However, lead investigator Dr Gregg Stone (Columbia University Medical Center Cardiovascular Research Foundation, New York, NY) pointed out that the overall results of the ACUITY trial, presented yesterday at the ACC meeting, showed that IIb/IIIa blockers are not needed at all if bivalirudin is used as the antithrombotic agent.

Stone commented to heartwire: "From all the results together, I would recommend that bivalirudin monotherapy be the preferred option for ACS undergoing an early invasive strategy and suggest that IIb/IIIa blockers are not needed at all, apart from for bailout use. But there will still be some interventionalists who will want to use IIb/IIIa blockers routinely, and in that situation the ACUITY Timing trial supports the ability to defer starting these agents until the patient is in the cath lab and then treating only those who are undergoing PCI."

He added, "The current US practice pattern is to defer treatment with these agents, so we are saying that operators can feel comfortable with that practice, although it is probably better after the main ACUITY results to use bivalirudin alone without routine IIb/IIIa blockers at all."

Introducing his presentation today, Stone explained that at present, IIb/IIIa blockers have a class I indication for use in ACS patients undergoing an early invasive strategy and that about 80% of such patients currently receive one of these agents. But it is uncertain whether to give them up front to everyone or to defer treatment until the patient is in the cath lab and the anatomy is known and then give a IIb/IIIa blocker just to those patients who will definitely undergo PCI. "Upstream use may be more effective, but this will probably increase bleeding complications, given all the other antithrombotic drugs used," he added. They therefore looked at this question in the ACUITY Timing trial.

The ACUITY trial involved 13 819 patients with moderate- to high-risk ACS who all underwent cardiac catheterization within 72 hours, followed by percutaneous or surgical revascularization when appropriate. They were randomized to one of three arms: unfractionated heparin or enoxaparin plus routine IIb/IIIa inhibition; bivalirudin plus routine IIb/IIIa inhibition; or bivalirudin alone, with IIb/IIIa inhibition only given as bailout.

The ACUITY Timing trial involves a second randomization of patients in the two groups receiving routine IIb/IIIa blockers, to early or deferred treatment with a IIb/IIIa blocker. Of patients given a IIb/IIIa blocker up front, two thirds received eptifibatide and one third were given tirofiban. Of those given a IIb/IIIa blocker in the cath lab, 60% received eptifibatide and 40% abciximab.

Results showed that there was no difference in the net clinical outcome at 30 days (a composite of death/MI/unplanned revascularization or major bleeding) between the two approaches. Deferred use of IIb/IIIa blockers was associated with a slightly higher rate of ischemic events, which was accounted for mainly by unplanned revascularizations, but this approach also gave a significantly lower incidence of major bleeding.

Stone noted that overall, 98% of the patients in the upstream group received a IIb/IIIa blocker vs 55.7% in the deferred group and that the time from randomization to the start of IIb/IIIa blocker treatment was 0.6 hours in the upstream group and 4.6 hours in the deferred group.

He also reported that patients taken to the cath lab earlier did better than those waiting longer for a PCI. "Basically, the longer you are on a IIb/IIIa blocker waiting to go to the cath lab, the more adverse ischemic events occur," he said.