| In
patients undergoing stent procedures, glycoprotein IIb/IIIa
inhibitors have been shown to reduce the risk of immediate complications
and improve patient outcomes. However, not yet established is
the relative safety and efficacy of different IIb/IIIa agents
and whether the acuity of the presenting clinical syndrome,
which may affect the degree of platelet inhibition required
or achieved, influences the response to different anti-platelet
agents.
The
Do Tirofiban and ReoPro Give Similar Efficacy Trial, or TARGET,
may shed some light on this issue. In the trial, patients
who needed stenting as a result of an acute coronary syndrome
(ACS) were significantly less likely to experience a heart
attack within 30 days and six months if they were treated
initially with abciximab vs. tirofiban.
The
trial randomized 4,809 patients undergoing PCI with stenting
to either abciximab or tirofiban. Of these, 3,025 had ACS
and 1,784 were non-ACS patients. In particular, said TARGET
lead researcher Gregg W. Stone, MD, of the Lenox Hill Heart
and Vascular Institute, New York, abciximab proved to be more
effective than tirofiban in reducing the combined endpoint
of death, myocardial infarction (MI), and urgent target vessel
revascularization (TVR) 30 days after stenting. The 30-day
composite incidence of death, MI, or urgent TVR in ACS patients
occurred in 6.3 percent of patients given abciximab vs. 9.3
percent given tirofiban. Those percentages were 5.6 and 4.5
percent, respectively, in non-ACS patients. Dr. Stone presented
his findings at a press conference Sunday.
By
six months, 15.1 percent of ACS patients on abciximab vs.
17.6 percent of ACS patients on tirofiban experienced death,
MI, or any TVR. For non-ACS patients, the percentages were
13 percent and 10.2 percent, respectively. The TARGET trial,
published last November in The New England Journal of Medicine,
showed no apparent difference in mortality with either inhibitor
at 30 days, six months, or one year.
In
terms of specific events, ACS patients treated with abciximab
undergoing stent implantation had lower 30-day (5.8 percent
vs. 8.5 percent, respectively) and six-month (7.1 percent
vs. 9.6 percent, respectively) rates of MI than ACS patients
with tirofiban. However, survival was identical, said Dr.
Stone. For ACS patients, 0.5 percent on abciximab and 1.1
percent on tirofiban experienced urgent TVR vs. 0.9 percent
and 0.5 percent of non-ACS patients, respectively.
For
Dr. Stone, the potency of these IIb/IIIa inhibitors have far-reaching
implications. “These data raise important issues regarding
the relative pharmacocdynamic potency of IIb/IIIa inhibition
required in varying clinical scenarios,” he said, “as
well as having important implications for cost-effective utilization
of IIb/IIIa inhibitors.”
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