ABSTRACT
BACKGROUND/AIMS: Symptom-to-door time is associated with the prognosis for ST-segment elevation myocardial infarction. However, this value has not been a concern in patients with non-ST segment elevation myocardial infarction (NSTEMI). The aim of this study was to assess the relationship between symptom-to-door time and clinical outcomes in patients with NSTEMI. METHODS: In total, 1,971 patients with NSTEMI (64.8+/-12.1 years, 23.6% women) were enrolled between Nov. 2005 and Jan. 2008. The patients were divided into two groups according to the time difference between the presentation of symptoms and first medical contact: group I (12 hours, n=538). One-year mortality rates were compared between the groups. Thrombolysis In Myocardial Infarction (TIMI) and Global Registry of Acute Coronary Events (GRACE) risk scores were calculated in all study patients. RESULTS: The mean age was 64.4+/-12.2 years in group I and 65.6+/-12.0 years in group II (p=0.046). No significant differences existed between the two groups, except for the prevalence of hypertension, diabetes mellitus, initial systolic blood pressure, and initial serum creatinine levels. One-year mortality rates decreased significantly in group I patients [hazard ratio (HR)=1.35, 95% CI (confidential interval): 1.03~1.75, p=0.028] based on a multivariate Cox proportional analysis, which was adjusted by GRACE score, baseline characteristic variables, and predictors of a 1-year mortality in a univariate analysis. In intermediate-to high-risk patients (n=1,184, defined as having a TIMI risk score above 3 points), significant differences were observed in mortality rates between the two groups (HR=1.35, 95% CI: 1.02~1.80, p=0.037); the low-risk patients (n=787, HR=1.57, 95% CI: 0.80~3.05, p=0.188), however, showed no such differences. CONCLUSIONS: Symptom-to-door time was an independent long-term clinical predictor in patients with NSTEMI, especially in intermediate-to high-risk groups.