/IIIA inhibitor, contrast and heparin used, and TIMI flow pre and post PCI were similar in both groups (P>0.05). Time from arrival in the catheterization laboratory to the first balloon inflation (Group 1: 44.0+/-21.5 versus Group 2 38.8+/-18.7 min) was also similar, but was significantly longer (61.2+/-11.1 min) compared to both groups in patients with a failed radial approach (7 pts, 8%). Angiographic success, and in-hospital MACE were also similar in the two groups, but vascular access site complications were significantly higher in Group 2 (0 versus 2.9%, P<0.05).

CONCLUSION

The use of the radial approach in elderly patients undergoing primary and rescue PCI, when successful, is safe and effective as the femoral approach, and leads to fewer vascular complications.

Switch from abciximab to eptifibatide during percutaneous coronary intervention

BACKGROUND

Treatment with glycoprotein (GP) IIb/IIIa inhibitors during percutaneous coronary intervention (PCI) reduce ischemic complications and improve outcome. Of the GPIIb/IIIa inhibitors abciximab is better documented than eptifibatide, but the former is more expensive. The aim of this study was to monitor a switch from abciximab to eptifibatide with respect to clinical outcome up to six months after PCI.

METHODS

All consecutive patients that six months before and six months after a switch from abciximab to eptifibatide received GPIIb/IIIa inhibitors during and after de novo PCIs were followed for six months with respect to clinical outcome.

RESULTS

310 patients received abciximab and 350 eptifibatide. Baseline characteristics were similar in the two groups. 55% of the patients underwent PCI for acute ST-elevation myocardial infarction and 41% for unstable coronary artery disease. There were trends for lower mortality among abciximab-treated than among the eptifibatide-treated patients during in-hospital stay (0.6% vs 2.0%:NS) as well as during the six month follow up (2.3% vs 3.7%:NS). The combined endpoint of death, myocardial infarction, stroke, repeated revascularisation and serious bleeding occurred in 14.9% in the abciximab group vs 16.8% in the eptifibatide group (NS).

CONCLUSION

The study could not demonstrate any significant deterioration of clinical results after a switch from abciximab to eptifibatide as routine GPIIb/IIIa inhibition during PCI. With respect to the limited number of patients a clinical significant difference between the two GPIIb/IIIa inhibitors cannot, however, be excluded.

Early versus delayed, provisional eptifibatide in acute coronary syndromes

BACKGROUND

Glycoprotein IIb/IIIa inhibitors are indicated in patients with acute coronary syndromes who are undergoing an invasive procedure. The optimal timing of the initiation of such therapy is unknown.

METHODS

We compared a strategy of early, routine administration of eptifibatide with delayed, provisional administration in 9492 patients who had acute coronary syndromes without ST-segment elevation and who were assigned to an invasive strategy. Patients were randomly assigned to receive either early eptifibatide (two boluses, each containing 180 microg per kilogram of body weight, administered 10 minutes apart, and a standard infusion > or = 12 hours before angiography) or a matching placebo infusion with provisional use of eptifibatide after angiography (delayed eptifibatide). The primary efficacy end point was a composite of death, myocardial infarction, recurrent ischemia requiring urgent revascularization, or the occurrence of a thrombotic complication during percutaneous coronary intervention that required bolus therapy opposite to the initial study-group assignment ("thrombotic bailout") at 96 hours. The key secondary end point was a composite of death or myocardial infarction within the first 30 days. Key safety end points were bleeding and the need for transfusion within the first 120 hours after randomization.

RESULTS

The primary end point occurred in 9.3% of patients in the early-eptifibatide group and in 10.0% in the delayed-eptifibatide group (odds ratio, 0.92; 95% confidence interval [CI], 0.80 to 1.06; P=0.23). At 30 days, the rate of death or myocardial infarction was 11.2% in the early-eptifibatide group, as compared with 12.3% in the delayed-eptifibatide group (odds ratio, 0.89; 95% CI, 0.79 to 1.01; P=0.08). Patients in the early-eptifibatide group had significantly higher rates of bleeding and red-cell transfusion. There was no significant difference between the two groups in rates of severe bleeding or nonhemorrhagic serious adverse events.

CONCLUSIONS

In patients who had acute coronary syndromes without ST-segment elevation, the use of eptifibatide 12 hours or more before angiography was not superior to the provisional use of eptifibatide after angiography. The early use of eptifibatide was associated with an increased risk of non-life-threatening bleeding and need for transfusion. (ClinicalTrials.gov number, NCT00089895.)

Management of patients with unstable angina / non-ST-elevation myocardial infarction: a critical review of the 2007 ACC /AHA guidelines

BACKGROUND

In 2007, the American College of Cardiology/American Heart Association (ACC/AHA) published new guidelines for the diagnosis and management of patients with unstable angina/non-ST segment elevation myocardial infarction (UA/NSTEMI). These guidelines include some important updates on the use of clopidogrel, fondaparinux, bivalirudin and low-molecular-weight heparins (LMWHs) all of which have published landmark clinical trials in patients with acute coronary syndromes (ACS) since the publication of the 2002 guidelines. While these 2007 guidelines are more comprehensive and up-to-date compared with the recommendations published in 2002, they also raise many questions for practising emergency physicians and cardiologists.

METHODS

This article presents a critical review of the 2007 ACC/AHA UA/NSTEMI guidelines, highlighting some of the areas of controversy, with the aim of providing some further guidance to practising physicians.

CONCLUSIONS

Despite recent updates to the ACC/AHA UA/NSTEMI guidelines, additional factors need to be taken into consideration in the management of UA/NSTEMI patients. Integrating initial responses with early or selectively invasive strategies and the risks of complications in subsequent procedures require careful consideration. Protocol development within an institution is required to risk-stratify patients rapidly, provide optimum precatheterisation medical management and allow seamless and rapid transitions to the catheterisation laboratory in patients at risk for adverse events.

Safety and tolerability of SCH 530348 in patients undergoing non-urgent percutaneous coronary intervention: a randomised, double-blind, placebo-controlled phase II study

BACKGROUND

An antithrombotic drug is needed that safely reduces cardiovascular events in patients undergoing percutaneous coronary intervention (PCI). We therefore assessed the tolerability and safety of SCH 530348-an oral platelet protease-activated receptor-1 antagonist.

METHODS

We randomly assigned patients aged 45 years or older and undergoing non-urgent PCI or coronary angiography with planned PCI to an oral loading dose of SCH 530348 (10 mg, 20 mg, or 40 mg) or matching placebo in a 3:1 ratio in a multicentre international study. Those in the SCH 530348 group who subsequently underwent PCI (primary PCI cohort) continued taking an oral maintenance dose (0.5 mg, 1.0 mg, or 2.5 mg per day), and patients in the placebo group continued placebo for 60 days. The primary endpoint was the incidence of clinically significant major or minor bleeding according to the thrombolysis in myocardial infarction (TIMI) scale. Both investigators and patients were unaware of treatment allocation. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00132912.

FINDINGS

257 patients were assigned to placebo and 773 to SCH 530348. The primary endpoint occurred in 2 (2%) of 129, 3 (3%) of 120, and 7 (4%) of 173 patients, respectively, in the SCH 530348 10 mg, 20 mg, and 40 mg groups compared with 5 (3%) of 151 patients in the placebo group (p=0.5786). TIMI major plus minor bleeding occurred in 3 (2%) of 136, 5 (4%) of 139, and 4 (3%) of 138 patients given SCH 530348 0.5 mg, 1.0 mg, and 2.5 mg once per day, respectively (p=0.7561).

INTERPRETATION

Oral SCH 530348 was generally well tolerated and did not cause increased TIMI bleeding, even when administered concomitantly with aspirin and clopidogrel. Further testing in phase III trials to accurately define the safety and efficacy of SCH 530348 is warranted.

Eptifibatide-induced thrombocytopenia and thrombosis in humans require FcgammaRIIa and the integrin beta3 cytoplasmic domain

Thrombocytopenia and thrombosis following treatment with the integrin alphaIIbbeta3 antagonist eptifibatide are rare complications caused by patient antibodies specific for ligand-occupied alphaIIbbeta3. Whether such antibodies induce platelet clearance by simple opsonization, by inducing mild platelet activation, or both is poorly understood. To gain insight into the mechanism by which eptifibatide-dependent antibodies initiate platelet clearance, we incubated normal human platelets with patient serum containing an alphaIIbbeta3-specific, eptifibatide-dependent antibody. We observed that in the presence of eptifibatide, patient IgG induced platelet secretion and aggregation as well as tyrosine phosphorylation of the integrin beta3 cytoplasmic domain, the platelet FcgammaRIIa Fc receptor, the protein-tyrosine kinase Syk, and phospholipase Cgamma2. Each activation event was inhibited by preincubation of the platelets with Fab fragments of the FcgammaRIIa-specific mAb IV.3 or with the Src family kinase inhibitor PP2. Patient serum plus eptifibatide did not, however, activate platelets from a patient with a variant form of Glanzmann thrombasthenia that expressed normal levels of FcgammaRIIa and the alphaIIbbeta3 complex but lacked most of the beta3 cytoplasmic domain. Taken together, these data suggest a novel mechanism whereby eptifibatide-dependent antibodies engage the integrin beta3 subunit such that FcgammaRIIa and its downstream signaling components become activated, resulting in thrombocytopenia and a predisposition to thrombosis.

Stent parameters predict major adverse clinical events and the response to platelet glycoprotein IIb/IIIa blockade: findings of the ESPRIT trial

BACKGROUND

Only limited data describe relationships between stent parameters (length and diameter), adverse events after percutaneous coronary intervention, and effects of platelet glycoprotein IIb/IIIa blockade by stent parameters.

METHODS AND RESULTS

In this post hoc analysis of the 1983 patients receiving a stent in the Enhanced Suppression of the Platelet Glycoprotein IIb/IIIa Receptor with Integrilin Therapy randomized percutaneous coronary intervention trial of eptifibatide versus placebo, rates of the major adverse cardiac event (MACE) end point (death, myocardial infarction, urgent target-vessel revascularization, or thrombotic bailout) at 48 hours and 1 year were correlated with stent parameters and then analyzed by randomization to eptifibatide versus placebo. In the placebo group, MACE increased with number of stents implanted, total stent length (by quartiles of <15, 15 to <18, 18 to <30, and >or=30 mm), and total stented vessel area (by quartiles of area <141, 141 to <188, 188 to <292, and >or=292 mm(2)). By stent parameters, MACE at 48 hours was reduced in the eptifibatide group at stent lengths of 18 to <30 mm (odds ratio [OR], 0.55; 95% CI, 0.32 to 0.94; P=0.030) and >or=30 mm (OR, 0.43; 95% CI, 0.25 to 0.75; P=0.003), stent diameters of >2.5 to <3.5 mm (OR, 0.56; 95% CI, 0.39 to 0.82; P=0.002), and with 2 stents implanted (OR, 0.39; 95% CI, 0.22 to 0.69; P=0.001). In the placebo group, near-linear relationships were observed between both increasing stent length and increasing stented vessel area and MACE at 48 hours and 1 year (all, P<0.001); these gradients were flattened in the eptifibatide group (P=0.005 for stent length).

CONCLUSIONS

Stent parameters predict MACE after percutaneous coronary intervention. Glycoprotein IIb/IIIa blockade mitigates much of the hazard of increasing procedural complexity.

Bolus-only versus bolus + infusion of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention

BACKGROUND

The present study was done to analyze if glycoprotein IIb/IIIa inhibitors (GPI) bolus-only will reduce vascular/bleeding complications and cost with similar major adverse cardiac events (MACE) when compared with GPI bolus + infusion. Evidence-based therapy of GPI inhibitors during percutaneous coronary intervention (PCI) incorporates intravenous bolus followed by 12 to 18 hours of infusion. However, GPI bolus + infusion may increase vascular/bleeding complications and may not reduce MACE when compared with GPI bolus-only.

METHODS

From January 1, 2003, to December 31, 2004, 2,629 consecutive patients received GPI during PCI at a single center. Of these, 1,064 patients received GPI bolus + infusion in 2003 and were compared with 1,565 patients that received GPI bolus-only in 2004. Baseline characteristics were similar in both groups.

RESULTS

Patients receiving GPI bolus-only had reduced vascular/bleeding complications when compared with bolus + infusion (4.9% vs 7%, P < .05, odds ratio 0.62, 95% confidence interval 0.45-0.89). Furthermore, ischemic complications were similar in both groups, including periprocedural creatine kinase-MB enzyme release (12.8% vs 15.3%, P = NS), MACE at 30 days (3.2% vs 3%, P = NS), and death and myocardial infarction at 1 year (7.1% vs 7.8%, P = NS). In addition, GPI bolus-only reduced cost in US dollars ($323 vs $706, P < .001) and increased ambulatory PCI (13.1% vs 3.2%, P < .01), with reduced length of stay (1.1 vs 1.6 days, P < .01), when compared with GPI bolus + infusion.

CONCLUSIONS

Glycoprotein inhibitor bolus-only reduces vascular/bleeding complications with similar MACE and reduced cost when compared with GPI bolus + infusion. In addition, GPI bolus-only improved ambulatory PCI and reduced length of stay. These results are consistent with a safer and cost-effective strategy for bolus-only when GPI therapy is considered during PCI.

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.

Effects of coronary prestenting platelet inhibition on coronary poststenting inflammation

The aim of this study was to analyze the effect of 2 antiplatelet regimens on the inhibition of GP IIb/IIIa-dependent platelet activation and their association with the poststenting inflammatory response. Seventeen patients with acute myocardial infarction were divided into 2 groups: (A) clopidogrel plus tirofiban infusion administered together during inclusion (n = 10); (B) clopidogrel administered at inclusion and followed 2 hours after by tirofiban (n = 7). Blood samples were obtained at inclusion and at 24 and 48 hours after stenting. Before stenting, a greater reduction of GP IIb/IIIa-dependent platelet activation was found in both groups, although it was greater in group A than in group B. This statistical difference was not observed at 24 and 48 hours after the procedure. At 48 hours after stenting, interleukin-6, interleukin-10, soluble intracellular adhesion molecule-1, and soluble CD40 ligand plasma values were not different between experimental groups. By proteomics, different isoforms of the following proteins were identified: alpha 1-antitrypsin (ATT-1), fibrinogen gamma chain, apolipoprotein A-IV, apolipoprotein A-I, vitamin D binding protein, haptoglobin, and serotransferrin. At 48 hours after stenting, only the plasma expression of the ATT-1 isoform 5 was significantly increased in group A compared with group B. In conclusion, a greater inhibition of GP IIb/IIIa-dependent platelet activation before stenting was not correlated with a different inflammatory activity early after stenting.

Bleeding risk and outcomes of Bivalirudin versus Glycoprotein IIb/IIIa inhibitors with targeted low-dose unfractionated Heparin in patients having percutaneous coronary intervention for either stable or unstable angina pectoris

For patients undergoing elective percutaneous coronary intervention (PCI), procedural anticoagulation with bivalirudin was previously shown to significantly reduce bleeding complications at the cost of a modest increase in ischemic events compared with unfractionated heparin (UFH) and glycoprotein IIb/IIIa inhibitors (GPIs). However, the excess bleeding in patients treated with UFH and GPIs may have been caused by excessively high UFH doses and increased activated clotting times. This study sought to determine the bleeding risk of targeted low-dose UFH with GPIs compared with bivalirudin in patients undergoing elective PCI. Of 1,205 patients undergoing elective PCI, 602 underwent PCI with adjunctive UFH and GPIs with the UFH dose targeted to an activated clotting time of approximately 250 seconds, and 603 patients matched for baseline characteristics underwent PCI with bivalirudin. Outcomes were analyzed for major bleeding (hematocrit decrease >15%, gastrointestinal bleed, or major hematoma) and 6-month major adverse cardiac events (death, myocardial infarction, and target-lesion revascularization). The maximum activated clotting time achieved was 261.7 +/- 61.6 seconds in the UFH/GPI group and 355.4 +/- 66.6 in the bivalirudin group (p <0.001). In-hospital major bleeding rates were similar between groups (1.8% UFH/GPI vs 1.7% bivalirudin; p = 0.83), as were transfusion requirements (1.2% UFH/GPI vs 0.5% bivalirudin; p = 0.61). The 6-month major adverse cardiac event rate was also similar between groups (9.5% UFH/GPI vs 9.0% bivalirudin; p = 0.81). In conclusion, there were no significant differences in major bleeding and 6-month major adverse cardiac events for patients undergoing elective PCI treated with targeted low-dose UFH and GPIs compared with those treated with bivalirudin.

A review of clinical trials with eptifibatide in cardiology

Glycoprotein (GP) IIb/IIIa receptor antagonists inhibit the binding of ligands to activated platelet GP IIb/IIIa receptors and, therefore, prevent the formation of platelet thrombi. Additional antithrombin therapy should be given in connection with GP IIb/IIIa administration. Eptifibatide is a small heptapeptide, which is highly selective and rapidly dissociates from its receptor after cessation of therapy. In clinical trials (IMPACT-II and ESPRIT) concomitant administration of eptifibatide to patients undergoing percutaneous coronary intervention (PCI) reduced thrombotic complications. In the PURSUIT trial, in patients with non-ST-elevation acute coronary syndromes, eptifibatide, compared to placebo, significantly reduced the primary endpoint of death and nonfatal myocardial infarction at 30 days. In patients with STEMI eptifibatide has been studied as an adjunct to fibrinolysis and primary PCI; it improved epicardial flow and tissue reperfusion. Current studies are evaluating eptifibatide as upstream therapy in high-risk patients with NSTE-ACS, in the EARLY-ACS and in comparison with abciximab in patients with primary PCI in the EVA-AMI trial.

A longitudinal analysis of outcomes associated with abciximab and eptifibatide in a consecutive series of 3074 percutaneous coronary interventions

BACKGROUND

Although the efficacy of platelet glycoprotein IIb/IIIa inhibitors (GPIIb/IIIa) in reducing complication rates during percutaneous coronary intervention (PCI) is well established, comparative studies assessing currently approved agents as administered in current practice are limited. We studied the clinical and length of stay (LOS) outcomes of patients undergoing PCI who received either abciximab or eptifibatide.

METHODS

All patients undergoing elective, urgent, or emergency PCI at Mayo Clinic Rochester between November 17, 2000 and August 31, 2004 who received either abciximab or eptifibatide were included. Clinical, angiographic, and follow-up data were prospectively recorded in the Mayo Clinic PCI Registry; administrative data recorded LOS. We used logistic and Cox proportional hazard models to estimate the risk of adverse events and generalized linear modeling to predict LOS. Propensity score and standard risk adjustments were used to account for baseline differences.

RESULTS

A total of 2123 PCI patients received eptifibatide and 951 received abciximab. The adjusted odds ratio for in-hospital death and myocardial infarction (MI) with eptifibatide was 0.80 (95% CI 0.56-1.14, P = 0.21) versus abciximab. Adjusted hazard ratios for death and MI and for death, MI, or target vessel revascularization during a median follow-up of 24.6 months were 0.84 (95% CI 0.68-1.02, P = 0.08) and 0.95 (95% CI 0.81-1.11, P = 0.53), respectively. Adjusted postprocedural LOS was similar at 3.4 days.

CONCLUSION

This large observational study found no evidence of a clinical or LOS advantage to physician choice of either abciximab or eptifibatide during PCI in contemporary practice.

Efficacy and safety of clopidogrel pretreatment before percutaneous coronary intervention with and without glycoprotein IIb/IIIa inhibitor use

BACKGROUND

Clopidogrel pretreatment before percutaneous coronary intervention (PCI) has been shown to reduce the risk of death and ischemic complications after PCI. However, the need for clopidogrel pretreatment is debated in patients receiving a glycoprotein IIb/IIIa inhibitor (GPI).

METHODS

We performed a collaborative meta-analysis of the results of 3 randomized trials of clopidogrel pretreatment: PCI-CURE, CREDO, and PCI-CLARITY. Patients were stratified based on GPI use at the time of PCI (a postrandomization subgroup analysis). Odds ratios (ORs) and 95% CIs for the effect of clopidogrel pretreatment versus placebo pretreatment on the incidence of cardiovascular death, myocardial infarction (MI), or stroke for up to 30 days after PCI were calculated for each trial within each GPI stratum and were combined using a random effects model.

RESULTS

Six thousand three hundred twenty-five patients were included, 32.4% of whom received a GPI. There was a consistent benefit of clopidogrel pretreatment in reducing the incidence of cardiovascular death, MI, or stroke after PCI both in patients who did not receive a GPI (OR 0.72, 95% CI 0.53-0.98, P = .03) and in those who did (OR 0.69, 95% CI 0.47-1.00, P = .05). There was no evidence of heterogeneity in the benefit of clopidogrel pretreatment between GPI use strata (P = .85 for heterogeneity). Clopidogrel pretreatment was not associated with a significant excess of TIMI major or minor bleeding, either in those who did not receive a GPI (OR 1.20, 95% CI 0.76-1.92) or in those who did (OR 1.22, 95% CI 0.71-2.09) (P = .97 for heterogeneity).

CONCLUSION

Clopidogrel pretreatment before PCI is beneficial and safe regardless of whether a GPI is used at the time of PCI.

Current issues in non-inferiority trials

Non-inferiority (NI) trials enable a direct comparison of the relative benefit-to-risk profiles of an experimental intervention and a standard-of-care regimen. When the standard has clinical efficacy of substantial magnitude that is precisely estimated ideally using data from multiple adequate and well-controlled trials, with such estimates being relevant to the setting of the NI trial, then the NI trial can provide the scientific and regulatory evidence required to reliably assess the efficacy of the new intervention. In clinical practice, considerable uncertainty remains regarding when such trials should be conducted, how they should be designed, what standards for quality of trial conduct must be achieved, and how results should be interpreted. Recent examples will be considered to provide important insights and to highlight some of the challenges that remain to be adequately addressed regarding the use of the NI approach for the evaluation of new interventions. 'Imputed placebo' and 'margin'-based approaches to NI trial design will be considered, as well as the risk of 'bio-creep' with repeated NI trials, use of NI trials when determining whether excess safety risks can be ruled out, higher standards regarding quality of study conduct required with NI trials, and the myth that NI trials always require huge sample sizes.

Clinical, procedural, and pharmacologic correlates of acute and subacute stent thrombosis: results of a multicenter case-control study with 145 thrombosis events

OBJECTIVES

The aim of this study was to determine correlates of acute/subacute coronary stent thrombosis among unselected patients treated in the era of routine dual antiplatelet therapy and specifically to investigate the influence of prophylactic administration of glycoprotein IIb/IIIa (GpIIb-IIIa) inhibitors and use of clopidogrel versus ticlopidine on the development of coronary stent thrombosis (ST).

BACKGROUND

Because of a relative infrequency of ST events and relatively uniform practice patterns within randomized trials, previous studies have had a limited ability to address whether the use of different antiplatelet regimens at the time of coronary stenting is associated with differences in ST.

METHODS

We performed a multicenter, case-control study to evaluate clinical, angiographic, and pharmacologic/procedural correlates of ST. Between 1996 and 2000, all cases of angiographically-confirmed ST (n = 145) among patients receiving dual antiplatelet therapy were identified from 10 participating clinical sites and were matched with a control without ST randomly selected from the same institution.

RESULTS

Multivariable conditional logistic regression identified higher pre-procedure platelet count, stenting for acute myocardial infarction, use of a coil or self-expanding stent, and overt angiographic thrombus prior to the procedure, as independent predictors of ST (all P < .05). After adjusting for these factors, the use of clopidogrel (vs ticlopidine) was independently associated with an increased risk of ST (OR 2.1, 95% CI 1.0-4.1, P = .04). The use of prophylactic glycoprotein IIb/IIIa inhibitors was not associated with reduced ST in the overall analysis, but appeared to confer some protection against ST within the first 24 hours post procedure (OR 0.5 [95% CI 0.2-1.1] for ST during first day, OR 1.7 [95% CI 0.7-4.3] for ST on subsequent days).

CONCLUSION

Both biologic and pharmacologic factors are independently associated with acute/subacute ST. The association between clopidogrel use (vs ticlopidine) and increased ST in this analysis requires confirmation in adequately powered clinical trials and suggests a potential role for newer and more potent antiplatelet agents.