In patients with a ruptured aortic abdominal aneurysm (RAAA), Endovascular Aneurysm Repair (EVAR) is the preferred treatment relative to Open Repair (OR) when feasible. CT angiography (CTA) plays a decisive role in determining EVAR suitability. Fast and accurate treatment choice is of great importance in RAAA, to minimize mortality rate, intra- and postoperative complications. Limited and dated literature showed that determining EVAR suitability based on CTA was not consistent. There is no available data on the ability of vascular surgeons to assess suitability of RAAA for EVAR. A study was designed to map accuracy and inter observer variability in determining EVAR suitability in patients with a suspected RAAA based on CTA by comparing observations to those of a reference committee.

20 CTA's of patients with suspected RAAA were gathered from our database from 2016-2020. Inclusion criteria were: infrarenal abdominal aortic aneurysm, angulation could vary. Exclusion criteria were: infrarenal neck length <5mm, previous abdominal aortic intervention. Sixteen vascular surgeons assessed 20 retrospectively gathered CTA's of patients with a suspected RAAA in a SECTRA IDS7® diagnostic workstation. To simulate RAAA assessment setting, participants were observed and time was measured. Outcomes noted were: type of intervention (EVAR/OR), if EVAR, dimensions of te main body and iliac extensions and motivation if outside of the manufacturer's Instructions For Use IFU). Allowed was: off-the-shelf endografts available the te participant to treat RAAA, aorto-uni-iliac devices, overstenting internal iliac arteries, overstenting accessory renal arteries with a non-significant contribution to renal perfusion (<33%). Using endostaplers or chimney's was not allowed. The same CTA's were assessed by a reference committee (2 vascular surgeons, 1 interventional radiologist) in a semi- automatic sizing software workstation (3mensio Vascular™). Consensus between committee members had to be achieved. Primary outcomes were: EVAR suitability compared to the reference, inter observer variability. Secondary outcomes were: mean time-to-treatment decision, mean time-to-decision on endograft dimensions, motivation of treatment decision and EVAR specifics. EVAR suitability compared to the reference was expressed as percentage of OR chosen by observers where EVAR was chosen by the reference committee. Inter observer variability was expressed in kappa value and interpreted according to the method of Landis & Koch.

16 vascular surgeons originated from 7 vascular clinics assessed 320 CTA's in total. Experience as a vascular surgeon ranged from 0-5 (43.8%) to >25 years (20%). Experience with RAAA treated with EVAR ranged from 20-50 (43.8%) to 100-150 cases (12.5%). Experience with RAAA treated with OR ranged from 20-50 (56,3%) to >200 cases (7,1%). 10 (63%) surgeons used plain CTA to assess RAAA in daily practice. Characteristics of the CTA's measured by the reference committee were: neck length range: 4-34mm, infrarenal angulation range: 0-120°, suprarenal angulation range: 0-88°. Suitable for EVAR: 16 CTA's, EVAR outside of IFU: 5 CTA's. In 51.6% of the CTA's there was agreement on choice for EVAR between the observers and the reference (range: 12,5-75%). In 48,4% of de CTA's OR was chosen by the observers where EVAR was possible according to the reference. Insufficient proximal neck length and proximal neck angulation were most common reasons for choosing OR. Calculated kappa-value for EVAR suitability was 0.282. Mean time-to-treatment decision was 2.40 minutes (95% CI 2.28 - 2.52). Mean time-to-decision on endograft dimensions was 8:10 minutes (95% CI 7.31 - 8.50).

Our study has shown a substantial disagreement on EVAR suitability based on CTA in patients with a suspected RAAA. Deciding under time pressure might be of influence, a condition we attempted to mimic by measuring time to treatment-decision. Vascular surgeons needed a limited amount of time to make a treatment decision. Time-to-treatment decision in RAAA was, to our knowledge, reported for the first time. Making semi-automatic sizing software accessible in the RAAA setting might lead to increased agreement on EVAR suitability between vascular surgeons.