Purpose: To report the results of a trial comparing endovascular aneurysm repair (EVAR) to open repair (OR) and best medical therapy (BMT) involving high-risk patients with abdominal aortic aneurysms (AAA) suitable for EVAR.Methods: From 2002 to 2007, 1083 patients with aortic aneurysm disease were referred to a tertiary care university hospital. Of these, 162 (119 men; mean age 76 years) were high-risk patients with AAAs anatomically suitable for EVAR. Following comprehensive consultation with the patient, the family, and the primary physician, elective treatment was selected: OR (n=52), EVAR (n=66), or BMT (n=44). Outcomes were compared using Kaplan-Meier survival analyses and a parameter that measured the quality time spent without symptoms of disease or toxicity of treatment (Q-TWIST).Results: Four-year freedom from aneurysm-related death following EVAR (96.7%) was markedly better compared to BMT (66.8%; p=0.002) and was similar to OR (93.9%, p=0.483). Four-year freedom from major adverse clinical events was significantly better with EVAR (78%) compared with BMT (28%; p=0.001) and was equivalent to OR (75%; p=0.519). The 4-year intervention-free survival rate for EVAR (95%) almost matched OR (98%; p=0.410). At 4 years, Q-TWIST was 3.64 years for EVAR patients, 3.60 years for OR, and 2.22 years for BIVIT. Q-TWIST significantly improved with EVAR compared to OR (p<0.003). In the cost analysis, 52 high-risk patients were treated with OR over the 5-year period (2002-2007) at a total inpatient cost of (sic)1,257,457. The 66 patients treated with EVAR (14 patients more than OR) incurred a lower cost of (sic)1,129,138. Including the cost of follow-up over 4 years, the mean cost per patient was (sic)18,476 for EVAR and (sic)24,252 for OR, a savings of (sic)5,776 per patient treated with EVAR.Conclusion: In high-risk patients, EVAR reduces aneurysm-related death compared to BMT. Equated to the gold standard of open repair, EVAR, as a "one-time procedure," substantially reduces operative morbidity, hospital stay, costs, and utilization of intensive care facilities if performed in a high-volume center.