Early reperfusion therapy has improved the clinical outcomes of patients with acute myocardial infarction (AMI), but these benefits are limited in some patients by reperfusion injuries. There is now increasing evidence that reactive oxygen species cause reperfusion injury. This study was designed to examine the effects of edaravone, a novel free radical scavenger, in patients with AMI.

Initial AMI patients were randomly assigned to receive 30 mg of edaravone or a placebo intravenously just before reperfusion. We compared infarct size, using serial determination of serum biomarkers and Q wave formations, and the incidence of reperfusion arrhythmia between the groups. Cardiovascular event-free curves were estimated by Kaplan-Meier method. In addition, we determined serum thioredoxin levels, an oxidative stress marker, to assess the antioxidant effect of edaravone.

Inclusion Criteria:

• Initial AMI patients admitted to the investigators' institution within 6 hours of symptom onset and treated primary percutaneous coronary intervention.

Exclusion Criteria:

• Renal insufficiency defined as serum creatinine > 1.2 mg/dl and altered hepatic function defined as serum asparate aminotransferase > 50 IU/L, alanine aminotransferase > 50 IU/L and total bilirubin > 1.2 mg/dl.

adverse events were only collected during the therapy period, up to 2 weeks