Editor's Choice - Feasibility and Safety of Using Carbon Dioxide Exclusively in Regular Endovascular Aortic Aneurysm Repair: Results of a Multicentre, Prospective, Zero Iodine Contrast Endovascular Aneurysm Repair Study

Objective: Carbon dioxide (CO2) angiography has emerged as a viable alternative to regular iodinated contrast medium (ICM) for guiding endovascular aneurysm repair (EVAR) procedures. This study aimed to evaluate the feasibility and safety of a standardised EVAR procedure using only CO2 angiography. Methods: A prospective, multicentre, national study enrolled consecutive patients between January 2023 and January 2024 with asymptomatic abdominal aortic aneurysms measuring > 55 mm and for whom a standard endovascular graft (instructions for use) was anatomically feasible. The study involved the use of an automatic CO2 injector to standardise intra-operative imaging. A strategy comprising five standardised steps was devised to visualise a target vessel (TV) that could not be seen during the first CO(2 )angiogram. The five steps were: (A) place the introducer closer to the TV; (B) tilt the table by 5- 10 degrees in the direction opposite to the TV; (C) selectively cannulate the TV; (D) cannulate the contralateral gate (only for repositionable devices); CO2 angiography was repeated in steps 1- 2; and (E) use ICM. Results: Two hundred and ninety-three patients were enrolled (10 centres), with a median age of 78 (interquartile range [IQR] 72, 83) years; 256 (87.4%) were male. The overall procedure time, fluoroscopy time, and injected CO(2 )volume were 90 (IQR 65, 125) minutes, 15 (IQR 10, 22) minutes, and 600 (IQR 400, 800) mL, respectively. The 30 day mortality, complication, and re-intervention rates were 0.3% (n = 1), 6.8% (n = 20), and 2.4% (n = 7), respectively. CO(2 )related adverse events were rare (1%; n = 3) and minor. A zero iodine contrast EVAR procedure was feasible in 240 (patients 81.9%). The five standardised steps were used extensively: step A, 170 procedures (58.0%); step B, 109 procedures (37.2%); step C, 21 procedures (7.2%); step D, 14 procedures (4.8%); and step E, 53 procedures (18.1%), with a median volume of 20 (IQR 10, 35) mL. Significant predictors for ICM use were aneurysm diameter > 70 mm and a lowermost renal artery positioned between 3 and 9 o'clock. Conclusion: This study demonstrated that the standardised zero iodine contrast EVAR protocol reported here is both safe and feasible and is applicable in 82% of consecutive non-selected patients. Limitations primarily arose from anatomical factors, and adjunctive standardised manoeuvres can effectively address these challenges in most cases.