A retrospective descriptive analysis of consecutive f/bEVAR procedures to treat complex aortic aneurysms between March 2007 and December 2023 was performed. Patients were identified from a prospectively maintained aortic database of the Department of Vascular and Endovascular Surgery at TUM University Hospital (Klinikum rechts der Isar, Technical University of Munich). The study was conducted following the Strobe Statement (9). The Ethics Committee of the University Hospital of the Technical University of Munich approved the data collection under the reference number 2025-194-S-KK. The analysis follows the predefined reporting standard for endovascular aortic repair of aneurysms involving the renal-mesenteric arteries (10).

Patients were included, if they underwent f/bEVAR during the study period (Figure 1). Treated pathologies included TAAAs (classified according to modified Crawford classification) (11), juxta/pararenal abdominal aortic aneurysms (j/pAAA), and/or aortic dissections. Decisions on indications for repair were achieved in a multidisciplinary team meeting and based on international guidelines (1). TAAAs and j/pAAAs were usually operated, if they reached a threshold diameter of at least 60 mm, showed rapid growth (≥5 mm/6months or ≥10 mm/12 months), were symptomatic or ruptured, or featured penetrating aortic ulcer (PAU) morphology. All included aortic dissections showed chronic degenerative expansions. Decisions whether to perform open surgical repair or f/bEVAR based on patients’ preference, patients’ age and comorbidities, and feasibility. If f/bEVAR was performed, a percutaneous access was performed as standard approach. For transbrachial implantation of bridging-stents, an open surgical access close to the axilla was conducted. During the procedure, patients were fully heparinized with continuous heparin infusion aiming for an activated clotting time (ACT) of 250–280 s. Stent grafts were chosen based on patients’ anatomy, availability (in urgent or emergency cases), and surgeons’ preference. Spinal cord ischemia (SCI) prevention strategies considered extent and location of the aortic pathology, patency of vertebral arteries and internal iliac arteries, existence, number, and diameter of intercostal/lumbar arteries. If the risk for SCI was considered as relevant, staged repair (if feasible) or preemptive spinal drainage were performed. During and after the operation, it was aimed to achieve a mean arterial pressure (MAP) ≥90 mmHg, a hemoglobin value ≥9 mg/dL, and oxygen was applied through a nasal cannula after extubation. If the patient presented with signs of SCI and no spinal drain had been applied beforehand, it was established urgently. Especially towards the end of the study period, the mentioned postoperative measures were adhered to meticulously and if a spinal drain had been placed, it was removed not before the third postoperative day. If a staged repair was performed, usually one branch was used as perfusion branch. The completion procedure was performed at the earliest 6 weeks after the index procedure. In the second half of the study period, we aimed to perform the completion procedure under local anesthesia, blocked the branch with a balloon catheter for 15 min, and only implanted the bridging stent if the patient remained asymptomatic. The first f/bEVAR procedures were performed with a mobile C-arm (Veradius, Philips Medical Systems, Eindhoven, Netherlands or OEC 9800, GE Healthcare, Chicago, USA), from 2013 all procedures were performed in a hybrid operating room (2013–2017: Allura Xper FD20, Philips Medical Systems, Eindhoven, Netherlands; 2017–2023: Azurion 7 C20 with FlexArm, Philips Medical Systems, Eindhoven, Netherlands). The follow-up (FU) algorithm in our department comprises routine follow-up visits with contrast enhanced ultrasound (CEUS) scans at 1, 6, and 12 months after the index procedure. Thereafter, follow-up is conducted annually. Computed tomography angiography (CTA) scans are usually performed within one month after the procedure and annually thereafter. (Endovascular) repair is indicated, if a high-flow endoleak (type I or III) or a low-flow endoleak (type II) with relevant aneurysm growth (≥5 mm in diameter) is detected.

Clinical patient data during the hospital stay, including pre-operative and operative characteristics and complications, and FU data were obtained from electronic medical records. FU intervals and modalities varied according to clinical practice.

The primary outcome was defined as in-hospital death after the index procedure. Secondary outcomes were death within 30 days after the index procedure and death during the FU. Other outcomes included length of intensive care unit (ICU) stay, length of hospital stay, any secondary intervention, aortic secondary intervention, occurrence of any component or a combination of major adverse events [MAE; comprising blood loss >1,000 mL, myocardial infarction, acute kidney injury (i.e., >50% decrease in glomerular filtration rate), respiratory failure, paraplegia, stroke, bowel ischemia], and evidence of an endoleak in post-operative CTA scans.

Categorical variables were presented as absolute numbers and percentages. Continuous data were presented as median and interquartile range if not normally distributed. Normally distributed interval scaled data were presented as mean and standard deviation. To assess temporal trends in treatment and outcomes, the cohort was divided into three equal treatment periods: early phase (2007–2016), intermediate phase (2017–2020), and recent phase (2021–2023). Time intervals were defined a priori after a first assessment of data in order to contain similar numbers of patients. As a certain number of patients was excluded from the final analyses (Figure 1), the final number of analyzable patients per period varied slightly.

Univariate analyses were used to assess for clinically associated risk factors for the occurrence of in-hospital death. Survival analyses were performed using the Kaplan–Meier method with log-rank testing. Group comparisons were made using Kruskal–Wallis and chi-square tests as appropriate. A p-value < 0.05 was considered statistically significant. Statistical analyses were performed using R Studio, version 4.0.3 (R Foundation for Statistical Computing, Vienna, Austria).

The median age of the population was 75 years with 80% being male (Table 1). The proportion of octogenarians increased from 14% in the early phase to 31% in the recent phase (p = 0.022).

In 13% of cases, f/bEVAR was performed as an emergency procedure. The median diameter of the aortic aneurysm amounted to 59 mm. Regarding aneurysm type, patients with juxta/pararenal aneurysms represented the largest cohort (68%), followed by TAAAs type IV (8.5%), type III (8.0%), type I and II (5.7% each), and type V (1.7%) according to the modified Crawford classification (11).

Comorbidities included hypertension (97%), coronary artery disease (53%), peripheral arterial occlusive disease (22%), stroke or transient ischemic attack (20%), chronic obstructive pulmonary disease (COPD; 19%), diabetes mellitus (21%), and hypercholesterolaemia (85%).

Most patients ranged in American Society of Anaesthesiologists (ASA) stage III (73%), followed by stages II (19%) and IV (7.4%).

Medical treatment included antiplatelet agents (98%), anticoagulants (23%), antihypertensives (93%), and statins (81%). Statin use significantly increased across treatment phases (p < 0.001).

The majority of patients (71%) were treated with custom made devices, while 26% underwent treatment with an off-the-shelf device. In 2.8%, a physician modified endograft (PMEG) was implanted (Table 2).

The number of incorporated vessels increased from an average of 3.7 in the early phase to 4.0 in the recent phase (p < 0.001). Accordingly, the proportion of patients receiving fenestrations for the celiac axis increased from 26% to 34% (p = 0.001) comparing the early and recent phases. Contrarily, a decline of scallops for the celiac axis (25 vs. 4.7%) and the superior mesenteric artery (SMA; 14 vs. 1.6%) was observed.

Regarding types of implanted devices, custom made devices (CMD) manufactured by Cook (Cook Medical, Bloomington, USA) were implanted most frequently (47%), followed by the off-the-shelf t-Branch endograft (24%; Cook Medical, Bloomington, USA) and the fenestrated Anaconda (22%; Vascutek/Terumo Aortic, Inchinnan, UK). While fenestrations were frequently combined with scallops (37% of all devices) in the early phase, only 3.1% of patients in the recent phase were treated with a combination of fenestrations and scallop. The proportion of purely fenestrated endografts manufactured by Cook declined from 30% in the early phase to 16% in the recent phase. Conversely, the proportion of fenestrated Anaconda endografts rose from 1.8% in the early phase to 41% in the recent phase. Regarding the t-Branch endograft, the implantation habit remained stable over time.

Overall, f/bEVAR was combined with iliac branch devices (IBD) in 2.3% and with cervical debranching procedures in 1.1%.

All operations were performed under general anesthesia (Table 3). Cerebrospinal fluid drainage was applied in a third of the patients and in 99% of the patients a percutaneous access was used. Brachial access was performed in one third of the patients with a non-significant decline comparing early and recent phases (39 vs. 23%; p = 0.072).

Staged aortic repair was performed in 16% of the patients.

The mean operating time declined significantly between early and recent phases (321 vs. 241 min; p = 0.002).

A significant reduction of used contrast media was observed when comparing early and recent phases (398 vs. 190 mL; p = 0.001).

With an average of 65 min, total fluoroscopy time remained stable throughout the observed period.

Overall, in-hospital mortality was 4.5% and showed a non-significant trend (p = 0.062) favoring the recent treatment phase (1.6%) compared to the intermediate and the early phases (3.6 and 8.8%). When comparing the early with the recent treatment phases, length of ICU stay declined significantly (8.1 vs. 2.7 days; p < 0.001) and length of hospital stay showed a non-significant downward trend (20 vs. 15 days; p = 0.248).

Any MAE occurred in 34% of the cohort. Comparing early and recent phases, the occurrence of acute kidney injury (16 vs. 4.7%; p = 0.034) and respiratory failure (18% vs. 0%; p = 0.001) declined significantly.

Paraplegia showed a non-significant downward trend when comparing the three treatment phases (8.8 vs. 3.6 vs. 1.6%; p = 0.062).

Among perioperative endoleaks, type II represented the most common entity (20%), followed by type III (11%) and type I (8%). No significant changes were observed between time periods.

Results of the univariate analyses are given in Table 4. The univariate analysis showed a non-significant association between the operation being performed during the recent treatment phase compared to the early phase and in-hospital death (OR 0.17; 95% CI 0.02–1.46). For age and sex, no associations were found with regard to the primary outcome event.

Emergency procedures showed a non-significant trend towards higher in-hospital death compared to non-emergency procedures (OR 4.40; 95% CI 0.86–19.5).

Equally, presence of TAAA Crawford types I/II/III/V were associated with a non-significant trend towards higher in-hospital death rates compared to juxtarenal, pararenal AAAs or TAAAs Crawford type IV (OR 2.09; 95% CI 0.41–8.93).

None of the assessed comorbidities showed a significant association with the occurrence of the primary outcome event.

An elevated operating time was significantly associated with in-hospital mortality (per 10 min increase; OR 1.06; 95% CI 1.02–1.11).

The occurrence of a MAE was significantly associated with in-hospital mortality (OR 37.40; 95% CI 4.52–4,869).

The mean FU was 19.4 months (590 days; Table 5).

The Kaplan–Meier curves are given in Figure 2. Probability of survival was highest in the recent treatment phase and lowest in the early phase. The difference between the recent and the early phase was statistically significant (p = 0.024).

The univariate analyses (Table 6) revealed, that aneurysm type (TAAA Crawford types I/II/III/V vs. juxta/pararenal AAA or TAAA Crawford type IV) was significantly associated with mortality during FU (OR 3.94; 95% CI 1.35–12). Aortic dissection showed a trend towards higher mortality during FU (OR 2.60; 95% CI 0.13–19).

None of the comorbidities showed a significant association with mortality during FU.

The occurrence of a MAE was significantly associated with death during FU (OR 6.94; 95% CI 2.29–26). Regarding the different components of the combined outcome MAE, perioperative acute kidney injury (OR 10.0; 95% CI 2.88–34.0), respiratory failure (OR 3.74; 95% CI 1.00–13.0), and stroke (OR 4.36; 95% CI 1.03–18.4) were significantly associated with mortality during FU.