Since the introduction of endovascular treatment (EVT) for aneurysms, it has become the preferred modality for patients with suitable anatomy [1]. Numerous studies, including randomized controlled trials, have compared EVT of abdominal aortic aneurysms (AAAs) with open surgical repair (OSR) to prove the efficacy of endovascular aneurysm repair (EVAR) [2,3]. However, there is a concern that rupture may still occur after EVAR, and re-interventions are not uncommon [4].

Several decades ago, the standard treatment for isolated iliac artery aneurysms (IAAs) was OSR, typically involving ligation or resection of aneurysms, with graft interposition if necessary [5,6]. With advances in EVT, several studies have examined its efficacy for isolated IAAs, showing comparable early- and mid-term effectiveness and safety. Based on these results, the European Society for Vascular Surgery (ESVS) recommended EVT as a potential first-line therapy for IAAs in its 2019 guidelines [7,8]. However, many of these studies were performed over a decade ago, and there have been concerns that they do not account for improvements in perioperative care, surgical techniques, or endovascular devices. Moreover, even in studies that reported comparable outcomes, a significant number of re-interventions after EVT were still observed, and long-term follow-up data remain limited. Reflecting on recent studies, the 2024 ESVS guidelines now recommend that the choice of surgical technique for IAA should be based on individual patient and lesion characteristics [9].

This study aimed to compare the outcomes of OSR and EVT using data from a single-center database.

1) Inclusion and exclusion criteria

This retrospective, single-center study received ethical approval from the Institutional Review Board (IRB) of the Asan Medical Center (IRB No. 2020-1497). The requirement for informed consent was waived due to the retrospective nature of this study. From January 2007 to December 2018, patients who underwent OSR or EVT for isolated IAAs were initially included, regardless of aneurysm size, multiplicity, or urgency. The exclusion criteria were: (1) patients with infectious, inflammatory, or traumatic aneurysms; (2) patients with AAA, defined as an abdominal aortic diameter of >30 mm; (3) patients without preoperative computed tomography images; and (4) patients with prior aortoiliac surgery.

2) Data collection and definition

Iliac artery aneurysm was defined as having a common iliac artery (CIA) diameter >18 mm in men and 15 mm in women, and an IIA diameter >8 mm, according to current guidelines [7]. Patient baseline characteristics, symptoms, degree of urgency, treatment type, treatment results, complications, and mortality were obtained from electronic medical records. We used the American Society of Anesthesiologists (ASA) Classification and Comorbidity Severity Score proposed by the Society for Vascular Surgery/American Association for Vascular Surgery (SVS/AAVS) for patient risk stratification. According to this scoring scheme, the maximum SVS/AAVS comorbidity severity score was 30. The scores were divided by 10 to yield a comorbidity severity score on a 3-point scale, and grades of 0 to 3 corresponded to absent, mild, moderate, and severe, respectively [10]. Measurement of anatomical values was performed semi-automatically using automated software to reconstruct images in three dimensions and draw the centerline (AW Server 2, GE HealthCare). The IAAs were schematically categorized based on a previously reported method [11].

3) Practical strategy

Treatment decisions were primarily based on patient symptoms and aneurysm size. Patients with symptoms, such as claudication, pain, discomfort, or compression of adjacent structures due to mass effects, were preferentially considered for treatment. When aneurysms were found incidentally, size was the key factor in deciding on treatment. Treatment was considered for aneurysms larger than 35 mm in maximum diameter, with adjustments made based on the patient’s age and comorbidities [7]. In the early part of the study, aneurysms >30 mm in diameter were subject to treatment. However, the criterion was updated to align with guideline changes [6].

The choice between OSR and EVT was made by the vascular surgeons after discussion with a vascular-specialized interventional radiologist. Three primary factors influenced the decision: the patient’s general health, including age at the time of operation, the suitability of aneurysm’s anatomy for EVT, and patient preference. OSR included excision of the aneurysm with artificial graft interposition of one or both iliac arteries using straight or bifurcated grafts, depending on the extent of the aneurysmal disease. If possible, ipsilateral IIA revascularization was usually performed during OSR [5]. A hybrid procedure comprising IIA excision with branch embolization was included in OSR [12]. Endovascular treatment included EVAR or stent graft insertion of a single iliac artery from the CIA to the external iliac artery (EIA) with IIA embolization according to the anatomical classification of the IAA by Fahrni et al. [13]. If necessary, bilateral IIA embolization was permitted in a staged fashion [14]. Embolization alone without stent graft insertion for IIA aneurysms was also included in the EVT. Three brands of prosthetic vascular grafts were used for OSR: Gore-Tex (Gore), Gelsoft (Terumo Aortic), and Intergard (Maquet). Five endovascular device brands were used during the study period: Endurant (Medtronic), Zenith (Cook Medical), Excluder and Viabahn (Gore), and Seal (S&G).

The type of anesthesia was determined by vascular surgeons after discussion with anesthesiologists. General anesthesia was used for OSR, and general or local anesthesia was used for EVT. During the EVT procedures, both surgical cut-down and totally percutaneous access were used based on the operator’s preference. Cutdown access was performed under general anesthesia.

Follow-up was performed using contrast-enhanced computed tomography (CT) or Doppler ultrasonography. However, non-contrast-enhanced CT was used to measure alterations in size and configuration in patients with impaired renal function. The first follow-up CT scan was performed within seven days of the procedure to detect technical errors or immediate complications. Follow-up imaging of patients who underwent OSR was performed annually or biennially. In the EVT group, follow-up imaging was performed 3 months and 1 year after the procedure. Subsequently, the follow-up schedule was adjusted for risk stratification according to guidelines [9].

4) Primary and secondary outcomes

Primary outcomes were procedure time, quantity of transfusion during admission, length of hospitalization, early and late complications, number of preserved IIA, and occurrence of major adverse cardiovascular events (MACEs). The secondary outcomes were all-cause and aneurysm-related mortality, and re-intervention rates. Early complications were defined as those that occurred within 30 days of the procedure and late complications were defined as those occurring after the first 30 days. Endoleaks after EVT were not included as early or late complications. However, endoleaks with significant sac expansion (≥5 mm in any direction) were considered as a late complication.

5) Statistical analyses

Statistical analyses were performed using the PASW Statistics for Windows, version 18.0 (SPSS Inc.) and R software, version 3.6.3 (R Foundation for Statistical Computing). The independent t-test, chi-square test, and Mann–Whitney U-test were used to compare the baseline characteristics, anatomical values, and perioperative details between OSR and EVT. Survival analysis was used to compare late complication and re-intervention rates. Mortality was compared using Cox proportional hazards analysis. Variables with P<0.05 were considered statistically significant.

A total of 58 patients were enrolled in the study. Among them, 25 and 33 underwent OSR and EVT, respectively. Among the patients who underwent OSR, 15 underwent aneurysm resection and bifurcated graft interposition for bi-iliac lesions, 9 underwent aneurysm resection and straight graft interposition for uni-iliac lesions, and the remaining 1 patient underwent a hybrid procedure, comprising IIA resection with embolization of its branches for IIA aneurysms. Among the patients who underwent EVT, 20 underwent EVAR using a bifurcated aortoiliac stent graft for CIA aneurysms without a suitable proximal neck, and 12 underwent straight iliac stent-graft insertion for CIA aneurysms with a proximal neck [13]. Among the patients who underwent EVAR, one underwent the sandwich technique to preserve the IIA flow [15]. One other patient underwent only embolization for an IIA aneurysm (Fig. 1). The median follow-up period was 75 (range: 39-133) months for all patients, 61 (range: 40-103) months for patients with OSR, and 79 (range: 36-103) months for EVT (P=0.970).

Figure 1. Selection flow chart. Flow chart of study patients. CIA, common iliac artery; AAA, abdominal aortic aneurysm; CT, computed tomography; OSR, open surgical repair; EVT, endovascular treatment; EVAR, endovascular aneurysm repair; IIA, internal iliac artery.
^aBifurcated graft interposition. ^bStraight graft inserposition. ^cBifurcated aorto-iliac stent-graft insertion. ^dStraight iliac stent-graft insertion.

1) Baseline characteristics

There were no significant differences in comorbidities, ASA classification, or SVS/AAVS scores between the two groups, except for age, which was significantly higher in the EVT group than in the OSR group. According to the SVS/AAVS comorbidity severity scoring scheme, both groups had a mild to moderate risk of comorbidity.

There was no significant difference in the number of symptomatic patients between the OSR and EVT groups. The most common symptom was claudication due to thrombosis of the aneurysm, followed by pain. Two patients had hydronephrosis or deep vein thrombosis due to compression of the adjacent structure by the mass effect of the aneurysm (Table 1).

Table 1 . Demographics and baseline characteristics.

	OSR (n=25)	EVT (n=33)	P-value
Age (mean±SD)	66.0±8.2	73.1±8.6	0.003
Median [IQR]	68 [57-73]	75 [69-79]	0.001
Male sex	24 (96.0)	30 (90.9)	0.630
Hypertension	12 (48.0)	18 (54.5)	0.790
Diabetes	4 (16.0)	6 (18.2)	>0.999
Hyperlipidemia	8 (32.0)	8 (24.2)	0.560
Smoking			0.160
Current	3 (12.0)	7 (21.2)
Past	14 (56.0)	10 (30.3)
CVA	3 (12.0)	2 (6.1)	0.640
CAD	3 (12.0)	2 (6.1)	0.640
CKD	3 (12.0)	5 (15.2)	>0.999
COPD	4 (16.0)	6 (18.2)	>0.999
Cancer	4 (16.0)	6 (18.2)	>0.999
Transplantationa	0 (0)	2 (6.1)	0.500
ASA classification			>0.999
2	17 (68.0)	23 (69.7)
3	8 (32.0)	10 (30.3)
SVS/AAVS score [IQR]	3 [1-8]	3 [2-8]	0.260
Symptomatic	6 (24.0)	5 (15.2)	0.500
Claudication	3	2
Pain	1	2
Palpable mass	0	1
Hydronephrosis	1	0
DVT	1	0
Follow-up duration (mo) [IQR]	61 [40-103]	79 [36-103]	0.970
Mean±SD	72.0±37.8	72.3±44.2	0.980

Values are presented as number (%), mean±standard deviation, or median [interquartile range]..

OSR, open surgical repair; EVT, endovascular treatment; SD, standard deviation; IQR, interquartile range; CVA, cerebrovascular accident; CAD, coronary artery disease; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; ASA, American Society of Anesthesiologists; SVS/AAVS, Society for Vascular Surgery/American Association for Vascular Surgery; DVT, deep vein thrombosis..

^aOne liver and one kidney transplantation..

2) Anatomical distribution

Two patients (3.4%) with ruptured aneurysm or impending rupture underwent emergency treatment. Both were treated for CIA aneurysms with maximum diameters of 40 mm and 45 mm. Additionally, two patients were treated urgently because of symptoms such as severe claudication and pain; 55 patients (94.8%) had CIA aneurysms and 37 patients (63.8%) had IIA aneurysms. Bilateral CIA aneurysms were observed in 36 patients (58.6%). The maximum diameters of CIA aneurysms were not significantly different between the OSR and EVT groups (34.7±10.6 vs. 31.7±10.6 mm, P=0.20). Thirty-one patients (53.4 %) had combined CIA and IIA aneurysms. When aneurysms were categorized according to the classification reported by Sandhu and Pipinos [11], there was no significant difference in their distribution. Type E was the most common type in both groups, whereas type B was more common in the EVT group than in the OSR group (Table 2).

Table 2 . Anatomical distribution and classification.

	OSR (n=25)	EVT (n=33)	P-value
Rupturea	1 (4.0)	1 (3.0)	1.00
Aorta diameter (mm)	24.1±4.5	24.0±3.5	0.94
CIA aneurysm	23 (92.0)	33 (100)	0.18
Bilateral	13 (52.0)	21 (63.6)	0.43
Maximum diameter (mm)	34.7±10.6 (n=36)	31.7±10.6 (n=54)	0.20
Median [IQR]	33 [28-43]	31 [22-40]	0.20
IIA aneurysm	15 (60.0)	22 (66.7)	0.78
Bilateral	5 (20.0)	9 (27.3)	0.56
Maximum diameter (mm)	23.2±17.6 (n=20)	23.4±13.7 (n=31)	0.96
Median [IQR]	19 [13-23]	18 [12-32]	0.78
Combinedb	12 (48.0)	19 (57.6)	0.60
Sandhu classification			0.13
A	1 (2.0)	0 (0)
B	1 (2.0)	6 (9.1)
C	4 (8.0)	1 (1.5)
D	1 (2.0)	0 (0)
E	18 (36.0)	26 (39.4)

Values are presented as number (%), mean±standard deviation, or median [interquartile range]..

OSR, open surgical repair; EVT, endovascular treatment; IAA, iliac artery aneurysm; CIA, common iliac artery; IQR, interquartile range; IIA, internal iliac artery..

^aRupture or impending rupture. ^bCombined IIA and CIA aneurysm..

3) Procedures and in-hospital course

The mean procedure time was significantly longer in the OSR group than in the EVT group. In the OSR group, the unilateral iliac procedure required a significantly shorter time (225 [172-235] vs. 340 [301-362] minutes, P<0.001) and a significantly smaller number of red blood cell transfusions than in the bilateral procedure (0 [0-3] vs. 4 [2-8] units, P=0.02). However, in the EVT group, there was no significant difference between the unilateral and bilateral iliac procedures with respect to operation time (P=0.29) and quantity of transfusion (P=0.15). The length of hospital stay was significantly longer in the OSR group than in the EVT group. In the OSR and EVT groups, patients undergoing bilateral iliac procedures usually stayed longer than those who underwent unilateral procedures (8 [7-12] vs. 6 [5-9] days, P=0.02 and 5 [4-6] vs. 4 [3-4] days, P=0.08, respectively; Table 3).

Table 3 . Details of peri- and intra-operative data.

	OSR (n=25)	EVT (n=33)	P-value
Anesthesia			<0.001
General	25 (100)	18 (54.5)
Local	0 (0)	15 (45.5)
Procedure time (min) [IQR]	301 [227-355]	145 [102-185]	<0.001
Unilateral	225 [172-235]	133 [89-180]
Bilateral	340 [301-362]	161 [110-188]
Transfusion	15 (60.0)	7 (21.2)	0.003
RBC (unit) [IQR]	2 [0-6]	0	<0.001
Unilateral	0 [0-3]	0
Bilateral	4 [2-8]	0 [0-2]
Length of stay (d) [IQR]	8 [7-10]	4 [4-5]	<0.001
Unilateral	6 [5-9]	4 [3-4]
Bilateral	8 [7-12]	5 [4-6]

Values are presented as number (%), mean±standard deviation, or median [interquartile range]..

OSR, open surgical repair; EVT, endovascular treatment; IQR, interquartile range; RBC, red blood cell..

4) Early and late complications

Although not statistically significant, early complications occurred more frequently in the OSR group than in the EVT group (24.0% vs. 6.1%, P=0.07). The most common complication after OSR was ileus, which resolved with conservative management. Aortic dissection due to aortic cross-clamp injury occurred in one OSR patient and was managed with blood pressure control. One postoperative hemorrhage case required emergency surgical hemostasis after OSR. In the EVT group, the most common complication was thrombotic occlusion of the stent graft. This was observed not only in the early phase but also in the late phase.

Late complications, including sac expansion and thrombotic occlusion, were significantly more common in the EVT group than in the OSR group (15.2% vs. 0%, P=0.04; Fig. 2). Furthermore, eight cases of endoleaks were observed in the EVT group, most of which were type II. Among them, three patients experienced sac expansion during follow-up. Late complications were not significantly different between patients who underwent bifurcated aortoiliac stent-graft insertion and those who underwent straight iliac stent-graft insertion (2/20 vs. 3/12, P=0.43).

Figure 2. Late complication-free survival of the OSR and EVT groups. Kaplan-Meier plot of freedom for late complication probability with 95% confidence intervals for EVT and OSR. EVT, endovascular treatment; OSR, open surgical repair.

OSR was associated with a higher likelihood of preserving IIA flow compared to EVT. Only one OSR case required the sacrifice of both IIAs, whereas this occurred in six EVT cases (4.0% vs. 18.2%). The patency preservation rates of both IIAs were significantly higher in the OSR group compared to the EVT group (40.0% vs. 3.0%, P<0.001). Overall, three cases of MACEs were observed during the follow-up, with no significant difference between the two groups. Among them, one case of stroke was observed within 30 days after EVT, and the others were observed more than 2 years after the procedure (Table 4).

Table 4 . Early and late complications, and future MACE of OSR and EVT.

	OSR (n=25)	Endovascular (n=33)	P-value
Early complication	6 (24.0)	2 (6.1)	0.070
Hemorrhagea	1 (4.0)	0
DVT	1 (4.0)	0
Ileusb	3 (12.0)	0
Thrombotic occlusion	0	2 (6.1)
Aortic dissection	1 (4.0)	0
Late complication	0 (0)	5 (15.2)	0.040
Thrombotic occlusion	0	2 (6.1)
Sac expansion	0	3 (9.1)
Endoleak (type)	N/A	8 (24.2)	N/A
I	N/A	1 (3.0)
II	N/A	6 (18.2)
III	N/A	1 (3.0)
Re-intervention	1 (4.0)	3 (9.1)	0.440
Bleeding control	1 (4.0)	0
Bypass	0	1 (3.0)
Thrombectomy	0	1 (3.0)
Graft interposition	0	1 (3.0)
Patent IIA			<0.001
0	1 (4.0)	6 (18.2)
1	14 (56.0)	25 (78.8)
2	10 (40.0)	1 (3.0)
MACE	1 (4.0)	2 (6.1)	0.660
CVA	1 (4.0)	1 (3.0)
ACS	0	1 (3.0)

Values are presented as number (%)..

OSR, open surgical repair; DVT, deep vein thrombosis; PTE, pulmonary thromboembolism; EIA, external iliac artery; IIA, internal iliac artery; MACE, major adverse cardiovascular event; CVA, cerebrovascular accident; ACS, acute coronary syndrome; N/A, not applicable..

^aNeed for hemostatic procedures. ^bDefinite signs on plain abdominal radiography and the need for hospitalization..

5) Mortality and re-intervention rate

Re-interventions during the follow-up were more frequent in the EVT group than in the OSR group; however, it was not significant (9.1% vs. 4.0%, P=0.44). In the EVT group, four cases of thrombotic limb occlusions and three cases of sac expansions were observed. Among these, two patients with thrombotic limb occlusion and one with sac expansion underwent re-intervention. Remaining two patients with limb occlusion refused or did not require treatment because of mild symptoms. Additionally, two patients with endoleak and sac expansion declined re-intervention due to their advanced and overall health condition and were conservatively observed in the outpatient department (Table 4).

No mortality was recorded within 30 days of the procedure. Overall mortality between the two group showed no statistically significant difference (P=0.12), and there were no aneurysm-related deaths. As the baseline age in each group differed, an adjusted analysis for age was performed, which showed no statistically significant differences (P=0.27; Table 5).

Table 5 . Cox regression analysis on the association between treatment option and mortality, unadjusted and adjusted for age at the treatment.

Variable	HR (95% CI)	P-value
Unadjusted model
OSR (vs. EVT)	0.29 (0.06-1.37)	0.12
Adjusted model
OSR (vs. EVT)	0.37 (0.06-2.18)	0.27
Age	1.02 (0.94-1.12)	0.59

OSR, open surgical repair; EVT, endovascular treatment; HR, hazard ratio; CI, confidence interval..

Isolated IAAs are relatively uncommon, with an incidence of approximately 0.03% in the general population based on autopsy series [16]. It is more prevalent in men (94%), typically around 70 years of age and up to 65% of cases present with multiple or bilateral aneurysms in the iliac system. Huang et al. [8] reported that 29% of CIA aneurysms were symptomatic, and 5% ruptured.

Prior to the introduction of EVT in the early 1990s, open surgery was the standard treatment for iliac aneurysms [5]. In 1988, Richardson and Greenfield [5] reported that the overall mortality rates for patients undergoing emergency and elective OSR were 33% and 11%, respectively. The causes of death included hemorrhage, graft infection, pulmonary sepsis, cardiac complications, and renal failure. However, there are limited data on recent OSR outcomes despite advancements in perioperative management and supportive care. More recently, Patel et al. [17] reported improved outcomes of OSR for isolated IAAs (20.8% morbidity and 6.1% 30-day mortality) with no aneurysm-related deaths. Among the morbidity cases, one atheroembolization, two ureteral injuries, one wound problem, and one postoperative hemorrhage were observed. In our study, the morbidity rate for OSR was 24.0%. Morbidity was observed only in the early postoperative period, with no 30-day or aneurysm-related mortality. This improvement in the OSR outcomes can be attributed to better preoperative optimization, risk stratification, and advancements in operative techniques [18,19]. Despite this improvement, OSR still has significant drawbacks in terms of longer hospitalization, extended operation time, and increased transfusion requirement [20].

Since 2000, there has been a steady shift from OSR to EVT due to its high technical success rate and a comparable complication rates, including stent graft occlusion and endoleaks [7]. In a previous study on patients who underwent single-limb stent-graft insertion for IAAs, Scheinert et al. [21] reported primary patency rates of 97.9% after 2 years and 87.6% after 4 years, with no cases of sac expansion. Zhorzel et al. [22] further demonstrated that EVT was favorable in terms of length of stay and intra-operative transfusion. Similarly, our study showed that EVT provided benefits in terms of shorter hospital stay reduced procedure time, and fewer transfusions.

However, Zhorzel et al. [22] also reported that freedom from re-intervention was higher with OSR than with EVT in the same study (P<0.01). Additionally, Huang et al. [8] reported a primary patency rate of 95% at 3 years and an ongoing endoleak rate of 20% at the time of the last imaging study in 44 patients who underwent endovascular repair. In this study, the 30-day and 3-year mortality rates did not differ between the OSR and EVT groups, which is consistent with the results of our study. However, the re-intervention rate was higher in the EVT group than in the OSR group during a mean follow-up of 5.4 years (18% vs. 9%, P=0.06).

In previous studies that included several patients who underwent EVT showed similar short- and mid-term results compared to OSR, with an 81%-96% patency rate and 80%-88% re-intervention-free survival at 2 years after EVT [17,23]. However, in those studies, the follow-up duration was too short to obtain long-term results and the re-intervention-free survival rate in the EVT group decreased with increasing follow-up length, whereas that in the OSR group remained relatively flat [24]. Similar patterns were observed in our study, in which late complications, namely limb occlusion and sac expansion, were observed only in the EVT group. Although re-intervention-rate appeared not to be significantly different between the two groups, it was attributed to patients’ refusal of treatment due to their general condition or older age despite limb occlusion or sac expansion.

In EVT for isolated IAAs, the EIA often serves as the distal sealing zone for the stent graft. Since EIA typically requires a smaller limb graft for sealing, this increases the risk of graft occlusion, which can occur in the early postoperative period and even more than 3-4 years after surgery [25]. Additionally, EVT for isolated IAAs has a significant risk of endoleaks, similar to EVAR for AAAs [22]. Some of these endoleaks lead to sac expansion, requiring lifelong surveillance with computed tomography, and potential re-intervention. As demonstrated in the EVAR-1 trial for AAAs, EVT for isolated IAAs may be beneficial for short- and mid-term outcomes; however, it results in inferior late outcomes [26,27]. In the latest guidelines, the ESVS recommends OSR over EVT for AAA in patients with a long life expectancy [7]. Furthermore, in terms of IIA patency, OSR may have an advantage over EVT. Although the development of iliac branch devices (IBD) has complemented this limitation their use is restricted to patients with suitable anatomy. However, OSR is not only effective in cases with challenging anatomy for EVT but also advantageous when aneurysmal excision is necessary, such as in cases of hydronephrosis or DVT caused by the mass effect. In this study, only one case of OSR required sacrifice of both IIAs, and the rates of patency preservation of both IIAs were significantly higher in OSR than in EVT. Buttock claudication due to pelvic ischemia can lead to severe impairment of quality of life [27].

Previous studies have reported that younger, non-frail patients experience significantly better short- and mid-term outcomes after open vascular surgery [28]. Our data suggest that younger patients with a mild risk who undergo OSR for isolated IAAs have lower rates of late complications than those undergoing EVT, without an increase in the 30-days and overall mortality. Although the OSR group experienced higher early complication rates, most cases resolved completely without significant sequelae. Considering these findings, socially active younger patients with longer life expectancies are expected to benefit more from OSR than from EVT. In situations where there are no randomized controlled trials, long-term results, or concrete recommendations for the treatment of isolated IAA, this study is expected to guide the choice of treatment owing to its relatively long-term results based on recent data.

This study has several limitations, primarily its retrospective design. As a result, the age distribution of the included patients was broad, with the OSR group being younger on average than the EVT group. However, other patient characteristics in both groups were comparable, and mortality was analyzed using multivariable analysis adjusted for age.

Additionally, the small number of included patients precluded a more detailed analysis through stratification by age and evaluation of high-risk features for late complications in the EVT group. No studies have assessed the risk factors for endoleaks and limb occlusion during EVT for isolated IAAs. Further studies are required to establish tailored treatments for isolated IAAs.

For patients with mild risk factors, EVT for isolated IAAs offers no benefit in terms of survival or re-intervention compared with OSR. Although OSR requires more transfusions, a longer hospital stay, and has a higher early complication rate, EVT has a greater risk of late complications, including limb occlusion or sac expansion, which could lead to a lower performance status or the need for re-intervention. Therefore, OSR should be considered the first-line treatment for isolated IAA in relatively young and mild-risk patients.

None.

The authors have nothing to disclose.

Conception and design: all authors. Analysis and interpretation: EC. Data collection: all authors. Writing the article: EC. Critical revision of the article: TWK. Final approval of the article: TWK. Statistical analysis: EC. Obtained funding: none. Overall responsibility: EC.