Background: Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) lower atherosclerotic cardiovascular disease (ASCVD) event risk. Objective: Analyze patient characteristics associated with time to PCSK9i initiation following an acute myocardial infarction (AMI). Methods: We analyzed characteristics of patients ≥21 years of age in the Marketscan or Medicare databases who initiated a PCSK9i 0-89 days, 90-179 days, or 180-365 days after an AMI between July 2015 and December 2018 (n=1,705). We estimated the cumulative incidence of recurrent ASCVD events before PCSK9i initiation. Results: Overall, 42%, 25%, and 33% of patients who initiated a PCSK9i did so 0-89 days, 90-179 days, and 180-365 days following AMI hospital discharge, respectively. Taking ezetimibe prior to AMI hospitalization and initiating ezetimibe within 30 days after AMI hospital discharge were each associated with a higher likelihood of PCSK9i initiation in the 0-89 days versus 180-365 days post-discharge (adjusted odds ratio [OR] 1.83, 95% confidence interval [95%CI] 1.35-2.49 and 1.76, 95%CI 1.11-2.80, respectively). Statin use before and statin initiation within 30 days after AMI hospitalization were associated with a lower likelihood of PCSK9i initiation 0-89 days versus 180-365 days post-discharge (adjusted OR 0.64, 95%CI 0.49-0.84 and 0.39, 95%CI 0.28-0.54, respectively). Overall, 8.0%, 10.5%, and 12.5% of patients had an ASCVD event at 90, 180, and 365 days following AMI hospital discharge and before initiating a PCSK9i, respectively. Conclusion: Among patients initiating a PCSK9i after AMI, a low proportion did so within 89 days of hospital discharge. Many patients had a recurrent ASCVD event before treatment initiation.