Background Cardiac arrest is one of the most serious complications of acute myocardial infarction (AMI),especially in the out-of-hospital patients.There is no general consensus as to whether percutaneous coronary intervention (PCI) is effective in treating ST-segment elevation myocardial infarction (STEMI) patients complicated by out-of-hospital cardiac arrest (OHCA).In our study,we evaluated the efficacy of PCI in treating STEMI patients complicated by OHCA through observing their clinical conditions in hospital; including total mortality,adverse cardiac events,stroke,acute renal failure,and gastrointestinal bleeding events.Methods A total of 1827 STEMI patients were enrolled in this study,where 81 were STEMI with OHCA.Between the patients with and without OHCA,and the OHCA patients with and without PCI,we compared the clinical characteristics during hospitalization,including total mortality and incidences of adverse cardiac events,and stroke.Results Compared to the patients without OHCA,the OHCA patients had significantly lower systolic blood pressure (P ＜0.05) and a faster heart rate (P＜0.05),and a higher percentage of Killip class IV or Glasgow coma scale (GCS) ≤7 onadmission (P ＜0.001).And the in-hospital mortality was higher in the OHCA patients (55.6％ vs.2.4％,P ＜0.001).Comparing the OHCA patients without PCI to the patients with PCI,there was no obvious difference of heart rate,blood pressure or the percentage of Killip class IV and GCS ≤7 on admission,but the incidences of cardiogenic shock,stroke were significantly lower in the with-PCI group during hospitalization (P ＜0.001,P ＜0.05).And the in-hospital mortality of the OHCA patients receiving PCI was significantly lower (36.7％ vs.84.3％,P＜0.001).Conclusions During hospitalization,the incidence of adverse events and mortality are higher in the STEMI with OHCA patients,comparing with the STEMI without OHCA.Emergency PCI reduces the incidence of adverse events and decreases mortality during hospitalization,which is effective for treating STEMI with OHCA patients.