The theory seems straightforward and reasonable: For STEMI patients, direct intracoronary (IC) bolus administration of the glycoprotein IIb/IIIa receptor antagonist abciximab during PCI would boost concentration of the drug at the treatment site—which would potentially limit heart tissue destruction and improve blood flow. Short-term, 90-day follow-up data from AIDA STEMI (Abciximab Intracoronary versus intravenous Drug Application in ST-Elevation Myocardial Infarction), the largest trial to date to compare standard intravenous (IV) and IC delivery of abciximab, however, showed no significant differences between the two delivery routes. Now, an update with 1-year follow-up data suggests that the standard of care should remain in place.

More than 2,000 STEMI patients were enrolled in the AIDA STEMI trial; patients were randomized to either IV or IC infusion of the antiplatelet agent. The IC delivery route was shown to be as safe and similarly as efficacious as standard IV delivery at 90 days: 7% of those receiving direct IC administration of abciximab died, suffered reinfarction, or developed new HF, compared to 7.6% of those receiving IV abciximab. And, in fact, there was a significantly lower rate of new cases of HF in those patients assigned to IC delivery.

However, in the 1-year follow-up period, as reported by Steffen Desch, MD, from the University of Leipzig – Heart Center in Germany, and fellow investigators from AIDA STEMI in JACC, there was no benefit of IC abciximab over standard IV administration, suggesting that the 90-day findings were most likely due to chance. The composite endpoint (all-cause death, reinfarction, or development of new HF) at 12 months was not significantly different between patients assigned to IC versus IV abciximab bolus administration.

Intracoronary delivery did not exert any significant protective effect on myocardial microcirculation at the time of reperfusion, as the researchers initially hypothesized. “This might seem surprising given previous data that direct intracoronary compared to intravenous abciximab bolus administration is associated with a variety of beneficial effects on surrogate markers in STEMI patients,” Dr. Desch and colleagues wrote.

“It is possible that intracoronary abciximab might only be advantageous in selected patients such as those with large thrombus burden, total occlusion, or reduced flow,” they added, but noted that AIDA STEMI subgroup analyses do not support a selective benefit of IC over IV bolus abciximab in high-risk patients.

Dr. Desch and colleagues also suggested that, compared to the standard of care (an IV bolus followed by a 12-hour infusion), the short-lived local effect of IC injection of abciximab might not be enough to produce changes in the clinically meaningful endpoints evaluated in AIDA STEMI.

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Desch S, Wohrle J, Hambrecht R, et al. J Am Coll Cardiol. 2013;62:1214-5.

Keywords: Myocardial Infarction, Follow-Up Studies, Platelet Aggregation Inhibitors, Biomarkers, Thrombosis, Microcirculation, Standard of Care, Immunoglobulin Fab Fragments, Platelet Glycoprotein GPIIb-IIIa Complex

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