Ann Arbor, MI - Despite there being more data on the use of abciximab than other GP IIb/IIIa blockers in primary PCI patients, eptifibatide appears to be used more in this setting, and which agent is chosen does not seem to affect short-term clinical outcomes, a new study suggests [1].

The study, published in the February 5, 2008 issue of the Journal of the American College of Cardiology, was conducted by a group led by Dr Hitinder Gurm (University of Michigan, Ann Arbor).

They explain that data from randomized controlled trials suggest that the adjunctive use of abciximab may be associated with a survival advantage vs placebo in patients undergoing primary PCI, and although the guidelines support the use of abciximab in this setting, there is significant variability in the choice of antiplatelet therapy in real-world clinical practice. They suggest that this is because the magnitude of survival benefit associated with abciximab is still controversial and the other two IIb/IIIa blockers (eptifibatide and tirofiban) are less expensive and more widely available in many hospitals.

They thus set out to evaluate how often these other agents are used in patients undergoing primary PCI and whether their use is associated with any adverse clinical impact. To do this, they evaluated the outcomes of 3541 patients who underwent primary PCI for STEMI between 2002 and 2006 and were recorded in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium database, a large regional PCI registry that includes demographic, procedural, and hospital-outcome information from several interventional cardiology centers. Of these patients, 729 were treated with abciximab and 2812 with eptifibatide.

Results showed there was no difference in the incidence of in-hospital death, recurrent MI, stroke/transient ischemic attack (TIA), or the need for blood transfusion with the two agents, but there was a greater incidence of gastrointestinal (GI) bleeding with abciximab. In parsimonious risk-adjusted models, no significant difference between abciximab and eptifibatide was observed with respect to any of the outcome measures.

Gurm et al say that "although purists would argue that abciximab is the only agent that should be used in patients undergoing primary PCI for STEMI, market forces work against that," noting that the wholesale acquisition cost of treating a 70-kg man with a standard dose of eptifibatide is $885.48, compared with $1980.42 for abciximab, which is the likely reason that many hospital formularies stock eptifibatide in preference to abciximab.

They comment that these observational data are important given that a randomized trial comparing these two agents in this setting is never likely to be performed and that, according to their results, "there is no evidence to suggest that the use of eptifibatide in lieu of abciximab is associated with worse short-term outcomes." However, they add that this finding and the question of whether differences in the use of these agents affect longer-term outcomes should be examined in larger prospective studies.

In an accompanying editorial [2], Drs David Moliterno and Khaled Ziada (University of Kentucky, Lexington) say there is good evidence that abciximab as adjunctive pharmacologic therapy for primary PCI improves outcomes, with several randomized, placebo-controlled trials having shown a 40% to 60% reduction in a 30-day composite ischemic end point (death, re-MI, and urgent target vessel revascularization [TVR]), the benefit primarily driven by a reduction in the rates of re-MI and urgent TVR. They point out that while no individual trial has shown a significant reduction in 30-day mortality, a meta-analysis of placebo-controlled abciximab trials for STEMI did demonstrate a moderate reduction in mortality at 30 days and at six to 12 months among those receiving abciximab during primary PCI and that in the ACC/AHA guidelines abciximab has a class-IIa recommendation (level of evidence B) in this indication. The small-molecule IIb/IIIa blockers, eptifibatide and tirofiban, have fewer data in primary PCI, and in the guidelines they have a class-IIb recommendation (level of evidence C).

Moliterno and Ziada comment that the current study is the largest prospective registry report of primary-PCI patients treated with eptifibatide and that the patient population studied should accurately represent contemporary practice and includes patients with high-risk features such as old age, reduced ejection fraction, and cardiogenic shock, who are not included in many randomized studies. They point out that the rates of transfusion (12%) and major adverse cardiovascular events (8%-10%) in this registry are somewhat higher than those reported in the placebo-controlled abciximab trials, but this is a reflection of real-world outcome.

They say that "the aggregate evidence for the use of small-molecule GP IIb/IIIa inhibitors in primary PCI is favorable, with no clear disadvantage compared with abciximab." They add that "the data of Gurm et al are probably not enough to upgrade the guideline recommendations for small-molecule IIb/IIIa inhibitors from class IIb to IIa, but they greatly add to the accumulating support and may raise the level-of-evidence classification from C to B."

With the recent report of the FINESSE trial casting doubt on the value of early administration of abciximab, these combined findings suggest that there are more options for GP IIb/IIIa inhibitors during primary PCI and more time to decide, they conclude.