Design and methodology of the ESPRIT trial: evaluating a novel dosing regimen of eptifibatide in percutaneous coronary intervention

Adjusting Eptifibatide Doses for Renal Impairment: A Model of Dosing Agreement Among Various Methods of Estimating Creatinine Clearance

Background:

Because of the renal elimination and increased risk for bleeding events at supratherapeutic doses of eptifibatide, the manufacturer recommends dosing adjustment in patients with renal dysfunction. Methods commonly used to estimate renal dysfunction in hospital settings may be inconsistent with those studied and recommended by the manufacturer

Objective:

To compare hypothetical renal dosing adjustments of eptifibatide using both the recommended method and several other commonly used formulas for estimating kidney function.

Methods:

Sex, age, weight, height, serum creatinine, and estimated glomerular filtration rate (eGFR) were obtained retrospectively from the records of patients who received eptifibatide during a 12-month period. Renal dosing decisions were determined for each patient based on creatinine clearance (CrCI) estimates via the Cockcroft-Gault formula (CG) with actual body weight (ABW), ideal body weight (IBW) or adjusted weight (ADJW), and eGFR from the Modification of Diet in Renal Disease formula. Percent agreement and Cohen κ were calculated comparing dosing decisions for each formula to the standard CG-ABW.

Results:

In this analysis of 179 patients, percent agreement as compared to CG-ABW varied (CG-IBW: 90.50%, CG-ADJW: 95.53%, and eGFR: 93.30%). All κ coefficients were categorized as good. In the 20% of patients receiving an adjusted dose by any of the methods, 68.6% could have received a dose different from that determined using the CG-ABW formula.

Conclusions:

In the patients with renal impairment (CrCI <50 mL/min) in this study, two thirds would have received an unnecessary 50% dose adjustment discordant from the manufacturer's recommendation. Because failure to adjust eptifibatide doses in patients with renal impairment has led to increased bleeding events, practitioners may be inclined to err on the side of caution. However, studies have shown that suboptimal doses of eptifibatide lead to suboptimal outcomes. Therefore, correct dosing of eptifibatide is important to both patient safety and efficacy.

The kinetics of integrilin limited by obesity: a multicenter randomized pharmacokinetic and pharmacodynamic clinical trial

BACKGROUND

KILO tested 2 novel weight-based eptifibatide dosing strategies compared with standard dosing in obese patients undergoing elective percutaneous coronary intervention (PCI). Eptifibatide dosing is weight adjusted for patients up to 121 kg. Patients above this weight receive the same maximal dose, although it is unknown if this provides adequate eptifibatide concentration or platelet inhibition.

METHODS

Sixty-seven patients weighing ≥125 kg undergoing elective PCI were randomized to 1 of 3 eptifibatide dosing regimens: standard dosing using a weight of 121 kg, actual body weight (ABW)-based dosing with no upper limit, or ideal body weight (IBW)-based dosing. Boluses of 180 μg/kg were given 10 minutes apart, followed by a 2.0 μg/kg per minute infusion. Plasma eptifibatide concentrations were drawn at 12 to 18 hours after initiating the infusion. Platelet aggregation was assessed at baseline and 10 minutes after the second bolus.

RESULTS

Sixty-seven patients were randomized to standard (n = 22), ABW (n = 23), or IBW (n = 22) dosing. The median (25th, 75th) steady-state plasma eptifibatide concentrations were 1,740 ng/mL (1,350, 2,350), 1,780 ng/mL (1,510, 2,350), and 1,055 ng/mL (738, 1,405), respectively (P < .001). Ten-minute median (25th, 75th) platelet aggregation units were 7 (0, 21), 2 (0, 8), and 14 (8, 20), respectively (P = .001).

CONCLUSIONS

Actual body weight eptifibatide dosing leads to higher plasma concentrations and greater platelet inhibition than standard or IBW dosing in obese patients undergoing PCI. Current recommendations for eptifibatide dosing may be inadequate in patients >121 kg. Further study is warranted to define the optimal dosing of eptifibatide and other medications in obese patients.

Bivalirudin and clopidogrel with and without eptifibatide for elective stenting: effects on platelet function, thrombelastographic indexes, and their relation to periprocedural infarction results of the CLEAR PLATELETS-2 (Clopidogrel with Eptifibatide to Arrest the Reactivity of Platelets) study

OBJECTIVES

The primary objective of this study was to compare the effect of therapy with bivalirudin alone versus bivalirudin plus eptifibatide on platelet reactivity measured by turbidometric aggregometry and thrombin-induced platelet-fibrin clot strength (TIP-FCS) measured by thrombelastography in percutaneous coronary intervention (PCI) patients. The secondary aim was to study the relation of platelet aggregation and TIP-FCS to the occurrence of periprocedural infarction.

BACKGROUND

Bivalirudin is commonly administered alone to clopidogrel naïve (CN) patients and to patients on maintenance clopidogrel therapy (MT) undergoing elective stenting. The effect of adding eptifibatide to bivalirudin on platelet reactivity (PR) and TIP-FCS, and their relation to periprocedural infarction in these patients are unknown.

METHODS

Patients (n = 200) stratified to clopidogrel treatment status were randomly treated with bivalirudin (n = 102) or bivalirudin plus eptifibatide (n = 98). One hundred twenty-eight CN patients were loaded with 600 mg clopidogrel immediately after stenting, and 72 MT patients were not loaded. The PR, TIP-FCS, and myonecrosis markers were serially determined.

RESULTS

In CN and MT patients, bivalirudin plus eptifibatide was associated with markedly lower PR at all times (5- and 20-microM adenosine diphosphate-induced, and 15- and 25-microM thrombin receptor activator peptide-induced aggregation; p < 0.001 for all) and reduced mean TIP-FCS (p < 0.05). Patients who had a periprocedural infarction had higher mean 18-h PR (p < 0.0001) and TIP-FCS (p = 0.002).

CONCLUSIONS

For elective stenting, the addition of eptifibatide to bivalirudin lowered PR to multiple agonists and the tensile strength of the TIP-FCS, 2 measurements strongly associated with periprocedural myonecrosis. Future studies of PR and TIP-FCS for elective stenting may facilitate personalized antiplatelet therapy and enhance the selection of patients for glycoprotein IIb/IIIa blockade. (Peri-Procedural Myocardial Infarction, Platelet Reactivity, Thrombin Generation, and Clot Strength: Differential Effects of Eptifibatide + Bivalirudin Versus Bivalirudin [CLEAR PLATELETS-2]; NCT00370045.

Platelet reactivity to adenosine diphosphate and long-term ischemic event occurrence following percutaneous coronary intervention: a potential antiplatelet therapeutic target

Platelets play a central role in the genesis of post-percutaneous coronary intervention (PCI) ischemic events. High post-procedural platelet reactivity to adenosine diphosphate (HPR(ADP)) may be a risk factor for ischemic events after PCI. The study was designed to evaluate a cutpoint of platelet reactivity that is associated with the occurrence of ischemic events after PCI. Post-procedural platelet reactivity to ADP was measured by conventional aggregometry in 297 consecutive patients undergoing non-emergent PCI. Patients were prospectively followed for up to 2 years for post-discharge ischemic events. All patients had received clopidogrel and aspirin therapy at the time of aggregation measurements. Eighty-one patients (27%) suffered ischemic events. Patients with ischemic events had higher 5 microM ADP-induced platelet aggregation (46 +/- 14% vs. 30 +/- 17%, p < 0.001) and 20 microM ADP-induced platelet aggregation (60 +/- 13% vs. 43 +/- 19%, p < 0.001) compared to patients without ischemic events. Using a combined receiver operator curve analysis, cutpoints of >46% aggregation following 5 microM ADP stimulation and >59% aggregation following 20 microM ADP stimulation (HPR(ADP)) were associated with 58 and 54% of ischemic events, respectively. Multivariate Cox regression demonstrated a significant relation between event occurrence and post-procedural HPR(ADP) cutpoints (5 microM ADP, OR=3.9, and 20 microM ADP, OR=3.8, p < 0.001 for both). High post-procedural platelet reactivity to ADP is an independent risk factor for ischemic events within 2 years of non-emergent PCI. These data support a potential therapeutic target for antiplatelet therapy based on the results of an ex vivo platelet function test. The study is a step towards a personalized medicine approach to guide the intensity of antiplatelet therapy.

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.

Platelet aggregation inhibition in acute coronary syndrome. Facts and expectations

A szerző áttekinti az akut coronariaszindróma thrombocytaaggregáció-gátló kezelésének jelenlegi gyakorlatát. Ismerteti a thrombocytaaggregáció-gátlásra használt gyógyszereket, azok adagolását és klinikai hasznosságát. Felhívja a figyelmet arra, hogy a III. fázisú vizsgálatokban alkalmazott gyógyszeradagolás az ismételt vizsgálatok során változhat. Mind az acetilszalicilsav, mind pedig a clopidogrel esetében számolni kell csökkent reaktivitással, amit rezisztenciaként is lehet értelmezni. Mivel ennek jelentősége lehet a klinikai hatékonyság vonatkozásában, ezért is fontos lesz a jövőben a thrombocytaaggregáció-gátlásának mérése, betegágy mellett is használható, gyors, megbízható módszerekkel. A dolgozat végén a szerző áttekinti a kifejlesztés alatt álló újabb thrombocytaaggregáció-gátló szereket.

Increased Risk in Patients With High Platelet Aggregation Receiving Chronic Clopidogrel Therapy Undergoing Percutaneous Coronary Intervention

OBJECTIVES

We sought to determine whether patients receiving chronic clopidogrel therapy undergoing nonemergent stenting who display high on-treatment preprocedural platelet aggregation measured by standard light transmittance aggregometry and thrombelastography (TEG) will be at increased risk for poststenting ischemic events.

BACKGROUND

Patients exhibiting heightened platelet reactivity to adenosine diphosphate (ADP) might be at increased risk for recurrent ischemic events after coronary stenting.

METHODS

A total of 100 consecutive patients receiving chronic antiplatelet therapy consisting of aspirin (325 mg qd) and clopidogrel (75 mg qd) were studied before undergoing nonemergent stenting. Patients were followed for 1 year after coronary stenting for the occurrence of death, myocardial infarction, stent thrombosis, stroke, or ischemia requiring a hospital stay.

RESULTS

All patients were aspirin responsive. Patients with ischemic events (23 of 100, 23%) within 1 year had greater on-treatment prestent ADP-induced platelet aggregation than patients without ischemic events by aggregometry and TEG (p < 0.001 for both measurements). Of patients with an ischemic event, 70% and 87% displayed high on-treatment platelet reactivity at baseline by aggregometry and TEG, respectively. High on-treatment platelet reactivity as measured by aggregometry and TEG were the only variables significantly related to ischemic events (p < 0.001 for both assays). The administration of eptifibatide reduced periprocedural elevation in platelet reactivity, with no significant differences in bleeding events.

CONCLUSIONS

Patients receiving chronic clopidogrel therapy undergoing nonemergent percutaneous coronary intervention who exhibit high on-treatment ADP-induced platelet aggregation are at increased risk for postprocedural ischemic events. These findings might have implications for the alteration in clopidogrel maintenance dose and use of glycoprotein IIb/IIIa inhibitors in selected patients.

Complementary effects of thienopyridine pretreatment and platelet glycoprotein IIb/IIIa integrin blockade with eptifibatide in coronary stent intervention; Results from the ESPRIT trial

OBJECTIVES

This analysis sought to investigate the complementary effect of thienopyridine pretreatment and platelet glycoprotein (GP) IIb/IIIa integrin blockade in coronary stent intervention.

BACKGROUND

Definitive evidence supporting combined antiplatelet therapy consisting of thienopyridine pretreatment and GP IIb/IIIa receptor blockade in patients undergoing percutaneous coronary intervention (PCI) with stent implantation is limited.

METHODS

We retrospectively analyzed clinical outcomes by thienopyridine use in the 2,040 patients randomized to eptifibatide or placebo who underwent PCI in the ESPRIT trial.

RESULTS

A total of 901 patients received a loading dose of thienopyridine before PCI (group 1), 123 received thienopyridine pretreatment without a loading dose (group 2), and 1,016 were not treated with thienopyridine before PCI (group 3). The composite incidence of death or myocardial infarction at 30 days was significantly lower in group 1 than in groups 2 and 3 combined (OR, 0.71 [95%CI, 0.52-0.99]; P = 0.0417). A similar trend was seen for the composite of death, myocardial infarction, or urgent target vessel revascularization (unadjusted OR, 0.77 [0.57-1.05]; P = 0.1025). After adjusting for baseline characteristics, these differences were no longer significant. No interactions were identified with eptifibatide assignment for any of the group comparisons.

CONCLUSIONS

Pretreatment with a loading dose of thienopyridine lowers the rate of ischemic complications regardless of treatment with a GP IIb/IIIa inhibitor. Conversely, the efficacy of eptifibatide is maintained whether or not a loading dose of a thienopyridine is administered. Optimal outcomes are achieved in patients receiving thienopyridine pretreatment along with platelet GP IIb/IIIa inhibitor therapy.

Anti-platelet and anti-thrombotic approaches in patients undergoing percutaneous coronary intervention

Over the past three decades, there has been a tremendous increase in the use of percutaneous coronary interventions (PCI) for the treatment of patients with atherosclerotic coronary artery disease. However, PCI causes disruption of atherosclerotic plaque and denudation of the endothelium, leading to stimulation of platelet aggregation and activation of the coagulation cascade. Therefore, anti-platelet and anti-thrombotic agents have a pivotal role as adjuncts before, during and after PCI, in order to minimize the risk of procedural ischemic complications, such as myocardial infarction, stent thrombosis, and various degrees of myonecrosis. The current article presents a comprehensive review of the evolution of current anti-platelet and anticoagulation regimens used in the setting of PCI. It starts with a summary of the current perspective of the coagulation process along with platelet activation and aggregation. The review then focuses specifically on individual anti-platelet and anti-thrombotic drugs including their mechanism of action and the scientific evidence which led to their use in PCI. Finally, we present summary recommendations from the AHA/ACC guidelines for individual anticoagulant and anti-platelet regimens given peri-PCI.

Therapeutic approaches in arterial thrombosis

The current standard of care for the treatment of arterial thrombosis includes anticoagulants and three classes of antiplatelet agents--aspirin, thienopyridines and glycoprotein IIb-IIIa antagonists. Although these drugs have had a significant impact on morbidity and mortality in several patient populations, up to 15% of the high risk patients with acute coronary syndrome continue to suffer from ischemic events. This problem may occur, in part, because the platelets in many patients are non-responsive to aspirin and clopidogrel. Murine models now indicate that platelets are not only responsible for arterial occlusion, they are also involved in the progression of atherosclerotic disease. New opportunities have emerged identifying potential targets and strategies for drug discovery suited to address these deficiencies by more effectively modulating platelet adhesion, thrombus growth, thrombus stability and the pro-inflammatory activity of platelets. In addition, a growing need has emerged for the development of bedside devices capable of bringing personalized medicine to patients being treated with antithrombotic drugs in order to measure the pharmacodynamic activities of new therapies, to assess the activities achieved by combined antithrombotic therapy, and to identify patients that fail to respond.

Clopidogrel Loading With Eptifibatide to Arrest the Reactivity of Platelets

Background— Pretreatment is not the most common strategy practiced for clopidogrel administration in elective coronary stenting. Moreover, limited information is available on the antiplatelet pharmacodynamics of a 300-mg versus a 600-mg clopidogrel loading dose, and the comparative effect of eptifibatide with these regimens is unknown.

Methods and Results— Patients undergoing elective stenting (n=120) were enrolled in a 2×2 factorial study (300 mg clopidogrel with or without eptifibatide; 600 mg clopidogrel with or without eptifibatide) (Clopidogrel Loading With Eptifibatide to Arrest the Reactivity of Platelets [CLEAR PLATELETS] Study). Clopidogrel was administered immediately after stenting. Aggregometry and flow cytometry were used to assess platelet reactivity. Eptifibatide added a ≥2-fold increase in platelet inhibition to 600 mg clopidogrel alone at 3, 8, and 18 to 24 hours after stenting as measured by 5 μmol/L ADP–induced aggregation ( P <0.001). Without eptifibatide, 600 mg clopidogrel produced better inhibition than 300 mg clopidogrel at all time points ( P <0.001). Glycoprotein IIb/IIIa (GPIIb/IIIa) blockade was associated with lower cardiac marker release. Active GPIIb/IIIa expression was inhibited most in the groups treated with eptifibatide ( P <0.05).

Conclusions— In elective stenting without clopidogrel pretreatment, use of a GPIIb/IIIa inhibitor produces superior platelet inhibition and lower myocardial necrosis compared with high-dose (600 mg) or standard-dose (300 mg) clopidogrel loading alone. In the absence of a GPIIb/IIIa inhibitor, 600 mg clopidogrel provides better platelet inhibition than the standard 300-mg dose. These results require confirmation in a large-scale clinical trial.

Optimal duration of eptifibatide infusion in percutaneous coronary intervention (an ESPRIT substudy)

Although randomized trials have clearly demonstrated the clinical efficacy with regimens of platelet glycoprotein IIb/IIIa antagonists that result in >80% inhibition of baseline platelet aggregation in percutaneous coronary intervention (PCI), there are no data available concerning the optimal duration of infusion of these agents. In an era when the length of hospitalization has a major impact on health care costs, the determination of the optimal duration of the infusion of these drugs after PCI is of great relevance. The investigators therefore sought to determine the optimal length of the infusion of eptifibatide after PCI by analyzing the outcomes of patients enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor With Integrilin Therapy trial who were randomized to treatment with eptifibatide.

Platelet glycoprotein IIb/IIIa inhibitors in percutaneous coronary intervention: focus on the pharmacokinetic-pharmacodynamic relationships of eptifibatide

Eptifibatide is a truncated derivative of the naturally occurring rattlesnake venom protein known as barbourin. It is a cyclic heptapeptide that mimics the tertiary structure found in the parent compound which allows it to bind receptors with the KGD (Lys-Gly-Asp) peptide recognition sequence. Specifically, eptifibatide is a competitive antagonist for the activated platelet glycoprotein IIb/IIIa receptor. Its mechanism of action involves preventing the binding and cross-linking of fibrinogen to the platelet surface. This binding site for fibrinogen is associated with five Ca2+ ions that help maintain the tertiary structure of the receptor and affect the affinity of other ligands such as eptifibatide. Arterial injury induced by percutaneous coronary interventions (PCI) such as balloon angioplasty and stenting, and the spontaneously occurring disease process known as the acute coronary syndrome (ACS), share a common underlying pathophysiology. In both situations, disruption of integrity of the arterial wall initiates a cascade of platelet activation, adhesion and aggregation. Ultimately, this process may proceed to arterial thrombosis unless controlled or modified. Advances in understanding how the platelet plays a pivotal role in this process have significantly enhanced therapy for patients with ACS and have resulted in important reductions in thrombotic complications from PCI procedures. Central to these advances has been evolving understanding of platelet-inhibiting pharmaceutical agents such as eptifibatide. The development of a rational administration regimen for eptifibatide parallels the growth in the understanding of the underlying mechanisms of platelet receptor functions. The binding of eptifibatide to the receptor involves displacement of receptor-associated Ca2+ from the activated binding site. Early in the clinical development of eptifibatide, this was poorly appreciated and resulted in an underestimation of the appropriate doses for this agent. Through a series of small clinical trials and laboratory studies, deficiencies in the early administration regimens were identified and a more effective dose schedule was determined. Modelling of the drug based on its two-compartment pharmacokinetics further defined the role of a newer double-bolus initiation of therapy verses the original single-bolus approach. In a large-scale clinical trial using this double-bolus followed by infusion regimen in PCI procedures, clinical efficacy was shown to be significantly improved over placebo and the earlier, low-dose regimens used in the original trials of eptifibatide.

Treatment effects of eptifibatide in planned coronary stent implantation in patients with chronic kidney disease (ESPRIT Trial)

The role of platelet glycoprotein IIb/IIIa inhibitor therapy in patients with mild renal impairment is not well characterized. Our objective was to explore the associations of creatinine clearance (CrCl) with outcomes in a trial of eptifibatide therapy in patients who underwent percutaneous coronary intervention (PCI). We analyzed 48-hour and 30-day outcomes of patients enrolled in the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial. Patients were randomly assigned to placebo or eptifibatide as an adjunct to stent implantation (1,755 with CrCl > or =60 ml/min and 289 with CrCl <60 ml/min). CrCl was calculated using the Cockcroft and Gault formula, and the associations of CrCl with outcomes were evaluated using logistic regression models. Patients with CrCl <60 ml/min were more likely to be older, women, hypertensive, and have a history of coronary artery bypass surgery, stroke, or peripheral vascular disease. The interaction of eptifibatide with CrCl had borderline significance for the 30-day outcome (p = 0.109). Treatment effect trended toward a greater magnitude in patients with lower CrCl (60 ml/min) (odds ratio 0.53, confidence interval 0.34 to 0.83) compared with those with higher CrCl (90 ml/min) (odds ratio 0.68, confidence interval 0.49 to 0.94). An accompanying increase in bleeding risk also was not apparent with lower CrCl. The treatment effect of eptifibatide is realized regardless of renal function and trends toward being greater in patients with mild renal impairment.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Differential effects of citrate versus PPACK anticoagulation on measured platelet inhibition by abciximab, eptifibatide and tirofiban

BACKGROUND

High levels of glycoprotein (GP) IIb/IIIa receptor inhibition are required to prevent arterial thrombosis following percutaneous coronary intervention. Ex-vivo turbidometric platelet aggregation in citrate anticoagulated blood samples has been the primary method previously utilized to derive dose regimens for administering platelet GP IIb/IIIa inhibitors. Enhanced GP IIb/IIIa binding and inhibition of platelet aggregation for eptifibatide secondary to citrate induced reduction of ionized plasma calcium concentrations has been reported.

METHODS/RESULTS

We evaluated the differential effects of citrate versus PPACK anticoagulation on turbidometric platelet inhibition in normal volunteers by eptifibatide, tirofiban or abciximab. The decrease in ionized calcium afforded by citrate was associated with enhanced in vitro platelet inhibition for all three GP IIb/IIIa inhibitors, including abciximab. The magnitude of citrate effect was greatest for eptifibatide. Both tirofiban and abciximab have similar citrate calcium chelation associated enhancement of measured platelet inhibition.

CONCLUSION

Accurate assessment and comparison of platelet inhibition by GP IIb/IIIa inhibitors may require avoidance of calcium chelating anticoagulants.

Effect of glycoprotein IIb/IIIa receptor inhibition on angiographic complications during percutaneous coronary intervention in the ESPRIT trial

OBJECTIVES

We sought to determine whether eptifibatide decreases the incidence of in-laboratory angiographic complications and to determine the relationship of angiographically evident complications to elevations of creatine kinase-MB (CK-MB) enzyme levels during percutaneous coronary intervention.

BACKGROUND

In the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial, eptifibatide during coronary intervention was associated with decreased ischemic complications at 48 h and 30 days.

METHODS

Patients (n = 2,064) were randomized to placebo versus eptifibatide (two 180 microg/kg boluses 10 min apart and as a continuous infusion of 2 microg/kg per min) during percutaneous coronary stenting. Angiographic complications including major dissection, distal embolization, residual thrombus, abrupt closure, residual stenosis >50% and side-branch occlusion were prospectively recorded by the operator. Creatine kinase-MB levels were measured after the procedure and every 6 h thereafter. The incidence of angiographic complications and CK-MB elevation was determined for eptifibatide versus placebo groups.

RESULTS

Eptifibatide-treated patients demonstrated nonsignificant trends toward fewer angiographic complications (10 vs. 12% for placebo patients, p = 0.13) and, for patients with angiographic complications, fewer subsequent CK-MB elevations (43 vs. 50% for placebo patients, p = 0.31). In patients without any angiographic complications, the incidence of CK-MB elevation >3 times the normal was 7% with placebo and 4% with eptifibatide (p = 0.003).

CONCLUSIONS

Eptifibatide during nonurgent coronary stent intervention only minimally (and insignificantly) reduces the incidence of angiographic complications and subsequent CK-MB elevations in patients developing an angiographic complication. The greater effect is to reduce myocardial infarction in patients undergoing otherwise uneventful coronary stent implantation as well as in the overall study population.

Dalteparin in combination with abciximab during percutaneous coronary intervention

BACKGROUND

Despite proved efficacy for either dalteparin or platelet glycoprotein IIb/IIIa blockade in improving clinical outcomes of patients with non-ST-segment elevation acute coronary syndromes, algorithms guiding concomitant therapy with these agents have not been devised. The purpose of this study was to assess anticoagulant effect and clinical safety for several dose regimens of dalteparin administered in combination with abciximab during percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Patients undergoing PCI with standard dose abciximab received dalteparin as follows: 120 IU/kg subcutaneously (SQ) to a maximum of 10,000 U if < or =8 hours before PCI (n = 3); for PCI 8-12 hours after the SQ dose, an additional 40 IU/kg intravenously (IV) was administered (n = 1); for PCI >12 hours after SQ dalteparin or with no prior dalteparin therapy, random allocation to 40 (n = 27) or 60 (n = 28) IU/kg IV during PCI was performed. Those patients who received 60 IU/kg of dalteparin IV had a lower incidence of procedural thrombosis (0% vs 11.1%, P <.01), more consistent antithrombotic effect (anti-factor Xa activity) and a similar incidence of major bleeding (3.7% vs 2.6%) compared with patients who received 40 IU/kg of intravenous dalteparin.

CONCLUSIONS

Dalteparin 60 IU/kg IV appears to be safe and effective when administered in conjunction with abciximab for percutaneous coronary intervention.

Novel dosing regimen of eptifibatide in planned coronary stent implantation (ESPRIT): a randomised, placebo-controlled trial

BACKGROUND

The platelet glycoprotein IIb/IIIa inhibitors, although effective in reducing ischaemic complications of percutaneous coronary intervention, are used in few coronary stent implantation procedures. ESPRIT (Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy) is a randomised, placebo-controlled trial to assess whether a novel, double-bolus dose of eptifibatide could improve outcomes of patients undergoing coronary stenting.

METHODS

We recruited 2064 patients undergoing stent implantation in a native coronary artery. Immediately before percutaneous coronary intervention, patients were randomly allocated to receive eptifibatide, given as two 180 microg/kg boluses 10 min apart and a continuous infusion of 2.0 microg/kg/min for 18-24 h, or placebo, in addition to aspirin, heparin, and a thienopyridine. The primary endpoint was the composite of death, myocardial infarction, urgent target vessel revascularisation, and thrombotic bailout glycoprotein IIb/IIIa inhibitor therapy within 48 h after randomisation. The key secondary endpoint was the composite of death, myocardial infarction, or urgent target vessel revascularisation at 30 days.

FINDINGS

The trial was terminated early for efficacy. The primary endpoint was reduced from 10.5% (108 of 1024 patients on placebo [95% CI 8.7-12.4%]) to 6.6% (69 of 1040 [5.1-8.1%]) with treatment (p=0.0015). The key 30 day secondary endpoint was also reduced, from 10.5% (107 of 1024 patients on placebo [8.6-12.3%]) to 6.8% (71 of 1040 [5.3-8.4%]; p=0.0034). There was consistency in reduction of events across all components of the composite endpoint and among the major subgroups. Major bleeding was infrequent but arose more often with eptifibatide than placebo (1.3%, 13 of 1040 [0.7-2.1%]) vs 0.4%, 4 of 1024 [0.1-1.0%]; p=0.027).

INTERPRETATION

Routine glycoprotein IIb/IIIa inhibitor pretreatment with eptifibatide substantially reduces ischaemic complications in coronary stent intervention and is better than a strategy of reserving treatment to the bailout situation.