Strict control measures under the COVID epidemic have brought an inevitable impact on ST-segment elevation myocardial infarction (STEMI)'s emergency treatment. We investigated the impact of the COVID on the treatment of patients with STEMI undergoing primary PCI.In this single center cohort study, we selected a time frame of 6 month after declaration of COVID-19 infection (Jan 24-July 24, 2020); a group of STEMI patients in the same period of 2019 was used as control. Finally, a total of 246 STEMI patients, who were underwent primary PCI, were enrolled into the study (136 non COVID-19 outbreak periods and 110 COVID-19 outbreak periods). The impact of COVID on the time of symptom onset to the first medical contact (symptom-to-FMC) and door to balloon (D-to-B) was investigated. Moreover, the primary outcome was in-hospital major adverse cardiac events (MACE), defined as a composite of cardiac death, heart failure and malignant arrhythmia.Compared with the same period in 2019, there was a 19% decrease in the total number of STEMI patients undergoing primary PCI at the peak of the pandemic in 2020. The delay in symptom-to-FMC was significantly longer in COVID Outbreak period (180 [68.75, 342] vs 120 [60,240] min, P = 0.003), and the D-to-B times increased significantly (148 [115-190] vs 84 [70-120] min, P < 0.001). However, among patients with STEMI, MACE was similar in both time periods (18.3% vs 25.7%, p = 0.168). On multivariable analysis, COVID was not independently associated with MACE; the history of diabetes, left main disease and age>65 years were the strongest predictors of MACE in the overall population.The COVID pandemic was not independently associated with MACE; suggesting that active primary PCI treatment preserved high-quality standards even when challenged by a severe epidemic.URL: https://ClinicalTrials.gov Unique identifier: NCT04427735.Copyright © 2022. Published by Elsevier Inc.