Characteristics and Outcomes of Ruptured Abdominal Aortic Aneurysms Below the Size Threshold for Elective Repair

Abstract

The current guidelines recommend elective abdominal aortic aneurysm (AAA) repair at 5.5 cm in men and 5.0 cm in women. However, rupture occurs in patients with aneurysm size below these thresholds. This study aimed to investigate the proportion of small ruptured AAAs (rAAAs) below elective operative thresholds and to compare outcomes of repair with larger aneurysms. The 2011 to 2018 American College of Surgeons National Surgical Quality Improvement Program open and endovascular AAA repair databases were reviewed for all cases of rAAA. Patients were divided into two groups: small rAAA for those who present below size thresholds and large rAAA for the remainder. The proximal/distal extent of rAAA and the preoperative characteristics and outcomes of infrarenal rAAA were compared. Of the 1612 ruptured AAA repairs, 167 (10.4%) were small rAAAs. The proportion of small rAAA did not significantly change during the study period (P = .15; Fig). Patients in the large rAAA group were more likely to have juxtarenal or suprarenal aneurysms (27% vs 16%; P = .001). Patients in the small infrarenal rAAA group had significantly lower body mass index and were more likely to be African American and to have hypertension. Patients in the small AAA group were more likely to be assigned to American Society of Anesthesiologists class ≤3 and to undergo endovascular aneurysm repair but less likely to have hypotension on presentation. Repair of small rAAA was associated with lower bleeding, mortality, and mean operative time and higher readmission (Table). Multivariate analysis showed that rupture with hypotension, open repair, general anesthesia, age, and high American Society of Anesthesiologists class were associated with increased mortality, but aneurysm size was not. Current guidelines for elective repair based solely on AAA sac diameter fail to identify 10% of patients presenting with rupture. Ruptured AAA carries significant mortality regardless of the size of the aneurysm. Further research into sac morphology and more sensitive imaging modalities may help identify small rAAA at high risk of rupture that would benefit from elective repair.TableDemographics, comorbidities, operative characteristics, and outcomes of ruptured abdominal aortic aneurysm (rAAA)Small infrarenal rAAALarge infrarenal rAAAP valueTotal141 (100)1051 (100)Age, years <503 (2.1)40 (3.8) 51-6429 (20.5)200 (19.0) 65-7942 (29.7)311 (29.5) 80+56 (39.7)371 (35.3).86 Mean (SD)71.8 (11.6)70.8 (11.8).38Male sex105 (74.4)817 (77.7).38Functional status.16 Dependent8 (5.6)35 (3.3)BMI, kg/m2<.02 <1814 (9.9)95 (9.0) 18-2447 (33.3)217 (20.6) 25-3039 (27.6)282 (26.8) 30-3412 (8.5)188 (17.8) 35+16 (11.3)134 (12.7)BMI, kg/m2, mean (SEM)26.1 (0.6)27.8 (0.2)Height, inches, mean (SEM)67.6 (0.3)67.7 (0.1).65Weight, kg, mean (SEM)80.3 (1.8)86.8 (0.7)<.01Race White102 (72.3)790 (75.1) African American17 (12.1)53 (5.0)<.01 Other22 (15.6)208 (19.7)Comorbidities Diabetes mellitus22 (15.6)144 (13.7).54 Current smoker52 (36.8)401 (38.1).76 COPD26 (18.4)162 (15.4).35 CHF3 (2.1)32 (3.0).54 HTN106 (75.1)692 (65.8).02 Current dialysis3 (2.1)16 (1.5).59Presentation AAA diameter, mean (SEM)4.4 (0.1)8.0 (0.1)<.01 Rupture with hypotension47 (33.3)521 (49.5)<.01Surgical technique EVAR111 (78.7)685 (65.1)<.01 Open30 (21.2)366 (34.8)Anesthesia technique GA126 (89.3)959 (91.2) Other15 (10.6)92 (8.7).46ASA class ≥499 (70.2)862 (82.0)<.01Operating time, minutes, mean (SEM)163.7 (8.9)182.3 (8.9).03Complications Wound infection5 (3.5)36 (3.4).94 Pneumonia10 (7.0)100 (9.5).35 Unplanned intubation11 (7.8)93 (8.8).67 Failed vent weaning24 (17.0)224 (21.3).23 Cardiac arrest10 (7.0)103 (9.8).3 Myocardial infarction6 (4.2)90 (8.5).07 Stroke2 (1.4)20 (1.9).68 Bleeding77 (54.6)713 (67.8)<.01 DVT/thrombophlebitis4 (2.8)39 (3.7).6 Sepsis11 (7.8)108 (10.2).35 Renal failure1 (0.7)11 (1.0).7 Ischemic colitis8 (5.6)81 (7.7).38 Repeated rupture of aneurysm7 (4.9)61 (5.8).68 Lower extremity ischemia3 (2.1)50 (4.7).15 Any morbidity92 (65.2)776 (73.8).03Mortality24 (17.0)260 (24.7).04Readmission19 (13.4)60 (5.7)<.01Reoperation23 (16.3)151 (14.3).53Hospital length of stay, days (SD)9.78 (12.2)9.71 (15.2).84ASA, American Society of Anesthesiologists; BMI, body mass index; COPD, chronic obstructive pulmonary disease; CHF, congestive heart failure; DVT, deep venous thrombosis; EVAR, endovascular aneurysm repair; GA, general anesthesia, HTN, hypertension; SD, standard deviation; SEM, standard error of the mean.Values are reported as number (%) unless otherwise indicated. Boldface P values represent statistical significance. Open table in a new tab