Morphological and Clinical Predictors of Early/Follow-up Failure of the Endovascular Infrarenal Abdominal Aneurysm Repair With Currently Available Endografts

Abstract

Purpose:

To report outcomes of endovascular repair (EVAR) of infrarenal abdominal aortic aneurysms (AAAs) with currently-available endografts and identify predictors of technical/clinical failure.

Materials and Methods:

Patients undergoing EVAR between 2012 and 2020 were prospectively collected and retrospectively analyzed. Technical success (TS: no type I–III endoleaks, renal/hypogastric arteries loss, iliac leg occlusion, conversion to open repair and mortality within 24 postoperative hour), proximal neck–related TS (nr-TS: no proximal type I endoleaks, unplanned renal arteries coverage), and 30-day mortality were assessed as early outcomes. Proximal type I endoleak (ELIa), survival and freedom from reinterventions (FFRs) were assessed during follow-up. Uni/multivariate analysis and Cox-regression were used to identified factors associated with early and follow-up outcomes; FFR and survival were assessed by Kaplan-Meier analysis.

Results:

A total of 710 were included. Technical success and nr-TS were 692 (98%) and 700 (99%), respectively. The presence of ≥2 hostile anatomical infrarenal neck characteristics was associated with technical failure (odds ratio [OR]: 2.4; 95% confidence interval [CI]: 1.3–4.1; p: 0.007). Infrarenal neck angle >90° (OR: 2.88; 95% CI: 9.6–50.3; p: 0.004), barrel shape (OR: 2.33; 95% CI: 11.1–100.3; p: 0.02) or presence of ≥2 hostile anatomical infrarenal neck characteristics (OR: 2.16; 95% CI: 2.5–5.3; p: 0.03) were independent risk factors for neck-related technical failures. Six (0.8%) patients died within 30 postoperative days. Chronic obstructive pulmonary disease (OR: 16; 95% CI: 1.1–218.3; p: 0.04) and urgent repair (OR: 15; 95% CI: 1.8–119.6; p: 0.01) were independent risk factors for 30-day mortality. The mean follow-up was 53±13 months. There were 12 (1.7%) ELIa during follow-up. Infrarenal neck length <15 mm (hazard ratio [HR]: 2.8; 95% CI: 1.9–9.6; p: 0.005), diameter >28 mm (HR: 2.7; 95% CI: 1.6–9.5; p: 0.006), angle ≥90° (HR: 2.7; 95% CI: 8.3–50.1; p: 0.007), and persistent type II endoleak (HR: 2.9; 95% CI: 1.6–10.1; p: 0.004) were independent risk factors for ELIa. Freedom from reintervention was 91% at 5 years. The ELIa was an independent risk factor for reinterventions during follow-up (HR: 29.5; 95% CI: 1.4–1.6; p<0.001). Survival was 74% at 5 years with 2 cases (0.3%) of late aortic-related mortality. Peripheral arterial occlusive disease (HR: 1.9; 95% CI: 1.4–3.65; p: 0.03), aneurysm diameter ≥65 mm (HR: 2.2; 95% CI: 1.4–3.26; p<0.001), and infrarenal neck length <15 mm (HR: 1.7; 95% CI: 1.2–2.35; p: 0.04) were independent risk factors for mortality during follow-up.

Conclusion:

Endovascular repair with currently-available endografts has high TS and low 30-day mortality. Survival and FFRs were satisfactory at mid-term. Pre/postoperative risk factors for technical and clinical failure were identified and they should be considered in EVAR indication and postoperative management to reduce complications and improve mid-term outcome.

Clinical Impact

Pre and postoperative risk factors for technical and clinical EVAR failure can be identified and they should be considered in EVAR indication and postoperative management to reduce complications and improve mid-term outcome.

Keywords

aneurysm aneurysm neck aneurysm sac endograft endovascular aneurysm repair outcome analysis

Introduction

Randomized controlled trials have shown that the perioperative mortality and morbidity is lower after endovascular abdominal aneurysm repair (EVAR) compared with open repair (OR),^1,2 with a subsequent effect on the worldwide distribution of the 2 techniques.^3,4 Differently, long-term data suggest that EVAR advantages disappear during mid-term and long-term follow-up, due to an increase in reintervention or abdominal aortic aneurysm (AAA) rupture.^5–7

Case selection, preoperative sizing, and planning are crucial to optimize EVAR results and to reduce late complications.⁸ Preoperative anatomical risk factors for technical and clinical failure were identified⁹ in large and multicenter studies/registries, particularly the anatomical characteristics of the infrarenal neck, but also the morphology of the iliac arteries.^10–14 Most endografts examined in these experiences are not currently available in either Europe or United States^10–12 and their results should not be compared with the devices used in our contemporary daily practice.^15,16 Finally, the endovascular skills of modern vascular surgeons have increased in the last years, with a subsequent theoretical positive impact on the EVAR outcomes.^8,17

The aim of the present study was, therefore, to report early/late EVAR outcomes of currently-available endografts, and to identify predictors of failure in a single center at high volume for AAA repair.

Patient Population and Methods

Study Design and Patient Selection

This was a single-center, observational and retrospective study. All consecutive patients undergoing EVAR between 2012 and 2020 were prospectively collected in an electronic dedicated database. According to the European General Data Protection Regulation (GDPR), all cases were deidentified with a coding number. Preoperative, procedural, and postoperative data were retrospectively analyzed. Patients signed an informed consent for the aortic repair and their anonymous data management. The study was approved by the Local Institutional Review Board and no funding was obtained from companies or other institutions.

Preoperative Planning

All patients were studied through a thoracoabdominal computed tomography angiography (CTA) performed within 6 months before the procedure. Postprocessing analysis (3-dimensional, multiplanar, and center lumen line reconstructions) was performed with a dedicated software for vessel analysis (3Mensio Vascular Imaging, Bilthoven, The Netherlands). The anatomical sizing and endograft planning were performed by the same vascular surgeons who performed the procedures. All surgeons had high experience in EVAR planning and procedures (>10 years of experience).

Procedures

The procedures were performed by a team of vascular surgeons (6 physicians) in an operative room equipped with a mobile angiographic C-arm (Ziehm Vision Hybrid RFD; Ziehm Imaging GmbH, Nürnberg, Germany) and since 2016 in a Philips hybrid room (www.philips.it/healthcare). Surgical or percutaneous femoral approach was performed according to the anatomy of the common femoral arteries and the surgeon preference. The intraoperative AAA sac embolization was performed by Cook M-Reye coils (M-Reye Embolization Coil, IMWCE-38-16-45; Cook Medical, Limerick, Ireland), in anatomically-selected patients (presence of at least 6 efferent patent vessels from the AAA sac and/or AAA thrombus volume <40% of the total AAA volume),¹⁸ to reduce the incidence of persistent type II endoleaks.¹⁹ A dedicated protocol for intraoperative iliac limb management was adopted to minimize the risk of iliac limb occlusion during follow-up as previously reported.²⁰

Cook Zenith (Flex and Alpha), Gore Excluder (C3 and Comformable), Medtronic Endurant (II and IIs), and Terumo Anaconda (One lock) are the 4 types of endografts used in our department during the study period.

Follow-up

After discharge, patients entered into a dedicated clinical, laboratory, and imaging follow-up protocol. Laboratory evaluation of renal function and duplex ultrasound (DUS) was performed before discharge and at 6 months; a CTA was performed at 12 months, and DUS or CTA was repeated yearly thereafter according to the AAA sac size and patient’s body mass index. In case of AAA enlargement, contrast-enhanced ultrasound sonography (CEUS) was performed to detect and characterize low-flow endoleaks possibly undetected with standard imaging. In case of any doubt following DUS/CEUS or when a reintervention was indicated, a CTA was performed.

Endpoints and Definition

Technical success (TS), neck-related TS, and 30-day mortality were assessed as early endpoints. Proximal type I endoleaks, survival, and freedom from reinterventions (FFRs) were assessed during follow-up. Risk factors for early and follow-up outcomes were analyzed. Technical success was defined as absence of type I–III endoleaks, unplanned renal or hypogastric arteries coverage, iliac leg occlusion, conversion to OR, and mortality within 24 postoperative hours. Neck-related TS was defined as absence of proximal type I endoleak and unplanned renal artery loss at the completion angiography. Postoperative morbidity and endoleaks were defined and classified according to the Society of Vascular Surgery reporting standards.²¹ Reinterventions were defined as any procedure aneurysm, device, or access-related, occurring after the index EVAR operation. The anatomical proximal neck characteristics evaluated were extensively described in our previous reports^22,23 and they are defined and summarized in Supplementary Table 1. The AAA sac diameter was considered stable for changes <5 mm of the preoperative value. Aneurysm shrinkage was defined as AAA diameter reduction >5 mm of the preoperative value.

Statistical Analysis

Continuous variables were reported as mean and standard deviation (SD). Categorical variables were expressed as frequencies. Univariate (Fisher exact or Chi Square when appropriate) and multivariate analysis were used to identify factors associated with early outcomes. Freedom from reinterventions and survival were assessed by Kaplan-Meier analysis. Cox regression was used to determine risk factors for type I endoleak, mortality, and reinterventions during follow-up. All the statistical tests were 2-sided and p values ≤0.05 were considered as statistically significant. Statistical analysis was performed by SPSS 25.0 for Windows (SPSS Inc, Chicago, IL, USA).

Results

Patient Selections and Preoperative Characteristics

Between 2012 and 2020, 983 patients were treated for infrarenal AAA. Among these, 710 (72%) cases were managed by standard EVAR and enrolled in the present study.

Six hundred thirty-eight (90%) patients were men; the mean age was 76±8 years and the American Society of Anesthesiology (ASA) score was ≥3 in 686 (96%) cases. Thirty (4%) patients were treated in urgent setting (symptoms/rupture) and 4 (0.6%) had an inflammatory AAA. Demographics, preoperative cardiovascular risk factors, and comorbidities are reported in Table 1. The mean AAA diameter was 58±6 mm. The mean infrarenal neck length and diameter was 24±10 and 23±3 mm, respectively. In 265 (37%) cases, there was at least one hostile morphological neck characteristic. Preoperative anatomical details of the proximal neck are reported in Table 1.

Table 1.

Preoperative Cardiovascular Risk Factors, Comorbidities, and Anatomical Characteristic of the Infrarenal Neck of Patients Underwent Endovascular Aneurysm Repair.

Preoperative risk factors/comorbidities	N	%
Male	638	90
Hypertension	613	86
Active smoker	199	28
Previous tobacco use	188	27
Diabetes	110	16
Dyslipidemia	461	65
Body mass index ≥31	99	14
Chronic obstructive pulmonary disease	273	39
Cerebrovascular insufficiency	85	12
Coronary artery disease	242	34
Atrial fibrillation	90	13
Chronic renal failure	280	39
Dialysis	8	1.1
History of cancer	126	18
Peripheral arterial occlusive disease	49	7
Oral anticoagulant therapy	84	12
Dual antiplatelet therapy	31	4
Statin therapy	447	63
Symptomatic or ruptured AAA	30	4
ASA 3	528	75
ASA 4	158	22
Infrarenal neck features	N	%
Length <15 mm	164	23
Diameter >28 mm	130	18
β-angle ≥60°	159	22
β-angle ≥90°	5	3
Calcification ≥50%	16	2
Thrombus ≥50%	100	14
Tapered shape	15	2
Reverse tapered shape	82	11
Barrel shape	32	4
	Mean	SD
Length	24	10
Diameter	23	3

Chronic renal failure expressed as estimated glomerular filtration rate (eGFR) <60 mL/min.

Abbreviations: AAA, abdominal aortic aneurysm; ASA, American Society of Anesthesiology; β-angle, infrarenal neck angle—between the infrarenal neck and aneurysm sac.

Endograft Sizing and Planning

Endografts with suprarenal and infrarenal fixation were planned in 380 (53%) and 330 (47%) cases, respectively. Particularly, the types of device were as follows: Cook Zenith 243—34%, Gore Excluder 224—32%, Medtronic Endurant 137—19%, Terumo Anaconda 106—15%. Tube and aorto-mono-iliac stent grafts were planned in 2 (0.3%) and 9 (1.3%) cases, respectively. The mean proximal main body diameter was 28±3 mm with a mean oversize of 22±7%. An iliac branch device was designed in 73 (10%) cases (bilateral—7 cases). Hypogastric artery coiling was planned in 19 (3%) patients due to aneurysm extension in common/internal iliac artery or anatomical contraindication for an iliac branch device.

Procedure

Procedures were performed under local, loco-regional, and general anesthesia in 11 (2%), 412 (58%), and 287 (40%) cases, respectively. The femoral access was surgical or percutaneous in 630 (89%) and 80 (11%) cases, respectively. The AAA sac embolization was performed in 247 (35%) cases as a preventive maneuver to reduce the incidence of persistent type II endoleak in anatomically -selected high-risk patients. An adjunctive/unplanned intraoperative aortic cuff deployment and iliac stenting were performed in 10 (1.4%) and 107 (15%) cases, respectively. The mean fluoroscopy and procedural times were 25±8 and 146±32 minutes, respectively, with a mean amount of iodinated contrast media delivery of 61±20 mL.

Technical success and neck-related TS were 692 (97.5%) and 700 (98.6%), respectively. The 10 cases of proximal neck–related failures were renal artery loss—2 and proximal type I endoleak—8. The coexistence of 2 or more anatomical hostile characteristics of the infrarenal neck was associated with early proximal type I endoleak (OR: 2.4; 95% confidence interval: 1.38–4.05; p: 0.007). Infrarenal neck angle >90° (p: 0.004), barrel shape (p: 0.02), or presence of ≥2 hostile anatomical neck characteristics (p: 0.03) were independently associated with neck-related technical failures (Table 2). There was no intraoperative mortality or conversion to OR; postoperative intensive cares were required in 96 (14%) patients, for a mean time of 24±12 hours.

Table 2.

Risk Factors for Proximal Neck–Related Technical Failure—Univariate and Multivariate Analysis.

	Univariate analysis			Multivariate analysis
	OR	95% CI	p	OR	95% CI	p
Neck length <15 mm	1.30	0.50–3.3	0.60	—	—	—
Neck diameter ≥28 mm	1.65	0.63–4.3	0.33	—	—	—
β-angle ≥60°	2.74	1.6–4.6	0.004	1.47	0.05–1.7	0.14
β-angle ≥ 90°	6.08	1.6–22.4	0.004	2.88	9.6–50.3	0.004
Neck thrombus ≥50%	1.48	0.18–11.8	0.70	—	—	—
Neck calcification ≥50%	1.02	1.01–1.03	0.63	—	—	—
Taper-shaped neck	5.0	0.72–34.4	0.08	—	—	—
Reverse taper–shaped neck	1.13	1.10–1.16	0.25	—	—	—
Barrel-shaped neck	4.66	1.2–16.9	0.01	2.33	11.1–100.3	0.02
Hostile neck characteristics ≥2	2.63	1.3–4.9	0.01	2.16	2.5–5.3	0.03
Suprarenal fixation	1.50	1.09–2.06	0.09	—	—	—

Abbreviations: β-angle, infrarenal neck angle—between the infrarenal neck and aneurysm sac; CI, confidence interval; OR, odds ratio.

Early Results

Cardiac and pulmonary morbidity occurred in 14 (1.9%) and 15 (2.2%) cases, respectively.

Six (0.8%) patients had a postoperative renal function worsening. One case, with severe preoperative chronic renal impairment, required postoperative hemodialysis. Neurological complications were reported in 3 (0.4%) patients (transient ischemic attack: 2; minor stroke: 1). Gastrointestinal complications were reported in 4 (0.5%) cases (colitis: 3; colic ischemia: 1). Five (0.7%) patients had lower limb ischemia (common femoral artery complication: 4; peripheral embolization: 1). Sixteen patients (2.3%) required reintervention within 30 postoperative days (Supplementary Table 2). Six (0.8%) patients died within 30 postoperative days. Preoperative chronic obstructive pulmonary disease (p: 0.04) and urgent repair (p: 0.01) were independent risk factors for 30-day mortality (Table 3). The mean hospitalization was 4±2 days.

Table 3.

Risk Factors for Mortality at 30-Day Mortality—Univariate and Multivariate Analysis.

	Unadjusted			Adjusted
	OR	95% CI	p	OR	95% CI	p
Demographics/Preoperative
Age ≥80 years	1.92	0.38–9.63	0.41	—	—	—
Female	1.78	0.20–15.4	0.51	—	—	—
Hypertension	0.31	0.05–1.72	0.15	—	—	—
Diabetes	0.84	0.81–0.87	0.29	—	—	—
Dyslipidemia	0.53	0.10–2.68	0.44	—	—	—
Body mass index ≥31	0.85	0.83–0.88	0.32	—	—	—
Chronic obstructive pulmonary disease	8.13	0.94–70.0	0.02	15.5	1.10–218.3	0.04
Coronary artery disease	0.96	0.17–5.31	0.96	—	—	—
Atrial fibrillation	7.09	1.40–35.6	0.006	1.39	0.03–59.2	0.87
Chronic renal failure	3.10	0.56–17.04	0.17	—	—	—
Dialysis	0.98	0.98–0.99	0.79	—	—	—
Neoplastic disease	0.82	0.79–0.85	0.25	—	—	—
Peripheral arterial occlusive disease	2.73	0.31–23.8	0.34	—	—	—
Oral anticoagulant therapy	7.67	1.52–38.6	0.004	1.54	0.03–68.5	0.82
Dual antiplatelet therapy	4.49	0.50–39.6	0.13	—	—	—
Statin therapy	0.58	0.11–2.92	0.50	—	—	—
Symptomatic/urgent AAA	25.7	4.83–130.02	0.000	14.8	1.83–119.6	0.01
Anatomical features
AAA diameter ≥65 mm	0.19	0.17–0.23	0.000	2.24	0.10–0.21	0.09
Neck length <15 mm	0.66	0.07–5.72	0.70	—	—	—
Neck diameter >28 mm	2.25	0.40–12.4	0.33	—	—	—
β-angle ≥60°	1.74	0.31–9.59	0.51	—	—	—
β-angle ≥90°	5.66	0.63–50.3	0.07	—	—	—
Neck thrombus >50%	0.85	0.83–0.88	0.31	—	—	—
Neck calcification >50%	0.97	0.96–0.99	0.70	—	—	—
Taper-shaped neck	0.97	0.96–0.98	0.71	—	—	—
Reverse taper–shaped neck	0.88	0.86–0.90	0.37	—	—	—
Barrel-shaped neck	0.95	0.93–0.97	0.59	—	—	—
Hostile neck characteristics ≥2	0.92	0.91–0.94	0.49	—	—	—
Procedural factors
Technical success	0.97	0.96–0.98	0.69	—	—	—
Neck-related technical success	0.98	0.97–0.99	0.76	—	—	—
Aortic cuff	15.4	1.63–145.8	0.001	11.2	0.03–68.5	0.10
Renal artery loss	0.99	0.99–1.00	0.89	—	—	—
Early type IA endoleak	0.98	0.97–0.99	0.76	—	—	—
Reintervention at 30 days	10.6	1.15–97.4	0.009	0.96	0.03–25.4	0.98

Chronic renal failure expressed as estimated glomerular renal filtration rate (eGFR) <60 mL/min/1.73 m²).

Abbreviations: AAA, abdominal aortic aneurism; β-angle, infrarenal neck angle—between the infrarenal neck and aneurysm sac; CI, confidence interval; OR, odds ratio.

Follow-up Results

The mean follow-up was 53±13 months (range min–max: 1–114 months).

The imaging follow-up protocol identified an overall of 101 (14%) endoleaks. Persistent type II endoleak was reported in 95 (13.4%) patients. In 12 (1.7%) cases, a proximal type I endoleak was detected during follow-up (6 of them were reported in patients with a previous persistent type II endoleak). Aneurysm shrinkage or AAA sac stability was obtained in 604 (85%) patients. Preoperative neck length <15 mm (p: 0.005), neck diameter >28 mm (p: 0.006), infrarenal neck angle ≥90° (p: 0.007), and persistent type II endoleak during follow-up (p: 0.004) were independent risk factors for proximal type I endoleak (Table 4).

Table 4.

Risk Factors for Proximal Type IA Endoleak During Follow-up—Univariate and Multivariate Analysis.

	Univariate analysis			Multivariate analysis
	HR	95% CI	p	HR	95% CI	p
Neck length <15 mm	4.01	1.3–12.2	0.008	2.83	1.9–9.6	0.005
Neck diameter >28 mm	3.96	1.3–11.9	0.009	2.75	1.6–9.5	0.006
β-angle ≥60°	2.20	0.71–6.8	0.16	—	—	—
β-angle ≥90°	5.32	1.1–25.4	0.01	2.72	8.3–50.1	0.007
Neck thrombus ≥50%	1.11	0.24–5.09	0.89	—	—	—
Neck calcification ≥50%	0.97	0.96–0.98	0.58	—	—	—
Taper-shaped neck	4.6	0.49–33.4	0.15	—	—	—
Reverse taper–shaped neck	1.40	0.30–6.4	0.66	—	—	—
Barrel-shaped neck	0.95	0.93–0.97	0.42	—	—	—
Hostile neck characteristics ≥2	7.08	2.05–24.4	0.00	1.43	0.05–1.77	0.15
Suprarenal fixation endograft	2.94	0.80–10.7	0.08	—	—	—
Persistent type II endoleak	5.85	1.92–17.8	0.00	2.89	1.6–10.1	0.004

Abbreviations: β-angle, infrarenal neck angle—between the infrarenal neck and aneurysm sac; CI, confidence interval; HR, hazard ratio.

Overall, 53 (7.5%) patients required at least one reintervention (9 cases of multiple reinterventions). Fourteen (1.9%) patients had proximal neck–related reinterventions with 12 (1.7%) conversion to OR. Freedom from reintervention at 1, 3, and 5 years was 97%, 95%, and 91%, respectively (Figure 1A). Proximal type I endoleak was an independent risk factor for reinterventions during follow-up (p<0.001; Supplementary Table 3).

Overall, 190 (27%) patients died during follow-up; the causes of mortality (within and after 30 days) are summarized in Supplementary Table 4. Survival at 1, 3, and 5 years was 95%, 86%, and 74%, respectively (Figure 1B). Preoperative peripheral arterial occlusive disease (p: 0.03), aneurysm diameter ≥65 mm (p<0.001), and neck length <15 mm (p: 0.04) were independent risk factors for mortality during follow-up (Table 5).

Table 5.

Risk Factors for Mortality During Follow-up—Univariate and Multivariate Analysis.

	Univariate analysis			Multivariate analysis
	OR	95% CI	p	OR	95% CI	p
Age ≥80 years	1.07	0.75–1.52	0.69	—	—	—
Aneurysm diameter ≥65 mm	2.61	1.78–3.82	0.000	2.15	1.42–3.26	0.000
Female	1.14	0.66–1.95	0.62	—	—	—
Hypertension	1.85	1.06–3.21	0.02	2.02	1.12–3.65	0.01
Diabetes	0.97	0.61–1.54	0.91	—	—	—
Dyslipidemia	0.72	0.51–1.02	0.06	—	—	—
Body mass index ≥31	1.44	0.91–2.28	0.11	—	—	—
Peripheral artery occlusive disease	1.99	1.09–3.06	0.02	1.95	1.04–3.65	0.03
Chronic obstructive pulmonary disease	1.30	0.93–1.83	0.11	—	—	—
Coronary artery disease	0.88	0.62–1.26	0.50	—	—	—
Atrial fibrillation	1.43	0.89–2.30	0.13	—	—	—
Chronic renal failure	1.65	1.18–2.32	0.003	1.37	0.96–1.96	0.08
Dialysis	4.65	1.10–19.6	0.02	3.03	0.67–13.5	0.14
Neck length <15 mm	1.71	1.17–2.49	0.005	1.55	1.02–2.35	0.04
Neck diameter >28 mm	1.52	1.01–2.28	0.04	1.20	0.75–1.92	0.43
β-angle ≥60°	1.51	1.03–2.21	0.03	1.26	0.82–1.92	0.27
β-angle ≥90°	0.86	0.33–2.18	0.75	—	—	—
Neck thrombus >50%	0.84	0.51–1.38	0.50	—	—	—
Neck calcification >50%	1.25	0.42–3.64	0.68	—	—	—
Taper-shaped neck	1.37	0.46–4.08	0.56	—	—	—
Reverse taper–shaped neck	1.00	0.59–1.68	0.98	—	—	—
Barrel-shaped neck	1.93	0.93–4.00	0.07	—	—	—
Hostile neck characteristics ≥2	2.30	1.28–4.13	0.004	1.38	0.67–2.85	0.37
Technical success	0.94	0.33–2.69	0.92	—	—	—
Neck-related technical success	0.35	0.10–1.25	0.09	—	—	—
Aortic cuff	1.17	0.30–4.59	0.81	—	—	—
Renal artery loss	2.74	0.17–44.9	0.45	—	—	—
Early type IA endoleak	1.84	0.51–6.60	0.34	—	—	—
30-day reinterventions	1.09	0.34–3.54	0.87	—	—	—
Persistent type II endoleak	1.10	0.68–1.78	0.69	—	—	—
Follow-up type IA endoleak	1.98	0.62–6.31	0.23	—	—	—

Chronic renal failure expressed as glomerular renal filtration rate (GFR <60 mL/min/1.73 m²).

Abbreviations: β-angle, infrarenal neck angle—between the infrarenal neck and aneurysm sac; CI, confidence interval; HR, hazard ratio; PAOD, peripheral artery occlusive disease.

Discussion

In the present study, we report a 9-year single-center experience collecting 710 consecutive EVAR procedures, performed with the last generation of endografts commercially available in Europe. Results were satisfactory, with high technical (>97%) and clinical success at early and mid-term follow-up and low 30-day mortality (0.8%). Estimated 5-year survival and FFR were as high as of 74% and 91%, respectively.

Epidemiological data report EVAR in up to 80% of all the infrarenal AAA repairs.^3,4 The EVAR has gained a wide diffusion in the last decades due to its advantages in terms of invasiveness, 30-day mortality and morbidity compared with OR,^1,2 becoming in several centers the first-line strategy for AAA repair.

The anatomical feasibility and appropriate endograft sizing and planning are crucial for the safety and the effectiveness of this technique. One of the main reasons of EVAR exclusion is the anatomy of the proximal infrarenal neck. Several studies suggest that in case of short (<15 mm), wide (>28 mm), and angulated neck (>60°) as well as calcification/thrombus extension >50% or not cylindrical shape, the risk of technical and clinical failures is higher than cases with friendly anatomies.^9–14 However, the device evolution and the operator learning curve could impact these results.^8,16,17 Moreover, all the endografts used in the randomized trials, multicenter registries, or historical papers are not commercially-available anymore,^{10–14,23–25} having been replaced by new devices able to fit most hostile anatomical situation.¹⁵

In our center, the impact of EVAR was similar to the epidemiological reports worldwide, with a rate ranging from 70% to 85% of all AAA repairs in the last 10 years. In our series, EVAR was usually proposed particularly in high-risk patients, as demonstrated by the ASA score (≥3: 96%), the incidence of chronic obstructive pulmonary disease (COPD) (38%), coronary artery disease (44%), chronic renal failure (40%), and urgent clinical setting (4%). This is an important aspect to consider in the analysis of our early and mid-term outcomes. For these reasons, a 30-day mortality rate of 0.8% can be considered an excellent result. Independent risk factors for 30-day mortality were urgent clinical setting and preoperative COPD. If the urgent repair is an expected predictor of mortality, the preoperative respiratory function and the potential postoperative respiratory morbidities/complications should be analyzed carefully. Hypothetically, by reducing the rate of orotracheal intubations—general anesthesia was used in 40% of our cases—and promoting early patient reactivation/mobilization and breathing physiotherapy, postoperative respiratory complications and their impact on perioperative mortality can be reduced, especially in patients with a preoperative respiratory function impairment.

Similar considerations can be made also about the rate of TS and preoperative anatomical proximal neck characteristics of hostility, as short, wide, and angulated neck were present in one-fifth of the patients. From our analysis, the coexistence of 2 or more of those characteristics predicts the technical failure, as reported in our preliminary experiences, where we suggested that a short and angulated neck or a wide and short neck were more prone to be associated with proximal type I endoleak than cases presenting with short or wide neck alone.^21,22 Moreover, if we focus only to the proximal neck–related TS, a barrel-shaped neck, an angle >90°, and again 2 or more anatomical characteristics of neck hostility independently predict the technical failure, which are determined uniquely by proximal type I endoleak (80%) and unplanned loss of one renal artery (20%).

Nevertheless, the Achilles heel of EVAR remains its higher reintervention rate with AAA-related mortality during follow-up.^2,5

In the single-center experience of Abdulrasak et al²⁶ with a currently-available endograft (Cook Zenith device), the estimated 10-year survival and FFR were 32% and 72%, respectively, at a median radiological follow-up of 50 months. In our study, we are unable to analyze long-term results since we deal with the devices of last generations. However, our mean follow-up was 53 months (range 1–114) and about 280 patients were still present at the 5-year interval in the Kaplan-Mayer analysis.

The rate of proximal sealing failure was acceptable with less than 2% proximal late type I endoleak, which compares favorably with the previous literature experiences and the most recent multicentre studies/registries (2%–8%).^26–29 According to our data, this complication was associated with well-known anatomical risk factors such as neck length <15 mm, neck diameter >28 mm, and β-angle >90°. These independent risk factors were identified in previous literature experience including our own.^10–14 The preoperative anatomical characteristics are therefore crucial not only to determine the EVAR feasibility but also to establish their durability.

Another important finding of our analysis is the role of persistent type II endoleak in the development of proximal type I endoleak during follow-up. Until now, a strong consensus about the natural history of type II endoleaks is lacking.³⁰

If any surgeons consider a persistent type II endoleak a benign event, others report AAA sac enlargement, rupture, and need of reinterventions³⁰ caused by persistent type II endoleak. Moreover, reinterventions to seal a type II endoleak in presence of AAA sac enlargement are technical demanding procedures leading often to unsatisfactory results.^31,32 Even if the post EVAR AAA rupture caused by an isolated type II endoleak could be considered rare,^30,33 this complication could be the cause of a high-flow endoleak with subsequent high risk of rupture in our experience. The hypothetical mechanism could be the continued sac pressurization caused by a type II endoleak, enlarging the AAA with proximal and distal neck degeneration and subsequent loss of sealing. According to these findings, we suggest that preventive strategies to reduce the incidence of persistent type II endoleak should be considered in EVAR. The AAA sac embolization with coils during the EVAR procedure in anatomically-selected patients is a safe and effective technique in reducing the incidence of persistent type II endoeak.¹⁹ Similar results were reported also in other clinical experiences with the combinations of coils and glues.^34,35

Overall, reinterventions occurred in 7.5% of patients (within 30 days: 2.1%; after 30 days: 5.4%) with few cases (1.9%) of proximal neck–related events. Most of them were managed electively by endovascular techniques and only very few cases required conversion to OR (1.6%); FFRs was >90% at 5 years which compares favorably with the available literature (79%–81%).^36,37

The 74% survival rate at 5 years is particularly satisfactory if one considers the high-risk patients undergoing AAA repair, with only 0.5% deaths being aortic-related. Interestingly, preoperative peripheral artery occlusive disease (PAOD), AAA diameter >65 mm, and neck length <15 mm were independent risk factors for mortality. While the PAOD could be an indicator of advanced atherosclerotic disease, the large AAA diameter and short infrarenal neck reflect the presence of extensive aortic disease. These are important preoperative findings that should be considered during indication to EVAR to further ameliorate our clinical success during follow-up.

The present study has several limitations. First, it is a single-center, retrospective study of a cohort of patients managed during 9 years. Follow-up results are evaluated only at mid-term and no long-term results are available. However, it should be considered that we are reporting an analysis of currently-available endografts in Europe (last generations’ devices), and data with longer follow-up are not available at the moment.

Endograft sizing/planning and procedures were performed by surgeons with high EVAR experience and the operator’s learning curve cannot be evaluated retrospectively. This is a potential important bias because the operator skills and the hospital volume play a crucial role in the optimization of results. A subanalysis and comparison of outcomes of the different endografts were not performed. If it could be reported as a lack of the present experience, on the contrary, it should be considered that different endografts have different characteristics, instruction for uses (IFUs), and they are usually implanted in different anatomical situations; it could create an important bias in a comparison of different anatomical scenarios. Finally, due to the retrospective study design, a complete comparison of patients treated inside and outside the manufacture’s instruction for use was not feasible.

Conclusion

Endovascular aneurysm repair with currently-available endografts has excellent TS and 30-day mortality, with satisfactory survival and FFRs at mid-term follow-up. According to the present data, EVAR could be proposed as the first-line treatment in high-risk patients with anatomical feasibility. These data are relevant as they report a real-world practice involving a surgical team with high volume of AAA repair. Late results will be necessary to confirm mid-term favorable outcomes and propose this technique also in patients with lower comorbidities and longer life expectancy. Several preoperative and postoperative independent predictors of failure were identified. The presence of ≥2 hostile anatomical infrarenal neck characteristics is a risk factor for technical failure. Infrarenal neck angle >90°, barrel shape, or presence of ≥2 hostile anatomical infrarenal neck characteristics are risk factors for neck-related technical failures. Chronic obstructive pulmonary disease and urgent repair are risk factors for 30-day mortality. Infrarenal neck length <15 mm, diameter >28 mm, angle ≥90°, and persistent type II endoleak are risk factors for ELIa. Finally, peripheral arterial occlusive disease, aneurysm diameter ≥65 mm, and infrarenal neck length <15 mm are independent risk factors for mortality during follow-up.

These risk factors should be considered in EVAR indication and postoperative patient management to reduce the risk of postoperative complications and improve long-term outcome.

Supplemental Material

sj-docx-1-jet-10.1177_15266028231158312 – Supplemental material for Morphological and Clinical Predictors of Early/Follow-up Failure of the Endovascular Infrarenal Abdominal Aneurysm Repair With Currently Available Endografts

Supplemental material, sj-docx-1-jet-10.1177_15266028231158312 for Morphological and Clinical Predictors of Early/Follow-up Failure of the Endovascular Infrarenal Abdominal Aneurysm Repair With Currently Available Endografts by Enrico Gallitto, Gianluca Faggioli, Chiara Mascoli, Martina Goretti, Rodolfo Pini, Antonino Logiacco, Cristina Rocchi, Francesca Feroldi, Stefania Caputo and Mauro Gargiulo in Journal of Endovascular Therapy

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Enrico Gallitto

Gianluca Faggioli

Chiara Mascoli

Rodolfo Pini

Francesca Feroldi

Supplemental Material

Supplemental material for this article is available online.

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