The PROTAGORAS 2.0 study to identify sizing and planning predictors for optimal outcomes in abdominal chimney endovascular procedures

Objective: The aim was to identify predictors of adequate pre-operative sizing and planning for chimney endovascular aortic repair (ChEVAR) in order to reduce the incidence of persistent type Ia endoleaks (IaELs) without influencing chimney graft (CG) patency. Methods: Consecutive patients who underwent ChEVAR between January 2009 and December 2017 at a single centre were evaluated retrospectively. Included were patients treated with one device combination (Medtronic Endurant mated with Getinge Advanta V12/iCast) and placement of single or double CG. The freedom from IaEL related re-interventions and primary CG patency was estimated by measuring aortic stent graft oversizing (OS), total neck length (TNL), and a composite parameter (L-OS: TNL [mm] + OS [%]). Results: Seventy-three patients who underwent placement of 101 CGs (45 single, 28 double) met the inclusion criteria. The median radiological follow up was 25.5 (interquartile range [IQR] 12–48) months. Freedom from IaEL related re-intervention was achieved in 94.6% with a median OS of 38.5% (IQR 30%–44%, p = .004), TNL 19 mm (16–25 mm, p = .62), and L-OS 59 (51–65, p = .018). Primary CG patency was achieved in 95% of the cases with a median OS of 36% (29%–42%, p = .008), TNL 19 mm (15.5–26 mm, p = .91), and L-OS 57 (50–64, p = .005). By using the receiver operating characteristic curve, an optimal cut off to prevent IaEL related re-interventions was identified by an OS of 30% (p < .001; L-OS 55, p = .006) and to avoid CG stenosis/occlusions by OS 42% (p < .001; L-OS 65, p < .001). In multivariable analysis, aortic endograft OS was the only independent parameter preventive for IaEL related re-intervention (odds ratio, 0.78; 95% confidence interval, 0.61–0.99). Conclusion: With the Endurant-Advanta V12/iCast combination, an aortic stent graft OS of at least 30% (range 30%–42%) should be used to avoid type Ia endoleaks and likewise to ensure CG patency.