Technical challenges during emergent endovascular aneurysm repair with the ALTO system.

INTRODUCTION: Ruptured abdominal aortic aneurysms (AAAs) pose an immediate threat for patient's life and endovascular repair (EVAR) is currently the preferred treatment modality in the presence of suitable anatomy. This is determined based on the requirements of each endograft as described in the instructions for use (IFU). The new ALTO system (Endologix, Irvin, CA, U.S.A.), can accommodate a great range of anatomies such as short necks and/or narrow access, but its unique design requires specific technical modifications during treatment of ruptured AAAs. AREAS COVERED: The standard double balloon technique has long been described and it is used to provide circulatory support during EVAR for ruptured AAA. While this technique is straightforward with the use of endografts with a traditional design, this would not be the case if one uses the ALTO system. In that case specific maneuvers would be required to treat AAA patients in an acute setting. EXPERT OPINION: The ALTO system although being able to treat AAAs with adverse anatomy, it may not be appropriate during treatment of ruptured AAA patients with profound hemodynamic instability. A careful evaluation of the individual's patient anatomy and hemodynamic condition is mandatory in order to decide the best endograft for each case.

Concomitant vascular and orthopedic trauma: 10 points to consider.

Although vascular injuries complicate only 1-2% of patients with orthopedic trauma, they may be encountered in a much higher rate of around 10 % in injuries around the knee and elbow joints following both fractures and dislocations. In case of vascular involvement, specific diagnostic and therapeutic challenges arise and there is a higher risk for significant morbidity (i.e. limb loss) or mortality. In the absence of randomized data, diagnostic and therapeutic algorithms are not always straightforward and clinical practice may be based on experience and local protocols rather than firm evidence. With this article we intend to review available literature regarding concomitant skeletal and vascular trauma in order to provide concise information and clear guidelines of when to operate with least investigations and when to go for a full spectrum of investigations in the absence of hard clinical signs. Additionally, other aspects concerning the manipulation of these patients are discussed, such as the indications of primary amputation, the potential role of endovascular techniques and the value of the Resuscitative Endovascular Balloon Occlusion of the Aorta. In summary, this scoping review summarizes current practices in the diagnostic and therapeutic management of patients with concomitant orthopedic and vascular injuries, discusses different treatment strategies and gives a practical perspective for implementation on every day practice.

A hemodynamic study of blood flow models on various stent graft configurations during aorto-iliac reconstruction.

PURPOSE: To compare the hemodynamic performance of three (Bottom Up non-ballet, Top-Down non-ballet, Top Down ballet) idealized stent graft configurations used during endovascular repair of abdominal aortic aneurysms, under the influence of various rheological models. METHODS: Ten rheological models are assumed and a commercial finite volume solver is employed for the simulation of blood flow under realistic boundary conditions. An appropriate mesh convergence study is performed and five hemodynamic variables are computed: the time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), endothelial cell activation potential and displacement force (DF) for all three configurations. RESULTS: The choice of blood flow model may affect results, but does not constitute a significant determinant on the overall performance of the assumed stent grafts. On the contrary, stent graft geometry has a major effect. Specifically, the Bottom Up non-ballet type is characterized by the least favorable performance presenting the lowest TAWSS and the highest OSI, RRT and ECAP values. On the other hand, the Top Down ballet type presents hemodynamic advantages yielding the highest TAWSS and lowest OSI, RRT and ECAP average values. Furthermore, the ballet type is characterized by the lowest DF, although differences observed are small and their clinical relevance uncertain. CONCLUSIONS: The effect of the assumed rheological model on the overall performance of the grafts is not significant. It is thus relatively safe to claim that it is the type of stent graft that determines its overall performance rather than the adopted blood flow model.

Systematic Review and Meta-Analysis of the Effect of Anticoagulation on Outcomes After Endovascular Aneurysm Repair.

PURPOSE: Our objective was to investigate whether patients who receive anticoagulation therapy have different outcomes after endovascular aneurysm repair (EVAR) from those who do not. MATERIALS AND METHODS: We conducted a systematic review of studies that compared outcomes of EVAR in patients who were on therapeutic anticoagulation vs those who were not. We developed and reported the review in accordance with the PRISMA guidelines with a registered protocol (CRD42022375894). The Ovid interface was used to search Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica Database (EMBASE), and Cochrane Central Register of Controlled Trials (CENTRAL) up to November 2022. The quality of studies was assessed with the Newcastle-Ottawa Scale (NOS) (maximum score=9), and the evidence was appraised with the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. The hazard ratio (HR) and 95% confidence interval (CI) was the effect estimate in time-to-event meta-analyses, calculated using the inverse-variance statistical method and random-effects models. RESULTS: Sixteen studies qualified for inclusion reporting a total of 35 739 individuals. Anticoagulated patients had a statistically significantly higher hazard of death (HR=1.93, 95% CI=1.03-3.63), endoleak (HR=2.13, 95% CI=1.55-2.93), reintervention (HR=1.79, 95% CI=1.27-2.52), and aneurysm sac expansion (HR=2.72, 95% CI=1.57-4.72) than patients not receiving anticoagulation therapy. The median score on the NOS was 7 (range=4-9). The certainty of evidence was very low for mortality and reintervention and low for endoleak and sac expansion. CONCLUSIONS: Anticoagulation is a poor prognostic factor after standard EVAR and should be considered in decision-making, consent processes, and surveillance strategies. CLINICAL IMPACT: The number of individuals who take anticoagulation treatment has been rapidly increasing over the recent years. We aimed to investigate the effect of such treatment on outcomes after endovascular aneurysm repair (EVAR). Anticoagulated patients were found to have increased mortality, endoleak, and reintervention rates after EVAR compared to their non-anticoagulated counterparts. Anticoagulation therapy has a prognostic role in EVAR and should be considered in decision making and EVAR surveillance. Anticoagulated patients need to be informed of the higher failure rates of EVAR, and intensified surveillance strategies may need to be implemented in this patient cohort.

Retroperitoneal Soft Tissue Sarcoma: Emerging Therapeutic Strategies.

Retroperitoneal soft tissue sarcoma (RPS) is a rare and heterogenous disease for which surgery is the cornerstone of treatment. However, the local recurrence rate is much higher than in soft tissue sarcoma of the extremities since wide resection is usually unfeasible in RPS due to its large size, indistinct tumour borders, anatomical constraints and the thinness of the overlying peritoneum. Local recurrence is the leading cause of death for low-grade RPS, whereas high-grade tumours are prone to distant metastases. In recent decades, the role of emerging therapeutic strategies, such as more extended surgery and (neo)adjuvant treatments to improve oncological outcome in primary localised RPS, has been extensively investigated. In this review, the recent data on the evolving multidisciplinary management of primary localised RPS are comprehensively discussed. The heterogeneity of RPS, with their different histological subtypes and biological behaviour, renders a standard therapeutic 'one-size-fits-all' approach inappropriate, and treatment should be modified according to histological type and malignancy grade. There is sufficient evidence that frontline extended surgery with compartmental resection including all ipsilateral retroperitoneal fat and liberal en bloc resection of adjacent organs and structures, even if they are not macroscopically involved, increases local tumour control in low-grade sarcoma and liposarcoma, but not in leiomyosarcoma for which complete macroscopic resection seems sufficient. Additionally, preoperative radiotherapy is not indicated for all RPSs, but seems to be beneficial in well-differentiated liposarcoma and grade I/II dedifferentiated liposarcoma, and probably in solitary fibrous tumour. Whether neoadjuvant chemotherapy is of benefit in high-grade RPS remains unclear from retrospective data and is subject of the ongoing randomised STRASS 2 trial, from which the results are eagerly awaited. Personalised, histology-tailored multimodality treatment is promising and will likely further evolve as our understanding of the molecular and genetic characteristics within RPS improves.

Comparison of the Haemodynamic Performance of Various Treatment Options for Aorto-Iliac Occlusive Disease.

Introduction: Several surgical and endovascular techniques are used during the treatment of aorto-iliac occlusive disease. Aortobifemoral bypass (AoBFB) is the standard of care, but other options such as axillobifemoral (AxBFB) bypass, aorto-iliac kissing stents (KS), and covered endovascular reconstruction of aortic bifurcation (CERAB) are also available. This study aimed to perform a computational comparison of these four modalities to investigate their haemodynamic performance. Report: Eight patient specific anatomies were analysed, with each of the abovementioned techniques used to treat two anatomies. The CT angiograms were segmented from the renal (or axillary) to common femoral arteries and the 3D geometries were exported. A commercial finite volume solver was implemented for numerical simulations. Outcomes that were assessed were pressure drop (ΔP) between the inlet and the outlet for every configuration and haemodynamic indices of Time Average Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), and Relative Residence Time (RRT) as markers of a thrombogenic environment. The results indicate that maximum ΔP was observed at peak systole for all models, with values ranging between 12 mmHg and 21 mmHg for the AoBFB, 64 mmHg and 96 mmHg for the AxBFB, 31 mmHg and 46 mmHg for the KS, and 43 mmHg and 46 mmHg for the CERAB configuration. TAWSS, OSI, and RRT varied among different configurations, mostly presenting values well above thrombogenic thresholds. Regarding RRT, the percentage of total surface area presenting such values is 2.5%, 3.2%, 2%, and 4.3% for the AoBFB, AxBFB, KS, and CERAB configurations, respectively. Discussion: Computational modelling indicates a favourable haemodynamic performance of AoBFB compared with the other configurations. This leads to a smaller pressure drop and sconsequently a higher pressure in the outlet of the conduit, which is the perfusion pressure of the limb. Notably, lower patency rates of the latter modalities cannot be explained based on haemodynamic indices.

Endovascular Versus Surgical Treatment for All Comer Patients With Prosthetic Bypass Graft Occlusion: The Multicentre ENSUPRO Study.

OBJECTIVE: Bypass surgery plays a key role in complex lower limb lesions. However, there is a lack of evidence regarding the management of symptomatic prosthetic bypass graft (PBG) occlusion. This study aimed to report outcomes following open, hybrid, or endovascular management of patients presenting with symptomatic PBG occlusion. METHODS: A multicentre, retrospective cohort study was conducted, including patients presenting with PBG occlusion between January 2014 and December 2021 from 18 centres. It assessed the comparative value of treatment strategies, including (1) recanalisation of native vessels, (2) endovascular treatment of the failed PBG, (3) hybrid treatment, and (4) open surgery. The primary outcome measure was amputation free survival (AFS, time to major amputation and or death), whereas all cause mortality, major amputation, PBG re-occlusion, target lesion revascularisation (TLR), and Rutherford category (RC) improvement during follow up were considered as secondary endpoints. RESULTS: Of 260 patients with occluded PBGs, 108 (41.5%) were treated endovascularly (24 [22.2%] by recanalisation of native vessels and 84 [77.7%] by PBG re-opening), 57 (21.9%) underwent hybrid revascularisation, and 58 (22.3%) had surgery. In addition, 27 (10.4%) were treated conservatively and 10 (3.8%) received systemic thrombolysis. With a median follow up of 1.4 (0.6 - 3.0) years, AFS was 95.5%, 76.4%, 45.5%, and 37.1%, respectively in Groups 1 - 4 (p = .007). Older age and non-endovascular treatment (HR 1.05 and 1.70; p < .01 for both) were independent predictors of poor AFS. Endovascular treatment was associated with lower rates of major amputation (p = .04), PBG re-occlusion (p < .001), and TLR (p = .037), and higher RC improvements (p < .001), whereas all cause mortality was comparable between treatment groups (p = .21). CONCLUSION: Endovascular treatment is associated with higher rates of AFS and RC improvement and lower rates of PBG re-occlusion and TLR in patients with PBG occlusion.

Selection of Bifurcated Grafts' Dimensions during Aorto-Iliac Vascular Reconstruction Based on Their Hemodynamic Performance.

During the vascular surgical reconstruction of aorto-iliac occlusive/aneurysmal disease, bifurcated grafts are used where vascular surgeons intra-operatively select the size and the relative lengths of the parent and daughter portions of the graft. Currently, clinical practice regarding the selection of the most favorable geometric configuration of the graft is an understudied research subject: decisions are solely based on the clinical experience of the operating surgeon. This manuscript aims to evaluate the hemodynamic performance of various diameters, D, of bifurcated aortic grafts and relate those with proximal/distal part length ratios (the angle φ between the limbs is used as a surrogate marker of the main body-to-limb length ratio) in order to provide insights regarding the effects of different geometries on the hemodynamic environment. To this end, a computationally intensive set of simulations is conducted, and the resulting data are analyzed with modern statistical regression tools. A negative curvilinear relationship of TAWSS with both φ and D is recorded. It is shown that the angle between limbs is a more important predictor for the variability of TAWSS, while the graft's diameter is an important determinant for the variability of OSI. Large percentages of the total graft area with TAWSS < 0.4 Pa, which correspond to thrombogenic stimulating environments, are only observed for large values of φ and D > 20 mm. This variable ranges from 10% (for the smallest values of φ and D) to 55% (for the largest φ and D values). Our findings suggest that grafts with the smallest possible angle between the limbs (i.e., smallest parent-to-daughter length ratio) present the most favorable hemodynamic performance, yielding the smallest percentage of total graft area under thrombogenic simulating environments. Similarly, grafts with the smallest acceptable diameter should be preferred for the same reason. Especially, grafts with diameters greater than 20 mm should be avoided, given the abrupt increase in estimated thrombogenic areas.

Systematic Review With Meta-Analysis of Endovascular Versus Open Repair of Abdominal Aortic Aneurysm Repair in the Young.

PURPOSE: The purpose of this study was to investigate which treatment method for abdominal aortic aneurysm (AAA), endovascular or open repair, has better outcomes in young patients. MATERIALS AND METHODS: A systematic review was conducted to identify observational studies or randomized controlled trials (RCTs) that compared endovascular and open repair of intact AAA in young patients. MEDLINE, EMBASE, and CENTRAL were searched up to March 2022 using the Ovid interface. The risk of bias was assessed with the Newcastle-Ottawa scale (NOS), with a maximum score of 9, or version 2 of the Cochrane risk of bias tool. The certainty of evidence was assessed with the GRADE framework. Primary outcomes were perioperative, overall, and aneurysm-related mortality. Secondary outcomes were reintervention, hospital length of stay, and perioperative complications. Effect measures in syntheses were the odds ratio (OR), risk difference (RD), mean difference (MD), or hazard ratio (HR) and were calculated with the Mantel-Haenszel or inverse variance statistical method and random-effects models. RESULTS: Fifteen observational studies and 1 RCT were included, reporting a total of 48 976 young patients. Definitions of young ranged from 60 to 70 years. The median score on the NOS was 8 (range: 4-9), and the RCT was judged to be high risk of bias. The perioperative mortality was lower after EVAR (RD: -0.01, 95% CI: -0.02 to -0.00), but the overall and aneurysm-related mortality was not significantly different between EVAR and open repair (HR: 1.38, 95% CI: 0.81 to 2.33; HR: 4.68, 95% CI: 0.71 to 31.04, respectively), as was the hazard of reintervention (HR: 1.50, 95% CI: 0.88 to 2.56). The hospital length of stay was shorter after EVAR (MD: -4.44 days, 95% CI: -4.79 to -4.09), and the odds of cardiac (OR: 0.22, 95% CI: 0.13 to 0.35), respiratory (OR: 0.17, 95% CI: 0.11 to 0.26), and bleeding complications were lower after EVAR (OR: 0.26, 95% CI: 0.11 to 0.64). The level of evidence was low or very low. CONCLUSION: Patient preferences and perspectives should be considered during shared decision-making process considering the available evidence. EVAR may be considered in young and fit patients with a suitable anatomy. PROTOCOL REGISTRATION: PROSPERO, CRD42022325051. CLINICAL IMPACT: Uncertainty surrounds the optimal treatment strategy for abdominal aortic aneurysm in young patients. Meta-analysis of some 48,976 young patients showed that endovascular aneurysm repair (EVAR) has a lower perioperative mortality and morbidity and a shorter hospital and intensive care unit stay than open surgical repair, but the overall and aneurysm-related mortality in the short to medium term are not significantly different between EVAR and open repair. EVAR can be considered in young patients.

Systematic Review of the Effect of Cerebrospinal Fluid Drainage on Outcomes After Endovascular Descending Thoracic/Thoraco-Abdominal Aortic Aneurysm Repair.

OBJECTIVE: This study aimed to investigate whether prophylactic use of cerebrospinal fluid (CSF) drainage in endovascular descending thoracic aortic aneurysm (DTAA) and thoraco-abdominal aortic aneurysm (TAAA) repair contributes to a lower rate of post-operative spinal cord ischaemia (SCI). DATA SOURCES: MEDLINE, Embase, and CINAHL. REVIEW METHODS: A literature review was conducted in accordance with PRISMA guidelines (PROSPERO registration no. CRD42021245893). Risk of bias was assessed through the Newcastle-Ottawa scale (NOS), and the certainty of evidence was graded using the GRADE approach. A proportion meta-analysis was conducted to calculate the pooled rate and 95% confidence interval (CI) of both early and late onset SCI. Pooled outcome estimates were calculated using the odds ratio (OR) and associated 95% CI. The primary outcome was SCI, both early and lateonset. Secondary outcomes were complications of CSF drainage, length of hospital stay, and peri-operative (30 day or in hospital) mortality rates. RESULTS: Twenty-eight observational, retrospective studies were included, reporting 4 814 patients (2 599 patients with and 2 215 without CSF drainage). The NOS showed a moderate risk of bias. The incidence of SCI was similar in patients with CSF drainage (0.05, 95% CI 0.03 ‒ 0.08) and without CSF drainage (0.05, 95% CI 0.00 ‒ 0.14). No significant decrease in SCI was found when using CSF drainage (OR 0.67, 95% CI 0.29 ‒ 1.55, p = .35). The incidence rate of CSF drainage related complication was 0.10 (95% CI 0.04 ‒ 0.19). The 30 day and in hospital mortality rate with CSF drainage was 0.08 (95% CI 0.05 ‒ 0.12). The 30 day and in hospital mortality rate without CSF drainage and comparison with late mortality and length of hospital stay could not be determined due to lack of data. The quality of evidence was considered very low. CONCLUSION: Pre-operative CSF drainage placement was not related to a favourable outcome regarding SCI rate in endovascular TAAA and DTAA repair. Due to the low quality of evidence, no clear recommendation on pre-operative use of CSF drainage placement can be made.

Does the Routine Skin-Only Closure in Ruptured Abdominal Aortic Aneurysm Repair Safely Diminish Abdominal Compartment Syndrome? A Hypothesis Generating Retrospective Study.

BACKGROUND: Abdominal compartment syndrome (ACS) often complicates ruptured abdominal aortic aneurysm (rAAA) repair. We report results with routine skin-only abdominal wound closure after rAAA surgical repair. METHODS: This was a single-center retrospective study including consecutive patients undergoing rAAA surgical repair for the duration of 7 years. Skin-only closure was routinely performed, and if possible, secondary abdominal closure was performed during the same admission. Demographic information, preoperative hemodynamic condition, and perioperative information (ACS, mortality, rate of abdominal closure, and postoperative outcomes) were collected. RESULTS: During the study period, 93 rAAAs were recorded. Ten patients were too frail to undergo repair or refused treatment. Eighty-three patients underwent immediate surgical repair. The mean age was 72.4 ± 10.5 years, and the vast majority were male (82:1). Preoperative systolic blood pressure <90 mm Hg was recorded in 31 patients. Intraoperative mortality was recorded in nine cases. Overall in-hospital mortality was 34.9% (29/83). Primary fascial closure was performed in five patients, while skin-only closure was performed in 69. ACS was recorded in two cases in whom skin sutures were removed and negative pressure wound treatment was applied. Secondary fascial closure was feasible in 30 patients during the same admission. Among 37 patients not undergoing fascial closure, 18 died and 19 survived and were discharged with a planned ventral hernia repair. Median length of intensive care unit and hospital stay were 5 (1-24) and 13 (8-35) days, respectively. After a mean follow-up of 21 months, telephone contact was possible with 14/19 patients who left the hospital with an abdominal hernia. Three reported hernia-related complications mandating surgical repair, while in 11, this was well tolerated. CONCLUSION: Routine skin-only closure during rAAA surgical repair results in low rates of ACS at the expense of a high rate of patients being discharged with a planned ventral hernia which, however, seems to be well tolerated by the majority of patients.

Effect of Sac Asymmetry, Neck and Iliac Angle on the Hemodynamic Behavior of Idealized Abdominal Aortic Aneurysm Geometries.

BACKGROUND: Abdominal aortic aneurysms (AAAs) are currently treated based on the universal maximum diameter criterion, but other geometric variables may play a role in the risk of rupture. The hemodynamic environment inside the AAA sac has been shown to interact with several biologic processes which can affect prognosis. AAA geometric configuration has a significant impact in the hemodynamic conditions that develop, which has only been recently realized, with implications for rupture risk estimations. We aim to perform a parametric study to evaluate the effect of aortic neck angulation, angle between the iliac arteries, and sac asymmetry (SA) on the hemodynamic variables of AAAs. METHODS: This study uses idealized AAA models and it is parametrized in terms of 3 quantities as follows: the neck angle, φ (°), iliac angle, θ (°), and SA (%), each of which accepts 3 different values, specifically φ = (0°, 30°, 60°), θ = (40°, 60°, 80°), and SA = (S, °SS, °OS), where the SA can either be on the same side with respect to neck (SS) or on the opposite side (OS). Time average wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and the velocity profile are calculated for different geometric configurations, while the percentage of the total surface area under thrombogenic conditions, using thresholds previously reported in the literature, is also recorded. RESULTS: In case of an angulated neck and a higher angle between iliac arteries, favorable hemodynamic conditions are predicted with higher TAWSS and lower OSI and RRT values. The area under thrombogenic conditions reduces by 16-46% as the neck angle increases from 0° to 60°, depending on the hemodynamic variable under consideration. The effect of iliac angulation is present but less pronounced with 2.5-7.5% change between the lower and the higher angle. The effect of SA seems to be significant for OSI, with a nonsymmetrical configuration being hemodynamically favorable, which in the presence of an angulated neck is more pronounced for the OS outline. CONCLUSIONS: Favorable hemodynamic conditions develop inside the sac of idealized AAAs with increasing neck and iliac angles. Regarding the SA parameter, asymmetrical configurations most often appear advantageous. Concerning the velocity profile the triplet (φ, θ, SA) may affect outcomes under certain conditions and thus should be taken into account when parametrizing the geometric characteristics of AAAs.

The Effect of Blood Rheology and Inlet Boundary Conditions on Realistic Abdominal Aortic Aneurysms under Pulsatile Flow Conditions.

BACKGROUND: The effects of non-Newtonian rheology and boundary conditions on various pathophysiologies have been studied quite extensively in the literature. The majority of results present qualitative and/or quantitative conclusions that are not thoroughly assessed from a statistical perspective. METHODS: The finite volume method was employed for the numerical simulation of seven patient-specific abdominal aortic aneurysms. For each case, five rheological models and three inlet velocity boundary conditions were considered. Outlier- and heteroscedasticity-robust ANOVA tests assessed the simultaneous effect of rheological specifications and boundary conditions on fourteen variables that capture important characteristics of vascular flows. RESULTS: The selection of inlet velocity profiles appears as a more critical factor relative to rheological specifications, especially regarding differences in the oscillatory characteristics of computed flows. Response variables that relate to the average tangential force on the wall over the entire cycle do not differ significantly across alternative factor levels, as long as one focuses on non-Newtonian specifications. CONCLUSIONS: The two factors, namely blood rheological models and inlet velocity boundary condition, exert additive effects on variables that characterize vascular flows, with negligible interaction effects. Regarding thrombus-prone conditions, the Plug inlet profile offers an advantageous hemodynamic configuration with respect to the other two profiles.

Editor's Choice - Meta-Analysis of Compliance with Endovascular Aneurysm Repair Surveillance: The EVAR Surveillance Paradox.

OBJECTIVE: To compare the survival of patients who attended surveillance after endovascular aneurysm repair (EVAR) with those who were non-compliant. DATA SOURCES: MEDLINE and Embase were searched using the Ovid interface. REVIEW METHODS: A systematic review was conducted complying with the PRISMA guidelines. Eligible studies compared survival in EVAR surveillance compliant patients with non-compliant patients. Non-compliance was defined as failure to attend at least one post-EVAR follow up. The risk of bias was assessed with the Newcastle-Ottawa scale, and the certainty of evidence using the GRADE framework. Primary outcomes were survival and aneurysm related death. Effect measures were the hazard ratio (HR) or odds ratio (OR) and 95% confidence interval (CI) calculated using the inverse variance or Mantel-Haenszel statistical method and random effects models. RESULTS: Thirteen cohort studies with a total of 22 762 patients were included. Eight studies were deemed high risk of bias. The pooled proportion of patients who were non-compliant with EVAR surveillance was 43% (95% CI 36 - 51). No statistically significant difference was found in the hazard of all cause mortality (HR 1.04, 95% CI 0.61 - 1.77), aneurysm related mortality (HR 1.80, 95% CI 0.85-3.80), or secondary intervention (HR 0.66, 95% CI 0.31 - 1.41) between patients who had incomplete and complete follow up after EVAR. The odds of aneurysm rupture were lower in non-compliant patients (OR 0.63, 95% CI 0.39 - 1.01). The certainty of evidence was very low for all outcomes. Subgroup analysis for patients who had no surveillance vs. those with complete surveillance showed no significant difference in all cause mortality (HR 1.10, 95% CI 0.43 - 2.80). CONCLUSION: Patients who were non-compliant with EVAR surveillance had similar survival to those who were compliant. These findings question the value of intense surveillance in all patients post-EVAR and highlight the need for further research on individualised or risk adjusted surveillance.