Morbidity of endovascular abdominal aortic aneurysm repair is directly related to diameter

Objective: Previous randomized controlled trials have defined specific size thresholds to guide surgical decision-making in patients presenting with an abdominal aortic aneurysm (AAA). With recent advances in endovascular techniques, the anatomic considerations of AAA repair are rapidly changing. Our specific aims were to evaluate the most recent national population data to compare anatomic differences and perioperative outcomes in patients with AAA.

Methods: The American College of Surgeons National Surgical Quality Improvement Program was queried from 2011 to 2015 using the targeted vascular public use file. Patients with AAA undergoing elective open or endovascular repair were included. Risk factors and outcomes were stratified by size and divided into quartiles for categorical comparison. A logistic regression model was used to compare the impact of size on morbidity and mortality with each technique. A risk adjustment model used all preoperative criteria to generate observed and expected values for open and endovascular repair.

Results: There were 10,026 patients who underwent elective AAA repair, 8182 (81.6%) endovascular and 1844 (18.4%) open. Repairs were divided into density quartiles for a logistic analysis: smallest quartile, 3.5 to 5 cm; second quartile, 5.01 to 5.5 cm; third quartile, 5.51 to 6.2 cm; and largest quartile, >6.2 cm. Patients with larger aneurysms (>6.2 cm) were more likely to be male, to have a dependent functional status, and to have increased blood urea nitrogen concentration and American Society of Anesthesiologists score (P < .05). Larger aneurysms had longer operative time (162 vs 135 minutes) and greater extension toward the renal and iliac vessels (all P < .05). Risk adjustment revealed an observed/expected morbidity plot that favored endovascular repair throughout the size range but confirmed lack of size effect within the open repair category. The adjusted increase in morbidity with endovascular repair is 9.7% per centimeter increase in size of AAA. These trends remained true with an infrarenal subgroup analysis.

Conclusions: Patients with a larger AAA have comorbidities and anatomic factors associated with a more difficult repair. The higher morbidity seen with larger aneurysms represents both anatomic and patient factors but seems to have a greater impact on endovascular repairs. However, endovascular repair still results in fewer near-term complications than open repair across all size strata.