Endovascular Treatment of Infrarenal Aneurysms: Comparison of the Results of Second- and Third-Generation Stent Grafts

Editor's Choice - Comparison of Outcomes for Major Contemporary Endograft Devices Used for Endovascular Repair of Intact Abdominal Aortic Aneurysms

OBJECTIVE

To compare rates of mortality, rupture, and secondary intervention following endovascular repair (EVAR) of intact abdominal aortic aneurysms (AAA) using contemporary endograft devices from three major manufacturers.

METHODS

This was a retrospective cohort study using linked clinical registry (Australasian Vascular Audit) and all payer administrative data. Patients undergoing EVAR for intact AAA between 2010 and 2019 in New South Wales, Australia were identified. Rates of all cause death, secondary rupture, and secondary intervention (subsequent aneurysm repair; other secondary aortic intervention) were compared for patients treated with Cook, Medtronic, and Gore standard devices. Inverse probability of treatment weighted proportional hazards and competing risk regression were used to adjust for patient, clinical, and aneurysm characteristics, using Cook as the referent device.

RESULTS

This study identified 2 874 eligible EVAR patients, with a median follow up of 4.1 (maximum 9.5) years. Mortality rates were similar for patients receiving different devices (ranging between 7.0 and 7.3 per 100 person years). There was no statistically significant difference between devices in secondary rupture rates, which ranged between 0.4 and 0.5 per 100 person years. Patients receiving Medtronic and Gore devices tended to have higher crude rates of subsequent aneurysm repair (1.5 per 100 person years) than patients receiving Cook devices (0.8 per 100 person years). This finding remained in the adjusted analysis, but was only statistically significant for Medtronic devices (HR 1.57, 95% CI 1.02 - 2.47; HR 1.73, 95% CI 0.94 - 3.18, respectively).

CONCLUSION

Major endograft devices have similar overall long term safety profiles. However, there may be differences in rates of secondary intervention for some devices. This may reflect endograft durability, or patient selection for different devices based on aneurysm anatomy. Continuous comparative assessments are needed to guide evidence for treatment decisions across the range of available devices.

Decreasing Trends in Reintervention and Readmission After Endovascular Aneurysm Repair in a Multiregional Implant Registry

OBJECTIVES

As endovascular aortic aneurysm repair (EVAR) matures into its third decade, measures such as long-term reintervention and readmission have become a focus of quality improvement efforts. Within a large United States integrated healthcare system, we describe time trends in the rates of long-term reinterventions utilization measures.

METHODS

Data from a US multiregional EVAR registry was used to perform a descriptive study of 3,891 adults who underwent conventional infrarenal EVAR for infrarenal abdominal aortic aneurysm between 2010 to 2019. Three-year follow-up was 96.7%. Outcomes included 1-, 3-, and 5-year graft revision (defined as a procedure involving placement of a new endograft component), secondary interventions (defined as a procedure necessary for maintenance of EVAR integrity, e.g., coil embolization and balloon angioplasty/stenting), conversion to open, interventions for type II endoleaks alone, and 90-day readmission. Crude cause-specific reintervention probabilities were calculated by operative year using the Aalen-Johansen estimator, with death as a competing risk and December 31, 2020 as the study end date.

RESULTS

Excluding interventions for type II endoleak alone, 1-year secondary intervention incidence decreased from 5.9% for EVARs in 2010 to 2.0% in 2019 (p<0.001) and 3-year incidence decreased from 7.2% to 3.6% from 2010 to 2017 (p=0.03). The 3-year incidences of graft revision (mean incidence 3.4%) and conversion to open remained fairly stable (mean incidence 0.6%) over time. The 3-year incidence of interventions for type II endoleak alone also decreased from 3.4% in 2010 to 0.7% in 2017 (p=0.01). 90-day readmission rates decreased from 19.3% for index EVAR in 2010 to 9.2% in 2019 (p=0.03).

CONCLUSIONS

Comprehensive data from a multiregional healthcare system demonstrates decreasing long-term secondary intervention and readmission rates over time in patients undergoing EVAR. These trends are not explained by evolving management of type II endoleaks and suggest improving graft durability, patient selection or surgical technique. Further study is needed to define implant and anatomic predictors of different types of long-term reintervention.

3D finite-element modeling of vascular adaptation after endovascular aneurysm repair

Aneurysm shrinkage is clinically observed after successful endovascular aortic aneurysm repair (EVAR). However, global understanding of post-operative aneurysm evolutions remains weak. In this work, we propose to study these effects using numerical simulation. We set up a 3D finite-element model of post-EVAR vascular adaptation within an open-source finite-element code, which was initially developed for growth and remodeling (G&R). We modeled the endograft with a set of uniaxial prestrained springs that apply radial forces on the inner surface of the artery. Constitutive equations, momentum balance equations, and equations related to the mechanobiology of the artery were formulated based on the homogenized constrained mixture theory. We performed a sensitivity analysis by varying different selected parameters, namely oversizing and compliance of the stent-graft, gain parameters related to collagen G&R, and the residual pressure in the aneurysm sac. This permitted us to evaluate how each factor influences post-EVAR vascular adaptation. It was found that oversizing, compliance or gain parameters have a limited influence compared to that of the residual pressure in the aneurysm sac, which was found to play a critical role in the stability of aneurysm after stent-graft implantation. An excessive residual pressure larger than 50 mmHg can induce a continuous expansion of the aneurysm while a moderate residual pressure below this critical threshold yields continuous shrinkage of the aneurysm. Moreover, it was found that elderly patients, with relatively lower amounts of remnant elastin in the arterial wall, are more sensitive to the effect of residual pressure. Therefore, these results show that elderly patients may present a higher potential risk of aortic sac expansion due to intra-aneurysm sac pressure after EVAR than younger patients.

Experience With Unfavorable Iliac Access When Performing Fenestrated/Branched Endovascular Aneurysm Repair

PURPOSE

To review a single-center experience with fenestrated and branched endovascular aneurysm repair (f/bEVAR) in patients with challenging iliac anatomies.

MATERIALS AND METHODS

A retrospective review of the department's database identified 398 consecutive patients who underwent complex endovascular repair f/bEVAR between January 2010 and June 2018; of these, 67 had challenging accesses. The strategies implemented to overcome access issues were reviewed, using a dedicated scoring system to evaluate the access (integrating diameter, tortuosity, calcification, and previous open or endovascular repair).

RESULTS

In this subgroup of patients, the most common graft design was a 4-vessel fenestrated endograft (27, 40.3%). Hostile access was due to small diameter (<7 mm) in 25 patients (37.3%) and/or concentric calcifications in 19 patients (26.9%). Mean iliac diameter was 5.5±2.6 mm on the right side and 6.0±2.5 mm on the left side. Previous open or endovascular aortoiliac repair had been performed in 15 patients (22.4%), and 20 patients (29.9%) had a stent previously implanted in at least 1 iliac artery, resulting in the inability to perform standard fenestrated repair with access from both sides. Five patients (7.5%) had a single patent iliac access. Eight distinctive strategies were identified to overcome these access issues, including the use of preloaded renal catheters in the endograft delivery system, angioplasty, graft modification (branches instead of fenestrations or 4 preloaded fenestrations), a conduit via a retroperitoneal approach, iliac artery recanalization, and/or the multiple puncture technique. Technical success was achieved in 62 cases (92.5%). Four patients had access complications and 1 died in the early postoperative period of multiorgan failure. Median follow-up was 24.6 months (IQR 7.2, 41.3). Clinical success at the end of follow-up was achieved in 57 patients (85.1%). During follow-up, 14 patients died, including 4 from an aorta-related cause.

CONCLUSION

Dedicated strategies can be implemented to overcome hostile iliac access in patients with complex aneurysms when f/bEVAR is required. Typically, these maneuvers are associated with favorable outcomes.

Reporting of Complications and Mortality in Relation to Risk Communication in Patients with an Abdominal Aortic Aneurysm: A Systematic Review

OBJECTIVES

High-quality reporting of surgical risks is necessary for evidence-based risk communication in clinical practice. Risk communication is defined as the process of discussing benefits and harms of treatment options with patients. This review addressed the current quality of reporting of complications and mortality in publications on abdominal aortic aneurysm treatment, with a focus on items relevant to risk communication.

DESIGN

A systematic review.

MATERIALS

Randomised clinical trials, comparative observational studies and registries from 2010 onwards were eligible if they reported complications and/or mortality in patients with an asymptomatic abdominal aortic aneurysms who received primary treatment.

METHODS

Quality of reporting was assessed by scoring items relevant to risk communication from the reporting standards of the Society for Vascular Surgery (SVS) and the Consolidated Standards of Reporting Trials (CONSORT) statement. Screening, quality assessment and data extraction were independently undertaken by two authors.

RESULTS

Forty-seven publications were included. Nine of 47 publications (19%) provided no definition of complications. In 14 of 47 publications (30%), it was unclear whether the number of adverse events or the number of patients with adverse events were presented. Absolute risk differences were provided in 1 of 32 publications (3.1%) that compared complications between two treatment options. Forty-six of 47 publications reported mortality, of which 42 reported overall mortality rates (91%). Absolute risk differences were given in 2 of the 31 publications (6.5%) that compared mortality between two treatment options.

CONCLUSIONS

The quality of reporting of complications and mortality following primary abdominal aortic aneurysm treatment varied considerably. Better adherence to the SVS reporting standards and the CONSORT statement, as well as stating absolute risk differences may improve the quality of reporting and facilitate evidence-based risk communication.

Long-term results after standard endovascular aneurysm repair with the Endurant and Excluder stent grafts

OBJECTIVE

Many endografts are currently available for standard endovascular repair of infrarenal abdominal aortic aneurysms. Comparison of long-term outcomes between devices might aid in this decision process, but comparative data are scarce. The purpose of this study was to report long-term clinical outcomes of two commercially available endoprosthesis, the Endurant (Medtronic Vascular, Inc, Minneapolis, Minn) and the Excluder (W. L. Gore & Associates, Flagstaff, Ariz) stent grafts.

METHODS

Patients undergoing standard endovascular repair from July 2004 to December 2011 in a single institution with the Endurant or the Low-Porosity Excluder endografts were eligible. Only patients treated for intact degenerative abdominal infrarenal aneurysms were included. All measurements were performed on center-lumen line reconstructions obtained on dedicated software. The primary end point was primary clinical success, defined as clinical success without the need for an additional or secondary surgical or endovascular procedure. Neck-related events (a composite of type IA endoleak, neck-related secondary intervention, or migration of >5 mm), neck morphology changes, renal function, and overall survival were secondary end points.

RESULTS

The study included 277 patients (156 Endurants; 121 Excluders). The median follow-up was 5.8 years (range, 0.1-12.4 years) and did not differ between groups (P = .18). Patients treated with the Endurant stent graft had wider (neck diameter of >28 mm, 27.3% vs 1.7% [P < .001]; neck diameter of 27 mm, [interquartile range (IQR), 24-29 mm] for Endurant and 24 mm [IQR, 22-25 mm] for Excluder; P < .001) and more angulated necks (β-angle of >60°, 26.7% vs 12.5%; P = .004). Oversizing was greater in the Endurant group (16% [IQR, 12%-22%] vs 13% [IQR, 8%-17%], respectively; P < .001). Patients were treated outside device instructions for use regarding proximal neck: 16.7% in the Endurant and 17.3% in the Excluder group (P = .720). The 7-year primary clinical success was 54.7% for the Endurant and 58.1% for the Excluder groups (P = .53). Freedom from neck-related events at 7 years was 76.7% for the Endurant and 78.8% for Excluder group (P = .94). The Endurant stent graft (hazard ratio [HR], 2.7; 95% confidence interval [CI], 1.3-5.8; P = .009) was an independent predictor of significant renal function decline. Neck dilatation was greater in Endurant-implanted patients (13% [95% CI, 2%-22%] vs 4% [95% CI, 0%-10%]; P < .001). Overall survival at 7 years was 61.4% in the Endurant and 50.3% (n = 50; standard error, 0.047) in the Excluder group (P = .39).

CONCLUSIONS

This study reveals that durable and sustainable results can be obtained with either of these late generation devices. This finding suggests that careful planning and a tailored device selection taking into account the patient's anatomy are more relevant determinants than the graft model itself to obtain clinical success. The Endurant endoprosthesis seems to be associated with a higher rate of neck dilatation and faster decrease in the estimated glomerular filtration rate, but further studies with longer follow-up are necessary to determine the clinical relevance of these findings.