Characterizing the frequency and indications for repair of abdominal aortic aneurysms with diameters smaller than recommended by societal guidelines
OBJECTIVE: While the Society for Vascular Surgery recommends repair of abdominal aortic aneurysms (AAA) at ≥5.5 cm in men and ≥5.0 cm in women, AAA repair below these thresholds has been well documented. There are clear indications for repair other than these strict size criteria, but the expected proportion of such repairs in one's practice has not been studied. We sought to characterize the indications for repairs of aneurysms below diameter recommendations at a single academic center. Using the assumption that this real-world experience would approximate that of other practices, we then used national data to extrapolate these findings. METHODS: A single-center retrospective review was conducted of all elective open (oAAA) and endovascular (EVAR) AAA repairs (2010-20) to assess the incidence of and indications for repair of aneurysms below diameter recommendations (defined as <5.5cm in men and <5.0cm in women). Reasons for these repairs were defined as: 1) iliac aneurysm, 2) saccular morphology, 3) rapid expansion, 4) patient anxiety, 5) distal embolization, 6) other, and 7) no documented reason. The Vascular Quality Initiative (VQI) was queried for all asymptomatic oAAA and EVAR (2010-20) and repairs below diameter recommendations were identified. Findings from the single-center analysis were applied to the VQI cohort to extrapolate estimates of reasons for repairs done nationally. In-hospital mortality and major adverse cardiac events (MACE) were compared between those below size recommendations and those meeting size recommendations. RESULTS: Of 456 elective AAA repairs at our center, 147 (32%) were below size recommendations. This was more common for EVAR (35% vs 28%). Reasons were: not documented (41%), iliac aneurysm (23%), saccular (10%), rapid expansion (10%), patient anxiety (7%), other (6%), and distal embolism (3%). Of 44,820 elective AAA repairs in VQI, 17,057 (38%) were below size recommendations (40% EVAR, 26% oAAA). Patients who were repaired below size recommendations had lower in-hospital death (oAAA: 2.4% vs 4.6% p<0.0001; EVAR: 0.3% vs 0.8% p<0.0001). When single-center findings were applied to the VQI dataset, an estimated 10,064 repairs were performed nationally for acceptable indications other than size criteria. Conversely, there may have been 6993 repairs (with an associated 35 deaths) performed without documented indication. CONCLUSION: Repairs for AAA below recommended diameter guidelines account for approximately one third of all elective AAA procedures in both VQI and our single-center experience. Assuming our practice is typical, nearly 60% of repairs below size recommendations meet criteria for other clear reasons. The remaining 40% lack a documented reason, meaning 13% of all elective AAA repairs were done for aneurysms below size recommendations without an acceptable indication. As awareness of overuse/underuse is heightened, these data help estimate the expected proportion of repairs for less common pathologies. They also provide a potential baseline data point for efforts at reducing overuse.