BACKGROUND:Data is scarce on hemorrhagic and thrombotic complications in patients with ST-elevation myocardial infarction (STEMI) associated with out-of-hospital cardiac arrest (OHCA). METHODS:This is a monocentric, retrospective study conducted from January 2012 to December 2017 in a tertiary university hospital, which serves as a cardiac arrest center for a large urban area. Over the study period, all consecutive patients who were treated with stent implantation for STEMI with or without OHCA were included. Baseline characteristics, treatments, hemorrhagic and thrombotic events were compared between STEMI patients with and without OHCA. Univariate and multivariate analysis were performed in order to identify predictors of 30-day mortality, occurrence of major bleeding (MB), and early stent thrombosis (ST). RESULTS:A total of 549 patients treated for STEMI without OHCA and 146 patients for STEMI with OHCA were included. The incidence of definite ST and MB after coronary angioplasty was significantly higher in patients with OHCA (2.6% vs. 7.5%, p = 0.004 and 3.3% vs. 19.2%, p < 0.001, respectively). Independent predictors of MB in OHCA patients were anticoagulation therapy (HR = 3.11, 95%CI [1.22-7.98], p = 0.02) and the use of glycoprotein IIb/IIIa inhibitors (HR = 4.16, 95%CI [1.61-10.79], p = 0.003). Independent predictors of mortality in OHCA patients were age (HR = 1.05, 95%CI [1.02-1.09], p = 0.004) and ST (HR = 5.62, 95%CI [1.61-19.65], p = 0.007, with a protective effect of new anti-P2Y12 treatments (HR = 0.20, 95%CI [0.08-0.46], p < 0.001). CONCLUSION:Patients treated for STEMI associated with OHCA are at higher-risk of ST and MB than those who did not experience cardiac arrest. In this subset of patients, prospective studies are needed to better evaluate the balance of thrombosis and hemorrhage.