Impact of early abciximab administration on infarct size in patients with ST-elevation myocardial infarction.

Background: Early abciximab administration in patients requiring transportation to undergo primary percutaneous coronary intervention (PPCI) has been reported to improve clinical outcome. We aimed to verify whether early administration leads to reduced infarct size (IS), assessed by delayed-enhancement magnetic resonance imaging (DE-MRI).

Methods: We randomized 110 patients with acute myocardial infarction with symptom-to-diagnosis time <6h to either early (55 patients) or late (55 patients) abciximab administration. DE-MRI was performed at 4 days and 6 months. The primary end point was IS at 6 months. Secondary end points were the rate of ST-segment elevation resolution ≥ 50% (STR) at 60 min after PPCI, the extent of microvascular obstruction at 4 days, and the change in IS and transmurality at 6 months vs. 4 days.

Results: DE-MRI was performed in 103 patients after 4 days, and in 87 at 6 months. The mean IS at 6 months was 13.8 ± 9.0% in the early vs. 13.0 ± 9.9% in the Late group (P>0.2). Similarly, microvascular obstruction and the change in IS were not significantly different. The Early group showed a significantly higher STR (94.5% vs. 80.0%, P=0.04) and a larger reduction in infarct transmurality (-9.2 ± 7.0% vs. -5.9 ± 6.4%; P=0.03), while a larger reduction in IS was observed only in patients with ECG-to-Cath Lab time >60 min.

Conclusions: Early abciximab administration did not lead to a smaller IS at 6-month DE-MRI, and was associated with a significant reduction in IS and transmurality only in patients with longer transportation time, warranting further investigation in this patient subset.