The Impact of the COVID-19 Pandemic on a Dedicated Vascular Emergency Clinic.

BACKGROUND: Vascular Emergency Clinics (VEC) improve patient outcomes in chronic limb-threatening ischemia (CLTI). They provide a "1 stop" open access policy, whereby "suspicion of CLTI" by a healthcare professional or patient leads to a direct review. We assessed the resilience of the outpatient VEC model to the first year of the coronavirus disease (COVID-19) pandemic. METHODS: A retrospective review of a prospectively maintained database of all patients assessed in our VEC for lower limb pathologies between March 2020 and April 2021 was performed. This was cross-referenced to national and loco-regional Governmental COVID-19 data. Individuals with CLTI were further analysed to determine Peripheral Arterial Disease-Quality Improvement Framework compliance. RESULTS: Seven hundred and ninety one patients attended for 1,084 assessments (Male n = 484, 61%; Age 72.5 ± standard deviation 12.2 years; White British n = 645, 81.7%). In total, 322 patients were diagnosed with CLTI (40.7%). A total of 188 individuals (58.6%) underwent a first revascularization strategy (Endovascular n = 128, 39.8%; Hybrid n = 41, 12.7%; Open surgery n = 19, 5.9%; Conservative n = 134, 41.6%). Major lower limb amputation rate was 10.9% (n = 35) and mortality rate was 25.8% (n = 83) at 12 months of follow-up. Median referral to assessment time was 3 days (interquartile range: 1-5). For the nonadmitted patient with CLTI, the median assessment to intervention was 8 days (interquartile range: 6-15) and median referral to intervention time of 11 days (11-18). CONCLUSIONS: The VEC model has demonstrated strong resilience to the COVID-19 pandemic with rapid treatment timelines maintained for patients with CLTI.

Are major lower extremity amputations well recorded in primary care electronic health records?: Insights from primary care electronic health records in England.

AIMS: Major lower extremity amputations (MLEAs) are understood to be well recorded in secondary care in England in the Hospital Episode Statistics (HES) database. It is unclear how well MLEAs are recorded in primary care databases. BACKGROUND: This study compared MLEA event case ascertainment in Clinical Practice Research Datalink (CPRD) to that in HES. METHODS: MLEA events were ascertained in CPRD and in HES linkage between 1 January 2010 and 31 December 2019. The number of MLEA events and the number of patients with at least one MLEA in each database were recorded and compared. Individual events were matched between the databases using varying date-matching windows. Reasons for differences in case ascertainment were explored. FINDINGS: In total 23 262 patients had at least one MLEA record, 8716 (37.5%) had an MLEA record in HES only, 5393 (23.2%) in CPRD only and 9153 (39.4%) in both. Out of a total of 75 221 events, 13 071 (62.4%) were recorded in HES only and 44 151 (81.3%) in CPRD only. 7874 (37.6%) of HES events were recorded in CPRD and 10 125 (18.6%) of CPRD events were recorded in HES when using the maximum date matching window of 28 days plus the time between admission and procedure. The main reasons for differences in case ascertainment included, re-recordings and miscoding in CPRD.Compared to HES, MLEAs are poorly recorded in CPRD predominantly due to re-recordings of events and miscoding procedures. CPRD data cannot solely be relied upon to ascertain cases of MLEA; however, HES linkage to CPRD may be useful to obtain medical history of diagnoses, medication and diagnostic tests.

Understanding variations in reported epidemiology of major lower extremity amputation in the UK: a systematic review.

OBJECTIVE: Estimate the prevalence/incidence/number of major lower extremity amputations (MLEAs) in the UK; identify sources of routinely collected electronic health data used; assess time trends and regional variation; and identify reasons for variation in reported incidence/prevalence of MLEA. DESIGN: Systematic review and narrative synthesis. DATA SOURCES: Medline, Embase, EMcare, CINAHL, The Cochrane Library, AMED, Scopus and grey literature sources searched from 1 January 2009 to 1 August 2021. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Reports that provided population-based statistics, used routinely collected electronic health data, gave a measure of MLEA in adults in the general population or those with diabetes in the UK or constituent countries were included. DATA EXTRACTION AND SYNTHESIS: Data extraction and quality assessment using the Joanna Briggs Institute Critical Appraisal Instruments were performed by two reviewers independently. Due to considerable differences in study populations and methodology, data pooling was not possible; data were tabulated and narratively synthesised, and study differences were discussed. RESULTS: Twenty-seven reports were included. Incidence proportion for the general population ranged from 8.2 to 51.1 per 100 000 and from 70 to 291 per 100 000 for the population with diabetes. Evidence for trends over time was mixed, but there was no evidence of increasing incidence. Reports consistently found regional variation in England with incidence higher in the north. No studies reported prevalence. Differences in database use, MLEA definition, calculation methods and multiple procedure inclusion which, together with identified inaccuracies, may account for the variation in incidence. CONCLUSIONS: UK incidence and trends in MLEA remain unclear; estimates vary widely due to differences in methodology and inaccuracies. Reasons for regional variation also remain unexplained and prevalence uninvestigated. International consensus on the definition of MLEA and medical code list is needed. Future research should recommend standards for the reporting of such outcomes and investigate further the potential to use primary care data in MLEA epidemiology. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42020165592.

Effects of Left Renal Vein Ligation During Open Abdominal Aortic Aneurysm Repair on Renal Function.

OBJECTIVE: Left renal vein (LRV) ligation is performed during open abdominal aortic aneurysm (AAA) repair to facilitate proximal anastomosis. Its impact on short, medium, and long term renal function has not been investigated in detail using appropriately validated endpoints. METHODS: This was a nested case control study using data from a prospectively maintained AAA institutional dataset (tertiary centre). A total of 76 patients who underwent elective open AAA repair and had LRV ligation (1 January 2012 to 1 January 2018) were individually case matched based on age (within two years), sex, estimated glomerular filtration rate (eGFR), American Society of Anesthesiologist (ASA) score, chronic kidney disease (CKD) stage, and history of diabetes with 76 patients who had open AAA repair without LRV ligation. Renal outcomes were compared between groups, including proportion of patients developing acute kidney injury (AKI) using the Kidney Disease Improving Global Outcomes (KDIGO) criteria, proportion developing major adverse kidney events (MAKE90) at 90 days (comprising mortality and/or decrease in eGFR >25%), and absolute decrease in eGFR at latest follow up. RESULTS: A higher proportion of patients developed AKI and MAKE90 in the LRV ligation group (AKI: 11 patients [14.8%] vs. 2 [2.6%], p = .009; MAKE90: 6 [7.9%] vs. 1 [1.3%] p = .053, in the LRV ligation and the non-LRV ligation groups, respectively) - even though the difference in the MAKE90 endpoint was not statistically significant. Changes in eGFR were not statistically different in the LRV ligation group at 90 days (4.0 ± 1.1 mL/min/1.73 m2vs. 4.4 ± 2.1, p = .64) or by the time of latest follow up (median: 28 months; 3.7 ± 1.6 vs. 2.6 ± 2.0, p = .55). CONCLUSION: Ligation of the LRV is associated with increased levels of AKI and renal deterioration in the early post-operative phase using validated reporting criteria; however, long term renal function does not seem to be affected.

Epidemiology of major lower limb amputation using routinely collected electronic health data in the UK: a systematic review protocol.

INTRODUCTION: It is estimated that peripheral arterial disease occurs in one in five people aged over 60 years in the UK. Major lower limb amputation is a debilitating and life-changing potential outcome of peripheral arterial disease. A number of risk factors are involved in the development of the disease including smoking and diabetes. There is debate over the prevalence of major lower limb amputation in the UK with regional variations unexplained. The choice of data source can affect the epidemiological calculations and sources can also differ in the ability to explain variation. This study will aim to estimate the prevalence/incidence/number of major lower limb amputation in the UK. It will also identify sources of routinely collected electronic health data which report the epidemiology of major lower limb amputation in the UK. METHODS AND ANALYSIS: A systematic search of peer-reviewed journals will be conducted in Medline, Excerpta Medica database, Cumulative Index of Nursing and Allied Health Literature, Allied and Complementary Medicine Database, The Cochrane Library and Scopus. A grey literature search for government and parliament publications, conference abstracts, theses and unpublished articles will be performed. Articles will be screened against the inclusion/exclusion criteria and data extracted using a pretested extraction form by two independent reviewers. Prevalence, incidence or number of cases (depending on data reported) will be extracted. Disagreements will be resolved by discussion. Data synthesis will be performed either as a narrative summary or by meta-analysis. Heterogeneity will be assessed using the I2 statistic. If heterogeneity is low-moderate, pooled estimates will be calculated using random-effects models. If possible, meta-regression for time trends in the incidence of major lower limb amputation will be performed along with subgroup analysis, primarily in regional variation. ETHICS AND DISSEMINATION: Ethics approval is not required for this study as study data are anonymised and available in the public domain. Dissemination will be by publication in a peer reviewed journal and by appropriate conference presentation.PROSPERO registration numberCRD42020165592.

Editor's Choice - The Impact of Endovascular Aneurysm Repair on Long Term Renal Function Based on Hard Renal Outcomes.

INTRODUCTION: Over the short term endovascular aneurysm repair (EVAR) is associated with superior outcomes compared with open repair; however, the progression of renal function after EVAR remains unknown because of the use of inconsistent reporting measures. The aim was to define long term renal decline following elective EVAR using estimated glomerular filtration rate (eGFR). METHODS: The prospectively maintained in house database was used to identify consecutive patients having elective EVAR who had been followed up for more than five years. Overall, 275 patients (23 females, 8%; mean age, 75 years) who were not previously on renal replacement therapy (RRT) were included (January 2000 to July 2010). Pre-operative, post-operative, and most recent eGFR values were evaluated using the chronic kidney disease epidemiology collaboration equation. The primary outcome was change in eGFR at latest follow up. RESULTS: Patients were followed up over a median of 9 years (range 5-17 years). Their mean eGFR dropped from a pre-operative value of 67 mL/min/1.73 m2 (standard deviation [SD]: 9.4) to 52 mL/min/1.73 m2 (SD 7.7), which amounts to a yearly loss of 1.7 units; six patients (2%) required RRT (dialysis) during late follow up. Patients requiring RRT and those with an eGFR loss exceeding 20% at latest follow up compared with baseline were more likely to die during late follow up (odds ratio 2.4 and 3.3 respectively, p < .001). CONCLUSION: This analysis, with some of the longest available follow up to date, suggests that patients undergoing EVAR may experience a significant long term decrease in renal function. This needs to be taken into account when offering EVAR in younger patients; renal follow up and preservation should be optimised in this patient group.

Post-carotid Endarterectomy Hypertension. Part 2: Association with Peri-operative Clinical, Anaesthetic, and Transcranial Doppler Derived Parameters.

OBJECTIVE/BACKGROUND: The first paper in this series observed that pre-operative baroreceptor dysfunction and poorly controlled hypertension were independently predictive for identifying patients who went on to require treatment for post-endarterectomy hypertension (PEH). The second paper examines the influence of intra-operative patient, transcranial Doppler (TCD) ultrasound, and anaesthetic variables on the incidence of PEH. METHODS: In total, 106 patients underwent carotid endarterectomy (CEA) under general anaesthesia. Systolic blood pressure (SBP) changes, anaesthetic and vasoactive agents, analgesia, and post-operative pain scores, as well as TCD derived changes in middle cerebral artery (MCA) velocity during surgery were recorded. Patients who met pre-existing unit criteria for treating PEH after CEA (SBP > 170 mmHg without symptoms or SBP > 160 mmHg with headache/seizure/neurological deficit) were treated according to an established and validated protocol. RESULTS: In total, 40/106 patients (38%) required treatment for PEH following CEA (26 in theatre recovery [25%], 27 back on the vascular surgery ward [25%]), whereas seven (7%) had SBP surges > 200 mmHg on the ward. Patients requiring treatment for PEH had significantly higher pre-induction SBP (174 ± 21 mmHg vs. 153 ± 21 mmHg; p < .001), the greatest decreases in SBP after induction of anaesthesia (median decrease 100 ± 32 mmHg vs. 83 ± 24 mmHg; p = .01) and were significantly more likely to experience moderate/severe pain scores post-operatively (p = .003). Logistic regression analysis of the pre- and intra-operative data revealed that higher pre-induction mean SBP and lower pre-operative (impaired) BRS were the only independent predictors of PEH. CONCLUSION: This analysis of intra-operative variables has demonstrated that patients with poorly controlled and/or labile hypertension at induction of general anaesthesia were those at greatest risk of requiring treatment for PEH in the post-operative period after CEA. No other variables, including use of vasopressors, treatment of hypotension, anaesthetic agents, or changes in MCA velocity after clamp release and restoration of flow were able to predict who might go on to require treatment for PEH. Identification of at-risk individuals and aggressive blood pressure control in the post-operative period remains the mainstay of treatment.

Sex-related trends in mortality after elective abdominal aortic aneurysm surgery between 2002 and 2013 at National Health Service hospitals in England: less benefit for women compared with men.

AIMS: To quantify the difference in long-term survival and cardiovascular morbidity between women and men undergoing elective abdominal aortic aneurysm (AAA) repair at National Health Service hospitals in England. METHODS AND RESULTS: Patients having elective repair of AAA were reviewed using the Hospital Episode Statistics and Office for National Statistics (ONS) datasets. The primary outcome measure was 30-day mortality and the secondary outcomes were 1-year, 5-year, and aortic-related mortality and post-operative complication rates. We used logistic regression and survival models to assess risk factors on the primary and secondary outcomes. Between 1 April 2002 and 31 March 2013, a total of 31 090 patients (4795 women and 26 295 men) underwent open AAA repair. Between 1 January 2006 and 31 March 2013, a total of 16 777 patients (2036 women and 14 741 men) underwent endovascular aneurysm repair (EVAR). All-cause and aortic-related mortalities at 30 days, 1 year, and 5 years were all higher in women, despite a lower prevalence of pre-operative cardiovascular risk factors. Female sex was a significant independent risk factor for 30-day mortality in both open repair [odds ratio (OR) 1.39; 95% confidence interval (CI) 1.25-1.56; P < 0.001] and EVAR (OR 1.57; 95% CI 1.23-2.00; P < 0.001) groups. Based on an all-cause long-term survival model, conditional on 30-day survival, the estimated hazard for women in the open repair group was significantly (P = 0.006) higher than men, but the sex difference was not significant in the EVAR group (P = 0.356). In the open repair group, women had significantly (P < 0.001) higher cumulative incidence probabilities for both aortic-related mortality and other-cause mortality. In the EVAR group, women had significantly (P < 0.001) higher mean cumulative incidence probabilities for the aortic-related mortality compared with men, but not for the other-cause mortality (P = 0.235). CONCLUSION: Women undergoing elective AAA repair at National Health Service hospitals in England had increased short- and long-term mortality and post-operative morbidity compared with men. These findings can be used to improve pre-operative counselling for women undergoing AAA repair, and highlight the need for female-specific pre-, peri-, and post-operative management strategies.

Impact of hospital volume on outcomes following treatment of thoracic aortic aneurysms and type-B dissections.

Previous research suggests an association between hospital volume and outcomes in high-risk surgical pathologies. The association between hospital volume and outcomes in patients with isolated descending thoracic aortic aneurysms (DTAAs) and type-B thoracic aortic dissections (TBADs) is conflicting. We aimed to investigate this in a literature review and meta-analysis. A systematic review of the literature was performed to identify studies reporting mortality and morbidity following repair (elective or emergency) of DTAA and/or TBAD using the Medline and Embase Databases (2000-2015). Hospital volume was assessed based on the number of patients treated per institution: low volume (1-5 cases per year), medium volume (6-10) and high volume (>10). The primary outcome of interest was all-cause mortality during inpatient stay and at 30 days. Eighty-four series of non-dissecting DTAA or TBAD were included in data synthesis (4219 patients; mean age: 62 years; males: 73.5%). For all patients (emergency and elective) undergoing DTAA repair, in-hospital mortality was 8% [95% confidence interval (CI): 6-8%]. Results were not superior in high-volume centres (8 vs 6 vs 11% for high-, medium- and low-volume, respectively). Sub-analyses for emergency and elective repairs showed no significant differences. For TBAD repairs, in the combined population (emergency and elective), results reached borderline significance (P = 0.0475), favouring high-volume centres (6 vs 11 vs 14%), but this association disappeared when emergency and elective repairs were analysed separately. Nine series reported outcomes at 1 year and 5 series followed DTAA and 18 TBAD treatment. No meaningful long-term comparisons were possible due to the lack of data. No significant associations were detected between hospital volume and subsequent mortality following DTAA or TBAD treatment. Data were heterogeneous and long-term results were scarcely reported. A well-designed longitudinal study of sufficient size is required to inform future strategies in this area.

Type II endoleaks: challenges and solutions.

Type II endoleaks are the most common endovascular complications of endovascular abdominal aortic aneurysm repair (EVAR); however, there has been a divided opinion regarding their significance in EVAR. Some advocate a conservative approach unless there is clear evidence of sac expansion, while others maintain early intervention is best to prevent adverse late outcomes such as rupture. There is a lack of level-one evidence in this challenging group of patients, and due to a low event rate of complications, large numbers of patients would be required in well-designed trials to fully understand the natural history of type II endoleak. This review will discuss the imaging, management, and outcome of patients with isolated type II endoleaks following infra-renal EVAR.

Renal Function is the Main Predictor of Acute Kidney Injury after Endovascular Abdominal Aortic Aneurysm Repair.

BACKGROUND: Postoperative acute kidney injury (AKI) may occur in up to 18% of elective endovascular abdominal aortic aneurysm repair (EVAR) and has been associated with poor outcome; however, it is not clear which patients are at highest risk, to target renoprotection effectively. We sought to determine the predictive factors of AKI after elective EVAR. METHODS: Overall, 947 patients undergoing elective EVAR between January 2004 and December 2014 were analyzed, using prospectively collected data. Postoperative AKI was defined by serum creatinine change within 48 hr, as per the Kidney Disease Improving Global Outcomes guidelines. Cardiovascular and kidney-disease risk factors were entered in univariate and multivariate analyses to assess influence on AKI development. RESULTS: Overall, 167 (17.6%) patients developed AKI but only 2 patients required dialysis perioperatively. At multivariate analysis, adjusted for established AKI-risk factors and parameters that differed between groups at baseline, preoperative estimated glomerular filtration rate (eGFR; as per the chronic kidney disease epidemiology [CKD] formula); odds ratio (OR): 1.02 (per unit decrease); 95% confidence interval (CI): 1.003-1.041; P = 0.025; and chronic kidney disease (CKD) stage > 2 (OR: 1.28; 95% CI: 1.249-2.531, P = 0.001) were associated with development of AKI. CONCLUSIONS: AKI was common after elective infrarenal EVAR and preoperative renal function appears to be the main factor associated with AKI. Patients with a low eGFR need to be targeted with more aggressive renal protection.

Intervention Associated Acute Kidney Injury and Long-Term Cardiovascular Outcomes.

BACKGROUND: Acute kidney injury (AKI) has been associated with all-cause short- and long-term mortality. However, its association with cardiovascular (CV) events remains unclear. We sought to investigate this in patients undergoing open (OAR) or endovascular (EVAR) abdominal aortic aneurysm repair, as they are likely to develop both AKI and CV morbidity. A meta-analysis was subsequently performed to confirm this in other CV-interventions. METHODS: AKI-incidence was assessed in a multicentre-cohort of 1,068 patients undergoing EVAR (947 individuals) or OAR electively using the 'Acute Kidney Injury Network' criteria. A composite-endpoint was used, consisting of non-fatal myocardial infarction (MI), stroke, vascular event, hospitalisation due to heart failure and CV death. A systematic literature review identified studies reporting AKI-incidence and CV events. Risk ratios (RRs) at 1 and 5 years were combined using meta-analysis. RESULTS: During a median follow-up of 62 months (range 11-121), AKI was associated with CV events on adjusted (for CV risk-factors) analyses (Incidence 36% of EVAR, 32% of OAR patients; hazard ratio 1.73, 95% CI 1.06-3.39, p=0.03) for the overall population. In the meta-analysis, 7 studies reported incidence of MI on 23,936 patients 1-year after coronary intervention (PCI) with a pooled RR of 1.76 (95% CI 1.45-2.83, p<0.001); at 2 years, 3 studies reported MI incidence on 17,773 patients after PCI with a pooled RR of 1.34 (95% CI 1.10-1.63, p=0.003). MI-incidence was reported 5 years after cardiac surgery by 3 studies (33,701 patients) with a pooled RR of 1.60 (95% CI 1.43-1.81). CONCLUSION: AKI is associated with long-term CV events after surgery or endovascular intervention.

Long-Term Renal Function after Endovascular Aneurysm Repair.

BACKGROUND AND OBJECTIVES: Endovascular repair (EVAR) is a common treatment for abdominal aortic aneurysm (AAA). However, its long-term effects on renal function remain unclear. We aimed to assess long-term renal dysfunction after EVAR using a contemporary estimate of GFR and to compare long-term renal outcomes in patients after EVAR with open aneurysm repair (OAR) and in patients without an AAA. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: We performed a nested case-matched analysis of 726 patients (using a prospectively maintained database for repairs that took place between January 2000 and May 2010 in a tertiary center): 121 patients undergoing OAR (with data at baseline and 5 years postrepair) were case matched (age, sex, smoking, diabetes, baseline eGFR) to patients undergoing suprarenal and infrarenal fixation EVAR (242 in each group) and to 121 patients undergoing carotid endarterectomy (CEA) without AAA. Changes in eGFR were compared (1 and 5 years). RESULTS: The OAR patients lost an average of 7.4 ml/min per 1.73 m2 at 5 years (95% confidence interval [95% CI], 4.8 to 10.6), compared with 8.2 ml/min per 1.73 m2 (95% CI, 6.5 to 10.8; P<0.001) for infrarenal-fixation EVAR, 16.9 ml/min per 1.73 m2 (95% CI, 13.0 to 21.9, P<0.001) for suprarenal-fixation EVAR, and 5.4 ml/min per 1.73 m2 (95% CI, 1.7 to 7.5; P<0.001) for CEA. The decrease in eGFR was steeper during the first postoperative year, with each group losing -2.2 ml/min per 1.73 m2 (infrarenal-fixation EVAR), -10.7 ml/min per 1.73 m2 (suprarenal-fixation EVAR), and -4.6 ml/min per 1.73 m2 (OAR), compared with -1.9 ml/min per 1.73 m2 for CEA. CONCLUSIONS: Elective EVAR is associated with a significant decline in eGFR after 5 years, which is steeper in the first postoperative year and more pronounced compared with a similar population with atherosclerotic disease.

Impact of Fenestrated Endovascular Abdominal Aortic Aneurysm Repair on Renal Function.

PURPOSE: To investigate the impact of fenestrated endovascular aneurysm repair (fEVAR) on renal function perioperatively and at midterm. METHODS: A case-controlled study was performed involving 58 patients (mean age 75±7 years; 51 men) who underwent elective fEVAR for a juxtarenal or short-necked abdominal aortic aneurysm (AAA) matched on age, sex, smoking, diabetes, and baseline estimated glomerular filtration rate (eGFR) with a contemporaneous group undergoing open aneurysm repair (OAR) for the same indications. Perioperative incidence of acute kidney injury (AKI) and levels of eGFR at 30 days and 1 year were compared. A systematic literature review was performed to identify studies that had used eGFR as renal outcome after fEVAR; the pooled data were meta-analyzed using an eGFR drop >30% at 1 month and the latest follow-up as endpoints. Results are reported as the pooled proportion and 95% confidence interval (CI). RESULTS: The incidence of AKI after fEVAR was 28% compared to 10% after OAR (p=0.03). Following fEVAR, the mean eGFR dropped from 78±8 to 74±9 mL/min/1.73 m(2) at 30 days compared to a change from 79±8 to 80±16 mL/min/1.73 m(2) after OAR (p<0.01). However, the absolute drop in eGFR between fEVAR and OAR at 1 year was similar (7 mL/min/1.73 m(2); p=0.53); 7% of the fEVAR patients had an eGFR drop >30% at that point compared with none for OAR (p=0.12). The systematic literature review identified eGFR outcomes for 193 fEVAR patients. Combining these patients with the 58 from our cohort study, the pooled proportions of eGFR drop >30% were 20% (95% CI 9% to 39%) at 30 days and 8% (95% CI 0.5% to 13%) at the end of follow-up. CONCLUSION: fEVAR has a significant perioperative impact on renal function, but 1-year results are similar to OAR. fEVAR patients may benefit from targeted AKI prevention strategies that need to be assessed in relevant studies.

An Artificial Neural Network Stratifies the Risks of Reintervention and Mortality after Endovascular Aneurysm Repair; a Retrospective Observational study.

BACKGROUND: Lifelong surveillance after endovascular repair (EVAR) of abdominal aortic aneurysms (AAA) is considered mandatory to detect potentially life-threatening endograft complications. A minority of patients require reintervention but cannot be predictively identified by existing methods. This study aimed to improve the prediction of endograft complications and mortality, through the application of machine-learning techniques. METHODS: Patients undergoing EVAR at 2 centres were studied from 2004-2010. Pre-operative aneurysm morphology was quantified and endograft complications were recorded up to 5 years following surgery. An artificial neural networks (ANN) approach was used to predict whether patients would be at low- or high-risk of endograft complications (aortic/limb) or mortality. Centre 1 data were used for training and centre 2 data for validation. ANN performance was assessed by Kaplan-Meier analysis to compare the incidence of aortic complications, limb complications, and mortality; in patients predicted to be low-risk, versus those predicted to be high-risk. RESULTS: 761 patients aged 75 +/- 7 years underwent EVAR. Mean follow-up was 36+/- 20 months. An ANN was created from morphological features including angulation/length/areas/diameters/volume/tortuosity of the aneurysm neck/sac/iliac segments. ANN models predicted endograft complications and mortality with excellent discrimination between a low-risk and high-risk group. In external validation, the 5-year rates of freedom from aortic complications, limb complications and mortality were 95.9% vs 67.9%; 99.3% vs 92.0%; and 87.9% vs 79.3% respectively (p<0.001). CONCLUSION: This study presents ANN models that stratify the 5-year risk of endograft complications or mortality using routinely available pre-operative data.

International trends in patient selection for elective endovascular aneurysm repair: sicker patients with safer anatomy leading to improved 1-year survival.

BACKGROUND: To review the trends in patient selection and early death rate for patients undergoing elective endovascular repair of infrarenal abdominal aortic aneurysms (EVAR) in 3 countries. For this study, audit data from 4,163 patients who had undergone elective infrarenal EVAR were amalgamated. The data originated from Australia, Canada (Ontario), and England (London, Cambridge, and Leicester). METHODS: Statistical analyses were undertaken to determine whether patient characteristics and early death rate varied between and within study groups and over time. The study design was retrospective analysis of data collected prospectively between 1999 and 2012. RESULTS: One-year survival improved over time (P = 0.0013). Canadian patients were sicker than those in Australia or England (P < 0.001). American Society of Anesthesiologists classification (ASA) increased over time across all countries although more significantly in Canada. Age at operation remained constant, although older patients were treated more recently in London (P < 0.001). English centers treated larger aneurysms compared with Australia and Canada (P < 0.001). Australian centers treated a much larger proportion of aneurysms that were <55 mm than other countries. Preoperative creatinine levels decreased over time for all countries and centers (P < 0.001). Infrarenal neck angles have significantly decreased over time (P < 0.001). Recent data from London (UK) showed that operations were performed on longer (P < 0.001) and wider (P < 0.001) infrarenal necks than elsewhere. CONCLUSIONS: In this international comparison, several trends were noted including improved 1-year survival despite declining patient health (as measured by increasing ASA status). This may reflect greater knowledge regarding EVAR that centers from different countries have gained over the last decade and improved medical management of patients with aneurysmal disease.

Hydrogen sulfide reduces inflammation following abdominal aortic occlusion in rats.

BACKGROUND: Remote renal ischemia-reperfusion injury (IRI) following infra-renal aortic occlusion leads to acute kidney injury and systemic inflammation. Hydrogen sulfide is a mediator of IRI and can ameliorate tissue injury in many organ systems. Its role in vascular surgery has yet to be established. We assessed the role of hydrogen sulfide in a rodent model of aortic occlusion. METHODS: Wistar rats were divided into sham, control, and treatment groups (n = 6). Inflammation was assessed using a nonrecovery protocol. The infra-renal aorta was cross-clamped for 60 min and animals were reperfused for 120 min. Ten minutes before clamp release, treatment animals received hydrogen sulfide (10, 30, or 50 µg/kg) and control animals received 0.9% saline injected into the retroperitoneum. Renal injury and histology were assessed by a recovery protocol. The procedure was identical to the nonrecovery arm but with a single dose of hydrogen sulfide (30 µg/kg) and animals were recovered for 7 days. RESULTS: There was no difference in animal weight between the groups (P = 0.337). In the nonrecovery arm, there was a reduction in serum levels of tumor necrosis factor alpha in sulfide-treated animals compared with controls (909 ± 98 vs. 607 ± 159 pg/mL; P = 0.0038). There was also a reduction in myeloperoxidase-positive cells in renal tissue in the sulfide-treated animals compared with controls (8 ± 4 vs. 17 ± 9; P = 0.03). There was no difference in histological injury score or endothelin-1 levels. In the recovery arm, there was no difference in renal function, Kidney Injury Molecule-1 levels, or histological injury scores. CONCLUSION: Hydrogen sulfide has systemic and renal anti-inflammatory effects in remote IRI following aortic occlusion in rats.

A systematic review and meta-analysis of the association between markers of hemostasis and abdominal aortic aneurysm presence and size.

OBJECTIVE: The purpose of this study was to summarize the current evidence of the association between markers of hemostasis and both the presence and size of abdominal aortic aneurysms (AAAs). METHODS: A systematic review and meta-analysis was performed according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines by use of the search terms "aneurysm AND abdominal AND aortic AND coagulation" NOT "thoracic." Outcome data including concentration of hemostatic marker, number of patients, and significance level were recorded. RESULTS: A total of 22 nonrandomized studies were included in the analysis, with a total of 9862 patients. Fibrinogen mean difference (MD) (0.43 g/L; 95% confidence interval [CI], 0.28-0.58 g/L; P ≤ .00001), D-dimer MD (325.82 ng/mL; 95% CI, 199.74-451.89 ng/mL; P ≤ .00001), and thrombin-antithrombin III complex MD (5.58 g/L; 95% CI, 3.34-7.83 g/L; P ≤ .0001) were significantly elevated in the presence of AAAs. Tissue plasminogen activator, prothrombin fragments F1+F2, and platelet count were not shown to be significantly different between patients with and those without AAAs. Meta-regression of studies reporting plasma D-dimer concentration and aneurysm diameter suggests a strong and significant association (r(2) = 0.94; P ≤ .0001). CONCLUSIONS: This study suggests that the presence of AAAs is associated with increased fibrin turnover, fibrinolysis, and thrombin generation, as shown by increased levels of fibrinogen, D-dimer, and thrombin-antithrombin III complex. This is clinically relevant because markers of hemostasis are independent risk factors for cardiovascular events, highlighting the necessity of addressing all modifiable cardiovascular risk factors in patients with AAAs. Furthermore, the finding that plasma D-dimer concentration appears to have a linear relationship with aneurysm diameter may be useful as a future biomarker of AAAs.

Effect of anticoagulation and antiplatelet therapy on incidence of endoleaks and sac size expansions after endovascular aneurysm repair.

BACKGROUND: The effects of anticoagulation or antiplatelet therapy on the incidence of endoleak and aneurysm sac size after endovascular aneurysm repair (EVAR) are unclear. This study aims to determine whether these therapies affect the incidence of endoleaks or sac size expansions after EVAR. METHODS: The case notes of 407 patients (367 men and 40 women, mean age 74.7 years) who underwent elective EVAR between January 2006 and November 2011 were reviewed for medication history and EVAR-related outcomes. RESULTS: The median follow-up period was 18 months. There were 45 (11.1%) patients on warfarin (WA), 292 (71.7%) on antiplatelet therapy (AT) (aspirin, clopidogrel, or dipyridamole modified release), and 70 (17.2%) on no anticoagulation or antiplatelet therapy (NA). During the study period, 51 (12.5%) endoleaks were documented, 8 type I (AT = 6, NA = 0, and WA = 2) and 42 type II (AT = 31, NA = 9, and WA = 2). Medication did not significantly affect the incidence of type I (P = 0.24) (based on chi-squared analysis), type II (P = 0.33), or type III (P = 0.82) endoleaks, or sac expansions (P = 0.95). CONCLUSIONS: Warfarin and antiplatelet therapies are not associated with increased incidence of postoperative endoleaks or aneurysm sac expansion after EVAR. The data in this study support safe use of anticoagulant and antiplatelet medications in patients undergoing EVAR.

C-reactive protein polymorphism rs3091244 is associated with abdominal aortic aneurysm.

BACKGROUND: Abdominal aortic aneurysm (AAA) formation involves an inflammatory process with a strong genetic background. C-reactive protein (CRP) regulates inflammation and is elevated in patients with AAA. The aim of this study was to investigate the association of the triallelic (C, A, and T alleles) rs3091244 functional CRP single nucleotide polymorphism (SNP) with AAA. METHODS: This was a case-control study involving two independent populations: 351 AAA patients (mean aortic diameter, 6.25 ± 1.47 cm) and 391 controls (mean diameter, 2.4 ± 0.2 cm) were recruited from Greece (the main cohort); and 371 patients (mean diameter, 5.4 ± 1.0 cm) and 362 controls (mean diameter, 2.4 ± 0.6 cm) were recruited from the United Kingdom (replication cohort). The frequency of the functional triallelic (C, T, and A alleles) rs3091244 polymorphism was analyzed in univariate and adjusted (for cardiovascular risk factors) analyses, assuming that the rare T and A alleles have similar functional properties (pooled analysis for T and A). Three groups were constructed: group A included those with the rare T and A alleles (genotypes TT, AA, and TA), group B included heterozygotes for the C allele (CT, CA), and group C included C allele homozygotes (CC, reference genotype). Finally, meta-analysis of the two populations was performed together with previously reported results. RESULTS: Genotype distributions differed significantly between cases and controls in both cohorts (P < .001 and P = .001). Adjusted analysis (for all aneurysm-related risk-factors) showed an estimated odds ratio of 4.88 (95% confidence interval [CI], 2.96-8.04) for SNP group A and 2.38 (95% CI, 1.69-3.36) for SNP group B (P < .001 in both cases) in the initial cohort and 2.07 (95% CI, 1.33-3.21) for SNP group A and 1.70 (95% CI, 1.21-2.39) for SNP group B (P = .001 and .002) in the replication cohort. The SNP group A patients among the main cohort also had higher CRP levels (median, 26; interquartile range, 17-52 mg/L vs median, 4; interquartile range, 4-12 mg/L; P < .001). Aneurysms >5.5 cm were significantly more frequent among the SNP groups A and B compared with C allele homozygotes both in the main and the replication cohorts (P < .001 and P = .001, respectively). Meta-analysis of the two populations with previously reported results showed a positive association between minor-allele and aneurysm presence with an odds ratio of 1.47 (95% CI, 1.01-2.14; I(2) = 83.1%; P = .04). CONCLUSIONS: The rare T and A alleles were significantly related with AAA presence in both populations and correlated with higher CRP levels and AAA diameter.