Predicting Prosthetic Mobility at Discharge From Rehabilitation Following Major Amputation in Vascular Surgery.

OBJECTIVE: This study aimed to construct a decision aid to estimate the likelihood of independence with a prosthesis following rehabilitation for limb loss secondary to advanced ischaemia (acute or chronic limb threatening ischaemia) or diabetic foot disease (DFD). A secondary aim was to determine whether prosthetic independence is a surrogate marker of long term survival. METHODS: A retrospective cohort study of a prospectively maintained database of unilateral amputations due to ischaemia or DFD entering rehabilitation between 2007 and 2020 was performed. Predictors of independent prosthetic mobility (IPM) were used in construction of the IPM prediction model, which underwent bootstrap internal and criterion validation through correlation with predictors of other measures of function: Timed Up and Go (TUG) and two minute walk test. Kaplan-Meier and Cox regression analyses were performed to address the secondary aim. RESULTS: Of the 771 patients included, only 49.9% of amputees achieved IPM. Independent negative predictors of IPM were age > 75 years, female sex, higher amputation level, active malignancy, cerebrovascular disease, end stage renal disease, and cognitive impairment. The model yielded high discrimination (C statistic 0.778), and internal validation was demonstrated with bootstrapping (C statistic 0.778), confirming no over optimism. There was a strong correlation between IPM, TUG, and two minute distance and their predictors, confirming strong criterion validity. The IPM group had a median survival of 93.7 (80.7, 105) months, whereas the non-IPM group fared worse with a median survival of 56.6 (48.5, 66.7) months (p < .001). CONCLUSION: An internally validated decision aid for estimating the likelihood of independence with a prosthesis after major amputation was constructed. A strong association between female sex and poorer prosthetic mobility was observed. Prosthetic function was shown to be a surrogate marker of long term survival. Future research will involve external validation studies to confirm the generalisability of the decision aid in clinical practice.

Association between statin-use and mobility and long-term survival after major lower limb amputation.

AIM: The aim of this study was to determine if there is an association between statin-use and prosthetic mobility and long-term survival in patients receiving rehabilitation after major amputation for lower limb arterial disease. METHODS: A retrospective analysis of prospectively maintained data (2008-2020) from a centre for rehabilitation was performed. Patients were grouped by statin-use status and sub-grouped by the combination of statin and antithrombotic drugs (antiplatelets or anticoagulants). Outcomes were prosthetic mobility (SIGAM score, timed-up-go and 2-min walking distance) and long-term survival. Regression, Kaplan-Meier and Cox-proportional hazard analyses were performed to test associations adjusted to confounders. RESULTS: Of 771 patients, 499 (64.7%) were on a statin before amputation or prescribed a statin peri-operatively. Rate of statin-use was significantly lower among female (53.3%) compared to male (68.2%) patients, P < 0.001. Statin-use was associated with significantly better prosthetic independence (53.1% vs 44.1%, P = 0.017), timed-up-go (mean difference of 4 s, P = 0.04) and long-term survival HR 0.59 (0.48-0.72, P < 0.001). Significance persisted after adjusting for confounding factors and in subgroup analyses. The combination of statin with antiplatelet was associated with the most superior survival, HR 0.51 (0.40-0.65, P < 0.001). Sensitivity analysis (exclusion of non-users of prosthesis) showed that statin-use remained a significant indicator of longer survival, maximally when combined with antiplatelet use HR 0.52 (0.39-0.68, P < 0.001). CONCLUSIONS: Statin-use is associated with better mobility and long-term survival in rehabilitees after limb loss, particularly when used in combination with antiplatelets. Significantly lower rates of statin-use were observed in female patients. Further research is warranted on gender disparities in statin-use and causality in their association with improved mobility and survival.

An International Comparison of the Management of Gastrointestinal Surgical Emergencies in Octogenarians-England Versus United States: A National Population-based Cohort Study.

OBJECTIVE: To compare the United States and England for the utilization of surgical intervention and in-hospital mortality from 5 gastrointestinal emergencies in octogenarians. BACKGROUND: The proportion of older adults is growing and will represent a substantial challenge to clinicians in the next decade. METHODS: Between 2006 and 2012, the rate of surgical intervention and in-hospital mortality for 5 index conditions for octogenarians were compared between the United States and England: appendicitis, incarcerated/strangulated abdominal hernia, perforation of esophagus, small or large bowel, and peptic ulcer. Univariate and multivariate analyses were performed to adjust for underlying differences in patient demographics. RESULTS: Thirty-two thousand one hundred fifty-one admissions of octogenarians in England for 5 index surgical emergencies were compared with 162,142 admissions in the USA.Surgical intervention was significantly more common in the USA than in England for all 5 conditions: appendicitis [odds ratio (OR) 4.63, 95% confidence interval (95% CI) 4.21-5.09], abdominal hernia (OR 2.06, 95% CI 1.97-2.15), perforated esophagus (OR 1.71, 95% CI 1.31-2.24), small and large bowel perforation (OR 4.33, 95% CI 4.12-4.56), and peptic ulcer perforation (OR 4.63, 95% CI 4.27-5.02). In-hospital mortality was significantly more common in England than in the USA for all 5 conditions: appendicitis (OR 3.22, 95% CI 2.73-3.78), abdominal hernia (OR 3.49, 95% CI 3.29-3.70), perforated esophagus (OR 4.06, 95% CI 3.03-5.44), small and large bowel perforation (OR 6.97, 95% CI 6.60-7.37), and peptic ulcer perforation (OR 3.67, 95% CI 3.40-3.96). CONCLUSION: Surgery is used less commonly in England for emergency gastrointestinal conditions in octogenarians, which may be associated with a high rate of in-hospital mortality from these conditions compared with the USA.

Migration and sac expansion as modes of midterm therapeutic failure after endovascular aneurysm sealing.

BACKGROUND: Endovascular aneurysm sealing (EVAS) is a disruptive technology to treat abdominal aortic aneurysm (AAA). The use of sac filling rather than endograft fixation was designed to treat aortic aneurysms in a wide range of morphologic appearances and to reduce endoleaks. There are few data reporting outcomes beyond postoperative follow-up. This study reports outcomes up to 5 years for Nellix (Endologix, Irvine, Calif) EVAS. METHODS: Data were prospectively collected for EVAS patients from the time of adoption of EVAS in 2013. All patients treated with the Nellix device are included in this study, and as such, it reports on infrarenal, ruptured, and iliac aneurysms as well as the Nellix-in-Nellix application. Juxtarenal and suprarenal aneurysms were treated using the EVAS system with parallel grafts into the visceral vessels and are included. Therapeutic failure, a composite outcome of migration, sac expansion >5 mm, type Ia and type Ib endoleak, and secondary aortic rupture, was the primary outcome along with all-cause mortality, aneurysm-related mortality, and reintervention rates. RESULTS: There were 295 EVAS cases undertaken between March 2013 and July 2018. Indications for treatment were infrarenal (n = 185), juxtarenal and suprarenal (n = 73), ruptured (n = 18), and iliac (n = 13) aneurysms. There were 15 reinterventions using the Nellix-in-Nellix application. In some cases, EVAS was used to salvage failing endovascular or open aneurysm repairs. Median follow-up was 2.42 years (interquartile range, 1.07-3.57 years). Therapeutic failure was observed in 98 of the 295 cases (33.2%) overall and exceeded 50% in some subgroups. In 71 cases (24.1%), reintervention was performed, with reasons for no reintervention being mainly physiologic. Complications leading to therapeutic failure were most commonly seen beyond 2 years of follow-up. There were 15 secondary ruptures (5.36%), and 9 EVAS devices required explantation either electively or for aortic rupture. CONCLUSIONS: EVAS with the Nellix device has not met expectations, and early encouraging results have been eroded. The incidence of therapeutic failure has been high, occurring 2 years and beyond after implantation. The Nellix system has been voluntarily recalled by Endologix, and the CE mark has subsequently been suspended. The adoption of EVAS as a disruptive technology highlights the need for cautious adoption of novel technologies and the strict governance around such arrangements.

Comparison of Surgical Intervention and Mortality for Seven Surgical Emergencies in England and the United States.

OBJECTIVE: To examine differences between England and the USA in the rate of surgical intervention and in-hospital mortality for 7 index surgical emergencies. BACKGROUND: Considerable international variation exists in the configuration, provision, and outcomes of emergency healthcare. METHODS: Patients aged <80 years hospitalized with 1 of 7 surgical emergencies (ruptured abdominal aortic aneurysm, aortic dissection, appendicitis, perforated esophagus, peptic ulcer, small bowel or large bowel, and incarcerated or strangulated hernias) were identified from English Hospital Episode Statistics and the USA Nationwide Inpatient Sample (2006-2012) and classified by whether they received a corrective surgical intervention. The rates of surgical intervention and population mortality were compared between England and the USA after adjustment for patient demographic factors. RESULTS: From 2006 to 2012, there were 136,047 admissions in English hospitals and 1,863,626 admissions in US hospitals due to the index surgical emergencies.Proportion of patients receiving no surgical intervention, for all 7 conditions was greater in the England (OR 4.25, 1.55, 8.53, 1.92, 2.06, 2.42, 1.75) and population in-hospital mortality was greater in England (OR 1.34, 1.67, 2.22, 1.65, 2.7, 4.46, 3.22) for ruptured abdominal aortic aneurysm, aortic dissection, appendicitis, perforated esophagus, peptic ulcer, small bowel or large bowel, and incarcerated or strangulated hernias respectively.In England (where follow-up was available), lack of utilization of surgery was also associated with increased in-hospital and long-term mortality for all conditions. CONCLUSION: England and US hospitals differ in the threshold for surgical intervention, which may be associated with increases in mortality in England for these 7 general surgical emergencies.

Thresholds for Abdominal Aortic Aneurysm Repair in England and the United States.

BACKGROUND: Thresholds for repair of abdominal aortic aneurysms vary considerably among countries. METHODS: We examined differences between England and the United States in the frequency of aneurysm repair, the mean aneurysm diameter at the time of the procedure, and rates of aneurysm rupture and aneurysm-related death. Data on the frequency of repair of intact (nonruptured) abdominal aortic aneurysms, in-hospital mortality among patients who had undergone aneurysm repair, and rates of aneurysm rupture during the period from 2005 through 2012 were extracted from the Hospital Episode Statistics database in England and the U.S. Nationwide Inpatient Sample. Data on the aneurysm diameter at the time of repair were extracted from the U.K. National Vascular Registry (2014 data) and from the U.S. National Surgical Quality Improvement Program (2013 data). Aneurysm-related mortality during the period from 2005 through 2012 was determined from data obtained from the Centers for Disease Control and Prevention and the U.K. Office of National Statistics. Data were adjusted with the use of direct standardization or conditional logistic regression for differences between England and the United States with respect to population age and sex. RESULTS: During the period from 2005 through 2012, a total of 29,300 patients in England and 278,921 patients in the United States underwent repair of intact abdominal aortic aneurysms. Aneurysm repair was less common in England than in the United States (odds ratio, 0.49; 95% confidence interval [CI], 0.48 to 0.49; P<0.001), and aneurysm-related death was more common in England than in the United States (odds ratio, 3.60; 95% CI, 3.55 to 3.64; P<0.001). Hospitalization due to an aneurysm rupture occurred more frequently in England than in the United States (odds ratio, 2.23; 95% CI, 2.19 to 2.27; P<0.001), and the mean aneurysm diameter at the time of repair was larger in England (63.7 mm vs. 58.3 mm, P<0.001). CONCLUSIONS: We found a lower rate of repair of abdominal aortic aneurysms and a larger mean aneurysm diameter at the time of repair in England than in the United States and lower rates of aneurysm rupture and aneurysm-related death in the United States than in England. (Funded by the Circulation Foundation and others.).

Midterm results of endovascular aneurysm sealing to treat abdominal aortic aneurysm.

BACKGROUND: Endovascular aneurysm sealing (EVAS) represents a novel approach to the treatment of abdominal aortic aneurysms. It uses polymer technology to achieve an anatomic seal within the sac of the aneurysm. This cohort study reports the early clinical outcomes, technical refinements, and learning curve during the initial EVAS experience at a single institution. METHODS: Results from 150 consecutive EVAS cases for intact, infrarenal abdominal aortic aneurysms are reported here. These cases were undertaken between March 2013 and July 2015. Preoperative, perioperative, and postoperative data were collected for each patient prospectively. RESULTS: The median age of the cohort was 76.6 years (interquartile range, 70.2-80.9 years), and 87.3% were male. Median aneurysm diameter was 62.0 mm (IQR, 58.0-69.0 mm). Adverse neck morphology was seen in 69 (46.0%) patients, including aneurysm neck length <10 mm (17.3%), neck diameter >32 mm or <18 mm (8.7%), and neck angulation >60 degrees (15.3%). Median follow-up was 687 days (IQR, 463-897 days); 37 patients (24.7%) underwent reintervention. The rates of unresolved endoleak are 1.3% type IA, 0.7% type IB, and 2.7% type I. There were no type III endoleaks. There have been seven secondary ruptures in this cohort; all but one of these patients survived after reintervention. Only one rupture occurred in an aneurysm that had been treated within the manufacturer's instructions for use (IFU). CONCLUSIONS: The rate of unresolved endoleaks is satisfactorily low. The incidence of secondary rupture is of concern; however, when the IFU are adhered to, the rate is very low. The results of this study suggest that working within the IFU yields better clinical results.

Multicentre Post-EVAR Surveillance Evaluation Study (EVAR-SCREEN).

OBJECTIVE: Surveillance imaging is considered mandatory after endovascular aneurysm repair (EVAR), but many patients are lost to follow up and the impact of this is poorly understood. This study aimed to examine compliance with post-operative surveillance in the UK and the impact of mal-/non-compliance on endograft re-interventions and survival. METHODS: EVAR-SCREEN centres reported EVAR for intact infrarenal abdominal aortic aneurysms (AAA) from 1 January 2007 to 31 December 2010, with follow up included up to 31 July 2014. Non-compliance was defined by the presence of a single 18 month period in which no surveillance imaging was performed. The outcomes were reported in compliant and non-compliant groups with survival analysis. RESULTS: EVAR was performed in 1414 patients in 10 UK centres. At the end of the study period there were 378 patients with five years of follow up available for analysis. Compliance with surveillance was 66% (61-68%). Compliance varied widely, from 9% to 88% between centres. Age (hazard ratio [HR] 1.03, 95% confidence interval [CI] 1.01-1.05; p = .02) and distance from hospital (HR 1.01, 95% CI 1.00-1.01; p < .001) were independent predictors of non-compliance. Non-compliant patients had lower all cause mortality in the first three years after EVAR, whereas compliant patients had lower all cause mortality 4-5 years after EVAR (p < .001). No significant difference in re-intervention rates was found between compliant and non-compliant patients. CONCLUSION: A substantial proportion of patients were non-compliant with surveillance after EVAR in the UK with considerable variation between centres. The survival benefit for EVAR after three years appeared to be related to compliance with surveillance which has implications for the future delivery of EVAR.

Short Stay EVAR is Safe and Cost Effective.

OBJECTIVE: Reducing length of stay (LOS) following surgery offers the potential to improve resource utilisation. Endovascular aneurysm repair (EVAR) is now delivered with a low level of morbidity and as such may be deliverable as a "23 hour stay" intervention. This systematic review aims to assess safety, feasibility and cost effectiveness of a short stay EVAR pathway. METHODS: A database search of Ovid MEDLINE (1996 - April 2018) and Embase (1974 - April 2018) was completed. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. A Newcastle-Ottawa Scale was applied to assess study bias. RESULTS: In total, 570 papers were identified through the literature search, of which 32 abstracts were screened. This led to nine papers being assessed for eligibility. From five suitable studies, 450 (75%) patients were successfully discharged the same or next day after EVAR. Complications most often occurred within 3 hours of surgery, and major complications requiring intensive treatment unit admission occurred within 6 hours. Readmission rates were 0-5% for those discharged early, with no difference in 30 day readmission. Early discharge led to a statistically significant cost saving of £13,360 (LOS four days) to £9844 (LOS one day). CONCLUSION: Selected patients can safely undergo EVAR using a short stay pathway. A period of monitoring 6 h post-operatively for low risk patients would be sufficient. Reducing length of stay after EVAR in the UK from the current median of three days to 1.5 days would free 4361 bed days and lead to a saving of approximately £1,800,000 annually.

Reversible FMN dissociation from Escherichia coli respiratory complex I.

Respiratory complex I transfers electrons from NADH to quinone, utilizing the reaction energy to translocate protons across the membrane. It is a key enzyme of the respiratory chain of many prokaryotic and most eukaryotic organisms. The reversible NADH oxidation reaction is facilitated in complex I by non-covalently bound flavin mononucleotide (FMN). Here we report that the catalytic activity of E. coli complex I with artificial electron acceptors potassium ferricyanide (FeCy) and hexaamineruthenium (HAR) is significantly inhibited in the enzyme pre-reduced by NADH. Further, we demonstrate that the inhibition is caused by reversible dissociation of FMN. The binding constant (Kd) for FMN increases from the femto- or picomolar range in oxidized complex I to the nanomolar range in the NADH reduced enzyme, with an FMN dissociation time constant of ~5s. The oxidation state of complex I, rather than that of FMN, proved critical to the dissociation. Such dissociation is not observed with the T. thermophilus enzyme and our analysis suggests that the difference may be due to the unusually high redox potential of Fe-S cluster N1a in E. coli. It is possible that the enzyme attenuates ROS production in vivo by releasing FMN under highly reducing conditions.

Early outcomes after left subclavian artery revascularisation in association with thoracic endovascular aortic repair.

Approximately 40-50% of patients undergoing thoracic endovascular aortic repair require left subclavian artery coverage for adequate proximal landing zone. Many of these patients undergo left subclavian artery revascularisation. However, outcomes data for left subclavian artery revascularisation in the context of thoracic endovascular aortic repair remain limited. In this study, 70 left subclavian artery revascularisation procedures, performed on thoracic endovascular aortic repair patients at a tertiary hospital, were retrospectively reviewed. Particular emphasis was placed on revascularisation-related outcomes during staging interval between revascularisation and thoracic endovascular aortic repair. Forty-six (66%) carotid-subclavian bypass, 17 (24%) carotid-carotid-subclavian bypass and 7 (10%) aorto-inominate-carotid-subclavian bypass procedures were performed. There were no strokes or mortalities following left subclavian artery revascularisation procedures alone. Three (10%) minor complications occurred including a seroma, a haematoma and a temporary neuropraxia. Separation of complications following left subclavian artery revascularisation from those of the associated thoracic endovascular aortic repair can be difficult. Early outcomes data from patients who underwent left subclavian artery revascularisation in isolation indicate that the procedure is safe with low complication rates.

Feature selection through validation and un-censoring of endovascular repair survival data for predicting the risk of re-intervention.

BACKGROUND: Feature selection (FS) process is essential in the medical area as it reduces the effort and time needed for physicians to measure unnecessary features. Choosing useful variables is a difficult task with the presence of censoring which is the unique characteristic in survival analysis. Most survival FS methods depend on Cox's proportional hazard model; however, machine learning techniques (MLT) are preferred but not commonly used due to censoring. Techniques that have been proposed to adopt MLT to perform FS with survival data cannot be used with the high level of censoring. The researcher's previous publications proposed a technique to deal with the high level of censoring. It also used existing FS techniques to reduce dataset dimension. However, in this paper a new FS technique was proposed and combined with feature transformation and the proposed uncensoring approaches to select a reduced set of features and produce a stable predictive model. METHODS: In this paper, a FS technique based on artificial neural network (ANN) MLT is proposed to deal with highly censored Endovascular Aortic Repair (EVAR). Survival data EVAR datasets were collected during 2004 to 2010 from two vascular centers in order to produce a final stable model. They contain almost 91% of censored patients. The proposed approach used a wrapper FS method with ANN to select a reduced subset of features that predict the risk of EVAR re-intervention after 5 years to patients from two different centers located in the United Kingdom, to allow it to be potentially applied to cross-centers predictions. The proposed model is compared with the two popular FS techniques; Akaike and Bayesian information criteria (AIC, BIC) that are used with Cox's model. RESULTS: The final model outperforms other methods in distinguishing the high and low risk groups; as they both have concordance index and estimated AUC better than the Cox's model based on AIC, BIC, Lasso, and SCAD approaches. These models have p-values lower than 0.05, meaning that patients with different risk groups can be separated significantly and those who would need re-intervention can be correctly predicted. CONCLUSION: The proposed approach will save time and effort made by physicians to collect unnecessary variables. The final reduced model was able to predict the long-term risk of aortic complications after EVAR. This predictive model can help clinicians decide patients' future observation plan.

Predicting Mid-term All-cause Mortality in Patients Undergoing Elective Endovascular Repair of a Descending Thoracic Aortic Aneurysm.

INTRODUCTION: All-cause mortality in patients after repair of aortic aneurysms of the descending thoracic aorta thoracic endovascular aortic repair (TEVAR) is relatively high at mid-term follow-up. The aim of this study was to derive and validate a system that could predict all-cause mortality after TEVAR to aid with patient selection. METHODS: The MOTHER database contained 625 patients that underwent elective surgery for descending thoracic aortic aneurysms. Univariate analysis identified preoperative factors associated with mid-term all-cause mortality, and a Cox proportional hazards model was developed. The model was internally validated using Kaplan-Meier comparison of observed vs predicted mortality. External validation was performed using a data set from the University of Florida College of Medicine. RESULTS: There were 625 patients that underwent TEVAR for descending thoracic aortic aneurysm in the MOTHER database and 231 in the University of Florida College of Medicine validation set. The mid-term mortality rate at 6 years of follow-up was 34.4% and 34%, respectively. The all-cause mortality risk score was calculated using 0.0398 × (age) + 0.516 × (renal insufficiency) + 0.46 × (previous cerebrovascular disease) + 0.352 × (prior tobacco use) + 0.376 × (number of devices >2) + 0.016 × (maximum aneurysm diameter). Using this score, low-, medium-, and high-risk groups were defined, with predicted survival at 5 years of 80%, 60%, and 40%. Patients at high risk of mid-term all-cause death were identified in the validation cohort using the prediction rule. CONCLUSIONS: Identifying patients with a limited life expectancy after TEVAR is possible using a preoperative risk-stratification system. This information can be used to inform decision making regarding when and whether to proceed with TEVAR.

Predicting reinterventions after open and endovascular aneurysm repair using the St George's Vascular Institute score.

BACKGROUND: Identifying patients at risk for aneurysm rupture and sac expansion after open and endovascular abdominal aortic aneurysm (AAA) repair (EVAR) may help to attenuate this risk by intensifying follow-up and early detection of problems. The goal of this study was to validate the St George's Vascular Institute (SGVI) score to identify patients at risk for a secondary intervention after elective aneurysm repair. METHODS: A post hoc on-treatment analysis of a randomized trial comparing open AAA repair and EVAR was performed. In this multicenter trial, 351 patients were randomly assigned to undergo open AAA repair or EVAR. Information on survival and reinterventions was available for all patients at 5 years postoperatively, for 79% at 6 years, and for 53% at 7 years. Open repair was completed in 173 patients and EVAR in 171, based on an on-treatment analysis. Because 17 patients had incomplete anatomic data, 327 patients (157 open repair and 170 EVAR) were available for analysis. During 6 years of follow-up, 78 patients underwent at least one reintervention. The SGVI score, which is calculated from preoperative AAA morphology using aneurysm and iliac diameter, predictively dichotomized patients into groups at high-risk or low-risk for a secondary intervention. The observed freedom from reintervention was compared between groups at predicted high-risk and predicted low-risk. RESULTS: The 20 patients in the high-risk group were indeed at higher risk for a secondary intervention compared with the 307 patients predicted to be at low risk (hazard ratio [HR], 3.82; 95% confidence interval [CI], 2.05-7.11; P < .001). Discrimination between high-risk and low-risk groups was valid for EVAR (HR, 4.06; 95% CI, 1.93-8.51; P < .001) and for open repair (HR, 3.41; 95% CI, 1.02-11.4; P = .033). CONCLUSIONS: The SGVI score appears to be a useful tool to predict reintervention risk in patients after open repair and EVAR.

The impact of endovascular aneurysm repair on mortality for elective abdominal aortic aneurysm repair in England and the United States.

BACKGROUND: Procedural mortality is of paramount importance for patients undergoing elective abdominal aortic aneurysm (AAA) repair. Previous comparative studies have demonstrated international differences in the care of ruptured AAA. This study compared the use of endovascular aneurysm repair (EVAR) and in-hospital mortality for elective AAA repair in England and the United States. METHODS: The English Hospital Episode Statistics and the U.S. Nationwide Inpatient Sample (NIS) were interrogated for elective AAA repair from 2005 to 2010. In-hospital mortality and the use of EVAR were analyzed separately for each health care system, after within-country risk adjustment for age, gender, year, and an accepted national comorbidity index. RESULTS: The study included 21,272 patients with AAA in England, of whom 86.61% were male, with median (interquartile range) age of 74 (69-79) years. There were 196,113 AAA patients in the United States, of whom 76.14% were male, with median (interquartile range) age of 73 (67-78) years. In-hospital mortality was greater in England (4.09% vs 1.96 %; P < .01) and EVAR less common (37.33% vs 64.36%; P < .01). These observations persisted in age- and gender-matched comparison. In both countries, lower mortality and greater use of EVAR were seen in centers performing greater numbers of AAA repairs per annum. In England, lower mortality and greater use of EVAR were seen in teaching hospitals with larger bed capacity. CONCLUSIONS: In-hospital survival and the uptake of EVAR are lower in England than in the United States. In both countries, mortality was lowest in high-caseload centers performing a greater proportion of cases with endovascular repair. These common factors suggest strategies for improving outcomes for patients requiring elective AAA repair.

A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair.

Deterioration in renal function has been described after endovascular repair of abdominal aortic aneurysms (EVRs). The etiology is multifactorial and represents an important therapeutic target. A need exists to quantitatively summarize incidence and severity of renal dysfunction after EVR to allow better-informed attempts to preserve renal function and improve life expectancy. Here a systematic search was performed using Medline and Embase for renal function after EVR applying PRISMA statements. Univariate and multivariate random-effects meta-analyses were performed to estimate pooled postoperative changes in serum creatinine and creatinine clearance at four time points after EVR. Clinically relevant deterioration in renal function was also estimated at 1 year or more after EVR. Pooled probability of clinically relevant deterioration in renal function at 1 year or more was 18% (95% confidence interval of 14-23%, I2 of 82.5%). Serum creatinine increased after EVR by 0.05 mg/dl at 30 days/1 month, 0.09 mg/dl at 1 month to 1 year, and 0.11 mg/dl at 1 year or more (all significant). Creatinine clearance decreased after EVR by 5.65 ml/min at 1 month-1 year and by 6.58 ml/min at 1 year or more (both significant). Thus, renal dysfunction after EVR is common and merits attention.

Mortality from ruptured abdominal aortic aneurysms: clinical lessons from a comparison of outcomes in England and the USA.

BACKGROUND: The outcome of patients with ruptured abdominal aortic aneurysm (rAAA) varies by country. Study of practice differences might allow the formulation of pathways to improve care. METHODS: We compared data from the Hospital Episode Statistics for England and the Nationwide Inpatient Sample for the USA for patients admitted to hospital with rAAA from 2005 to 2010. Primary outcomes were in-hospital mortality, mortality after intervention, and decision to follow non-corrective treatment. In-hospital mortality and the rate of non-corrective treatment were analysed by binary logistic regression for each health-care system, after adjustment for age, sex, year, and Charlson comorbidity index. FINDINGS: The study included 11,799 patients with rAAA in England and 23,838 patients with rAAA in the USA. In-hospital mortality was lower in the USA than in England (53·05% [95% CI 51·26-54·85] vs 65·90%; p<0·0001). Intervention (open or endovascular repair) was offered to a greater proportion of cases in the USA than in England (19,174 [80·43%] vs 6897 [58·45%]; p<0·0001) and endovascular repair was more common in the USA than in England (4003 [20·88%] vs 589 [8·54%]; p<0·0001). Postintervention mortality was similar in both countries (41·77% for England and 41·65% for USA). These observations persisted in age-matched and sex-matched comparisons. In both countries, reduced mortality was associated with increased use of endovascular repair, increased hospital caseload (volume) for rAAA, high hospital bed capacity, hospitals with teaching status, and admission on a weekday. INTERPRETATION: In-hospital survival from rAAA, intervention rates, and uptake of endovascular repair are lower in England than in the USA. In England and the USA, the lowest mortality for rAAA was seen in teaching hospitals with larger bed capacities and doing a greater proportion of cases with endovascular repair. These common factors suggest strategies for improving outcomes for patients with rAAA. FUNDING: None.

Evaluation of the Zenith low-profile abdominal aortic aneurysm stent graft.

BACKGROUND: Low-profile (LP) stent grafts are now commercially available in Europe for endovascular aortic aneurysm repair (EVAR). In this study the midterm outcomes and characteristics of patients treated with this last generation of stent grafts were compared with a cohort of patients treated with "standard-profile" (SP) stent grafts. METHODS: The current study enrolled all patients treated for elective EVAR by the SP Zenith Flex stent graft (Cook Medical, Bloomington, Ind) between March 2010 and November 2011 and patients treated for elective EVAR by the Zenith LP stent graft (Cook Medical) between November 2011 and March 2013. All patients had a follow-up >18 months. Preoperative computed tomography angiograms were analyzed on a dedicated three-dimensional workstation. All data were prospectively collected in an electronic database and retrospectively analyzed. A comparative study was conducted. RESULTS: The present study included 208 patients (107 SP and 101 LP). Patients' physiologic characteristics were similar in both groups. The iliac anatomy was considered "more challenging" in LP patients: respectively, 7% and 22% (P = .002) of SP and LP patients had bilateral external iliac diameter <7 mm; and 16% and 34% (P = .005) had a combination of an external iliac diameter <7 mm and an iliac tortuosity ratio index >1.5. No 30-day deaths were documented. The 24-month freedom from reintervention and overall survival rates after SP and LP were, respectively, 88% and 91% (P = .450) and 92% and 96% (P = .153). The 24-month rates for freedom from sac expansion and from limb occlusion were 96.4% and 98.7% (P = .320) and 92% and 95% (P = .293), respectively. One patient in each group presented with a type I endoleak during follow-up, and two LP patients presented with a type III endoleak (P = .235). CONCLUSIONS: This study demonstrates that the last-generation LP stent grafts have favorable midterm outcomes similar to SP stent grafts despite being used to treat more patients with unfavorable iliac anatomy.

Management of a type Ia endoleak with the Nellix endovascular aneurysm sealing system.

PURPOSE: To report the application of the Nellix endovascular aneurysm sealing (EVAS) device, including two chimney grafts, to successfully treat a type Ia endoleak. CASE REPORT: An 87-year-old man had an asymptomatic 7.6-cm infrarenal abdominal aortic aneurysm (AAA) and a 4.5-cm right internal iliac artery aneurysm treated using an aortouni-iliac stent-graft. Two years after the index endovascular repair, an asymptomatic type Ia endoleak was detected on duplex ultrasound; the computed tomographic angiogram (CTA) demonstrated significant sac enlargement and stent-graft migration. Initial attempts to treat the leak with 2 aortic cuffs only reduced the size of the endoleak. Another procedure was undertaken using the Nellix device with chimney grafts to increase the proximal sealing zone above the existing stent-graft. Imaging postoperatively demonstrated successful resolution of the endoleak and continuing patency of both renal artery chimney stent-grafts. CTA at 6 months demonstrated persistent sealing of the endoleak. CONCLUSION: The use of the EVAS system may represent another endovascular solution that can be added to the clinician's repertoire for treating type Ia endoleak after conventional endovascular repair of infrarenal AAA.

Appearance of the Nellix endovascular aneurysm sealing system on computed tomography: implications for postoperative imaging surveillance.

PURPOSE: To describe the imaging characteristics of the Nellix Endovascular Aneurysm Sealing (EVAS) System on serial computed tomography (CT) surveillance. METHODS: Sixty-eight patients undergoing EVAS were enrolled in a surveillance protocol that included CT scans prior to hospital discharge and at 3, 6, and 9 months postoperatively. Images were analyzed for the presence of gas within the endobag, endoleak, and for maximum radiodensity measured in Hounsfield units (HU) within the uppermost, middle, and lowermost regions of each endobag. RESULTS: Gas was seen within the endobags of all 68 EVAS repairs at the first postoperative CT compared with 2 (5.6%) of 36 undergoing the 3-month scan. The endobags appeared radiodense during initial imaging, and the median (interquartile range) radiodensity of the Nellix polymer decreased from 158.3 HU (149.5; 169.5) at the postoperative CT to 81.0 HU (74.0; 88.0) at 3 months, excluding 3 cases in which contrast pre-fill was utilized. Type I endoleak was seen at the periphery of the aneurysm sac or in the cleft between the endobags, with a substantially different appearance to endoleak after endovascular aneurysm repair. CONCLUSION: The evolution of CT appearances after EVAS was characteristic and predictable. The device endobags were initially radiodense, which may impact the detection of endoleak within 3 months of EVAS. Endoleaks after EVAS were seen in a different anatomical area to endoleaks after conventional stent-graft repair.