Editor's Choice - Post-operative Surveillance and Long Term Outcome after Endovascular Aortic Aneurysm Repair in Patients with an Initial Post-operative Computed Tomography Angiogram Without Abnormalities: the Multicentre Retrospective ODYSSEUS Study

Understanding Type II Endoleak: A Harmless Imaging Finding or a Silent Threat?

Type II endoleak (T2EL) represents a challenging clinical entity following endovascular abdominal aortic aneurysm repair (EVAR). Although several studies have suggested that T2ELs are related to an increased risk of aneurysm sac growth and subsequent rupture, the exact role that T2ELs play in long-term outcomes remains debatable. Understanding the pathophysiology, diagnostic modalities, and management options of T2ELs is important for patients' safety and proper resource utilization. While conservative management may be suitable for asymptomatic patients with a stable aneurysm size, interventional approaches, including transarterial embolization, direct sac puncture embolization and open conversion have been described for patients with persistent T2EL associated with sac expansion. However, more research is needed to better determine the clinical benefit of such interventions. A thorough evaluation of all endoleak types before T2EL treatment would be reasonable for patients with T2ELs associated with sac expansion. Further studies are needed to refine treatment strategies aimed at minimizing T2EL-related complications. Collaborative efforts among vascular specialists, radiologists, and researchers are of paramount importance to address this ongoing clinical challenge.

Machine Learning Based Prediction of Post-operative Infrarenal Endograft Apposition for Abdominal Aortic Aneurysms

OBJECTIVE

Challenging infrarenal aortic neck characteristics have been associated with an increased risk of type Ia endoleak after endovascular aneurysm repair (EVAR). Short apposition (< 10 mm circumferential shortest apposition length [SAL]) on the first post-operative computed tomography angiography (CTA) has been associated with type Ia endoleak. Therefore, this study aimed to develop a model to predict post-operative SAL in patients with an abdominal aortic aneurysm based on the pre-operative shape.

METHODS

A statistical shape model was developed to obtain principal component scores. The dataset comprised patients treated by standard EVAR without complications (n = 93) enriched with patients with a late type Ia endoleak (n = 54). The infrarenal SAL was obtained from the first post-operative CTA and subsequently binarised (< 10 mm and ≥ 10 mm). The principal component scores that were statistically different between the SAL groups were used as input for five classification models, and evaluated by means of leave one out cross validation. Area under the receiver operating characteristic curves (AUC), accuracy, sensitivity, and specificity were determined for each classification model.

RESULTS

Of the 147 patients, 24 patients had an infrarenal SAL < 10 mm and 123 patients had a SAL ≥ 10 mm. The gradient boosting model resulted in the highest AUC of 0.77. Using this model, 114 patients (77.6%) were correctly classified; sensitivity (< 10 mm apposition was correctly predicted) and specificity (≥ 10 mm apposition was correctly predicted) were 0.70 and 0.79 based on a threshold of 0.21, respectively.

CONCLUSION

A model was developed to predict which patients undergoing EVAR will achieve sufficient graft apposition (≥ 10 mm) in the infrarenal aortic neck based on a statistical shape model of pre-operative CTA data. This model can help vascular specialists during the planning phase to accurately identify patients who are unlikely to achieve sufficient apposition after standard EVAR.

Endovascular Treatment of Abdominal Aortic Aneurysm: Impact of Diabetes on Endoleaks and Reintervention

Background: Diabetes has a protective effect on abdominal aortic aneurysms (AAAs); however, there are contrasting reports on the impact of diabetes on endovascular aortic repair (EVAR) outcomes, endoleaks (ELs) being the major negative outcome. The present study characterizes ELs and their outcomes in AAA patients, diabetic or not. Methods: This single-center, retrospective, comparative study was carried out on 324 AAA patients who underwent elective EVARs between 2007 and 2016 at the University Hospital of Liège (Belgium). The primary endpoint was the incidence and effect of ELs on the evolution of the aneurysmal sac; the secondary endpoints were surgical reintervention and mortality rate. Diabetic and non-diabetic patients were compared with respect to various risk factors by logistic regression, while a Cox regression was used to analyze survival. Results: In AAA patients meeting the inclusion criteria (n = 248), 23% were diabetic. EL incidence was comparable (p = 0.74) in diabetic (38.7%) vs. non-diabetic (43.9%) patients. EL risk factors were age (HR = 1.04, p = 0.014) and fibrate intake (HR = 3.12, p = 0.043). A significant association was observed between ELs and aneurysm sac enlargement (p < 0.001), regardless of group (p = 0.46). Aneurysm sac regression per month for non-diabetic patients was -0.24 ± 0.013, while for diabetics it was -0.18 ± 0.027 (p = 0.059). Dyslipidemia (HR = 3.01, p = 0.0060) and sulfonylureas (HR = 8.43, p = 0.043) were associated with shorter EL duration, while diabetes (HR = 0.080, p = 0.038) and beta blockers (HR = 0.46, p = 0.036) were associated with longer EL duration. The likelihood of reoperation decreased with more recent surgery (OR = 0.90, p = 0.040), regardless of diabetic status. All-cause mortality was higher for the non-diabetic group (45.5% vs. 26.3%, p = 0.0096). Conclusions: Endoleak occurrence is a known risk factor for sac expansion. In diabetic patients, endoleaks lasted longer, and regression of the aneurysm sac tended to be slower. The number and type of reintervention was not related to the diabetic status of AAA patients, but overall survival was higher in patients with diabetes.

The sac evolution imaging follow-up after endovascular aortic repair: An international expert opinion-based Delphi consensus study

OBJECTIVE

Management of follow-up protocols after endovascular aortic repair (EVAR) varies significantly between centers and is not standardized according to sac regression. By designing an international expert-based Delphi consensus, the study aimed to create recommendations on follow-up after EVAR according to sac evolution.

METHODS

Eight facilitators created appropriate statements regarding the study topic that were voted, using a 4-point Likert scale, by a selected panel of international experts using a three-round modified Delphi consensus process. Based on the experts' responses, only those statements reaching a grade A (full agreement ≥75%) or B (overall agreement ≥80% and full disagreement <5%) were included in the final document.

RESULTS

One-hundred and seventy-four participants were included in the final analysis, and each voted the initial 29 statements related to the definition of sac regression (Q1-Q9), EVAR follow-up (Q10-Q14), and the assessment and role of sac regression during follow-up (Q15-Q29). At the end of the process, 2 statements (6.9%) were rejected, 9 statements (31%) received a grade B consensus strength, and 18 (62.1%) reached a grade A consensus strength. Of 27 final statements, 15 (55.6%) were classified as grade I, whereas 12 (44.4%) were classified as grade II. Experts agreed that sac regression should be considered an important indicator of EVAR success and always be assessed during follow-up after EVAR.

CONCLUSIONS

Based on the elevated strength and high consistency of this international expert-based Delphi consensus, most of the statements might guide the current clinical management of follow-up after EVAR according to the sac regression. Future studies are needed to clarify debated issues.

Estimation of the Added Cancer Risk Derived From EVAR and CTA Follow-Up

OBJECTIVE

The aim of this study was to assess the risk of radiation-induced cancer development in patients that have undergone an infrarenal EVAR, stratifying the relative contributions of the procedure and the preoperative and postoperative CTAs.

METHODS AND MATERIALS

The organ-specific absorbed radiation doses from CTA and the EVAR procedure were estimated from the radiation exposures of 95 and 45 male patients, respectively. Lifetime attributable risk (LAR) cancer predictions were calculated for 14 different organs. Life expectancy was assumed from a previous cohort of patients undergoing infra-renal EVAR.

RESULTS

The calculated total excess cancer risk was 0.0046, ie, 1 out of 220 patients will develop a neoplasm after being exposed to the ionizing radiation from the preoperative CTA, the EVAR and annual CTA examinations for 15 years. The procedure and the preoperative CTA contributed with 38% of the total excess risk, while the rest was derived from the follow-up. If the entire CTA based follow-up would have been eliminated, an excess risk of 0.0018 (1/560) would remain.

CONCLUSIONS

1 out of 219 patients who have undergone EVAR of an infra-renal AAA have a lifetime risk of developing cancer secondary to the radiation exposures related to the procedure and the CTAs used preoperatively and during follow-up. This risk derives mostly from the yearly postoperative CTAs, underlining the potential benefits of reducing or replacing their use.

CLINICAL IMPACT

A simulation-based estimation reinforced the potential deleterious effects of the radiation exposure for patients undergoing Endovascular Aneurysm Repair (EVAR) of Abdominal Aortic Aneurysms (AAA) and subsequently followed by yearly Computer Tomography Angiographies (CTAs). The risk could be as high as 1 out 219 patients developing a neoplasm after 15 years. The largest exposure derives from the follow-up CTAs and efforts to minimize their use as well as the intraoperative radiation are greatly needed. The simulation-based estimations done in this study reinforce potential deleterious effects of the radiation exposure for patients undergoing EVAR of AAA. Efforts should be done to minimize the intraoperative radiation and the number of CTAs used during follow-up.

A rare case of aortic endograft infection by Francisella tularensis: A case report

INTRODUCTION AND IMPORTANCE: endovascular repair is an alternative to open repair for abdominal aortic aneurysms (AAA), which lowers morbidity and mortality but may presents infectious complications. Endograft infection is a rare but serious life-threatening condition with a mortality rate up to 50 %. We reported a case of aortic endograft infection by Francisella tularensis, rare and highly virulent gram-negative coccobacillus known for use in bioterrorism. CASE PRESENTATION: A 79-year-old man presented with asthenia, weight loss, night sweats and one episode of fever. In 2007, he underwent aorto-bi-iliac endograft repair for AAA without any complication. The diagnostic workup showed some signs of inflammation, but negative blood cultures and no sign of infection on CT scan. The combination of positron emission tomography (PET) and white blood cell (WBC) scintigraphy led to the diagnosis of aortic endograft infection. The management was antimicrobial therapy and surgery. Perioperative analysis shows the presence of Francisella Tularensis. DISCUSSION AND CONCLUSIONS: Aortic endograft infection is a serious complication with a high mortality rate. Its diagnosis may be difficult, but the combination of WBC scintigraphy and PET scan may improve identification of the infection, even if blood cultures and CT scan are negative. The gold standard treatment is removal of the endograft, debridement, and in situ reconstruction along with antibacterial therapy.

Infrarenal Abdominal Aortic Aneurysm

Abdominal aortic aneurysms are found in up to 6% of men and 1.7% of women over the age of 65 years and are usually asymptomatic. The natural history of aortic aneurysms is continued dilation leading to rupture, which is associated with an overall 80% mortality. Of the patients with ruptured aneurysms that undergo intervention, half will not survive their hospitalization. Reduction in aneurysm mortality is therefore achieved by prophylactic repair during the asymptomatic period. On a population-based level, this is supported by abdominal aortic aneurysm screening programs. Approximately 60% of abdominal aortic aneurysms are confined to the infrarenal portion of the aorta and are amenable to repair with off-the-shelf endovascular devices. Endovascular techniques have now replaced open surgery as the primary modality for aneurysm repair.

Diminishing Endograft Apposition during Follow-Up Is an Important Indicator of Late Type 1a Endoleak after Endovascular Aneurysm Repair

Late type 1a endoleaks (T1aELs) after endovascular aneurysm repair (EVAR) are hazardous complications which should be avoided. This study investigated the evolution of the shortest apposition length (SAL) post-EVAR and hypothesised that a declining apposition during follow-up may be an indicator of T1aEL development. Patients with a late T1aEL were selected from a consecutive multicentre database. For each T1aEL patient, the preoperative computed tomography angiography (CTA), first postoperative CTA, and pre-endoleak CTA were analysed. T1aEL patients were matched 1:1 to uncomplicated controls, based on endograft type and follow-up duration. Anatomical characteristics and endograft dimensions, including the post-EVAR SAL, were measured. Included were 28 patients with a late T1aEL and 28 matched controls. The SAL decreased from 11.2 mm (5.6-20.6 mm) to 3.9 mm (0.0-11.4 mm) in the T1aEL group (p = 0.006), whereas an increase in SAL was seen in the control group from 21.3 mm (14.1-25.8 mm) to 25.4 mm (19.0-36.2 mm; p = 0.015). On the pre-endoleak CTA, 18 patients (64%) in the T1aEL group had a SAL < 10 mm, and one (4%) patient in the control group had a SAL < 10 mm on the matched CTAs. Moreover, three mechanisms of decreasing sealing zone were identified, which might be used to determine optimal imaging or reintervention strategies. Diminishing SAL < 10 mm is an indicator for T1aEL during follow-up, it is imperative to include apposition analysis during follow-up.

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.

Cost of Follow Up After Endovascular Abdominal Aortic Aneurysm Repair in Patients With an Initial Post-Operative Computed Tomography Angiogram Without Abnormalities

OBJECTIVE

The Observing a Decade of Yearly Standardised Surveillance in EVAR patients with Ultrasound or CT Scan (ODYSSEUS) study was conducted to assess differences in outcomes of patients with continued or discontinued yearly follow up after endovascular abdominal aortic aneurysm repair (EVAR). Earlier results of this study showed that discontinued follow up was not associated with poor outcomes. Therefore, an incremental cost analysis and budget impact analysis of de-implementation of yearly imaging following EVAR was performed.

METHODS

In total, 1 596 patients from the ODYSSEUS study were included. The expected cost savings were assessed if yearly imaging was reduced in patients with a post-operative computed tomography angiogram without abnormalities made around 30 days after EVAR. Costs were derived from the Dutch costs manual, benchmark cost prices, and literature review. Costs were expressed in euros (€) and displayed at 2019 prices. Sensitivity analysis was performed by varying costs.

RESULTS

A difference of 24% in cost was found between patients with continued and discontinued imaging follow up. The cost per patient was €1 935 in the continued group vs. €1 603 per patient in the discontinued group at five years post-EVAR, with a mean difference of €332 (95% bias corrected and accelerated bootstrap confidence interval -741 to 114). De-implementation of yearly imaging would result in an annual nationwide cost saving of €678 471. Sensitivity analysis with variation in adherence rates, imaging, or secondary intervention costs resulted in a saving of at least €271 388 per year.

CONCLUSION

This study provided an in depth analysis of hospital costs for post-EVAR patients in the Netherlands with a modest impact on the Dutch healthcare budget.