Intracoronary abciximab is superior to intravenous infusion in reducing infarct size during primary PCI

June 24, 2008 By Vijayalakshmi Kunadian MBBS MD MRCP [mailto:vkunadian@perfuse.org]

Circulation Leipzig-Germany: A new study published ahead of print in Circulation demonstrates that intracoronary abciximab is superior to intravenous infusion in reducing infarct size, microvascular obstruction and improving myocardial perfusion during primary PCI.

Primary percutaneous coronary intervention (PCI) is the preferred treatment strategy for the management of patients with ST segment elevation myocardial infarction. Various strategies have been developed to minimize myocardial damage and improve myocardial perfusion. Glycoprotein IIbIIIa inhibitors including abciximab therapy when administered during primary PCI have been demonstrated to be associated with a reduced incidence of major adverse cardiac events.

Intracoronary (IC) pharmacotherapy can result in very high concentration of the drug at the myocardial tissue level and might be more effective compared with intravenous (IV) therapy. Improvement in myocardial perfusion is demonstrated when there are fewer glycoprotein IIb/IIIa receptors remain unblocked. However, there are no randomized studies comparing IC and IV abciximab therapy during primary PCI following an acute myocardial infarction. The beneficial effects of IC abciximab over IC therapy were examined by Thiele and colleagues in a new research consisting of 154 patients with acute STEMI (77 received IC abciximab and 77 received IV abciximab). IC and IV bolus were administered at a dose of 0.25 mg/kg body weight followed by 12 hour IV infusion (0.125 μg/kg/minute). Patients with bleeding tendencies, cardiogenic shock and those with history of major surgery were excluded from the study.

The primary endpoint of this study consisted of infarct size and extent of microvascular obstruction measured using delayed enhanced magnetic resonance imaging. The secondary endpoints consisted of ST segment resolution at 90 minutes, TIMI flow and perfusion grade following PCI and major adverse cardiac events (composite of death, reinfarction, urgent target vessel revascularization and the occurrence of new congestive heart failure) within 30 days.

There were no significant differences in the baseline characteristics between the two groups. Prior to PCI the bolus dose was administered in 83% of cases in the IC group and 77% in the IV group (p=0.42). The drug was discontinued in 4 patients in the IC group and 5 patients in the IV group (p=0.93) due to bleeding complications. There was no significant difference in the reperfusion times between the two groups (p=0.47).

The infarct size was significantly reduced in the IC group compared with the IV group [% of left ventricle 15.1 (interquartile range: 6.1-25.2) vs. 23.4 (13.6-33.2), p=0.01] as was the early [1.1 (0.0-3.7) vs. 3.4 (0.1-7.3), p=0.01] and late MO [0.1 (0.0-1.6) vs. 1.1 (0.0-2.8), p=0.02]. However, there was no significant difference in the LV ejection fraction (p=0.71), LV end-diastolic volume index (p=0.65), LV end-systolic volume index (p=0.97) and LV mass index (p=0.84). Furthermore, ST segment resolution was significantly better in the IC group compared with the IV group (77.8% vs. 70%, p=0.006). There was a trend towards better TMPG following PCI in the IC group compared with the IV group (p=0.09). The composite major adverse cardiac events at 30-days occurred in 5.2% in the IC group and 15.6% in the IV group (RR 0.33; 95% CI, 0.09 to 1.05; p=0.06).

The beneficial effects of IC abciximab was particularly observed among patients with anterior infarction, patients undergoing reperfusion >4 hours after symptom onset and among patients with impaired TIMI flow and perfusion grades following PCI with respect to infarct size, early and late MO

The investigators of this study concluded that IC abciximab is superior to IV abciximab in reducing infarct size and microvascular obstruction and improving myocardial perfusion. Further adequately powered large scale studies are required to demonstrate the beneficial effects of IC abciximab on clinical outcomes.