Timing of Glycoprotein IIb/IIIa Inhibitors in Acute Coronary SyndromesTiming of Glycoprotein IIb/IIIa Inhibitors in Acute Coronary Syndromes

To the Editor: In the Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) Timing trial, Dr Stone and colleagues¹ reported that more than 10% of patients developed thrombocytopenia, defined as a platelet count of less than 150 000/μL. Prior studies have defined thrombocytopenia as either less than 100 000/μL or at least a 25% decrease from baseline, with incidence ranging from 0.5% to 5.6%.^{2 - 3} It is unclear how many patients in the ACUITY trial developed significant thrombocytopenia using these alternative definitions.

In the Randomized Evaluation in PCI Linking Angiomax to Reduced Clinical Events (REPLACE) 2 trial,⁴ the investigators showed a statistically significant decrease in incidence of moderate (<100 000/μL) and severe (<50 000/μL) thrombocytopenia with bivalirudin, a direct thrombin inhibitor, compared with combined unfractionated heparin and glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitors during percutaneous coronary intervention. Patients who develop thrombocytopenia with the use of GP IIb/IIIa inhibitors have increased risk of bleeding complications and ischemic events (30-day mortality and myocardial infarction).^{2 - 3}

It would have been informative if a subgroup analysis had been done to look at the incidence of thrombocytopenia with a combination of an anticoagulant (unfractionated heparin, enoxaparin, or bivalirudin) and a GP IIb/IIIa inhibitor. There could be a decreased incidence of thrombocytopenia with bivalirudin compared with enoxaparin or unfractionated heparin. If so, and if this were to result in a better survival outcome, bivalirudin may be preferable to heparin or enoxaparin during percutaneous coronary intervention.