Objective:This study aimed to assess the impact of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor treatment immediately after percutaneous coronary intervention (PCI) on the myocardial salvage index (MSI) in patients with anterior ST-segment elevation myocardial infarction (STEMI) 5-10 d after the procedure.Methods:The early PCSK9 inhibitor thERapy Following pErcutaneous Coronary inTervention (PERFECT) trial is a prospective randomized controlled trial. From January 2021 to December 2023, 32 patients with anterior STEMI from Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Songjiang Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, and Shanghai Tenth People's Hospital were enrolled in the PERFECT trial. Patients were randomly assigned in a 1 & ratio;1 ratio to the PCSK9 inhibitor group (n = 16) or the control group (n = 16), and their baseline data were collected. Patients in the PCSK9 inhibitor group (ie, alirocumab group) received a subcutaneous injection of PCSK9 inhibitor (alirocumab, 75 mg) immediately after PCI based on conventional treatment. In the control group, patients received only conventional treatment. The primary endpoint was the MSI measured by cardiovascular magnetic resonance 5-10 d after PCI. The secondary endpoints included the left ventricular ejection fraction measured by cardiovascular magnetic resonance 5-10 d after PCI and the time to peak of creatine kinase isoenzyme-MB and high-sensitivity cardiac troponin T. Safety endpoints included any clinical adverse events that occurred during the 6-month follow-up period.Results:Baseline data during admission showed no intergroup significance. No significant difference in MSI (55.54% +/- 14.80% vs. 44.72% +/- 15.42%, P = 0.056) and left ventricular ejection fraction (51.24% +/- 8.91% vs. 44.99% +/- 8.84%, P = 0.060) was observed. Additional, there was no significant difference in the time to peak of creatine kinase isoenzyme-MB ((12.97 +/- 5.67) h vs. (14.31 +/- 7.04) h, P = 0.557) and high-sensitivity cardiac troponin T ((21.03 +/- 12.46) h vs. (21.44 +/- 9.99) h, P = 0.920) between the 2 groups. During the 6-month follow-up period, only 1 patient in the PCSK9 inhibitor group developed cerebral hemorrhage 6 months after PCI.Conclusions:Early treatment with alirocumab did not exhibit a significant increase in MSI at 5-10 d in patients with anterior STEMI. Larger trials are necessary to evaluate the impact of early administration of PCSK9 inhibitors after myocardial infarction.