Timing of glycoprotein IIb/IIIa inhibitor use and outcomes among patients with non-ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention (results from CRUSADE)

Angiographic outcomes with early eptifibatide therapy in non-ST-segment elevation acute coronary syndrome (from the EARLY ACS Trial)

Early administration of glycoprotein IIbIIIa inhibitors results in improved angiographic parameters, including thrombolysis in myocardial infarction (TIMI) flow grade, corrected TIMI frame count, and TIMI myocardial perfusion grade (TMPG) among patients with ST-segment elevation myocardial infarction. Whether the same is true in the setting of non-ST-segment elevation acute coronary syndrome is unknown. The goal of the early glycoprotein IIbIIIa inhibition in non-ST-segment elevation acute coronary syndrome (EARLY ACS) angiographic substudy was to compare angiographic outcomes among patients with non-ST-segment elevation acute coronary syndrome who were administered early routine versus delayed provisional eptifibatide. Of 9,406 patients in the EARLY ACS trial, 2,066 patients were included in the angiographic substudy (early routine eptifibatide [n=1,042] or early placebo [n=1,024] with delayed provisional eptifibatide after angiography and before percutaneous coronary intervention [PCI]). The angiographic substudy primary end point was the incidence of TMPG 3 before and after PCI. TMPG 3 before (43.7% vs 44.9%, p=0.58) and after PCI (52.4% vs 50.1%, p=0.73) was similar for early routine versus delayed provisional eptifibatide, respectively. Angiographic procedural complications consisting of a composite of loss of side branch, abrupt vessel closure, distal embolization, and no reflow occurred less frequently in early routine group versus delayed provisional group (9.3% vs 13.6%, respectively, p=0.01). In the EARLY ACS angiographic substudy, the use of early routine eptifibatide resulted in fewer angiographic procedural complications. These data provide support for the use of eptifibatide in the catheterization laboratory during high-risk cases merely to prevent angiographic procedural complications.

Lessons learned from negative clinical trials evaluating antithrombotic therapy for ischemic heart disease

The clinical trials that failed to demonstrate significant efficacy may not result in development of new therapy but contribute to better understanding of antithrombotic therapy for ischemic heart disease. Negative trials provide important messages about how to interpret and understand the results of clinical trials and apply these results to clinical practices. Although every aspect of clinical trials may influence the outcomes of trials and interpretation of their results, selection of study subjects, endpoints, and measuring risk/benefit are crucial to success of clinical trial. We will review the recent key negative trials on antithrombotic therapy for ischemic heart disease and discuss about their results and implications. The challenge in the future for the development of antithrombotic therapies is to leverage these "lessons learned" from negative clinical trials to improve the design, conduct, and interpretation of future randomized clinical trials.

Comparative effectiveness of upstream glycoprotein IIb/IIIa inhibitors in patients with moderate- and high-risk acute coronary syndromes: an Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) substudy

BACKGROUND

Tirofiban and eptifibatide are both small-molecule, competitive glycoprotein IIb/IIIa receptor inhibitors (GPIs) that are guideline-supported for upstream therapy in acute coronary syndromes (ACS). This study sought to compare the efficacy and safety of tirofiban and eptifibatide in patients with ACS.

METHODS

Within the ACUITY trial, 4,323 patients with moderate- and high-risk ACS received upstream, adjunctive GPI (tirofiban or eptifibatide) in addition to an antithrombin. Primary outcomes included 30-day rates of composite major adverse cardiac events (MACE), major bleeding (not related to coronary artery bypass grafting), and composite net adverse clinical events (NACE). The outcomes were compared based on the upstream GPI administered.

RESULTS

There were significant differences in the baseline characteristics of patients treated with tirofiban vs eptifibatide, particularly related to country/region. In unadjusted analyses, treatment with upstream tirofiban vs eptifibatide was associated with similar rates of major bleeding (5.8% vs 6.5%, P = .39) and nonsignificantly lower rates of MACE (6.1% vs 7.6%, P = .06) and NACE (10.6% vs 12.6%, P = .06). After propensity-based multivariable adjustment, there were no significant differences between tirofiban and eptifibatide with respect to 30-day major bleeding, MACE, or NACE.

CONCLUSIONS

Among more than 4,000 patients with moderate- and high-risk ACS treated with upstream GPI as part of an early invasive management strategy, the use of tirofiban and eptifibatide resulted in similar clinical outcomes. These data suggest equivalence of these 2 agents for upstream use, while highlighting some of the difficulties of nonrandomized comparative effectiveness analyses, specifically the difficulty in addressing geographic differences in the use of nonrandomized treatments.

Upstream use of small-molecule glycoprotein iib/iiia inhibitors in patients with non-ST-segment elevation acute coronary syndromes: a systematic overview of randomized clinical trials

BACKGROUND

The use of upstream small-molecule glycoprotein (GP) IIb/IIIa inhibitors in non-ST-segment elevation acute coronary syndromes (NSTE ACS) has been studied in multiple randomized clinical trials. We systematically reviewed the effect of upstream GP IIb/IIIa inhibitor use in NSTE ACS as reported in published clinical trials.

METHODS AND RESULTS

Randomized clinical trials of upstream small-molecule GP IIb/IIIa inhibitors in NSTE ACS were identified through a PubMed and EMBASE search and were included if they contained 30-day outcome data. Odds ratios were generated from the published data and pooled by means of random effects modeling. The primary outcome measures were 30-day death and 30-day death or myocardial infarction. Primary safety measures were major bleeding and transfusion during the index hospitalization. Twelve clinical trials were included, evaluating tirofiban, eptifibatide, and lamifiban. Of these, 7 evaluated upstream GP IIb/IIIa inhibitors versus placebo (n=24 031) and 5 evaluated a strategy of upstream GP IIb/IIIa inhibitors versus upstream placebo with later provisional use at the time of percutaneous coronary intervention (n=19 643). Overall, upstream GP IIb/IIIa inhibitor use was associated with an 11% reduction in 30-day death/myocardial infarction (odds ratio [OR], 0.89; 95% confidence interval [CI], 0.83 to 0.95) but no significant mortality effect (OR, 0.93; 95% CI, 0.83 to 1.05). The risk of major bleeding was 23% higher in patients treated with upstream GP IIb/IIIa inhibitors (OR, 1.23; 95% CI, 1.02 to 1.48). Results were similar when only trials comparing upstream GP IIb/IIIa inhibitors versus placebo were considered: 30-day death/myocardial infarction (OR, 0.88; 95% CI, 0.81 to 0.95); 30-day death (OR, 0.89; 95% CI, 0.76 to 1.03); and major bleeding (OR, 1.17; 95% CI, 0.88 to 1.54). Upstream versus selective use at percutaneous coronary intervention trended toward lower 30-day death/myocardial infarction (OR, 0.91; 95% CI, 0.82 to 1.01) but had no effect on mortality (OR, 1.00; 95% CI, 0.81 to 1.23) and increased major bleeding risk by 34% (OR, 1.34; 95% CI, 1.10 to 1.63).

CONCLUSIONS

In NSTE ACS, treatment with upstream small-molecule GP IIb/IIIa inhibitors provides a significant but modest ischemic benefit when compared with initial placebo. Compared with delayed, selective use at percutaneous coronary intervention, early upstream use is associated with a trend toward fewer ischemic events. However, these modest benefits are associated with an increased risk of bleeding.

Antithrombotic strategy in non-ST-segment elevation myocardial infarction patients undergoing percutaneous coronary intervention: insights from the ACTION (Acute Coronary Treatment and Intervention Outcomes Network) Registry

OBJECTIVES

The aim of this study was to examine the use of and outcomes associated with antithrombotic strategies in patients with non-ST-segment elevation myocardial infarction (NSTEMI) who undergo percutaneous coronary intervention (PCI).

BACKGROUND

A variety of antithrombotic strategies have been tested in clinical trials for NSTEMI patients treated with PCI.

METHODS

Antithrombotic strategies for NSTEMI patients undergoing PCI at 217 ACTION (Acute Coronary Treatment and Intervention Outcomes Network) hospitals from January 1, 2007, to December 31, 2007, (n = 11,085) were classified into commonly observed antithrombotic groups: heparin alone (Hep alone; low-molecular-weight heparin or unfractionated heparin), bivalirudin alone (Bival alone), heparin with glycoprotein IIb/IIIa inhibitors (Hep/GPI), and bivalirudin with GPI (Bival/GPI). Baseline characteristics are shown across treatment groups. In addition, unadjusted and adjusted rates of in-hospital major bleeding and death are shown.

RESULTS

The standard strategy used was Hep/GPI (64%), followed by Hep or Bival alone (28%), and Bival/GPI (8%). Patients who received Hep or Bival alone were older with more comorbidities, higher baseline bleeding and mortality risk, and lower peak troponin. Compared with patients who received Hep/GPI , those who received Hep alone and Bival alone had lower rates of major bleeding (adjusted odds ratio [OR]: 0.52; 95% confidence interval [CI]: 0.42 to 0.65; adjusted OR: 0.48; 95% CI: 0.39 to 0.60; respectively), yet only patients who received Bival alone had lower mortality (adjusted OR: 0.39; 95% CI: 0.21 to 0.71).

CONCLUSIONS

NSTEMI patients undergoing PCI are more likely to receive Bival or Hep alone when at higher baseline bleeding risk than when at lower baseline bleeding risk. Despite higher baseline risk, those receiving Bival or Hep alone had less bleeding.

ED to catheterization laboratory: a roundtable integrating trials with practice

BACKGROUND

Clinical trials are the foundation underlying clinical decision-making. However, stringent inclusion and exclusion criteria may reduce the generalizability of their results, especially for patients seen in the emergency department (ED). Guideline recommendations, based on clinical trials and pertinent registries, apply to broad populations, but not all patients cared for at the bedside fit the predefined categories that make guidelines practical. Furthermore, these documents may not incorporate the latest evidence. As a result, other factors (eg, individual patient characteristics, clinician experience, cost, regulatory labels, expert opinions) often result in clinical decision-making that varies from strict adherence to guideline recommendations.

OBJECTIVES

These challenges demonstrate a need to integrate clinical data and guidelines advice with actual ED practice in a manner that will be consistent with decisions made later in the continuum of care.

DISCUSSION

In recognition of these issues, a roundtable was convened in New York City on June 5, 2009, to discuss the implications of recent trials involving patients with non-ST-segment elevation acute coronary syndromes. Eight physicians, representing both emergency medicine and cardiology, shared information on advances and clinical trial results in antiplatelet treatment, guidelines, and other developments in patient care. This article is based on transcripts of their presentations and the ensuing discussions that were of particular importance for emergency physicians.

CONCLUSIONS

Although guidelines and clinical registries can provide broad direction for practice, there is no substitute for a prospective, multidisciplinary, institution-specific, consistent, evidence-based approach to patient management.

Non-ST-elevation myocardial infarction patients who present during off hours have higher risk profiles and are treated less aggressively, but their outcomes are not worse: a report from Can Rapid Risk Stratification of Unstable Angina Patients Suppress ADverse Outcomes with Early Implementation of the ACC/AHA Guidelines CRUSADE initiative

Evidence-based guidelines call for advanced and definitive therapy for patients with non-ST-elevation myocardial infarction (NSTEMI). It is not known whether these guidelines are follow more diligently when patients arrive in the ED during regular hours, during which hospital resources including cardiology consultation may be more readily available. To determine whether patients with NSTEMI who present to the ED outside of usual hours have prolonged times to advanced and definitive therapy and poorer short-term outcomes.We examined NSTEMI patients from the Can Rapid Risk Stratification of Unstable Angina Patients Suppress ADverse Outcomes with Early Implementation of the ACC/AHA Guidelines (CRUSADE) national quality improvement initiative (January 2001-April 2003) and compared demographics, risk profiles, intensity of medical management, and timing and intensity of intervention by whether presentation occurred during usual or off hours. We analyzed 34,297 NSTEMI presentations; 15,090 (44%) occurred during usual hours; 19,207 (56%) occurred during off hours. Off-hours-presenting patients had generally higher cardiac risk and received initial ECGs more quickly than patients who presented during usual hours (median 15 minutes vs. 18 minutes, P < 0.0001), and received similar (although suboptimal) medical management. In contrast, those who presented during off hours were less likely to receive timely diagnostic angiography, PCI, and bypass surgery (cath: median 32.9 hours vs. 24.3 hours, P < 0.0001; PCI: 28.6 hours vs. 23.6 hours, P < 0.0001). Despite these differences, in-hospital outcomes were similar. Time of patient presentation has a modest impact on the timeliness of intervention in NSTEMI but was not associated with lower mortality. Although intensity of medical management was similar between groups, it was generally lower than current guidelines recommend, indicating potential for improvement in NSTEMI outcomes, regardless of time of presentation.

Variability of platelet aggregate dispersal with glycoprotein IIb-IIIa antagonists eptifibatide and abciximab

BACKGROUND

Utilization of glycoprotein IIb-IIIa (GPIIb-IIIa) inhibitors improves outcomes of patients with acute coronary syndromes (ACS), including those undergoing percutaneous coronary intervention (PCI). These results may be related to the ability of the inhibitors to destabilize coronary thrombi, reduce microembolization, and restore vessel patency.

OBJECTIVE

To evaluate in vitro the ability of GPIIb-IIIa antagonists, abciximab and eptifibatide, to promote the disaggregation of platelet-rich thrombus.

METHODS

Antagonist-induced disaggregation was assayed in plasma by aggregometry, as well as in whole blood by point of care and capillary perfusion systems. Fibrinogen dissociation from the platelet surface was quantified by flow cytometry.

RESULTS

Significant disaggregation of 5 microm ADP-induced aggregates was observed after addition of either agent. The maximum extent and rate of disaggregation were significantly higher with eptifibatide than with abciximab. Both antagonists also dispersed 2 microg mL(-1) collagen-induced aggregates, again with eptifibatide having a greater effect. Eptifibatide, but not abciximab (up to 10 microg mL(-1)), was efficient at dissociating aggregates to single platelets in whole blood and dispersing aggregates that had been aged for 30 min before treatment. Eptifibatide also reduced existing thrombus burden in the perfusion model under arterial flow conditions. A key mechanism of aggregate dispersal was antagonist-induced displacement of platelet-bound fibrinogen, which was greater with eptifibatide, a competitive inhibitor of fibrinogen binding, than with the noncompetitive inhibitor, abciximab.

CONCLUSIONS

These results suggest that drug concentration and residence time, along with thrombus extent and age, may be critical determinants in promoting timely recanalization.

GP IIb-IIIa inhibitors administered upstream: evidence for improved outcomes with conventional and newer antithrombotic agents?

Glycoprotein IIb-IIIa inhibitors provide the most benefit in patients with non-ST-elevation acute coronary syndromes and high-risk features and in those who undergo early invasive treatment. Current guidelines recommend glycoprotein IIb-IIIa inhibition in these patients but offer little guidance as to timing of initiation. Preliminary data suggest superior outcomes with upstream initiation (upon admission to a medical facility) compared with delayed initiation (in the catheterization laboratory, just before percutaneous coronary intervention). The availability of new antiplatelet and antithrombotic drugs renders even more complex the question of the best strategy.

2007 update to the ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: implications for emergency department practice

The American College of Cardiology and American Heart Association have updated their guidelines for the management of non-ST-segment-elevation acute coronary syndrome for the first time since 2002. In the interim, several important studies affecting choices of therapy potentially begun in the emergency department have been completed, and care patterns have changed and matured significantly. In this review, we present the new recommendations that are pertinent to emergency medicine practice and comment on their potential implementation into an evidence-based, multidisciplinary approach to the evaluation and management of this challenging patient population.