Systematic Review and Meta-analysis of 12 Years of Endovascular Abdominal Aortic Aneurysm Repair

Contemporary Management of Abdominal Aortic Aneurysms

PURPOSE OF REVIEW

Abdominal aortic aneurysms (AAA) can carry extremely high mortality rates and most will only present with symptoms with impending rupture. We present an overview of management of this disease process starting with screening, to medical management, surveillance and treatment options currently available, as well as those being studied for future use.

RECENT FINDINGS

Screening has been proven to reduce the mortality rate. There still remains a paucity of data to support medical therapies to help mitigate the rate of aneurysm growth and prevent rupture. However, on the topic of repair, there have been advancements in endovascular devices which have broadened the scope of treatment for patients with anatomy not amenable to standard endovascular repair or those who are not suitable candidates for open surgical repair. Appropriate surveillance, risk factor modification, and operative repair, when indicated, are the cornerstones of contemporary management of AAAs. Advancements in endovascular technologies have allowed us to treat more patients. Further research is warranted on non-operative medical therapies.

Midterm outcomes of 455 patients receiving the AFX2 endovascular graft for the treatment of abdominal aortic aneurysm: A retrospective multi-center analysis

Since being introduced into clinical practice the AFX family of endografts has undergone labelling updates, design and manufacturing changes to address a Type III failure mode. The published literature on the performance of the current endograft-AFX2 -is limited to small series with limited follow up. The present study reports the largest series of patients implanted with AFX2 for the treatment of abdominal aortic aneurysms. The study was a retrospective, 5 center study of patients receiving an AFX2 endograft from January 2016 until Dec 2020. Electronic case report forms were provided to four of the centers, with one additional site providing relevant outcomes in an independent dataset. Relevant outcomes were reported via Kaplan-Meier analysis and included all-cause mortality, aneurysm-related mortality, post EVAR aortic rupture, open conversion, device related reinterventions and endoleaks. Among a cohort of 460 patients, 405 underwent elective repair of an AAA, 50 were treated for a ruptured AAA, and 5 were aorto-iliac occlusive disease cases. For the elective cohort (mean age 73.7y, 77% male, mean AAA diameter 5.4cm), the peri-operative mortality was 1.7%. Freedom from aneurysm-related mortality was 98.2% at 1,2,3 and 4 years post-operatively, there were no post-operative aortic ruptures, and 2 patients required open conversion. Freedom from Type Ia endoleaks was 99.4% at 1, 2, 3 and 4 years. Freedom from Type IIIa and Type IIIb endoleaks were 100% and 100% (year 1), 100% and 99.6% (year 2), 99.4% and 99.6% (year 3), 99.4% and 99.6% (year 4) respectively. Freedom from all device-related reintervention (including Type II endoleaks) at 4 y was 86.8%. The AFX2 endograft appears to perform to a satisfactory standard in terms of patient centric outcomes in mid-term follow up. The Type Ia and Type III endoleaks rates at 4y appear to be within acceptable limits. Further follow up studies are warranted.

Aortic endograft sizing and endoleak, reintervention, and mortality following endovascular aneurysm repair

OBJECTIVE

Endograft sizing for endovascular abdominal aortic aneurysm repair (EVAR) is not consistent despite published instructions for use (IFU). We sought to identify factors associated with over/undersizing, determine sex influence on sizing, and examine sizing effects on endoleak, reintervention, and mortality by analyzing data obtained from the W.L. Gore & Associates Global Registry for Endovascular Aortic Treatment (GREAT).

METHODS

All patients enrolled in GREAT undergoing EVAR were included for analysis. Proximal/distal aortic landing zones were compared with device implanted to assess sizing as related to IFU. χ²/Fisher exact tests were used to evaluate associations between IFU sizing and demographics. Logistic regression modeling was used to identify predictors of outside IFU sizing. Cox proportional hazards regression analyzed the relationship between sizing and endoleak, device-related reinterventions, and all-cause/aortic mortality.

RESULTS

There were 3607 EVAR subjects enrolled in GREAT as of March 2020. Of them, 1896 (53%) were within IFU for sizing, 791 (22%) were oversized, 540 (15%) were undersized, and 380 (10%) had both over- and undersized components. Factors predictive of use outside of IFU included female sex (P = .001), non-white race (P = .0003), decreased proximal neck length (P < .061), or larger iliac diameters (P < .0001). Women were more likely than men to have proximal neck undersizing and iliac limb oversizing, and men were more likely to have iliac limb undersizing. On multivariate analysis, undersizing of the proximal graft was associated with endoleak (hazard ratio [HR], 1.8) and aortic (HR, 60.5) and all-cause (HR, 18.0) mortality. Undersizing of iliac limbs was associated with endoleak (HR, 1.5) and device-related reintervention (HR, 1.4). Iliac limb outside IFU sizing was associated with aortic (HR, 2.6) and all-cause (HR, 1.3) mortality. Proximal and distal oversizing was not associated with adverse outcomes. Female sex was associated with mortality on univariate but not multivariate analysis.

CONCLUSIONS

Women undergoing EVAR with GORE EXCLUDER abdominal aortic aneurysm Endoprosthesis (W.L. Gore & Associates Inc, Flagstaff, Ariz) are more likely to have proximal stent-graft undersizing and iliac limb oversizing, whereas men are more likely to have undersized iliac limbs. Proximal aortic graft undersizing is associated with endoleak and all-cause/aortic mortality, whereas undersizing of iliac limbs is associated with endoleak and device-related reintervention. Oversizing was not associated with adverse outcomes.

Artifacts in Contrast-Enhanced Ultrasound during Follow-up after Endovascular Aortic Repair: Impact on Endoleak Detection in Comparison with Computed Tomography Angiography

The study described here systematically analyzed how specific artifacts in contrast-enhanced ultrasound (CEUS) can affect the detection of endoleaks during follow-up after endovascular aortic repair (EVAR). Patients undergoing EVAR of atherosclerotic or mycotic abdominal aortic aneurysms using various standard and branched stent-graft material for visceral and iliac preservation were enrolled over 5 y and followed up with computed tomography angiography (CTA) and CEUS simultaneously. CEUS artifacts were frequently identified after EVAR procedures (59% of examinations) and were caused mainly by contrast agent, different prosthesis or embolization material and postinterventional changes in the aneurysm sac. This article describes how to identify important artifacts and how to avoid false-negative or false-positive interpretations of endoleaks. Despite artifacts, CEUS had higher sensitivity for endoleak detection after EVAR than CTA. CEUS was superior to CTA in the identification of late endoleaks type II and in follow-up examinations after embolization procedures, where beam-hardening artifacts limited CTA.

Descriptive and follow-up study of patients treated surgically for abdominal aortic aneurysm at tertiary hospitals in Spain

BACKGROUND

The aim of this study was to assess potential variability in the clinical characteristics and treatment of patients undergoing elective surgery for abdominal aortic aneurysm (AAA) across five hospitals in Spain.

METHODS

Multicenter, retrospective cohort study of patients diagnosed with AAA and treated with open surgical repair (OSR) or endovascular aneurysm repair (EVAR). We evaluated clinical and demographic variables, including comorbidity (Charlson Comorbidity Index [CCI]); anatomic characteristics; surgical risk (ASA Score); aneurysm characteristics; and in-hospital and overall mortality. All patients were followed for three years.

RESULTS

A total of 186 patients were included, mean age 72.5 (standard deviation [SD], 8.4), mean CCI 2.04 (SD, 1.9). The surgical technique was EVAR in 46.8% of cases (N.=87) and OSR in 53.2% (N.=99). The in-hospital mortality rate was 2.2%, with no differences between groups. The overall mortality rate during follow-up (mean, 2.9 years) was 24.1% for EVAR versus 8.1% for the OSR group (odds ratio [OR], 3.62; 95% confidence interval [CI], 3.60-3.64; P=0.004). EVAR was the only independent risk factor for mortality (OR, 3.89; 95% CI: 3.87-3.92; P=0.004). Inter-center variability in the type of surgery was high, with EVAR accounting for 19.4% to 75% of the surgical procedures, depending on the treating center (P<0.001).

CONCLUSIONS

In this study the in-hospital mortality rates for elective EVAR and OSR were similar. However, after the follow-up, patients who underwent EVAR had a three-fold greater mortality rate than those treated with OSR. There was substantial inter-hospital variability, underscoring the need to standardize treatment selection in patients who undergo elective surgery for AAA repair.

Variation in the choice of elective surgical procedure for abdominal aortic aneurysm in Spain

Objective

The two main surgical treatments for abdominal aortic aneurysm (AAA) are open surgical repair (OSR) and endovascular aneurysm repair (EVAR). The aim of this study was to analyze variation among Spanish hospitals in the use of OSR or EVAR for AAA. A secondary aim was to assess changes in preferences for these two procedures over time.

Methods

This was a retrospective longitudinal study based on discharge data from public hospitals in Spain during 2002–2012. Patient inclusion criteria were: age >18 years, elective admission, primary diagnosis of unruptured AAA, and surgical treatment with OSR or EVAR. The characteristics of the treating center, patients, and in-hospital mortality were recorded.

Results

We included 16,737 patients from 114 hospitals; 6,809 (40.7%) underwent EVAR and 9,928 (59.3%) underwent OSR. The total volume of surgeries increased throughout the period, and the probability that any given procedure was EVAR increased by 20% per year (OR 1.20, P<0.001). The volume and distribution of the two procedures varied highly across the participating hospitals. Overall, in-hospital mortality rate was 3.6% and it decreased during the study period (5.3% in 2002 and 3.2% in 2012), mainly due to a decrease in OSR-related mortality, despite a slight increase in EVAR-related mortality. Hospitals with higher surgical volumes were more likely to use EVAR and have lower in-hospital mortality rates.

Conclusion

This study reveals high variability in the surgical treatment of unruptured AAA across Spanish hospitals. The number of interventions has increased in recent years, with EVAR accounting for a growing percentage of these surgical procedures. Overall in-hospital mortality rates decreased significantly during this period, mainly due to lower mortality among patients undergoing OSR. In-hospital mortality rates were lower in higher-volume centers, regardless of the surgical approach used. Further research on variability and appropriateness of surgical management of AAA is required to assess the suitability of concentrating elective AAA repair in more experienced centers to potentially achieve better outcomes.

There Is Limited Value in the One Month Post Endovascular Aortic Aneurysm Repair Surveillance Computed Tomography Scan

BACKGROUND

Endovascular aortic aneurysm repair (EVAR) is the preferred first-line treatment for abdominal aortic aneurysms. Current postprocedure surveillance recommendations by manufacturers are a 1-month computed tomography angiography (CTA) followed by a 12-month CTA in most circumstances. The objective of this study is to determine the utility of the 1-month CTA following elective EVAR and determine if initial surveillance at 6-month CTA is appropriate.

METHODS

A single-center retrospective chart review of all elective EVARs at a tertiary medical center over a 12-year period was conducted. Patients were excluded if postoperative surveillance imaging was not available. Data analysis encompassed demographics, chart review, and imaging including angiogram and cross-sectional imaging to asses for endoleaks and other findings.

RESULTS

There were 363 patients who underwent elective EVAR and had available postoperative imaging during the study period. Within the 1-month follow-up, a CTA group of 316 patients was detected with 98 (31%) endoleaks. Of these, 5 (1.5%) required intervention: 1 for infolding of an iliac limb and 4 for type I endoleak which was present on completion angiogram-3 in patients treated outside of instructions for use and 1 with a type Ib endoleak on intraoperative completion imaging. In the 158 patients with 1 and 3-month CTAs, there were 47 persistent endoleaks, 9 previously undetected endoleaks not seen in 1-month CTA, and 13 resolved endoleaks. Three patients (1.2%) underwent intervention for type II endoleak and aneurysm expansion. In 47 patients with only a 6-month CTA, there were 16 endoleaks not seen on completion angiography and 2 of which were treated with reintervention-1 for a type I endoleak and 1 for a type II endoleak.

CONCLUSIONS

There is limited utility to 1-month surveillance CTA in patients undergoing elective EVAR within the device instructions for use that has no evidence of type I endoleak on completion angiography. It is safe to start routine EVAR surveillance at 6 months in this patient population. This has implications when considering bundled and value-based payments in the longitudinal care of abdominal aortic aneurysm patients.

Transcatheter Embolization of Type I Endoleaks Associated With Endovascular Abdominal Aortic Aneurysm Repair Using Ethylene Vinyl Alcohol Copolymer

Purpose:

To evaluate the feasibility, safety, and outcome of transcatheter embolization using ethylene vinyl alcohol copolymer (EVOH) of type I endoleaks associated with endovascular abdominal aortic aneurysm repair.

Patient Population and Methods:

Retrospective chart review was performed to identify 8 consecutive patients who had undergone EVOH embolization for type I endoleaks between 2012 and 2015. The primary approach used to access the endoleak was the perigraft technique, where the endoleak itself is catheterized at the anastomotic site.

Results:

Six type Ia and 2 type Ib endoleaks were treated. In 2 patients, a direct transabdominal approach was used to access the endoleak because it was inaccessible via the perigraft approach. Coils were used in addition to EVOH in 5 cases. Residual endoleak was noted in 1 case, whereas 2 patients developed a recurrent type I endoleak during follow-up. No EVOH complications were observed. The 5 remaining patients demonstrated freedom from endoleak and reintervention at a mean follow-up of 6.9 months.

Conclusion:

Type I endoleaks can be safely and effectively treated by embolotherapy with EVOH. Larger endoleaks resulting from grossly undersized endografts appear to be unsuitable for EVOH embolization.

Management of Immediate Post-Endovascular Aortic Aneurysm Repair Type Ia Endoleaks and Late Outcomes

BACKGROUND

Post-endovascular aortic aneurysm repair (EVAR) endoleaks and the need for reintervention are challenging. Additional endovascular treatment is advised for type Ia endoleaks detected on post-EVAR completion angiogram. This study analyzed management and late outcomes of these endoleaks.

STUDY DESIGN

This was a retrospective review of prospectively collected data from EVAR patients during a 10-year period. All post-EVAR type Ia endoleaks on completion angiogram were identified (group A) and their early (30-day) and late outcomes were compared with outcomes of patients without endoleaks (group B). Kaplan-Meier analysis was used for survival analysis, sac expansion, late type Ia endoleak, and reintervention.

RESULTS

Seventy-one of 565 (12.6%) patients had immediate post-EVAR type Ia endoleak. Early intervention (proximal aortic cuffs and/or stenting) was used in 56 of 71 (79%) in group A vs 31 of 494 (6%) in group B (p < 0.0001). Late type Ia endoleak was noted in 9 patients (13%) in group A at a mean follow-up of 28 months vs 10 patients (2%) in group B at a mean follow-up of 32 months (p < 0.0001). Late sac expansion and reintervention rates were 9% and 10% for group A vs 5% and 3% for group B (p = 0.2698 and p = 0.0198), respectively. Freedom rates from late type Ia endoleaks at 1, 3, and 5 years for group A were 88%, 85%, and 80% vs 98%, 98%, and 96% for group B (p < 0.001); and for late intervention, were 94%, 92%, and 77% for group A, and 99%, 97%, and 95% for group B (p = 0.007), respectively. Survival rates were similar.

CONCLUSIONS

Immediate post-EVAR type Ia endoleaks are associated with higher rates of early interventions, late endoleaks and reintervention, which will necessitate strict post-EVAR surveillance.

Endovascular aneurysm sealing addresses several limitations of conventional endovascular aneurysm repair

Endovascular aneurysm repair has enabled a broad population of patients with infrarenal abdominal aortic aneurysm to be treated by a less-invasive technique. However, endovascular aneurysm repair has therapeutic limitations, including the need for lifelong surveillance and a higher rate of secondary interventions than open repair. These outcomes can promote patient dissatisfaction and result in increased health care costs and associated morbidity and mortality. The primary reason for secondary interventions is continued abdominal aortic aneurysm sac enlargement due to endoleaks. Conventional endovascular aneurysm repair procedures do not address aortic branch vessels that are ligated during open repairs. Secondary measures to occlude these branch vessels have shown efficacy in limiting sac growth, but do not predictably eliminate the need for further interventions. Endovascular aneurysm sealing is a new technique that addresses some of the limitations of conventional endovascular repair. Endovascular aneurysm sealing secures the stent graft flow lumens within a biostable polymer. This stability prevents stent migration while also sealing branch vessels that are otherwise not addressed by other endovascular devices. This new approach to endovascular repair has shown early promise in reducing the rates of endoleak and need for secondary interventions, while opening up the possibility of durable endovascular repair to a more challenging type of anatomy.

Does the diameter of abdominal aortic aneurysm influence late survival following abdominal aortic aneurysm repair? A systematic review and meta-analysis

Background

Studies reporting the influence of preoperative abdominal aortic aneurysm diameter on late survival following abdominal aortic aneurysm repair have not been consistent. Aim: To report the influence of abdominal aortic aneurysm diameter on overall long-term survival following abdominal aortic aneurysm repair.

Methods

Embase, Medline and the Cochrane electronic databases were searched to identify articles reporting the influence of abdominal aortic aneurysm diameter on late survival following open aneurysm repair and endovascular aneurysm repair published up to April 2015. Data were extracted from multivariate analysis; estimated risks were expressed as hazard ratio.

Results

A total of 2167 titles/abstracts were retrieved, of which 76 studies were fully assessed; 19 studies reporting on 22,104 patients were included. Preoperative larger abdominal aortic aneurysm size was associated with a worse survival compared to smaller aneurysms with a pooled hazard ratio of 1.14 (95% CI: 1.09–1.18), per 1 cm increase in abdominal aortic aneurysm diameter. Subgroup analysis of the different types of repair was performed and the hazard ratio (95% CI), for open aneurysm repair and endovascular aneurysm repair were 1.08 (1.03–1.12) and 1.20 (1.15–1.25), respectively, per 1 cm increase. There was a significant difference between the groups p < 0.02.

Conclusions

This meta-analysis suggests that preoperative large abdominal aortic aneurysm independently influences overall late survival following abdominal aortic aneurysm repair, and this association was greater in abdominal aortic aneurysm repaired with endovascular aneurysm repair.

Endograft Sizing for Endovascular Aortic Repair and Incidence of Endoleak Type 1A

Objective

In endovascular aortic aneurysm repair (EVAR), proximal type 1A endoleaks can occur as a result of hostile neck anatomy or over- or undersizing of the endograft. As the current standard is based on the diameter or average of the short and long axes in a central lumen reconstruction image, it can falter in irregularly shaped aortic necks. An alternative method is circumference-based, therefore minimizing the measurement error. In this study we aimed to assess the degree of discrepancy between both methods and the association of this discrepancy with the occurrence of endoleak type 1A.

Methods

All patients with early (<30 days post-operative) endoleak type 1A after elective EVAR at our center between 2004 and 2016 were identified for a retrospective case-control study. Control patients were matched based on hostile neck anatomy, such as calcification, thrombus, reverse taper, and β-angulation. The aortic neck diameter was measured using the traditional, diameter-based method as well as an alternative method, based on the circumference of the aortic neck.

Results

In 482 EVAR patients, 18 early endoleak type 1A cases were found (3.9%). After exclusion, 12 cases remained and 48 matching controls were found. No significant differences were found between the two measuring methods at any level below the renal arteries. The inter-observer variability was significant for the D(mean) (0.4 ± 1.69 mm, P = .02) and was larger than the D(circ) method (-0.1 ± 1.03 mm, P = .35). In only four out of 12 cases the endograft size was 10–20% larger than the D(mean) and D(circ) measurements. The differences between the diameter of the D(mean) and D(circ) and the chosen endograft were smaller for the case group (-8 ± 25.6% and -7 ± 24%) than for the control group. (-12.4 ± 12.4% and -11 ± 10.7%).

Conclusion

The difference between the D(mean) and D(circ) methods for aortic neck measurement was not large enough to play a significant role in the incidence of endoleak type 1A. Inadequate oversizing and considerable β-angulation of the aortic neck may have been the cause of endoleak type 1A in this population. Robust and well-investigated sizing methods are paramount for accurate endograft sizing and prevention of endoleak type 1A. Therefore the lack of studies in this field and a sizeable inter-observer variability do not justify the widespread reliance on the traditional diameter-based methods for endograft sizing.

Management of late main-body aortic endograft component uncoupling and type IIIa endoleak encountered with the Endologix Powerlink and AFX platforms

OBJECTIVE

Junctional component separation producing type IIIa endoleak after endovascular abdominal aortic aneurysm repair (EVAR) is an uncommon but serious complication requiring unanticipated reinterventions. This retrospective study analyzed main-body EVAR component uncoupling and type IIIa endoleaks encountered with Powerlink and AFX (Endologix Inc, Irvine, Calif) endografts during an 8-year period.

METHODS

Type IIIa endoleaks were identified from a database of secondary interventions and clinical surveillance. Operative reports, medical records, and computed tomography studies were reviewed. Clinical and imaging characteristics were analyzed over time, and differences were compared at appropriate follow-up intervals.

RESULTS

Since 2006, 701 patients underwent primary EVAR using Endologix Powerlink (352 patients, 2006-2011) or AFX (349 patients, 2011-2014) endografts. Endoleaks required 32 secondary interventions (4.6%), including type Ia in 4 patients (1 proximal extension and 3 explants); type Ib in 8 patients (all distal extensions for enlarging iliac aneurysms); type II in 1 patient (explant); type IIIa in 17 patients (2.4%), who were the subject of this report; and type IIIb in 2 patients (both EVAR relining). The 17 patients with type IIIa endoleak were an average age of 71 years, and 14 (82%) were men. The mean preoperative abdominal aortic aneurysm (AAA) diameter was 70 ± 18 mm. The repair was elective in 16 patients and an emergency in one. Ten cases were performed with Powerlink and seven with AFX. Analysis of serial computed tomography scans found significant changes in AAA diameter; renal-to-bifurcation straight-line, centerline, and greater curvature lengths; EVAR angulation; and loss of EVAR component overlap. The average time from EVAR to reintervention was 32 months. Three patients returned with a ruptured AAA and three with AAA thrombosis, and three of these patients (18%) died ≤30 days of the emergency reintervention. Secondary procedures included EVAR relining with additional bridging components in 14 patients (82%), explant in 2, and axillobifemoral bypass in 1. No new cases of endograft uncoupling have been identified in patients treated with AFX since December 2012 after adoption of revised instructions for use.

CONCLUSIONS

Although a small number of secondary interventions were needed after EVAR with the Endologix Powerlink or AFX endografts, most were undertaken for late main-body component uncoupling and type IIIa endoleak, which can occur after sideways displacement of the endograft in large and angulated AAAs. Patients treated before 2013 under the old instructions for use should be evaluated for signs of impending component separation and monitored annually, noting that expected indicators of endograft failure, such as increasing AAA diameter and endoleak, may be absent.

Does lower limb exercise worsen renal artery hemodynamics in patients with abdominal aortic aneurysm?

Renal artery stenosis (RAS) and renal complications emerge in some patients after endovascular aneurysm repair (EVAR) to treat abdominal aorta aneurysm (AAA). The mechanisms for the causes of these problems are not clear. We hypothesized that for EVAR patients, lower limb exercise could negatively influence the physiology of the renal artery and the renal function, by decreasing the blood flow velocity and changing the hemodynamics in the renal arteries. To evaluate this hypothesis, pre- and post-operative models of the abdominal aorta were reconstructed based on CT images. The hemodynamic environment was numerically simulated under rest and lower limb exercise conditions. The results revealed that in the renal arteries, lower limb exercise decreased the wall shear stress (WSS), increased the oscillatory shear index (OSI) and increased the relative residence time (RRT). EVAR further enhanced these effects. Because these parameters are related to artery stenosis and atherosclerosis, this preliminary study concluded that lower limb exercise may increase the potential risk of inducing renal artery stenosis and renal complications for AAA patients. This finding could help elucidate the mechanism of renal artery stenosis and renal complications after EVAR and warn us to reconsider the management and nursing care of AAA patients.

Postoperative ICU management of vascular surgery patients

Critical care management of vascular surgical patients poses significant challenges owing to patients' comorbidities and the magnitude of the surgical procedures. The primary goals of the anesthesiologist and intensivist are reestablishing preoperative homeostasis, optimizing hemodynamics until return of normal organ function, and managing postoperative complications promptly and effectively. Postoperative critical care management demands a detailed knowledge of the various vascular surgical procedures and the potential postoperative complications. In this review, the authors describe the postoperative complications related to the major specific vascular surgical procedures and their perioperative management.

Endovascular repositioning of a migrated stent graft using "endoanchor capture"

Endovascular aneurysm repair is increasingly used to treat patients harboring abdominal aortic aneurysms with severe comorbidities that make them unfavorable candidates for open repair. Graft-related complications in these patients also require unique solutions. We report the novel technique of "endoanchor capture" for successful repositioning of a migrated stent graft.

In meta-analyses of proportion studies, funnel plots were found to be an inaccurate method of assessing publication bias

OBJECTIVE

To assess the utility of funnel plots in assessing publication bias (PB) in meta-analyses of proportion studies.

STUDY DESIGN AND SETTING

Meta-analysis simulation study and meta-analysis of published literature reporting peri-operative mortality after abdominal aortic aneurysm (AAA) repair. Data for the simulation study were stochastically generated. A literature search of Medline and Embase was performed to identify studies for inclusion in the published literature meta-analyses.

RESULTS

The simulation study demonstrated that conventionally constructed funnel plots (log odds vs. 1/standard error [1/SE]) for extreme proportional outcomes were asymmetric despite no PB. Alternative funnel plots constructed using study size rather than 1/SE showed no asymmetry for extreme proportional outcomes. When used in meta-analyses of the mortality of AAA repair, these alternative funnel plots highlighted the possibility for conventional funnel plots to demonstrate asymmetry when there was no evidence of PB.

CONCLUSION

Conventional funnel plots used to assess for potential PB in meta-analyses are inaccurate for meta-analyses of proportion studies with low proportion outcomes. Funnel plots of study size against log odds may be a more accurate way of assessing for PB in these studies.

Ruptured Abdominal Aortic Aneurysm with Antecedent Endovascular Repair of Abdominal Aortic Aneurysm

Late aortic rupture following successful endovascular repair of abdominal aortic aneurysm still does occur. It represents the ultimate failure of endovascular aortic repair of abdominal aortic aneurysm (EVAR) and subjects patients to equivalent risk of death as de novo rupture. Unfortunately, it is difficult to identify patients at risk for post-EVAR rupture as many present with aortic rupture in the absence of any endograft-related complications. Continued surveillance and timely intervention are of paramount importance to assure rupture-free survival, the ultimate goal of any aneurysm treatment modality. The vascular surgeon needs to be prepared to provide the optimal therapy, whether open or endovascular, for this challenging cohort of patients.

Endovascular strategy for the elective treatment of concomitant aortoiliac aneurysm and symptomatic large bowel diverticular disease

BACKGROUND

The purpose of this study was to evaluate the strategy for treatment of patients presenting with asymptomatic diverticular disease of the large bowel associated with an asymptomatic aortoiliac aneurysmal (AAA) disease.

METHODS

Sixty-nine patients were included in this retrospective study. The patients were divided into 5 groups according to the type and sequence of the surgical treatment: 32 patients (47%) underwent colectomy followed by a staged open AAA repair (group A); 10 patients (14%) were treated with open AAA repair followed by a staged colectomy (group B); 13 patients (18%) received endovascular aneurysm repair (EVAR) followed by a staged bowel resection (group C); 8 patients (12%) had a bowel resection followed by staged EVAR (group D); and 6 patients (9%) underwent simultaneous open AAA repair and bowel resection (group E). Primary end points were mortality and complications after any of the procedures. Secondary end point was the time interval between the staged procedures.

RESULTS

The cumulative death rate for delayed treatment of AAA was 6.5% and 0% for delayed treatment of diverticular disease [P=0.22]. The mean time interval between the staged procedures was 11 days for EVAR/colon resection (group C and group D) and 73 days for open AAA repair/colon resection (group A and group B; P<0.01).

CONCLUSIONS

EVAR allows a significant reduction in the time required between AAA repair and colon resection, but no definite rule can be established regarding the sequence of staged procedures. Combined procedures should be reserved for selected cases.

A clinical series of resuscitative endovascular balloon occlusion of the aorta for hemorrhage control and resuscitation

BACKGROUND

A requirement for improved methods of hemorrhage control and resuscitation along with the translation of endovascular specialty skills has resulted in reappraisal of resuscitative endovascular balloon occlusion of the aorta (REBOA) for end-stage shock. The objective of this report was to describe implementation of REBOA in civilian trauma centers.

METHODS

Descriptive case series of REBOA (December 2012 to March 2013) used in scenarios of end-stage hemorrhagic shock at the University of Maryland, R. Adams Cowley Shock Trauma Center, Baltimore, Maryland, and Herman Memorial Hospital, The Texas Trauma Institute, Houston, Texas.

RESULTS

REBOA was performed by trauma and acute care surgeons for blunt (n = 4) and penetrating (n = 2) mechanisms. Three cases were REBOA in the descending thoracic aorta (Zone I) and three in the infrarenal aorta (Zone III). Mean (SD) systolic blood pressure at the time of REBOA was 59 (27) mm Hg, and mean (SD) base deficit was 13 (5). Arterial access was accomplished using both direct cutdown (n = 3) and percutaneous (n = 3) access to the common femoral artery. REBOA resulted in a mean (SD) increase in blood pressure of 55 (20) mm Hg, and the mean (SD) aortic occlusion time was 18 (34) minutes. There were no REBOA-related complications, and there was no hemorrhage-related mortality.

CONCLUSION

REBOA is a feasible and effective means of proactive aortic control for patients in end-stage shock from blunt and penetrating mechanisms. With available technology, this method of resuscitation can be performed by trauma and acute care surgeons who have benefited from instruction on a limited endovascular skill set. Future work should be aimed at devices that allow easy, fluoroscopy-free access and studies to define patients most likely to benefit from this procedure.

LEVEL OF EVIDENCE

Therapeutic study, level V.

Comparison of endovascular and open repair of ruptured abdominal aortic aneurysm in the United States in the past decade

PURPOSE

The purpose of this study is national-level comparison of the endovascular (EVAR) and open repair (OAR) of ruptured abdominal aortic aneurysm (AAA) in the United States from 2001 to 2010.

METHODS

The data were obtained from nationwide inpatient sample from the Department of Health and Human Services. Ruptured AAA treated by OAR or EVAR were selected using combination ICD-9 codes.

RESULTS

There were 42,126 cases of ruptured AAA of which 8,140 (19.3%) were repaired by EVAR. EVAR patients were older (74.1 vs. 72.8 years, p < 0.001) and had higher incidence of comorbidities compared with OAR group. EVAR patients had lower in-hospital mortality (25.9 vs. 39.1%, p < 0.001) and shorter hospital stay (10.4 vs. 13.7 days, p < 0.001). More patients were discharged home following EVAR (36.8 vs. 21.5%, p < 0.001). There was reduced need for institutional rehabilitation following EVAR (26.3 vs. 29.1%, p < 0.001). Females had significantly higher mortality compared with males after both EVAR (32.2 vs. 24.1%, p < 0.001) and OAR (46.2 vs. 36.9%, p < 0.001). The hospital mortality (41.3-25.8%, p < 0.001) and mean length of stay (11.8-9.7 days, p < 0.01) of EVAR steadily improved over the study period.

CONCLUSIONS

National level comparison of data from the past decade shows that in suitable cases, EVAR for ruptured AAA is associated with reduced hospital mortality, shorter hospital stay, and reduced need for rehabilitation. EVAR outcomes showed consistent improvement with time. Regardless of the type of repair, women had higher mortality compared with men.

Ten-year results of endovascular abdominal aortic aneurysm repair from a large multicenter registry

OBJECTIVE

To assess outcomes after endovascular abdominal aortic aneurysm repair (EVAR) in an integrated health care system.

METHODS

Between 2000 and 2010, 1736 patients underwent EVAR at 17 centers. Demographic data, comorbidities, and outcomes of interest were collected. EVAR in patients presenting with ruptured or symptomatic aneurysms was categorized as urgent; otherwise, it was considered elective. Primary outcomes were mortality and aneurysm-related mortality (ARM). Secondary outcomes were change in aneurysm sac size, endoleak status, major adverse events, and reintervention.

RESULTS

Overall, the median age was 76 years (interquartile range, 70-81 years), 86% were male, and 82% were Caucasian. Most cases (93.8%) were elective, but urgent use of EVAR increased from 4% in the first 5 years to 7.3% in the last 5 years of the study period. Mean aneurysm size was 5.8 cm. Patients were followed for an average of 3 years (range, 1-11 years); 8% were lost to follow-up. Intraoperatively, 4.5% of patients required adjunctive maneuvers for endoleak, fixation, or flow-limiting issues. The 30-day mortality rate was 1.2%, and the perioperative morbidity rate was 6.6%. Intraoperative type I and II endoleaks were uncommon (2.3% and 9.3%, respectively). Life-table analysis at 5 years demonstrated excellent overall survival (66%) and freedom from ARM (97%). Postoperative endoleak was seen in 30% of patients and was associated with an increase in sac size over time. Finally, the total reintervention rate was 15%, including 91 instances (5%) of revisional EVAR. The overall major adverse event rate was 7.9% and decreased significantly from 12.3% in the first 5 years to 5.6% in the second 5 years of the study period (P < .001). Overall ARM was worse in patients with postoperative endoleak (4.1% vs 1.8%; P < .01) or in those who underwent reintervention (7.6% vs 1.6%; P < .001).

CONCLUSIONS

Results from a contemporary EVAR registry in an integrated health care system demonstrate favorable perioperative outcomes and excellent clinical efficacy. However, postoperative endoleak and the need for reintervention continue to be challenging problems for patients after EVAR.

Standardization of outcome measures in clinical trials of pharmacological treatment for abdominal aortic aneurysm

An abdominal aortic aneurysm (AAA) is a common aortic wall disease with an increased prevalence in the elderly population (4-8% for those aged >65 years). Many AAAs are slow growing and remain insidious. Current standard of care for patients with small AAAs (<49 mm) is surveillance, with interventional therapy (open surgical repair or endovascular aneurysm repair) recommended for large (>50-55 mm), rapidly growing (>10 mm/year) or symptomatic AAAs. Although open surgical repair or endovascular aneurysm repair are effective, significant short- and long-term postoperative morbidity and mortality occurs. Currently, there is no pharmacological treatment specific for AAA; the need for the development of targeted pharmacological therapies based on clinically relevant and feasible outcomes acceptable to the medical community, regulatory agencies and third-party payers is high. A consensus on such end points will be critical to accelerating the development of pharmacological agents to prevent formation, arrest the expansion and reduce the rupture risk of AAA.

Nationwide trends in abdominal aortic aneurysm repair and use of endovascular repair in the emergency setting

PURPOSE

To analyze nationwide trends in abdominal aortic aneurysm (AAA) repair and the use of endovascular abdominal aortic aneurysm repair (EVAR) in the emergency setting.

MATERIALS AND METHODS

Data were obtained from the Nationwide Inpatient Sample (NIS) using the International Classification of Diseases, Ninth Revision-Clinical Modification (ICD-9-CM) codes for open and endovascular repairs from 2001-2009. Trends in outcome parameters and hospital charges were compared.

RESULTS

The number of emergency EVAR procedures increased from 382 in 2001 to 1,247 in 2009 (P < .001). During the study period, length of hospital stay associated with total number of EVAR procedures decreased from 3.8 days to 3.4 days (P < .05), and the in-hospital mortality decreased from 2.4% to 2% (P = .32). From 2001-2009, mean hospital charges associated with EVAR increased from $50,630 to $91,401 (74% increase), whereas charges associated with open repairs increased from $54,578 to $128,925 (136% increase). The proportion of patients needing rehabilitation or nursing home placement after EVAR increased from 5.8% to 7.7% (P < .01), and need for home health increased from 6.9% to 10.5% (P < .01).

CONCLUSIONS

There was a significant increase in the number of emergency EVAR procedures during the study period; however, the overall in-hospital mortality associated with EVAR remained unchanged, and the length of hospital stay showed a decreasing trend. The total hospital charges for EVAR were lower than the charges for open abdominal aneurysm repair throughout the study period; the difference in charges between the procedures showed a significant increasing trend with time.

Early clinical experience with the Anaconda re-deployable endograft in 106 patients with abdominal aortic aneurism: the west of Scotland Anaconda registry

Endovascular repair of abdominal aortic aneurysm is a common procedure and not without complications. The aim of this study was to evaluate the early results of the Anaconda endograft (Vascutek Ltd., Inchinnan, Scotland, UK) in 106 patients in three hospitals in the west of Scotland. A prospective registry of 106 consecutive patients undergoing endoluminal repair of their abdominal aortic aneurysms using the Anaconda device was set up to record the clinical outcomes, with a mean follow-up of two years. There was no 30-day perioperative mortality in the 106 patients. Only type II endoleaks were detected on serial computed tomography scanning at follow-up. Technical success was achieved in 99% (105/106) in this study; one patient was converted to open surgical repair. Two cases of proximal device migration (>1 cm) were detected at one month and 19 months, respectively, with no associated endoleak or sac enlargement. Five cases of endograft limb thrombosis were noted in this study. Our early clinical experience with the Anaconda endograft compares favourably with other commercially available endografts in the treatment of abdominal aortic aneurysms. The main advantages of this device are that it is re-deployable and that it has a magnetic wire system which makes it easy to implant.

Use of baseline factors to predict complications and reinterventions after endovascular repair of abdominal aortic aneurysm

BACKGROUND

It is uncertain which baseline factors are associated with graft-related complications and reinterventions after endovascular aneurysm repair (EVAR) in patients with a large abdominal aortic aneurysm.

METHODS

Patients randomized to elective EVAR in EVAR Trial 1 or 2 were followed for serious graft-related complications (type 2 endoleaks excluded) and reinterventions. Cox regression analysis was used to investigate whether any prespecified baseline factors were associated with time to first serious complication or reintervention.

RESULTS

A total of 756 patients who had elective EVAR were followed for a mean of 3.7 years, by which time there were 179 serious graft complications (rate 6.5 per 100 person years) and 114 reinterventions (rate 3.8 per 100 person years). The highest rate was during the first 6 months, with an apparent increase again after 2 years. Multivariable analysis indicated that graft-related complications increased significantly with larger initial aneurysm diameter (P < 0.001) and older age (P = 0.040). There was also evidence that patients with larger common iliac diameters experienced higher complication rates (P = 0.011).

CONCLUSION

Graft-related complication and reintervention rates were common after EVAR in patients with a large aneurysm. Younger patients and those with aneurysms closer to the 5.5-cm threshold for intervention experienced lower rates.

[Imaging of endoleaks after endovascular aneurysm repair (EVAR) with contrast-enhanced ultrasound (CEUS)]

Endoleaks following endovascular aneurysm repair (EVAR) are common and present a diagnostic challenge in the follow-up after EVAR. Contrast-enhanced ultrasound (CEUS) is a promising new method for the diagnosis and follow-up of endoleaks. CEUS with SonoVue allows a rapid and non-invasive diagnosis in the follow-up after EVAR. The sensitivity and specificity of conventional ultrasound compared to the multislice CT angiography is estimated to be 33-63% and 63-93%, respectively. These values can be increased through the use of CEUS in up to 98-100% (sensitivity) and 82-93% (specificity). This article describes the etiology, classification and importance of different types of endoleaks. The value of CEUS in this clinical scenario will be discussed.