Randomized Early Versus Late Abciximab in Acute Myocardial Infarction Treated With Primary Coronary Intervention - RELAx-AMI
The goal of the trial was to evaluate the effect of early abciximab administration in the emergency room (ER) or in later administration in the catheterization laboratory among patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI).
Patients Enrolled: 210
Mean Follow Up: 1 month
Mean Patient Age: Mean age, 65 years
Planned primary PCI for first acute MI, and presentation within 12 hours of symptom onset with ST-segment elevation of ≥1 mm in ≥2 contiguous leads of the electrocardiogram
Previous MI, previous PCI or coronary artery bypass surgery, left bundle branch block, bleeding diathesis, administration of thrombolytic agents for the current episode, recent stroke, uncontrolled hypertension, recent surgery, oral anticoagulant therapy, and known contraindications to therapy with abciximab, aspirin, clopidogrel, or heparin
Pre-PCI TIMI flow grade
Infarct size and left ventricular functional recovery at 1 month
Patients were randomized to abciximab (0.25 mg/kg bolus and 12-hour infusion of 0.125 µg/kg/min) either in the ER (early group; n = 105) or in the catheterization laboratory after diagnostic angiography prior to PCI (late group; n = 105).
The majority of patients in the trial met the TIMI risk criteria for moderate to high risk (62%). Infarct artery was the left anterior descending in 49% of patients. Median time from abciximab to balloon was 55 minutes in the early group and 14 minutes in the late group (p = 0.001). Direct stenting was performed more often in the early group (29% vs. 13%, p = 0.004).
The primary endpoint of TIMI flow grade pre-PCI was more frequently grade 3 in the early group compared with the late group (24% vs. 10%, p = 0.001). Corrected TIMI frame count also indicated better flow in the early group (mean 78 frames for early vs. 92 frames for late, p = 0.001). Myocardial perfusion was more frequently grade 2 or 3 in the early group (15% vs. 6%, p = 0.02). There was no difference in post-PCI TIMI flow grade (92% grade 3 in both groups). However, post-PCI blush grade indicated better myocardial perfusion in the early group (grade 2 or 3 79% in the early group vs. 58% in the late group, p = 0.001).
Percent ST resolution was better in the early group both pre-PCI (14% vs. 4%, p = 0.01) and 60 minutes post-PCI (65% vs. 56%, p = 0.04). Peak creatine kinase-myocardial band (CK-MB) trended lower in the early group (282 ng/ml vs. 362 ng/ml, p = 0.06), as did cumulative CK-MB release by 48 hours (6483 ng/ml vs. 8087, p = 0.09).
Increase in ejection fraction at 1 month was higher in the early group (8% vs. 6%, p = 0.02), as was improvement in wall motion score index (0.4 vs. 0.3, p = 0.03). There was no difference in major adverse cardiac events at 1 month (5.7% for early vs. 8.6% for late, p = 0.42). The rate of bleeding complications did not differ between groups (8.6% for early vs. 5.7% for late, p = 0.44).
Among patients with acute MI undergoing primary PCI, early administration of abciximab in the ER was associated with improved epicardial flow compared with later administration of abciximab in the catheterization laboratory.
Findings of the present study are similar to other trials comparing early ER administration versus later catheterization lab administration of glycoprotein (GP) IIb/IIIa inhibitors, including the TITAN-TIMI 34, ON-TIME, and TIGER-PA trials, which all showed improvements in angiographic parameters with early GP IIb/IIIa administration. In the present study, there were no additional bleeding complications associated with the earlier administration of abciximab, which was approximately 40 minutes longer prior to PCI in the early administration group. A novel finding of the present study was in the larger increase in ejection fraction at 30 days in the early group, indicating sustained myocardial benefit not just in the peri-PCI period, but in the longer term.
Maioli M, Bellandi F, Leoncini M, Toso A, Dabizzi RP. Randomized early versus late abciximab in acute myocardial infarction treated with primary coronary intervention (RELAx-AMI Trial). J Am Coll Cardiol 2007;49:1517-24.
Keywords: Myocardial Infarction, Creatine Kinase, Platelet Aggregation Inhibitors, Coronary Disease, Immunoglobulin Fab Fragments, Emergency Service, Hospital, Electrocardiography, Platelet Membrane Glycoprotein IIb, Percutaneous Coronary Intervention, Catheterization
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