Abstract Body (Do not enter title and authors here): Patients with acute myocardial infarction (AMI) due to occlusion of the left main coronary artery are at high risk of death or major adverse cardiovascular events even if they undergo primary percutaneous coronary intervention (PCI) and stent implantation. Delayed stent implantation in infarct-related artery is thought to reduce no-reflow/slow-flow and may improve outcomes in AMI patients, especially those with heavy thrombus burden. No randomized clinical trials have been conducted to compare clinical outcomes of delayed stenting versus prompt stenting for primary PCI of left main coronary artery occlusion. The Optimal Strategies for Primary Percutaneous Coronary Intervention in Acute Myocardial Infarction Due to Unprotected Left Main Coronary Artery Occlusion (OPTIMAL) study (NCT03282773) is an prospective, open-label, randomized, multi-center clinical trial that aimed to compare deferred stenting to prompt stenting in AMI patients with left main coroanry artery occlusion. They were randomly assigned 1:1 to receive immediate stenting or deferred stenting (performed 4-10 days after primary PCI). The primary endpoint was a composite of all-cause death or recurrent myocardial infarction at 30 days follow-up. Secondary endpoints include all-cause death, cardiac death, recurrent myocardial infarction, and target vessel revascularization at 30 days, 6 months, and 12 months follow-up. Preliminary results of the study will be presented at AHA 2025.