Abstract 4505: One Year Results of a 2×2 Factorial Double-blind Randomized Study of Intracoronary and High-Dose Bolus of Abciximab in Acute ST-Elevation Myocardial Infarction
Background: Platelet aggregation inhibition (PAI) ≥95% has been associated with improved outcomes after percutaneous coronary intervention (PCI) and glycoproteins IIb/IIIa inhibitors. Higher thrombotic burden in acute ST-elevation myocardial infarction might require higher dose or intracoronary (IC) route of abciximab delivery to achieve optimal PAI. Whether these novel strategies would improve acute and late results is presently unknown.
Methods and Results: Using a 2×2 factorial placebo-controlled design, 109 patients referred for primary PCI within 6 hours of symptoms were randomized to IC or intravenous (IV) abciximab bolus delivery and high bolus-dose (~ 0.30 mg/kg) or standard (0.25 mg/kg) bolus-dose of abciximab. Using VerifyNow (Accumetrics, USA), the primary end-point was the PAI 10 minutes post-bolus abciximab delivery. After receiving a loading dose of aspirin and clopidogrel, patients were treated by transradial approach and culprit lesions were dilated with sirolimus-eluting stents (Cypher Select®, Cordis, USA). Thirty days, 6-Months and 1-year results using angiographic, ST-resolution, cardiac biomarkers, cardiac magnetic resonance imaging (MRI) and clinical end-points were compared between groups. Ten minutes post-abciximab bolus, the % of patients with ≥95% PAI was not different between IC or IV groups (53% vs 54%, P=1.00) nor between high-dose bolus or standard-dose bolus (56% vs 51%, P=0.70). Acutely, angiographic, ST-resolution, cardiac biomarkers and MRI end-points were similar between groups and did not suggest benefit for IC over IV or high-dose bolus versus standard dose of abciximab. There was no safety issue. At 6-months, angiographic and cardiac MRI results were comparable between groups. Clinical events at 12 months remained low with 1 cardiac death, 1 non-fatal MI (stent thrombosis) and 3 target lesions revascularization.
Conclusions: In patients presenting within 6 hours of symptoms and undergoing transradial primary coronary stenting, platelet aggregation inhibition remained sub-optimal despite higher bolus dose of abciximab. Conversely, higher bolus dose or IC delivery of abciximab was not associated with improved acute or 1-year results compared to standard IV bolus-dose and 12 hour infusion.