Background The clinical significance of ischemic chest pain before acute ST-elevation myocardial infarction (STEMI)remains an interesting issue of investigation particularly in the era of percutaneous coronary intervention (PCI).This study aimed to assess the impact of angina prior to STEMI on short-term clinical outcomes in patients with acute STEMI undergoing primary PCI.Methods Among a total of 875 consecutive patients with STEMI undergoing primary PCI,292 had episodes of angina within 24 hours of STEMI (PA group) and the remaining 583 were free of anginal symptoms (non-PA group).Clinical characteristics,angiographic and procedural features,and in-hospital and 30-day outcomes were compared between the two groups.Results Diabetes was less common (17.5％ vs.23.3％,P=-0.04) and symptom-to-door time was shortened ((191.6±96.8) minutes vs.(357.2±341.9) minutes,P ＜0.001) in the PA group than in the non-PA group.Patients with angina prior to STEMI had fewer totally or nearly totally occluded infarct-related artery (TIMI flow grade 0-1) at initial angiography (75.0％ vs.90.7％,P ＜0.001),and achieved more TIMI flow grade 3 after primary PCI (84.2％ vs.78.2％,P=0.04).These were associated with higher rates of overall procedural success (95.9％ vs.91.8％,F=0.02) and of complete ST-segment resolution at 90 minutes after the procedure (51.7％ vs.40.3％,P=0.001).During a 30-day clinical follow-up,the left ventricular ejection fraction was significantly improved ((53.0±8.6)％ vs.(51.1±9.7)％,P=0.002) and the primary endpoint of major adverse cardiac events was reduced in the PA group (7.2％ vs.12.7％,P=-0.01).Conclusion Presence of angina prior to acute STEMI is associated with better outcome at a 30-day clinical follow-up in patients undergoing primary PCI.