Abdominal aortic aneurysm and cardiometabolic traits share strong genetic susceptibility to lipid metabolism and inflammation

Abdominal aortic aneurysm has a high heritability and often co-occurs with other cardiometabolic disorders, suggesting shared genetic susceptibility. We investigate this commonality leveraging recent GWAS studies of abdominal aortic aneurysm and 32 cardiometabolic traits. We find significant genetic correlations between abdominal aortic aneurysm and 21 of the cardiometabolic traits investigated, including causal relationships with coronary artery disease, hypertension, lipid traits, and blood pressure. For each trait pair, we identify shared causal variants, genes, and pathways, revealing that cholesterol metabolism and inflammation are shared most prominently. Additionally, we show the tissue and cell type specificity in the shared signals, with strong enrichment across traits in the liver, arteries, adipose tissues, macrophages, adipocytes, and fibroblasts. Finally, we leverage drug-gene databases to identify several lipid-lowering drugs and antioxidants with high potential to treat abdominal aortic aneurysm with comorbidities. Our study provides insight into the shared genetic mechanism between abdominal aortic aneurysm and cardiometabolic traits, and identifies potential targets for pharmacological intervention.

Influence of cardiometabolic medications on abdominal aortic aneurysm growth in the UK Aneurysm Growth Study: metformin and angiotensin-converting enzyme inhibitors associated with slower aneurysm growth

BACKGROUND

There is a clinical need for treatments that can slow or prevent the growth of an abdominal aortic aneurysm, not only to reduce the need for surgery, but to provide a means to treat those who cannot undergo surgery.

METHODS

Analysis of the UK Aneurysm Growth Study (UKAGS) prospective cohort was conducted to test for an association between cardiometabolic medications and the growth of an abdominal aortic aneurysm above 30 mm in diameter, using linear mixed-effect models.

RESULTS

A total of 3670 male participants with data available on abdominal aortic aneurysm growth, smoking status, co-morbidities, and medication history were included. The mean age at recruitment was 69.5 years, the median number of surveillance scans was 6, and the mean(s.e.) unadjusted abdominal aortic aneurysm growth rate was 1.75(0.03) mm/year. In a multivariate linear mixed-effect model, smoking (mean(s.e.) +0.305(0.07) mm/year, P = 0.00003) and antiplatelet use (mean(s.e.) +0.235(0.06) mm/year, P = 0.00018) were found to be associated with more rapid abdominal aortic aneurysm growth, whilst metformin was strongly associated with slower abdominal aortic aneurysm growth (mean(s.e.) -0.38(0.1) mm/year, P = 0.00019), as were angiotensin-converting enzyme inhibitors (mean(s.e.) -0.243(0.07) mm/year, P = 0.0004), angiotensin II receptor antagonists (mean(s.e.) -0.253(0.08) mm/year, P = 0.00255), and thiazides/related diuretics (mean(s.e.) -0.307(0.09) mm/year, P = 0.00078).

CONCLUSION

The strong association of metformin with slower abdominal aortic aneurysm growth highlights the importance of the ongoing clinical trials assessing the effectiveness of metformin with regard to the prevention of abdominal aortic aneurysm growth and/or rupture. The association of angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, and diuretics with slower abdominal aortic aneurysm growth points to the possibility that optimization of cardiovascular risk management as part of abdominal aortic aneurysm surveillance may have the secondary benefit of also reducing abdominal aortic aneurysm growth rates.

Genome-wide association meta-analysis identifies risk loci for abdominal aortic aneurysm and highlights PCSK9 as a therapeutic target

Abdominal aortic aneurysm (AAA) is a common disease with substantial heritability. In this study, we performed a genome-wide association meta-analysis from 14 discovery cohorts and uncovered 141 independent associations, including 97 previously unreported loci. A polygenic risk score derived from meta-analysis explained AAA risk beyond clinical risk factors. Genes at AAA risk loci indicate involvement of lipid metabolism, vascular development and remodeling, extracellular matrix dysregulation and inflammation as key mechanisms in AAA pathogenesis. These genes also indicate overlap between the development of AAA and other monogenic aortopathies, particularly via transforming growth factor β signaling. Motivated by the strong evidence for the role of lipid metabolism in AAA, we used Mendelian randomization to establish the central role of nonhigh-density lipoprotein cholesterol in AAA and identified the opportunity for repurposing of proprotein convertase, subtilisin/kexin-type 9 (PCSK9) inhibitors. This was supported by a study demonstrating that PCSK9 loss of function prevented the development of AAA in a preclinical mouse model.

Novel pharmacological approaches in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a severe vascular disease and a major public health issue with an unmet medical need for therapy. This disease is featured by a progressive dilation of the abdominal aorta, boosted by atherosclerosis, ageing, and smoking as major risk factors. Aneurysm growth increases the risk of aortic rupture, a life-threatening emergency with high mortality rates. Despite the increasing progress in our knowledge about the etiopathology of AAA, an effective pharmacological treatment against this disorder remains elusive and surgical repair is still the unique available therapeutic approach for high-risk patients. Meanwhile, there is no medical alternative for patients with small aneurysms but close surveillance. Clinical trials assessing the efficacy of antihypertensive agents, statins, doxycycline, or anti-platelet drugs, among others, failed to demonstrate a clear benefit limiting AAA growth, while data from ongoing clinical trials addressing the benefit of metformin on aneurysm progression are eagerly awaited. Recent preclinical studies have postulated new therapeutic targets and pharmacological strategies paving the way for the implementation of future clinical studies exploring these novel therapeutic strategies. This review summarises some of the most relevant clinical and preclinical studies in search of new therapeutic approaches for AAA.

Role of Statins after Endovascular Repair of Abdominal Aortic Aneurysms: A Nationwide Population-Based Study

The role of statins after endovascular abdominal aortic aneurysm repair (EVAR) has not been well established in an Asian context. In this study, the use of statins and their association with long-term health outcomes were evaluated in patients undergoing EVAR using the Korean National Health Insurance Service database. Among the 8893 patients who underwent EVAR from 2008 to 2018, 3386 (38.1%) were on statins prior to the procedure. Patients using statins had a higher prevalence of comorbidities, such as hypertension (88.4% vs. 71.5%), diabetes mellitus (24.5% vs. 14.1%), and heart failure (21.6% vs. 13.1%), compared with non-users (all p < 0.001). After propensity score matching, statin use prior to EVAR was associated with a lower risk of all-cause mortality (HR 0.85, 95% CI 0.78-0.92, p < 0.001) and cardiovascular mortality (HR 0.66, 95% CI 0.51-0.86, p = 0.002). Statin use following EVAR was associated with a lower risk of adverse events, but not significantly so. Patients on statins both preceding and following EVAR had a lower risk of all-cause mortality (HR 0.82, 95% CI 0.73-0.91, p < 0.001) and cardiovascular mortality (HR 0.62, 95% CI 0.44-0.87, p = 0.007), compared with statin non-users. Among Korean patients undergoing EVAR, the persistent use of statins prior to and after the procedure was associated with a lower risk of mortality, compared with non-statin users.

Relationship Between Lipoprotein(a) Levels and Cardiovascular Outcomes in Postmenopausal Women: A Systematic Review

Elevated lipoprotein(a) [Lp(a)] levels are independently associated with atherosclerotic cardiovascular disease, although this association is less explored in postmenopausal women. The main objective of this systematic review was to analyze the association between elevated Lp(a) levels and cardiovascular outcomes in posmenopausal women. Studies that evaluated this association were searched in the current literature. Ten studies including 157.690 women were considered eligible for this study. In total, 4 prospective cohorts, 3 cross-sectional studies, 2 nested case-control studies, and one post-hoc analysis from a randomized clinical trial were analyzed. The included studies showed different results regarding the association between Lp(a) levels and cardiovascular outcomes: a positive association (4 studies), no association (2 studies), or different results depending on the subgroups or outcomes evaluated (4 studies). The results were robust when evaluating coronary events. The reduction in coronary events attributed to a hormone replacement therapy-associated decrease in Lp(a) levels was controversial.

How vascular smooth muscle cell phenotype switching contributes to vascular disease

Vascular smooth muscle cells (VSMCs) are the most abundant cell in vessels. Earlier experiments have found that VSMCs possess high plasticity. Vascular injury stimulates VSMCs to switch into a dedifferentiated type, also known as synthetic VSMCs, with a high migration and proliferation capacity for repairing vascular injury. In recent years, largely owing to rapid technological advances in single-cell sequencing and cell-lineage tracing techniques, multiple VSMCs phenotypes have been uncovered in vascular aging, atherosclerosis (AS), aortic aneurysm (AA), etc. These VSMCs all down-regulate contractile proteins such as α-SMA and calponin1, and obtain specific markers and similar cellular functions of osteoblast, fibroblast, macrophage, and mesenchymal cells. This highly plastic phenotype transformation is regulated by a complex network consisting of circulating plasma substances, transcription factors, growth factors, inflammatory factors, non-coding RNAs, integrin family, and Notch pathway. This review focuses on phenotypic characteristics, molecular profile and the functional role of VSMCs phenotype landscape; the molecular mechanism regulating VSMCs phenotype switching; and the contribution of VSMCs phenotype switching to vascular aging, AS, and AA. Video Abstract.

Effect of statins on abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a prevalent condition which causes progressive growth and rupture of aortic wall with a high death rate. Several studies have found that treatment with statins may decrease the progress of AAA and the risk of rupture by suppressing the inflammatory mediators, decreasing oxidative stress, and inhibiting mechanisms involved in extracellular matrix (ECM) degradation. Moreover, some studies have reported that prehospital therapy with statins can decrease mortality after surgery. The novelty of this paper is that different studies including those performed in humans and animals were reviewed and the potential mechanisms by which statins can have an effect on AAA were summarized. Overall, the evidence suggested an association between treatment with statins and improvement of AAA.

Deciphering the Intercellular Communication Between Immune Cells and Altered Vascular Smooth Muscle Cell Phenotypes in Aortic Aneurysm From Single-Cell Transcriptome Data

Background

Vascular smooth muscle cell (VSMC) phenotype switching has been preliminarily found in aortic aneurysms. However, two major questions were raised: (1) What factors drive phenotypic switching of VSMCs in aortic aneurysms? (2) What role does VSMC phenotype transformation play in aortic aneurysms? We speculated that the interaction between infiltrated immune cells and VSMCs played a pivotal role in aortic aneurysm expansion.

Materials and Methods

We obtained single-cell transcriptome data GSE155468 that incorporate eight aortic aneurysm samples and three normal aorta samples. A standard single-cell analysis procedure was performed by Seurat (v3.1.2) for identifying the general cell components. Subsequently, VSMCs were extracted separately and re-clustered for identifying switched VSMC phenotypes. VSMC phenotype annotation was relied on the definitions of specific VSMC phenotypes in published articles. Vital VSMC phenotypes were validated by immunofluorescence. Next, identified immune cells and annotated vital VSMC phenotypes were extracted for analyzing the intercellular communication. R package CellChat (v1.1.3) was used for investigating the communication strength, signaling pathways, and communication patterns between various VSMC phenotypes and immune cells.

Result

A total of 42,611 cells were identified as CD4 + T cells, CD8 + T cells, VSMC, monocytes, macrophages, fibroblasts, endothelial cells, and B cells. VSMCs were further classified into contractile VSMCs, secreting VSMCs, macrophage-like VSMCs, mesenchymal-like VSMCs, adipocyte-like VSMCs, and T-cell-like VSMCs. Intercellular communication analysis was performed between immune cells (macrophages, B cells, CD4 + T cells, CD8 + T cells) and immune related VSMCs (macrophage-like VSMCs, mesenchymal-like VSMCs, T-cell-like VSMCs, contractile VSMCs). Among selected cell populations, 27 significant signaling pathways with 61 ligand–receptor pairs were identified. Macrophages and macrophage-like VSMCs both assume the roles of a signaling sender and receiver, showing the highest communication capability. T cells acted more as senders, while B cells acted as receivers in the communication network. T-cell-like VSMCs and contractile VSMCs were used as senders, while mesenchymal-like VSMCs played a poor role in the communication network. Signaling macrophage migration inhibitory factor (MIF), galectin, and C-X-C motif chemokine ligand (CXCL) showed high information flow of intercellular communication, while signaling complement and chemerin were completely turned on in aortic aneurysms. MIF and galectin promoted VSMC switch into macrophage-like phenotypes, CXCL, and galectin promoted VSMCs transform into T-cell-like phenotypes. MIF, galectin, CXCL, complement, and chemerin all mediated the migration and recruitment of immune cells into aortic aneurysms.

Conclusion

The sophisticated intercellular communication network existed between immune cells and immune-related VSMCs and changed as the aortic aneurysm progressed. Signaling MIF, galectin, CXCL, chemerin, and complement made a significant contribution to aortic aneurysm progression through activating immune cells and promoting immune cell migration, which could serve as the potential target for the treatment of aortic aneurysms.

Predictors and Consequences of Sac Shrinkage after Endovascular Infrarenal Aortic Aneurysm Repair

Background: Aneurysm shrinkage has been proposed as a marker of successful endovascular aneurysm repair (EVAR). We evaluated the impact of sac shrinkage on secondary interventions, on survival and its association with endoleaks, and on compliance with instructions for use (IFU). Methods: This observational retrospective study was conducted on all consecutive patients receiving EVAR for an infrarenal abdominal aortic aneurysm (AAA) using exclusively Endurant II/IIs endograft from 2014 to 2018. Sixty patients were entered in the study. Aneurysm sac shrinkage was defined as decrease ≥5 mm of the maximum aortic diameter. Univariate methods and Kaplan–Meier plots assessed the potential impact of shrinkage. Results: Twenty-six patients (43.3%) experienced shrinkage at one year, and thirty-four (56.7%) had no shrinkage. Shrinkage was not significantly associated with any demographics or morbidity, except hypertension (p = 0.01). No aneurysm characteristics were associated with shrinkage. Non-compliance with instructions for use (IFU) in 13 patients (21.6%) was not associated with shrinkage. Three years after EVAR, freedom from secondary intervention was 85 ± 2% for the entire series, 92.3 ± 5.0% for the shrinkage group and 83.3 ± 9% for the no-shrinkage group (Logrank: p = 0.49). Survival at 3 years was not significantly different between the two groups (85.9 ± 7.0% vs. 79.0 ± 9.0%, Logrank; p = 0.59). Strict compliance with IFU was associated with less reinterventions at 3 years (92.1 ± 5.9% vs. 73.8 ± 15%, Logrank: p = 0.03). Similarly, survival at 3 years did not significantly differ between strict compliance with IFU and non-compliance (81.8 ± 7.0% vs. 78.6 ± 13.0%, Logrank; p = 0.32). Conclusion: This study suggests that shrinkage ≥5 mm at 1-year is not significantly associated with a better survival rate or a lower risk of secondary intervention than no-shrinkage. In this series, the risk of secondary intervention regardless of shrinkage seems to be linked more to non-compliance with IFU. Considering the small number of patients, these results must be confirmed by extensive prospective studies.

No Effect of Hypercholesterolemia on Elastase-Induced Experimental Abdominal Aortic Aneurysm Progression

OBJECTIVE

Epidemiological studies link hyperlipidemia with increased risk for abdominal aortic aneurysms (AAAs). However, the influence of lipid-lowering drugs statins on prevalence and progression of clinical and experimental AAAs varies between reports, engendering controversy on the association of hyperlipidemia with AAA disease. This study investigated the impact of hypercholesterolemia on elastase-induced experimental AAAs in mice.

METHODS

Both spontaneous (targeted deletion of apolipoprotein E) and induced mouse hypercholesterolemia models were employed. In male wild type (WT) C57BL/6J mice, hypercholesterolemia was induced via intraperitoneal injection of an adeno-associated virus (AAV) encoding a gain-of-function proprotein convertase subtilisin/kexin type 9 mutation (PCSK9) followed by the administration of a high-fat diet (HFD) (PCSK9+HFD) for two weeks. As normocholesterolemic controls for PCSK9+HFD mice, WT mice were infected with PCSK9 AAV and fed normal chow, or injected with phosphate-buffered saline alone and fed HFD chow. AAAs were induced in all mice by intra-aortic infusion of porcine pancreatic elastase and assessed by ultrasonography and histopathology.

RESULTS

In spontaneous hyper- and normo-cholesterolemic male mice, the aortic diameter enlarged at a constant rate from day 3 through day 14 following elastase infusion. AAAs, defined as a more than 50% diameter increase over baseline measurements, formed in all mice. AAA progression was more pronounced in male mice, with or without spontaneous hyperlipidemia. The extent of elastin degradation and smooth muscle cell depletion were similar in spontaneous hyper- (score 3.5 for elastin and 4.0 for smooth muscle) and normo- (both scores 4.0) cholesterolemic male mice. Aortic mural macrophage accumulation was also equivalent between the two groups. No differences were observed in aortic accumulation of CD4+ or CD8+ T cells, B cells, or mural angiogenesis between male spontaneous hyper- and normocholesterolemic mice. Similarly, no influence of spontaneous hypercholesterolemia on characteristic aneurysmal histopathology was noted in female mice. In confirmatory experiments, induced hypercholesterolemia also exerted no appreciable effect on AAA progression and histopathologies.

CONCLUSION

This study demonstrated no recognizable impact of hypercholesterolemia on elastase-induced experimental AAA progression in both spontaneous and induced hypercholesterolemia mouse models. These results add further uncertainty to the controversy surrounding the efficacy of statin therapy in clinical AAA disease.

Systematic review and Meta-Analysis of Mendelian randomisation analyses of Abdominal aortic aneurysms

Introduction

Mendelian randomisation (MR) has been suggested to be able to overcome biases of observational studies, but no meta-analysis is available on MR studies on abdominal aortic aneurysm (AAA). This systematic review and Meta-analysis examined the evidence of causal risk factors for AAA identified in MR studies.

Methods

Publicly available databases were systematically searched for MR studies that reported any causal risk factors for AAA diagnosis. Meta-analyses were performed using random effect models and reported as odds ratio (OR) and 95% confidence intervals (CI). Study quality was assessed using a modified version of Strengthening the Reporting of Mendelian Randomisation Studies (STROBE-MR) guidelines.

Results

Sixteen MR studies involving 34,050 patients with AAA and 2,205,894 controls were included. Meta-analyses suggested that one standard deviation increase in high density lipoprotein (HDL) significantly reduced (OR: 0.66, 95% CI: 0.61, 0.72) and one standard deviation increase in low density lipoprotein (LDL) significantly increased the risk (OR: 1.68, 95%, CI: 1.55, 1.82) of AAA. One standard deviation increase in triglycerides did not significantly increase the risk of AAA (OR: 1.21, 95% CI: 0.86, 1.71). Quality assessment suggested that ten and five studies were of low and moderate risk of bias respectively, with one study considered as high risk of bias.

Conclusion

This meta-analysis suggests LDL and HDL are positive and negative casual risk factors for AAA.

Current pharmacological management of aortic aneurysm

ABSTRACT

Aortic aneurysm (AA) remains one of the primary causes of death worldwide. Of the major treatments, prophylactic operative repair is used for AA to avoid potential aortic dissection (AD) or rupture. To halt the development of AA and alleviate its progression into AD, pharmacological treatment has been investigated for years. Currently, β-adrenergic blocking agents, losartan, irbesartan, angiotensin-converting-enzyme inhibitors, statins, antiplatelet agents, doxycycline, and metformin have been investigated as potential candidates for preventing AA progression. However, the paradox between preclinical successes and clinical failures still exists, with no medical therapy currently available for ideally negating the disease progression. This review describes the current drugs used for pharmacological management of AA and their individual potential mechanisms. Preclinical models for drug screening and evaluation are also discussed to gain a better understanding of the underlying pathophysiology and ultimately find new therapeutic targets for AA.

Impact of prosthesis-patient mismatch on early and late outcomes after mitral valve replacement: a meta-analysis

Background

Prognostic significance of prosthesis-patient mismatch (PPM) after mitral valve replacement (MVR) remains uncertain because of the limited studies reporting inconsistent or even contrary results. This meta-analysis pooled results of all available studies comparing early and late prognoses between patients with significant mitral PPM and those without.

Methods

Studies were identified by searching Pubmed, Excerpta Medica Database, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov. Impact of PPM on postoperative hemodynamic results, thirty-day mortality, overall mortality, mortality of thirty-day survivors, and primary morbidity after MVR was evaluated via meta-analysis. Robustness of pooled estimates, source of heterogeneity, and publication bias were assessed via sensitivity analyses, meta-regression as well as subgroup analysis stratified according to methodological or clinical heterogeneity, or sequential omission method, and funnel plot or Begg's and Egger's tests, respectively.

Results

Nineteen cohort studies involving 9302 individuals (PPM group: n = 5109, Control group: n = 4193) were included for meta-analysis. Total PPM and severe PPM prevalence were 3.8%-85.9% and 1%-27%, with a mean value of 54.9% and 14.1%, respectively. As compared with control group, mitral PPM group demonstrated a poorer postoperative hemodynamic status of higher mean and peak residual transprosthetic pressure gradients (TPG), higher postoperative systolic pulmonary artery pressure (SPAP) and less reduction, higher postoperative pulmonary hypertension (PH) prevalence and less PH regression, smaller net atrioventricular compliance, less NYHA class decrease, higher postoperative functional tricuspid regurgitation prevalence and less regression. The PPM group also revealed a higher thirty-day mortality, long-term overall mortality, mortality of thirty-day survivors, and postoperative congestive heart failure prevalence, which were positively correlated with the severity of PPM if it was classified into tri-level subgroups. Left ventricular end-diastolic diameter, postoperative atrial fibrillation (AF) prevalence, and the AF regression were analogous between groups. Most pooled estimates were robust according to sensitivity analyses. Male patients and bioprosthesis implantation proportion were prominent source of between-study heterogeneity on thirty-day mortality. Publication bias was not significant in tests for all the outcomes, except for SPAP and TPG.

Conclusions

Mitral PPM would result in poorer postoperative hemodynamics and worse early and late prognosis. Severe PPM must be avoided since deleterious impact of mitral PPM was severity dependent.

Statins Reduce Abdominal Aortic Aneurysm Growth, Rupture, and Perioperative Mortality: A Systematic Review and Meta-Analysis

Background

There are no recognized pharmacological treatments for abdominal aortic aneurysms (AAA), although statins are suggested to be beneficial. We sought to summarize the literature regarding the effects of statins on human AAA growth, rupture, and 30‐day mortality.

Methods and Results

We conducted a systematic review and meta‐analysis of randomized and observational studies using the Cochrane CENTRAL database, MEDLINE, and EMBASE up to June 15, 2018. Review, abstraction, and quality assessment were conducted by 2 independent reviewers, and a third author resolved discrepancies. Pooled mean differences and odds ratios with 95% confidence intervals were calculated using random effects models. Heterogeneity was quantified using the I² statistic, and publication bias was assessed using funnel plots. Our search yielded 911 articles. One case‐control and 21 cohort studies involving 80 428 patients were included. The risk of bias was low to moderate. Statin use was associated with a mean AAA growth rate reduction of 0.82 mm/y (95% confidence interval 0.33, 1.32, P=0.001, I²=86%). Statins were also associated with a lower rupture risk (odds ratio 0.63, 95% confidence interval 0.51, 0.78, P<0.0001, I²=27%), and preoperative statin use was associated with a lower 30‐day mortality following elective AAA repair (odds ratio 0.55, 95% confidence interval 0.36, 0.83, P=0.005, I²=57%).

Conclusions

Statin therapy may be associated with reduction in AAA progression, rupture, and lower rates of perioperative mortality following elective AAA repair. These data argue for widespread statin use in AAA patients.

Clinical Trial Registration

URL: http://www.crd.york.ac.uk. Unique identifier: CRD42017056480.

Current Status and Perspectives on Pharmacologic Therapy for Abdominal Aortic Aneurysm

Background:

Abdominal aortic aneurysm (AAA), a common disease involving the segmen-tal expansion and rupture of the aorta, has a high mortality rate. Therapeutic options for AAA are cur-rently limited to surgical repair to prevent catastrophic rupture. Non-surgical approaches, particularly pharmacotherapy, are lacking for the treatment of AAA.

Objective:

We review both basic and clinical studies and discuss the current challenges to developing medical therapy that reduces AAA progression.

Results:

Studies using animal models of AAA progression and human AAA explant cultures have identified several potential targets for preventing AAA growth. However, no clinical studies have con-vincingly confirmed the efficacy of any pharmacologic treatment against the growth of AAA. Thus, there is as yet no strong recommendation regarding pharmacotherapy to reduce the risk of AAA pro-gression and rupture.

Conclusion:

This review identifies concerns that need to be addressed for the field to progress and dis-cusses the challenges that must be overcome in order to develop effective pharmacotherapy to reduce AAA progression in the future.

APOA1 oxidation is associated to dysfunctional high-density lipoproteins in human abdominal aortic aneurysm

Background

High-density lipoproteins (HDL) are a complex mixture of lipids and proteins with vasculoprotective properties. However, HDL components could suffer post-translational modifications (PTMs) under pathological conditions, leading to dysfunctional HDL. We studied whether HDL are modified in abdominal aortic aneurysm (AAA) and the effect on HDL functionality.

Methods

HDL were isolated by ultracentrifugation from AAA tissue (HDL-T) and from plasma of healthy volunteers and then incubated with AAA tissue-conditioned medium (HDL-AAA CM). PTMs from these particles were characterized using Comet-PTM. The ability of HDL-AAA CM for promoting cholesterol efflux was determined ex vivo and in vivo by using J774A.1 [³H]cholesterol-labeled mouse macrophages and after injecting [³H]cholesterol-labeled mouse macrophages and HDL into the peritoneal cavity of wild-type C57BL/6 mice, respectively. Trp50 and Trp108 oxidized forms of APOA1 in HDL incubated with conditioned-medium of activated neutrophils and in plasma of AAA patients and controls were measured by targeted parallel reaction monitoring.

Findings

Oxidation was the most prevalent PTM in apolipoproteins, particularly in APOA1. Trp50 and Trp108 in APOA1 were the residues most clearly affected by oxidation in HDL-T and in HDL-AAA CM, when compared to their controls. In addition, cholesterol efflux was decreased in macrophages incubated with HDL-AAA CM in vitro and a decreased macrophage-to-serum reverse cholesterol transport was also observed in mice injected with HDL-AAA CM. Finally, both oxidized Trp50 and Trp108 forms of APOA1 were increased in HDL incubated with conditioned-medium of activated neutrophils and in plasma of AAA patients in relation to controls.

Interpretation

Oxidative modifications of HDL present in AAA tissue and plasma were closely associated with the loss of vasculoprotective properties of HDL in AAA.

Fund

MINECO, ISCiii-FEDER, CIBERDEM, CIBERCV and LA CAIXA.

Potential Medication Treatment According to Pathological Mechanisms in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a vascular disease with high mortality. Because of the lack of effective medications to stop or reverse the progression of AAA, surgical operation has become the most predominant recommendation of treatment for patients. There are many potential mechanisms, including inflammation, smooth muscle cell apoptosis, extracellular matrix degradation, oxidative stress, and so on, involving in AAA pathogenesis. According to those mechanisms, some potential therapeutic drugs have been proposed and tested in animal models and even in clinical trials. This review focuses on recent advances in both pathogenic mechanisms and potential pharmacologic therapies of AAA.

Statin therapy improved long-term prognosis in patients with major non-cardiac vascular surgeries: a systematic review and meta-analysis

OBJECTIVE

To investigate whether statin intervention will improve the long-term prognosis of patients undergoing major non-cardiac vascular surgeries.

METHODS

Major database searches for clinical trials enrolling patients undergoing major non-cardiac vascular surgeries, including lower limb revascularization, carotid artery surgeries, arteriovenous fistula, and aortic surgeries, were performed. Subgroup analyses, stratified by surgical types or study types, were employed to obtain statistical results regarding survival, patency rates, amputation, and cardiovascular and stroke events. Odds ratio (ORs) and 95% confidence intervals (CIs) were calculated by Review Manager 5.3. Sensitivity analysis, publication bias and meta-regression were conducted by Stata 14.0.

RESULTS

In total, 34 observational studies, 8 prospective cohort studies and 4 randomized controlled clinical trials (RCTs) were enrolled in the present analysis. It was demonstrated that statin usage improved all-cause mortality in lower limb, carotid, aortic and mixed types of vascular surgery subgroups compared with those in which statins were not used. Additionally, the employment of statins efficiently enhanced the primary and secondary patency rates and significantly decreased the amputation rates in the lower limb revascularization subgroup. Furthermore, for other complications, statin intervention decreased cardiovascular events in mixed types of vascular surgeries and stroke incidence in the carotid surgery subgroup. No significant publication bias was observed. The meta-regression results showed that the morbidity of cardiovascular disease or the use of aspirin might affect the overall estimates in several subgroups.

CONCLUSIONS

This meta-analysis demonstrated that statin therapy was associated with improved survival rates and patency rates and with reduced cardiovascular or stroke morbidities in patients who underwent non-cardiac vascular surgeries.

Plasma cholesterol lowering in an AngII‑infused atherosclerotic mouse model with moderate hypercholesterolemia

Atherosclerosis is the main underlying causes of cardiovascular disease. There is a well‑established association between high blood cholesterol levels and the extent of atherosclerosis. Furthermore, atherosclerosis has been proposed to augment abdominal aortic aneurysm (AAA) formation. As patients with AAA often have parallel atherosclerotic disease and are therefore often on cholesterol‑lowering therapy, it is not possible to fully address the independent effects of plasma cholesterol lowering (PCL) treatment on AAA. The present study investigated the effect of angiotensin II (AngII)‑infusion in modestly hypercholesterolemic Ldlr‑/‑Apob100/100Mttpflox/floxMx1‑Cre mice with or without PCL treatment on a morphological and molecular level, in terms of atherosclerosis and AAA development. AngII infusion in the study mice resulted in an increased atherosclerotic lesion area and increased infiltration of inflammatory leukocytes, which was not observed in mice with PCL induced prior to AngII infusion. This suggested that AngII infusion in this mouse model induced atherosclerosis development, and that plasma cholesterol levels represent a controlling factor. Furthermore, AngII infusion in Ldlr‑/‑Apob100/100Mttpflox/floxMx1‑Cre mice caused a modest aneurysmal phenotype, and no differences in AAA development were observed between the different study groups. However, the fact that modest hypercholesterolemic mice did not develop AAA in a classical aneurysmal model indicated that plasma cholesterol levels are important for disease development.

Effect of β-blocker on aneurysm sac behavior after endovascular abdominal aortic repair

OBJECTIVE

This study was conducted to determine whether β-blocker (BB) therapy is associated with abdominal aortic aneurysm (AAA) sac regression after endovascular abdominal aortic repair (EVAR).

METHODS

A total of 198 patients (mean age, 76 years) who underwent EVAR were analyzed (104 in the BB group and 94 in the non-BB group). The primary end point was the incidence of AAA sac regression at 1 and 2 years.

RESULTS

Hypertension, coronary artery disease, and hyperlipidemia were more common in the BB group. The BB group was also more likely to have been prescribed an aspirin and a statin than the non-BB group. The length of proximal neck was significantly longer in the non-BB group than in the BB group. All study patients were monitored for at least 1 year after EVAR, and 2-year follow-up was available in 104 patients (52.5%). There was no statistically significant difference in the incidence of aneurysm sac regression in either group at 1 year (52.1% in the non-BB group vs 45.2% in the BB group; P = .330) and 2 years (58.5% in the non-BB group vs 64.7% in the BB group; P = .515). The difference of the change of AAA maximum diameter between two groups did not reach statistical significance at 1 year (-6.0 ± 7.0 mm in the non-BB group vs -5.5 ± 8.1 mm in the BB group; P = .644) and 2 years (-9.0 ± 10.5 mm in the non-BB group vs -9.0 ± 10.0 mm in the BB group; P = .977). BB therapy was not associated with increased odds of AAA sac regression. The effect of third-generation BBs on AAA sac regression was not significant.

CONCLUSIONS

BB therapy had no effect on AAA sac regression. At the present time, there is insufficient evidence to recommend BB therapy for the purpose of AAA sac regression.

Association of statins with aortic, peripheral, and visceral artery aneurysm development

Objectives

Prior studies examining the effects of statins on arterial aneurysm development and progression yielded conflicting results due to their smaller size and presence of residual confounders. The objective of this study is to examine the association of statins with risk of being diagnosed with aortic, peripheral, and visceral artery aneurysm.

Methods

This was a retrospective cohort study of Tricare enrollees (from 1 October 2003 to 31 March 2012). Main outcomes were diagnosis of aortic, peripheral, or visceral artery aneurysm and undergoing aortic aneurysm repair procedure during follow-up period. Using 115 baseline characteristics, we generated a propensity score to match statin users and nonusers and examine the odds of outcomes (primary analysis). Secondary analysis examined outcomes at various subcohorts.

Results

Out of 10,910 statin users and 49,545 nonusers, we propensity score-matched 6728 pairs of statin users and nonusers. Statin users and nonusers had similar odds of being diagnosed with aortic, peripheral, and visceral artery aneurysms (odds ratio [OR]: 1.06, 95% confidence interval [95% CI]: 0.85–1.33) and of undergoing aortic aneurysm repair procedures (OR: 0.54, 95% CI: 0.22–1.35). Secondary analysis showed a tendency toward fewer aortic aneurysm procedures among statin users that did not reach statistical significance. However, high-intensity statin users in comparison to non-intensive statin users had higher adjusted odds of aortic, peripheral, and visceral artery aneurysms (OR: 1.76, 95% CI: 1.37–2.25, p < .0001).

Conclusions

This study does not support a clinically significant benefit or harm from statins regarding development of arterial aneurysm. However, secondary analyses may support the hypothesis proposed by previous research proposing a bidirectional role for statins.

Metformin treatment status and abdominal aortic aneurysm disease progression

OBJECTIVE

In population-based studies performed on multiple continents during the past two decades, diabetes mellitus has been negatively associated with the prevalence and progression of abdominal aortic aneurysm (AAA) disease. We investigated the possibility that metformin, the primary oral hypoglycemic agent in use worldwide, may influence the progression of AAA disease.

METHODS

Preoperative AAA patients with diabetes were identified from an institutional database. After tabulation of individual cardiovascular and demographic risk factors and prescription drug regimens, odds ratios for categorical influences on annual AAA enlargement were calculated through nominal logistical regression. Experimental AAA modeling experiments were subsequently performed in normoglycemic mice to validate the database-derived observations as well as to suggest potential mechanisms of metformin-mediated aneurysm suppression.

RESULTS

Fifty-eight patients met criteria for study inclusion. Of 11 distinct classes of medication considered, only metformin use was negatively associated with AAA enlargement. This association remained significant after controlling for gender, age, cigarette smoking status, and obesity. The median enlargement rate in AAA patients not taking oral diabetic medication was 1.5 mm/y; by nominal logistic regression, metformin, hyperlipidemia, and age ≥70 years were associated with below-median enlargement, whereas sulfonylurea therapy, initial aortic diameter ≥40 mm, and statin use were associated with above-median enlargement. In experimental modeling, metformin dramatically suppressed the formation and progression, with medial elastin and smooth muscle preservation and reduced aortic mural macrophage, CD8 T cell, and neovessel density.

CONCLUSIONS

Epidemiologic evidence of AAA suppression in diabetes may be attributable to concurrent therapy with the oral hypoglycemic agent metformin.

Calculating when elective abdominal aortic aneurysm repair improves survival for individual patients: development of the Aneurysm Repair Decision Aid and economic evaluation

BACKGROUND

Abdominal aortic aneurysm (AAA) repair aims to prevent premature death from AAA rupture. Elective repair is currently recommended when AAA diameter reaches 5.5 cm (men) and 5.0 cm (women). Applying population-based indications may not be appropriate for individual patient decisions, as the optimal indication is likely to differ between patients based on age and comorbidities.

OBJECTIVE

To develop an Aneurysm Repair Decision Aid (ARDA) to indicate when elective AAA repair optimises survival for individual patients and to assess the cost-effectiveness and associated uncertainty of elective repair at the aneurysm diameter recommended by the ARDA compared with current practice.

DATA SOURCES

The UK Vascular Governance North West and National Vascular Database provided individual patient data to develop predictive models for perioperative mortality and survival. Data from published literature were used to model AAA growth and risk of rupture. The cost-effectiveness analysis used data from published literature and from local and national databases.

METHODS

A combination of systematic review methods and clinical registries were used to provide data to populate models and inform the structure of the ARDA. Discrete event simulation (DES) was used to model the patient journey from diagnosis to death and synthesised data were used to estimate patient outcomes and costs for elective repair at alternative aneurysm diameters. Eight patient clinical scenarios (vignettes) were used as exemplars. The DES structure was validated by clinical and statistical experts. The economic evaluation estimated costs, quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs) from the NHS, social care provider and patient perspective over a lifetime horizon. Cost-effectiveness acceptability analyses and probabilistic sensitivity analyses explored uncertainty in the data and the value for money of ARDA-based decisions. The ARDA outcome measures include perioperative mortality risk, annual risk of rupture, 1-, 5- and 10-year survival, postoperative long-term survival, median life expectancy and predicted time to current threshold for aneurysm repair. The primary economic measure was the ICER using the QALY as the measure of health benefit.

RESULTS

The analysis demonstrated it is feasible to build and run a complex clinical decision aid using DES. The model results support current guidelines for most vignettes but suggest that earlier repair may be effective in younger, fitter patients and ongoing surveillance may be effective in elderly patients with comorbidities. The model adds information to support decisions for patients with aneurysms outside current indications. The economic evaluation suggests that using the ARDA compared with current guidelines could be cost-effective but there is a high level of uncertainty.

LIMITATIONS

Lack of high-quality long-term data to populate all sections of the model meant that there is high uncertainty about the long-term clinical and economic consequences of repair. Modelling assumptions were necessary and the developed survival models require external validation.

CONCLUSIONS

The ARDA provides detailed information on the potential consequences of AAA repair or a decision not to repair that may be helpful to vascular surgeons and their patients in reaching informed decisions. Further research is required to reduce uncertainty about key data, including reintervention following AAA repair, and assess the acceptability and feasibility of the ARDA for use in routine clinical practice.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

C-reactive protein predicts aortic aneurysmal disease progression after endovascular repair

OBJECTIVES

This study aims to investigate the prognostic significance of the rate of variation of C-reactive protein (CRP) levels as a predictor of aneurysmal sac and neck expansion and, therefore, of aneurysm disease progression, in patients undergoing endovascular aneurysm repair (EVAR) in the absence of endoleaks.

METHODS

192 patients following non-emergency elective EVAR for asymptomatic infra-renal abdominal aorta aneurysm (AAA) were included after a six-month period after intervention to ensure the treatment success and absence of endoleaks. Expansion of aneurysm sac or neck after the six-month stabilization term occurred in 120 (63%) and 128 (67%) patients for a mean follow-up of 53±23 months.

RESULTS

The relative CRP plasma level gradient significantly differed between the subgroups of patients according to relative sac expansion quartiles (7%, 26%, 39%, and 61%; p<0.001). In the bivariate analysis, the aorta sac diameter expansion rate progressively increased in the subgroups determined by CRP gradient quartiles (-0.5±1%, 3.6±1%, 8±2%, 10±3%; p<0.01). The median (25th; 75th quartile) CRP level rise in "rapid expanders" patients (those above the median annual sac expansion rate of 5.7%) was 51% (37%; 67%) compared with 15% (3%; 28%) in "slow- or non-expanders" (p<0.001). The multivariate age-adjusted logistic model confirmed the variation of CRP level and neck length as the only factors independently associated to sac expansion (odds ratio 4.3; 95% CI: 2.3-7.9 and 1.7; 95% CI: 1.3-2.2, respectively).

CONCLUSION

There is a significant time-related association between AAA sac diameter enlargement and CRP plasma level gradient after EVAR in the absence of endoleaks, confirming the latter as a proper marker of aneurysm disease progression and rate of expansion in these patients.

Effect of lipid-modifying therapy on long-term mortality after abdominal aortic aneurysm repair: a systemic review and meta-analysis

BACKGROUND

Several observational studies have demonstrated that lipid-modifying therapy may improve long-term survival in abdominal aortic aneurysm (AAA) patients after repair. We carried out a systematic review and meta-analysis of studies evaluating the effect of lipid-modifying therapy on long-term mortality.

PATIENTS AND METHODS

We conducted a systematic search of multiple databases up to April 2014. Studies that evaluated exposure to lipid-modifying therapy, reported mortality data and hazard ratio (HR) or provided survival curve for their estimation were included in the meta-analysis. Pooled HR estimates with 95% confidence intervals (CIs) were calculated using the random-effects model.

RESULTS

Eight studies (seven cohorts, one post hoc study of a randomization controlled trial) reporting 2,605 patients on lipid-modifying therapy were included. Meta-analysis showed a significant 39% reduction in long-term mortality with lipid-modifying therapy (HR 0.61; 95% CI 0.51-0.73). After exclusion of one study which was contributing to considerable heterogeneity, a significant 33% reduction in mortality risk was a more conservative, consistent estimate (HR 0.67; 95% CI 0.59-0.77).

CONCLUSION

Meta-analysis of studies supports a protective role of lipid-modifying therapy on mortality risk after AAA repair. Aggressive lipid intervention should be recommended to those who receiving AAA repair.

Inhibitory effect of statins on inflammation-related pathways in human abdominal aortic aneurysm tissue

HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitors (statins) have been suggested to attenuate abdominal aortic aneurysm (AAA) growth. However, the effects of statins in human AAA tissues are not fully elucidated. The aim of this study was to investigate the direct effects of statins on proinflammatory molecules in human AAA walls in ex vivo culture. Simvastatin strongly inhibited the activation of nuclear factor (NF)-κB induced by tumor necrosis factor (TNF)-α in human AAA walls, but showed little effect on c-jun N-terminal kinase (JNK) activation. Simvastatin, as well as pitavastatin significantly reduced the secretion of matrix metalloproteinase (MMP)-9, monocyte chemoattractant protein (MCP)-2 and epithelial neutrophil-activating peptide (CXCL5) under both basal and TNF-α-stimulated conditions. Similar to statins, the Rac1 inhibitor NSC23766 significantly inhibited the activation of NF-κB, accompanied by a decreased secretion of MMP-9, MCP-2 and CXCL5. Moreover, the effect of simvastatin and the JNK inhibitor SP600125 was additive in inhibiting the secretion of MMP-9, MCP-2 and CXCL5. These findings indicate that statins preferentially inhibit the Rac1/NF-κB pathway to suppress MMP-9 and chemokine secretion in human AAA, suggesting a mechanism for the potential effect of statins in attenuating AAA progression.

The impact of preoperative statin therapy on open and endovascular abdominal aortic aneurysm repair outcomes

OBJECTIVES

This study evaluated the utilization of preoperative statins and their impact on perioperative outcomes in patients undergoing open or endovascular aortic repair.

METHODS

Patients ≥50 years of age with non-ruptured abdominal aortic aneurysm repair were identified in MedPAR files 2007-2008 utilizing ICD-9-CM codes. Preoperative statins use was identified using National Drug Codes in Part D. Chi-square test, multivariable logistic regression, Kaplan-Meier and Cox regression modeling were performed.

RESULTS

In all, 19,323 patients were identified undergoing abdominal aortic aneurysm repair (14,602 endovascular aortic repair and 4721 open aortic repair); 9913 (50.3%) used statins before surgery. Bivariate analysis demonstrated lower rates of hospital, 30-, 90-day and 1-year mortality in patients with statins compared to those without statins after endovascular aortic repair (1.0% vs. 1.45%, p = 0.01; 1.51% vs. 2.3%, p = 0.0004; 3.05% vs. 4.66%, p < 0.0001; 7.91% vs. 11.56%, p < 0.0001, respectively). Multivariable logistic regression adjusting for age, gender, race, comorbidities and procedure demonstrated preoperative statins use was associated with a mortality reduction at 90-days postoperatively (odds ratio = 0.80; 95% CI 0.70-0.91, p = 0.0014) and 1-year postoperatively (odds ratio = 0.76; 95% CI 0.69-0.84, p = 0.0001).

CONCLUSIONS

Only half of the patients undergoing abdominal aortic aneurysm repair were prescribed preoperative statins. After adjustment, statins were significantly associated with improved survival during 1 year after surgery and a decreased incidence of lower extremity embolic complications after endovascular aortic repair. These data support a beneficial role of statin use prior to surgery for patients undergoing abdominal aortic aneurysm repair. Further prospective studies are needed to assess the benefit of statins in the perioperative period after 365 days.

Genomic insights into abdominal aortic aneurysms

INTRODUCTION

An individual's genetic background plays a significant role in his or her chances of developing an abdominal aortic aneurysm (AAA). This risk is likely to be due to a combination of multiple small effect genetic factors acting together, resulting in considerable difficulty in the identification of these factors.

METHODS

Methods for the identification of genetic factors associated with disease are usually based on the analysis of genetic variants in case-control studies. Over the last decade, owing to advances in bioinformatics and laboratory technology, these studies have progressed from focusing on the examination of a single genetic variant in each study to the examination of many millions of variants in a single experiment. We have conducted a series of such experiments using these methods.

RESULTS

Our original methods using candidate gene approaches led to the initial identification of a genetic variant in the interleukin-10 gene associated with AAA. However, further studies failed to confirm this association and highlighted the necessity for adequately powered studies to be conducted, as well as the need for confirmatory studies to be performed, prior to the acceptance of a variant as a risk for disease. The subsequent application of genomic techniques to our sample set, in a global collaboration, has led to the identification of three robustly verified risk loci for AAA in the LRP1, LDLR and SORT1 genes.

CONCLUSIONS

Genomic studies of AAA have led to the identification of new pathways involved in the pathogenesis of AAA. The exploration of these pathways has the potential to unlock new avenues for therapeutic intervention to prevent the development and progression of AAA.

Impact of statin therapy on patients with coronary heart disease and aortic aneurysm or dissection

OBJECTIVE

The impact of statin therapy on cardiovascular outcome in coronary artery disease (CAD) patients with aortic aneurysm or dissection (AD) is still unclear. The aim of this study was to elucidate the effect of statins at discharge to improve outcomes in CAD patients with AD.

METHODS

Among 14,834 consecutive patients who underwent first coronary revascularization in the CREDO-Kyoto PCI/CABG registry, we identified 699 patients (4.7%) with AD. The primary outcome measure was defined as a composite of all-cause death, myocardial infarction, and stroke. The effect of statin therapy was assessed by a Cox proportional hazards model incorporating clinically relevant factors.

RESULTS

The risk for the primary outcome measure was significantly higher in patients with AD (adjusted hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.23-1.66; P < .0001). In patients with AD, 215 patients (31%) had already undergone aneurysm repair, and only 274 patients (39%) were treated with statins at discharge. Patients treated with statins were younger, had higher body mass index, and were more often treated with percutaneous coronary intervention. Heart failure, anemia, and hemodialysis were more prevalent in patients treated without statins. In patients without AD, 7014 patients (50%) were treated with statins. Patients treated with statins were younger and had higher body mass index, and more patients were treated for CAD due to myocardial infarction. Heart failure, prior stroke, hemodialysis, anemia, and malignant disease were more prevalent in patients treated without statins. The use of statins was associated with lower risk for the primary outcome measure in patients with AD (adjusted HR, 0.71; 95% CI, 0.51-0.99; P = .045) as well as in patients without AD (adjusted HR, 0.79; 95% CI, 0.73-0.85; P < .0001). The effect size of statin use was similar between the patients with AD and those without AD (P interaction = .69).

CONCLUSIONS

CAD patients with AD had significantly higher long-term risk for cardiovascular events. Statin therapy was associated with lower risk for cardiovascular events in patients with CAD with AD as well as in patients without AD.

Cardiovascular effects of statins, beyond lipid-lowering properties

The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, better known as 'statins', are amongst the most widely used medications in the world. They have become a pivotal component in the primary and secondary prevention of coronary artery and vascular disease. However, a growing amount of evidence has suggested that statins also possess strong pleiotropic effects irrespective of their lipid-lowering properties, which include enhancement of endothelial function, anti-inflammatory and anti-atherothrombotic properties, and immunomodulation. The following provides a comprehensive and updated review of the clinical evidence regarding the pleiotropic effects of statins in cardiovascular disorders and their potential therapeutic benefits.

Payer status, preoperative surveillance, and rupture of abdominal aortic aneurysms in the US Medicare population

BACKGROUND

To determine the factors contributing to increased rate of ruptured abdominal aortic aneurysms (AAAs) for elderly poor patients.

METHODS

Medicare claims were analyzed for patients who underwent AAA repair from 2006 to 2009 with preoperative abdominal imaging. Repair for ruptured versus intact AAAs was our primary outcome measure. We used logistic regression to determine the relationship between Medicaid eligibility and the risk of rupture, sequentially adding variables related to patient characteristics, socioeconomic status, receipt of preoperative AAA surveillance, and hospital AAA volume. We then estimated the proportional effect of each factor.

RESULTS

No differences in rupture were observed in women based on payer status. Medicaid-eligible men were more likely to present with ruptured AAA (odds ratio [OR] 2.42, 95% confidence interval [CI] 1.65-3.52). After adjusting for patient and hospital factors, the poor remained at higher risk for rupture (OR 1.5, 95% CI 1.10-2.26). This disparate risk of rupture was more commonly observed in hospitals treating a higher proportion of Medicaid-eligible patients. We estimate that 36% of the observed disparity in rupture for the elderly poor is explained by patient factors, 27% by gaps in surveillance, 9% by hospital factors, and <1% by socioeconomic factors.

CONCLUSIONS

Incomplete preoperative surveillance is a key contributor to increased rupture of AAA in the elderly poor. Efforts aimed at improving disparities must include consistent access to medical care.

Statins Promote Residual Aneurysm Sac Regression Following Endovascular Aortic Aneurysm Repair

Background:

Regression of the residual sac is indicative of successful endovascular aortic aneurysm (EVAR) repair. Using color duplex ultrasound (CDU), we monitored the residual aneurysm sac following EVAR and correlated sac behavior with perioperative risk factors.

Methods:

Of 145 patients with EVAR, 106 (73.1%) patients between January 01, 2003, and July 01, 2010, had at least 2 consecutive postoperative scans and thus were eligible for inclusion. Mean (± standard deviation [SD]) CDU scans per person was 4.6 (±1.4). All were conducted by the same technologist using a standard protocol on the same machine. Aneurysm sac change in centimeters and percentage terms was calculated. The presence or absence of an endoleak was also recorded. Change in aneurysm sac size was correlated with preoperative risk factors.

Findings:

Mean sac size change at 1 month was a decrease of 0.24 cm, equating to a percentage change of 4.3%. At 7 months, the decrease was 0.59 cm (9.8%), at 12 months, 0.73 cm (12.4%), at 18 months 0.92 cm (15.8%), and at 36 months 1.0 cm (16.6%). Both univariate and multivariate analyses demonstrated that statin therapy ( P = .002) was the only risk factor variable positively associated with aneurysm regression while the presence of an endoleak was inversely related to sac reduction ( P = .01).

Interpretation:

Maximum aneurysmal sac reduction seems to occur in the first year following endograft implantation. Statin therapy appears to be associated with an increased likelihood of sac regression following EVAR. Further investigation of the role of statins in the biology of abdominal aortic aneurysmal disease is warranted.

Current status of medical treatment for abdominal aortic aneurysm

Although cardiovascular disease is widely recognized as the leading cause of death, a lesser known fact is that aortic aneurysm is the 15th leading cause of death over the age of 65 years in the USA. The golden standard of the treatments are invasive interventions either with open surgical repair (OS) or endovascular aneurysm repair (EVAR). The concept of medical treatment is to prevent abdominal aortic aneurysm (AAA) from rupture and avoid surgical treatment by preventing aneurysm enlargement or even reducing aneurysm size. Matrix metalloproteinases (MMP) are structurally related metalloendopeptidases that can degrade the extracellular matrix and is thought to play important roles in AAA. There are many proposed pharmacological treatments including: β-blockers, angiotensin-converting enzyme inhibitor (ACE inhibitors), angiotensin-receptor blocker (ARB), statins, macrolides and, doxycycline, an inhibitor of the MMP. The latter is a potential promising drug as medical treatment for AAA and the Non-invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA(3)CT) is currently ongoing in the USA. Here, the pathophysiology and potential medical therapy for AAA will be reviewed.