A limitation of the current guidelines regarding the timing of invasive coronary angiography for patients with non-ST-segment elevation acute coronary syndrome is the randomization time. To date, no study has reported the clinical outcomes of invasive strategy timing on the basis of the time of symptom onset.The aim of this study was to investigate the effect of invasive strategy timing from the time of symptom onset on the 3-year clinical outcomes of patients with non-ST-segment elevation myocardial infarction (NSTEMI).Among 13,104 patients from the Korea Acute Myocardial Infarction Registry-National Institutes of Health, 5,856 patients with NSTE myocardial infarction were evaluated. The patients were categorized according to symptom-to-catheter (StC) time (<48 or ≥48 hours). The primary outcome was 3-year all-cause mortality.Overall, 3,919 patients (66.9%) were classified into the StC time <48 hours group. This group had lower all-cause mortality than the group with StC time ≥48 hours (7.3% vs 13.4%; P < 0.001). The lower risk for all-cause mortality in the group with StC time <48 hours group was consistent in all subgroups. Notably, emergency medical service use (HR: 0.31; 95% CI: 0.19-0.52) showed a lower risk for all-cause mortality than no emergency medical service use (HR: 0.54; 95% CI: 0.46-0.65; P value for interaction = 0.008).An early invasive strategy on the basis of StC time was associated with a decreased risk for all-cause mortality in patients with NSTEMI. Because the study was based on a prospective registry, the results should be considered hypothesis generating, highlighting the need for further research. (iCReaT Study No. C110016).