Background: In this study, pre-operative medical complexity is estimated by the independently validated Vascular Quality Initiative VQI Cardiac Risk Index (CRI). This study aims to identify and correlate trends of CRI for open abdominal aortic aneurysm (OAR) with trends in the CRI for corresponding endovascular aortic repair (EVAR). This assessment of differences in estimated procedural risks will be used to support the theory that, patient migration is an important factor contributing to decreased POMI following open vascular procedures. Methods: A retrospective review of VQI data from 2003 to 2020 for all patients undergoing elective aortic repairs (OAR and EVAR) was conducted. The CRI scoring developed for the open repair (oCRI) was applied to both the OAR and EVAR cohorts, with variables specific to EVAR translated from similar open repair factors in the model where feasible. To evaluate for changes across time, patients were grouped into Eras based on year of procedure, subsequently, univariate analysis of post-operative myocardial infarction (POMI) rates and CRI scores were perfomed between each era. Results: A total of 56,067 elective aortic repairs were identified (83% EVAR, 17% OAR). Within the OAR cohort, the average oCRI estimate was 7.1% with significant decrease across the studied timeframe (8% ± 4.6%→6.9% ± 4.4%, P < 0.001), which corresponded to a significant decrease in observed clinical myocardial infarction (MI) rate (4.1%→1.4%, P < 0.001). Over that same time period, the open CRI was applied to the EVAR cohort, and the average oCRI estimate was 7.2% and showed a significant increase (6.6% ± 2.8%→7.2% ± 4.4%, P < 0.001). Within the EVAR cohort, the eCRI estimate did not show any significant changes over time (average 0.48%), while the actual rate of clinical MI showed a significant decrease (1.1%→0.3%, P = 0.002). Gap analysis was conducted within the EVAR cohort between CRI estimates of procedural risks from an open operation versus an EVAR, which demonstrated that patients within the EVAR cohort would, on an average, has had 6.7% higher risk of POMI had they undergone an open procedure. Conclusions: Paradigm shifts with regard to patient selection for aortic repair is evident within this large national cohort. Over time, OAR patients had fewer preoperative estimated cardiac comorbidities and there is a corresponding decrease in POMI rates. As high-risk patients migrate from OAR to EVAR, there has been a subsequent increase in EVAR estimated pre-operative risks as the patients become more medically high-risk. Despite increasing complexity, rates of POMI in EVAR significantly decreased, potentially explained by improved operative technique and peri-operative care.