© 2016 Society for Vascular Surgery Objective Open conversion after endovascular aortic aneurysm repair (EVAR-c) is performed nonelectively in up to 60% of cases. EVAR-c has been reported to have significantly greater risk of postoperative morbidity and mortality than primary aortic repair, but few data exist on outcomes for symptomatic or ruptured presentations. This study determined outcomes and identified predictors of postoperative major adverse cardiac events (MACEs) and mortality for patients undergoing nonelective EVAR-c compared with nonelective primary aortic repair (PAR) in the Vascular Quality Initiative (VQI). Methods All VQI patients undergoing urgent/emergency EVAR-c or urgent/emergency PAR from 2002 to 2014 were reviewed. Urgent presentation was defined by repair ≤24 hours of a nonelective admission, and emergency operations had clinical or radiographic evidence, or both, of rupture. End points included in-hospital MACE (myocardial infarction, dysrhythmia, congestive heart failure) and 30-day mortality. Possible covariates identified on univariate analysis (P <.2) were entered into a multivariable model, and stepwise elimination identified the best subset of predictors. Generalized estimating equations logistic regression analysis was used to determine the relative effect of EVAR-c compared with PAR on outcomes. Results During the study interval, we identified 277 EVAR-c, and 118 (43%) underwent urgent/emergency repair. nonelective PAR was performed in 1388 of 6152 total (23%). EVAR-c patients were older (75 ± 9 vs 71 ± 10 years; P < .0001), more likely to be male (84% vs 74%; P =.02), and had a higher prevalence of hypertension (88% vs 79%; P =.02) and coronary artery disease (38% vs 27%; P =.01). No differences in MACE (EVAR-c, 31% [n = 34] vs PAR, 30% [n = 398]) or any major postoperative complication (EVAR-c, 57% [n = 63] vs PAR, 55% [n = 740]; P =.8) were found; however, 30-day mortality was significantly greater in EVAR-c (37% [n = 41]) than in (PAR, 24% [n = 291]; P =.003), with an odds ratio (OR) of 2.2 (95% confidence interval [CI], 1.04-4.77; P =.04) for EVAR-c. Predictors of any MACE included age (OR, × 1.03 for each additional year; 95% CI, 1.01-1.03; P =.0002), male gender (OR, 1.3; 95% CI, 1.03-1.67; P =.03), body mass index ≤20 kg/m2 (OR, 1.8; 95% CI, 1.13-2.87; P =.01), chronic obstructive pulmonary disease (OR, 1.2; 95% CI, 0.86-1.80; P =.25), congestive heart failure (OR, 1.5; 95% CI, 0.98-2.34; P =.06), preoperative chronic β-blocker use (OR, 1.3; 95% CI, 0.97-1.63; P =.09), and emergency presentation (OR, 2.3; 95% CI, 1.8-3.01; area under the curve, 0.70; P <.0001). Significant predictors for 30-day mortality were age (OR × 1.07 for each additional year; 95% CI, 1.05-1.09; P <.0001), female gender (OR, 1.6; 95% CI, 1.01-2.46; P =.04), preoperative creatinine >1.8 mg/dL (OR, 1.6; 95% CI, 1.04-2.35; P =.03), an emergency presentation (OR, 4.8; 95% CI, 2.93-7.93; P <.0001), and renal/visceral ischemia (OR, × 1.1 for each unit increase log (time-minutes); 95% CI, 1.02-1.22; area under the curve, 0.84; P =.01). Conclusions Nonelective EVAR-c patients are older and have higher prevalence of cardiovascular risk factors than PAR patients. Similar rates of postoperative complications occur; however, urgent/emergency EVAR-c has a significantly higher risk of 30-day mortality than nonelective PAR. Several variables are identified that predict outcomes after these repairs and may help risk stratify patients to further inform clinical decision making when patients present nonelectively with EVAR failure.