OBJECTIVE: The traditional approach to stable blunt thoracic aortic injury (BTAI) endorsed by the Society for Vascular Surgery is early (<24 hours) thoracic endovascular aortic repair (TEVAR). Recently, some studies have shown improved mortality in stable BTAI patients repaired in a delayed manner (≥24 hours). However, the indications for use of delayed TEVAR for BTAI are not well characterized, and its overall impact on the patient's survival remains poorly understood. We sought to determine whether delayed TEVAR is associated with a decrease in mortality compared with early TEVAR in this population. METHODS: We conducted a retrospective cohort study of adult patients with BTAI (International Classification of Diseases, Ninth Revision diagnosis code 901.0) who underwent TEVAR (International Classification of Diseases, Ninth Revision procedure code 39.73) from 2009 to 2013 using the National Sample Program data set. Missing physiologic data were imputed using chained multiple imputation. Patients were parsed into groups based on the timing of TEVAR (early, <24 hours, vs delayed, ≥24 hours). The χ, Mann-Whitney, and Fisher exact tests were used to compare baseline characteristics and outcomes of interest between groups. Multivariable logistic regression for mortality was performed that included all variables significant at P ≤ .2 in univariate analyses. RESULTS: A total of 2045 adult patients with BTAI were identified, of whom 534 (26%) underwent TEVAR. Patients with missing data on TEVAR timing were excluded (n = 27), leaving a total of 507 patients for analysis (75% male; 69% white; median age, 40 years [interquartile range, 27-56 years]; median Injury Severity Score [ISS], 34 [interquartile range, 26-41]). Of these, 378 patients underwent early TEVAR and 129 underwent delayed TEVAR. The two groups were similar with regard to age, sex, race, ISS, and presenting physiology. Mortality was 11.9% in the early TEVAR group vs 5.4% in the delayed group, with the early group displaying a higher odds of death (odds ratio, 2.36; 95% confidence interval, 1.03-5.36; P = .042). After adjustment for age, ISS, and admission physiology, the association between early TEVAR and mortality was preserved (adjusted odds ratio, 2.39; 95% confidence interval, 1.01-5.67; P = .047). CONCLUSIONS: Consistent with current Society for Vascular Surgery recommendations, more BTAI patients underwent early TEVAR than delayed TEVAR during the study period. However, delayed TEVAR was associated with significantly reduced mortality in this population. Together, these findings support a need for critical appraisal and clarification of existing practice guidelines in management of BTAI. Future studies should seek to understand this survival disparity and to determine optimal selection of patients for early vs delayed TEVAR.