Four-Dimensional Flow MRI-Derived Hemodynamics in Abdominal Aortic Aneurysms: Reproducibility and Associations With Diameter, Intraluminal Thrombus Volume, and Vorticity

BACKGROUND

Maximum diameter measurements are used to assess the rupture risk of abdominal aortic aneurysms (AAAs); however, these are not precise enough to predict all ruptures. Four-dimensional (4D) flow MRI-derived parameters provide additional information by visualizing hemodynamics in AAAs but merit further investigation before they are clinically applicable.

PURPOSE

To assess the reproducibility of 4D flow MRI-derived hemodynamics, to investigate possible correlations with lumen and maximum diameter, and to explore potential relationships with vorticity and aneurysm growth.

STUDY TYPE

Prospective single-arm study.

POPULATION

A total of 22 (71.5 ± 6.1 years, 20 male) asymptomatic AAA patients with a maximum diameter of at least 30 mm.

FIELD STRENGTH/SEQUENCE

A 3.0 T/Free-breathing 4D flow MRI phase-contrast acquisition with retrospective ECG-gating.

ASSESSMENT

Patients underwent two consecutive 4D flow MRI scans 1-week apart. Aortic volumes were segmented from time-averaged phase contrast magnetic resonance angiographies. Reproducibility was assessed by voxelwise analysis after registration. Mean flow velocity, mean wall shear stress (WSS), mean lumen diameter, and qualitative vorticity scores were assessed. In addition, Dixon MRI and retrospective surveillance data were used to study maximum diameter (including thrombus), intraluminal thrombus volume (ILT), and growth rate.

STATISTICAL TESTS

For reproducibility assessment, Bland-Altman analyses, Pearson correlation, Spearman's correlation, and orthogonal regression were conducted. Potential correlations between hemodynamics and vorticity scores were assessed using linear regression. P < 0.05 was considered statistically significant.

RESULTS

Test-retest median Pearson correlation coefficients for flow velocity and WSS were 0.85 (IQR = 0.08) m/sec and 0.82 (IQR = 0.10) Pa, respectively. Mean WSS significantly correlated with mean flow velocity (R = 0.75) and inversely correlated with mean lumen diameter (R = -0.73). No significant associations were found between 4D flow MRI-derived hemodynamic parameters and maximum diameter (flow velocity: P = 0.98, WSS: P = 0.22).

DATA CONCLUSION

A 4D flow MRI is robust for assessing the hemodynamics within AAAs. No correlations were found between hemodynamic parameters and maximum diameter, ILT volume and growth rate.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Long-term clinical outcomes of losartan in patients with Marfan syndrome: follow-up of the multicentre randomized controlled COMPARE trial

AIMS

The COMPARE trial showed a small but significant beneficial effect of 3-year losartan treatment on aortic root dilatation rate in adults with Marfan syndrome (MFS). However, no significant effect was found on clinical endpoints, possibly due to a short follow-up period. The aim of the current study was therefore to investigate the long-term clinical outcomes after losartan treatment.

METHODS AND RESULTS

In the original COMPARE study (inclusion 2008-2009), adult patients with MFS (n = 233) were randomly allocated to either the angiotensin-II receptor blocker losartan® on top of regular treatment (β-blockers in 71% of the patients) or no additional medication. After the COMPARE trial period of 3 years, study subjects chose to continue their losartan medication or not. In a median follow-up period of 8 years, 75 patients continued losartan medication, whereas 78 patients, originally allocated to the control group, never used losartan after inclusion. No differences existed between baseline characteristics of the two groups except for age at inclusion [losartan 34 (interquartile range, IQR 26-43) years, control 41 (IQR 30-52) years; P = 0.031], and β-blocker use (losartan 81%, control 64%; P = 0.022). A pathological FBN1 mutation was present in 76% of patients and 58% of the patients were male. Clinical endpoints, defined as all-cause mortality, aortic dissection/rupture, elective aortic root replacement, reoperation, and vascular graft implantation beyond the aortic root, were compared between the two groups. A per-patient composite endpoint was also analysed. Five deaths, 14 aortic dissections, 23 aortic root replacements, 3 reoperations, and 3 vascular graft implantations beyond the aortic root occurred during follow-up. Except for aortic root replacement, all endpoints occurred in patients with an operated aortic root. Patients who used losartan during the entire follow-up period showed a reduced number of events compared to the control group (death: 0 vs. 5, P = 0.014; aortic dissection: 3 vs. 11, P = 0.013; elective aortic root replacement: 10 vs. 13, P = 0.264; reoperation: 1 vs. 2, P = 0.463; vascular graft implantations beyond the aortic root 0 vs. 3, P = 0.071; and composite endpoint: 14 vs. 26, P = 0.019). These results remained similar when corrected for age and β-blocker use in a multivariate analysis.

CONCLUSION

These results suggest a clinical benefit of combined losartan and β-blocker treatment in patients with MFS.

Context-Relative Norms Determine the Appropriate Type of Consent in Clinical Biobanks: Towards a Potential Solution for the Discrepancy between the General Data Protection Regulation and the European Data Protection Board on Requirements for Consent

Clinical biobanks processing data of participants in the European Union (EU) fall under the scope of the General Data Protection Regulation (GDPR), which among others includes requirements for consent. These requirements are further specified by the Article 29 Working Party (WP29)-an EU advisory body currently known as the European Data Protection Board (EDPB). Unfortunately, their guidance is cause for some confusion. While the GDPR allows participants to give broad consent for research when specific research purposes are still unknown, the WP29 guidelines suggest that additional consent for specific uses should be obtained in addition to broad consent when this becomes applicable. This discrepancy elicits the question whether clinical biobanks can fail the requirement of consent if they obtain broad consent, but not a specific consent for each biomedical study. We analysed this discrepancy within the framework of contextual integrity, in order to describe the context-relative informational norms that govern information flows in clinical biobanks. However, our analysis demonstrates that there is no uniform set of norms that can be applied to all clinical biobanks. As such, neither the GDPR nor the WP29 guidance can act as a "one size fits all" approach to all clinical biobanks. Rather, differences between clinical biobanks-especially regarding the scientific aims and patient populations-make the case for context-relative norms that determine the appropriate type of consent.

Editor's Choice - Nationwide Analysis of Patients Undergoing Iliac Artery Aneurysm Repair in the Netherlands

OBJECTIVE

The new 2019 guideline of the European Society for Vascular Surgery (ESVS) recommends consideration for elective iliac artery aneurysm (eIAA) repair when the iliac diameter exceeds 3.5 cm, as opposed to 3.0 cm previously. The current study assessed diameters at time of eIAA repair and ruptured IAA (rIAA) repair and compared clinical outcomes after open surgical repair (OSR) and endovascular aneurysm repair (EVAR).

METHODS

This retrospective observational study used the nationwide Dutch Surgical Aneurysm Audit (DSAA) registry that includes all patients who undergo aorto-iliac aneurysm repair in the Netherlands. All patients who underwent primary IAA repair between 1 January 2014 and 1 January 2018 were included. Diameters at time of eIAA and rIAA repair were compared in a descriptive fashion. The anatomical location of the IAA was not registered in the registry. Patient characteristics and outcomes of OSR and EVAR were compared with appropriate statistical tests.

RESULTS

The DSAA registry comprised 974 patients who underwent IAA repair. A total of 851 patients were included after exclusion of patients undergoing revision surgery and patients with missing essential variables. eIAA repair was carried out in 713 patients, rIAA repair in 102, and symptomatic IAA repair in 36. OSR was performed in 205, EVAR in 618, and hybrid repairs and conversions in 28. The median maximum IAA diameter at the time of eIAA and rIAA repair was 43 (IQR 38-50) mm and 68 (IQR 58-85) mm, respectively. Mortality was 1.3% (95% CI 0.7-2.4) after eIAA repair and 25.5% (95% CI 18.0-34.7) after rIAA repair. Mortality was not significantly different between the OSR and EVAR subgroups. Elective OSR was associated with significantly more complications than EVAR (intra-operative: 9.8% vs. 3.6%, post-operative: 34.0% vs. 13.8%, respectively).

CONCLUSION

In the Netherlands, most eIAA repairs are performed at diameters larger than recommended by the ESVS guideline. These findings appear to support the recent increase in the threshold diameter for eIAA repair.

Editor's Choice - Sex Related Differences in Peri-operative Mortality after Elective Repair of an Asymptomatic Abdominal Aortic Aneurysm in the Netherlands: a Retrospective Analysis of 2013 to 2018

OBJECTIVE

The aim was to compare peri-operative (30 day and/or in hospital) mortality between women and men in the Netherlands after elective repair of an asymptomatic abdominal aortic aneurysm (AAA).

METHODS

This was a retrospective study using data from the Dutch Surgical Aneurysm Audit (DSAA), a mandatory nationwide registry of patients undergoing AAA repair in the Netherlands. Patients who underwent elective open surgical (OSR) or endovascular aneurysm repair (EVAR) of an asymptomatic abdominal aortic aneurysm (AAA) between 2013 and 2018 were included. Absolute risk differences (ARDs) with 95% confidence intervals (CIs) in peri-operative mortality between women and men were estimated. Logistic regression analyses were performed to estimate adjusted odds ratios (ORs) for mortality. Confounders included pre-operative cardiac and pulmonary comorbidity, serum haemoglobin, serum creatinine, type of AAA repair, and AAA diameter.

RESULTS

Some 1662 women and 9637 men were included, of whom 507 (30.5%) women and 2056 (21.3%) men underwent OSR (p < .001). Crude peri-operative mortality was 3.01% in women and 1.60% in men (ARD = 1.41%, 95% CI 0.64-2.37). This significant difference was also observed for OSR (ARD = 2.63%, 95% CI 0.43-5.36), but not for EVAR (ARD = 0.36%, 95% CI -0.16 to 1.17). Female sex remained associated with peri-operative mortality after adjusting for confounders (OR = 1.79, 95% CI 1.20-2.65, p = .004), which was similarly observed for OSR (OR = 1.85, 95% CI 1.16-2.94, p = .01), but not for EVAR (OR = 1.46, 95% CI 0.72-2.95, p = .29).

CONCLUSIONS

Peri-operative mortality after elective repair of an asymptomatic AAA in the Netherlands is higher in women than in men. This disparity might be explained by the higher peri-operative mortality in women undergoing OSR, because no such difference was found in patients undergoing EVAR. Yet, it is likely that there are unaccounted factors at play since female sex remained significantly associated with mortality after adjusting for type of repair.

445Effects of losartan and beta-blockers on aortic root dilatation in patients with Marfan Syndrome - results of the extended COMPARE trial

Introduction

Despite several randomized trials, beneficial effects of Losartan and β-blockers in adults with Marfan syndrome (MFS) are not entirely clear. The COMPARE trial previously showed a small but significant beneficial effect of Losartan on top of β-blocker use on aortic root dilatation rate. Yet, this effect was not reproduced by other trials, although in general a favourable effect of Losartan could be demonstrated. All trials in adults with MFS showed lower than expected aortic root dilatation rates, suggesting mildly affected study populations. Therefore we extended the follow-up period of the COMPARE trial up to 10 years and aimed to assess the clinical outcomes of the study cohort, as well as the effect of medication regimes on aortic root dilatation rates in the subgroup of patients with a native aortic root at initial randomization.

Methods

Patients previously enrolled in the COMPARE trial were retrospectively analyzed. Cardiovascular events (aortic dissections, ruptures and operations) and all-cause mortality were assessed. Individual aortic root dilatation rates were estimated in patients with a native aortic root at time of randomization on the basis of linear regression analysis of multiple transthoracic echocardiogram (TTE) results. Correlations between aortic root dilatation rates and cumulative Losartan or β-blocker treatment days were assessed with Spearman's rho (ρ).

Results

During a median follow-up of 8.0 years, two dissections and three deaths occurred in the 151 patients with a native aortic root at time of randomization. The 122 patients that were eligible for aortic root dilatation analysis, underwent a median of 6 TTEs. The median aortic root dilatation rate in these patients was 0.28 (interquartile range 0.09 - 0.59) mm/y. These patients were further classified as either patients with a stable aortic root (n=102) or with aortic root growth (n=20), based on the threshold of 0.9 mm per year. Patients with aortic root growth had significantly more aortic root replacements during follow-up (17/20 vs 18/102, P=0.001).

Furthermore, aortic root dilatation rate was negatively correlated with the number of Losartan treatment days (ρ=−0.272, P=0.003), β-blocker treatment days (ρ=−0.217, P=0.017) and with the duration of follow-up (ρ=−0.437, P<0.001).

Conclusions

Our results support previous findings that Losartan and β-blockers appear to be equally effective on aortic root dilatation rate in Marfan Syndrome patients. The low event rate in the long term follow-up of this subgroup of the COMPARE trial represent a relatively mildly affected study population and an aggressive prophylactic surgical regime.

Design and protocol of a comprehensive multicentre biobank for abdominal aortic aneurysms

INTRODUCTION

The pathophysiology and natural course of abdominal aortic aneurysms (AAAs) are insufficiently understood. In order to improve our understanding, it is imperative to carry out longitudinal research that combines biomarkers with clinical and imaging data measured over multiple time points. Therefore, a multicentre biobank, databank and imagebank has been established in the Netherlands: the 'Pearl Abdominal Aortic Aneurysm' (AAA bank).

METHODS AND ANALYSIS

The AAA bank is a prospective multicentre observational biobank, databank and imagebank of patients with an AAA. It is embedded within the framework of the Parelsnoer Institute, which facilitates uniform biobanking in all university medical centres (UMCs) in the Netherlands. The AAA bank has been initiated by the two UMCs of Amsterdam UMC and by Leiden University Medical Center. Participants will be followed during AAA follow-up. Clinical data are collected every patient contact. Three types of biomaterials are collected at baseline and during follow-up: blood (including DNA and RNA), urine and AAA tissue if open surgical repair is performed. Imaging data that are obtained as part of clinical care are stored in the imagebank. All data and biomaterials are processed and stored in a standardised manner. AAA growth will be based on multiple measurements and will be analysed with a repeated measures analysis. Potential associations between AAA growth and risk factors that are also measured on multiple time points can be assessed with multivariable mixed-effects models, while potential associations between AAA rupture and risk factors can be tested with a conditional dynamic prediction model with landmarking or with joint models in which linear mixed-effects models are combined with Cox regression.

ETHICS AND DISSEMINATION

The AAA bank is approved by the Medical Ethics Board of the Amsterdam UMC (University of Amsterdam).

TRIAL REGISTRATION NUMBER

NCT03320408.

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

OBJECTIVES

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

DESIGN

A systematic review.

MATERIALS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Value of Sigmoidoscopy to Detect Colonic Ischaemia After Ruptured Abdominal Aortic Aneurysm Repair

OBJECTIVES

Diagnosing colonic ischaemia (CI) after ruptured abdominal aortic aneurysm (RAAA) repair is challenging. This study determined the diagnostic value of sigmoidoscopy in patients suspected of CI after RAAA repair.

METHODS

This was a retrospective multicentre cohort study. Patients who underwent RAAA repair in three hospitals in Amsterdam, the Netherlands, between 2004 and 2011 (AJAX cohort) were included. Sigmoidoscopies were carried out based on clinical judgment. Endoscopy results were classified as "no ischaemia," "mild CI," or "moderate to severe CI." The surgical diagnosis was classified as "transmural" or "no transmural" CI. The value of sigmoidoscopy was assessed with calculation of positive and negative predictive values (PPV, NPV) with 95% CI for transmural CI. Logistic regression analysis was used to express the association of risk factors with CI as adjusted OR.

RESULTS

Transmural CI was diagnosed in 23 of 351 patients (6.6%). Thirteen of sixteen patients (81%) who underwent direct laparotomy for high suspicion of CI indeed had transmural CI. Forty-six patients (13%) underwent sigmoidoscopy. The prevalence of transmural CI was 22% (10/46; 95% CI 12-36%) in these patients. The PPV for transmural CI of "moderate to severe CI" on sigmoidoscopy was 73% (8/11; 95% CI 43-90%). The PPV of "mild CI" on sigmoidoscopy was 11% (2/19; 95% CI 2.9-31%). The NPV of "no ischaemia" on sigmoidoscopy was 100% (95% CI 78-100%). Cardiac comorbidity (OR 3.1, 95% CI 1.19-7.97), low first haemoglobin (OR 0.6, 95% CI 0.47-0.87), and high vasopressor administration (OR 9.4, 95% CI 1.99-44.46) were independently associated with CI.

CONCLUSIONS

Sigmoidoscopy increases the likelihood of correctly identifying the presence or absence of transmural CI, especially in patients with a moderate clinical suspicion for CI after RAAA repair.

Systematic review and meta-analysis of the risk of bowel ischemia after ruptured abdominal aortic aneurysm repair

OBJECTIVE

Outcomes after repair of ruptured abdominal aortic aneurysm (RAAA) have improved in the last decade. It is unknown whether this has resulted in a reduction of postoperative bowel ischemia (BI). The primary objective was to determine BI prevalence after RAAA repair. Secondary objectives were to determine its major sequelae and differences between open repair (OR) and endovascular aneurysm repair (EVAR).

METHODS

This systematic review (PROSPERO CRD42017055920) followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. MEDLINE and Embase were searched for studies published from 2005 until 2018. The methodologic quality of observational studies was assessed with the Methodological Index for Non-Randomized Studies (MINORS) tool. The quality of the randomized controlled trials (RCTs) was assessed with the Cochrane Collaboration's tool for assessing risk of bias. BI prevalence and rates of BI as cause of death, reoperation, and bowel resection were estimated with meta-analyses with a random-effects model. Differences between OR and EVAR were estimated with pooled risk ratios with 95% confidence intervals (CIs). Changes over time were assessed with Spearman rank test (ρ). Publication bias was assessed with a funnel plot analysis.

RESULTS

A total of 101 studies with 52,670 patients were included; 72 studies were retrospective cohort studies, 14 studies were prospective cohort studies, 12 studies were retrospective administrative database studies, and 3 studies were RCTs. The overall methodologic quality of the RCTs was high, but that of observational studies was low. The pooled prevalence of BI ranged from of 0.08 (95% CI, 0.07-0.09) in database studies to 0.10 (95% CI, 0.08-0.12) in cohort studies. The risk of BI was higher after OR than after EVAR (risk ratio, 1.79; 95% CI, 1.25-2.57). The pooled rate of BI as cause of death was 0.04 (95% CI, 0.03-0.05), and that of BI as cause of reoperation and bowel resection ranged between 0.05 and 0.07. BI prevalence did not change over time (ρ, -0.01; P = .93). The funnel plot analysis was highly suggestive of publication bias.

CONCLUSIONS

The prevalence of clinically relevant BI after RAAA repair is approximately 10%. Approximately 5% of patients undergoing RAAA repair suffer from severe consequences of BI. BI is less prevalent after EVAR than after OR.

Prophylactic Mesh Reinforcement versus Sutured Closure to Prevent Incisional Hernias after Open Abdominal Aortic Aneurysm Repair via Midline Laparotomy: A Systematic Review and Meta-Analysis

OBJECTIVE/BACKGROUND

Incisional hernia is a frequent late complication after open abdominal aortic aneurysm (AAA) repair. We aimed to determine whether prophylactic mesh reinforcement of the abdominal wall at open AAA repair via midline laparotomy reduces the rate of incisional hernia compared to standard sutured closure.

METHODS

A systematic review and meta-analysis was carried out in accordance with the PRISMA statement (PROSPERO registration CRD42017072508). Randomised controlled trials (RCTs) comparing prophylactic mesh reinforcement with standard sutured closure were eligible for inclusion. MEDLINE, Embase, and the Cochrane Library were searched. A meta-analysis with a random effects model was carried out to estimate pooled risk ratios (RR) with 95% confidence intervals (CIs) for the incidence of, and re-operation rate for, incisional hernias. Assessments of methodological quality, quality of evidence, and strength of recommendations were done with the Cochrane Collaboration's tool for assessing risk of bias and the GRADE approach.

RESULTS

Four RCTs with a total of 388 patients were included in the meta-analysis. Pooled analysis showed that mesh reinforcement significantly reduced the risk of incisional hernia after AAA repair compared with standard sutured closure (RR 0.27, 95% CI 0.11-0.66). The pooled rate of re-operations was not different between groups (RR 0.23, 95% CI 0.11-1.05). Mesh reinforcement did not cause more intra-operative or post-operative complications than sutured closure. The risk of bias in studies was low and the quality of evidence was rated as moderate.

CONCLUSION

Prophylactic mesh reinforcement of the abdominal wall after open AAA repair via midline laparotomy significantly reduces the risk of incisional hernia. However, no significant difference in re-operation for incisional hernia was found.

Value of risk scores in the decision to palliate patients with ruptured abdominal aortic aneurysm

Background

The aim of this study was to develop a 48‐h mortality risk score, which included morphology data, for patients with ruptured abdominal aortic aneurysm presenting to an emergency department, and to assess its predictive accuracy and clinical effectiveness in triaging patients to immediate aneurysm repair, transfer or palliative care.

Methods

Data from patients in the IMPROVE (Immediate Management of the Patient With Ruptured Aneurysm: Open Versus Endovascular Repair) randomized trial were used to develop the risk score. Variables considered included age, sex, haemodynamic markers and aortic morphology. Backwards selection was used to identify relevant predictors. Predictive performance was assessed using calibration plots and the C‐statistic. Validation of the newly developed and other previously published scores was conducted in four external populations. The net benefit of treating patients based on a risk threshold compared with treating none was quantified.

Results

Data from 536 patients in the IMPROVE trial were included. The final variables retained were age, sex, haemoglobin level, serum creatinine level, systolic BP, aortic neck length and angle, and acute myocardial ischaemia. The discrimination of the score for 48‐h mortality in the IMPROVE data was reasonable (C‐statistic 0·710, 95 per cent c.i. 0·659 to 0·760), but varied in external populations (from 0·652 to 0·761). The new score outperformed other published risk scores in some, but not all, populations. An 8 (95 per cent c.i. 5 to 11) per cent improvement in the C‐statistic was estimated compared with using age alone.

Conclusion

The assessed risk scores did not have sufficient accuracy to enable potentially life‐saving decisions to be made regarding intervention. Focus should therefore shift to offering repair to more patients and reducing non‐intervention rates, while respecting the wishes of the patient and family.

Not much help

Psoas Muscle Area as a Prognostic Factor for Survival in Patients with an Asymptomatic Infrarenal Abdominal Aortic Aneurysm: A Retrospective Cohort Study

OBJECTIVES

Loss of muscle mass has been associated with poor survival in several surgical patient populations, including those with an abdominal aortic aneurysm (AAA). We wanted to replicate these findings and assess the association between psoas muscle area (PMA) and survival in patients with an asymptomatic AAA.

METHODS

Patients with an asymptomatic infrarenal AAA who underwent computed tomography (CT) scanning between January 1, 2007, and December 31, 2013, were included in this single-centre retrospective cohort study. PMA was measured with thresholding on an axial image at the centre level of the third lumbar vertebra. The lowest tertile of PMA in all patients was used as a cutoff value for a low PMA. Then, in separate analyses for conservatively and surgically managed patients, survival was estimated with the Kaplan-Meier method. Differences in survival between patients with and without a low PMA were tested with the log-rank test.

RESULTS

Of 228 patients, 104 were managed conservatively and 124 underwent AAA repair. Seventy-seven patients (62%) had an endovascular repair. In these 228 patients, the median PMA was 16.83 cm², while the cutoff value for low PMA was 14.56 cm². Patients who were managed conservatively were more often classified as having low PMA (45/104, 43%, vs. 31/124, 25%; p = .004) and were significantly older (mean 73.44 ± 9.05 years vs. 69.03 ± 7.46 years; p < .001). Low PMA was not associated with survival, either in patients managed conservatively, or in those who underwent AAA repair (p = .512 and p = .311, respectively).

CONCLUSIONS

The association between low PMA and poor survival could not be replicated; in this study, low PMA was not associated with survival in patients with an asymptomatic AAA. Further research is recommended before PMA can be used for pre-operative risk stratification.

Lasagna plots to visualize results in surgical studies

BACKGROUND

A lasagna plot is a graphical tool that can display multiple longitudinal outcomes. To our knowledge, lasagna plots have not been used in publications of surgical studies before. The objective of this study was to demonstrate the results of surgical randomized controlled trials (RCTs) with lasagna plots in order to assess whether this can lead to new observations of the data presented in the original studies.

MATERIAL AND METHODS

Lasagna plots were created with R for an RCT comparing endovascular and open repair for patients with a ruptured abdominal aortic aneurysm (AJAX trial), an RCT comparing laparoscopy or open surgery combined with either fast track or standard care for patients with colon cancer (LAFA trial) and an RCT comparing preoperative biliary drainage and early surgery for patients with pancreatic cancer (DROP trial).

RESULTS

Regarding the AJAX trial, the original article had reported the rate of outcomes at 30 days after repair in two tables. The plots additionally demonstrated the moments of occurrence, increase and decrease of multiple outcomes such as renal replacement therapy and occurrence of death within one plot. These observations were not presented in the original article. The lasagna plots of the LAFA and DROP trial revealed similar new observations on multiple longitudinal outcomes.

CONCLUSION

By revealing new observations of the previously published data, lasagna plots generate new hypotheses and theories regarding the outcomes. As such, lasagna plots may be a useful addition to traditional tables and figures and could improve the interpretation of results.

Biomechanical Imaging Markers as Predictors of Abdominal Aortic Aneurysm Growth or Rupture: A Systematic Review

OBJECTIVES

Biomechanical characteristics, such as wall stress, are important in the pathogenesis of abdominal aortic aneurysms (AAA) and can be visualised and quantified using imaging techniques. This systematic review aims to present an overview of all biomechanical imaging markers that have been studied in relation to AAA growth and rupture.

METHODS

This systematic review followed the PRISMA guidelines. A search in Medline, Embase, and the Cochrane Library identified 1503 potentially relevant articles. Studies were included if they assessed biomechanical imaging markers and their potential association with growth or rupture.

RESULTS

Twenty-seven articles comprising 1730 patients met the inclusion criteria. Eighteen studies performed wall stress analysis using finite element analysis (FEA), 13 of which used peak wall stress (PWS) to quantify wall stress. Ten of 13 case control FEA studies reported a significantly higher PWS for symptomatic or ruptured AAAs than for intact AAAs. However, in some studies there was confounding bias because of baseline differences in aneurysm diameter between groups. Clinical heterogeneity in methodology obstructed a meaningful meta-analysis of PWS. Three of five FEA studies reported a significant positive association between several wall stress markers, such as PWS and 99th percentile stress, and growth. One study reported a significant negative association and one other study reported no significant association. Studies assessing wall compliance, the augmentation index and wall stress analysis using Laplace's law, computational fluid dynamics and fluid structure interaction were also included in this systematic review.

CONCLUSIONS

Although PWS is significantly higher in symptomatic or ruptured AAAs in most FEA studies, confounding bias, clinical heterogeneity, and lack of standardisation limit the interpretation and generalisability of the results. Also, there is conflicting evidence on whether increased wall stress is associated with growth.

Inflammation as a Predictor of Abdominal Aortic Aneurysm Growth and Rupture: A Systematic Review of Imaging Biomarkers

BACKGROUND

Methods are required to identify abdominal aortic aneurysms (AAAs) at increased risk of rupture. Inflammatory characteristics of AAA can be visualised using advanced imaging techniques and have been proposed as potential predictors of aneurysm progression. The objective of this review was to determine which inflammatory imaging biomarkers are associated with AAA growth and rupture.

METHODS

A systematic review was carried out in accordance with the PRISMA guidelines. The electronic databases of Medline (PubMed), Embase, and the Cochrane Library were searched up to January 1, 2016 for studies to determine the potential association between inflammatory imaging biomarkers and AAA growth or rupture.

RESULTS

Seven studies were included, comprising 202 AAA patients. (18)F-fluoro-deoxy-glucose positron emission tomography ((18)F-FDG PET-CT) was evaluated in six studies. Magnetic resonance imaging with ultrasmall superparamagnetic particles of iron oxide (USPIO-MRI) was evaluated in one study. Two of six (18)F-FDG PET-CT studies reported a significant negative correlation (r=.383, p = .015) or a significant negative association (p = .04). Four of six (18)F-FDG PET-CT studies reported no significant association between (18)F-FDG uptake and AAA growth. The single study investigating USPIO-MRI demonstrated that AAA growth was three times higher in patients with focal USPIO uptake in the AAA wall compared to patients with diffuse or no USPIO uptake in the wall (0.66 vs. 0.24 vs. 0.22 cm/y, p = .020). In the single study relating (18)F-FDG uptake results to AAA rupture, the association was not significant.

CONCLUSIONS

Current evidence shows contradictory associations between (18)F-FDG uptake and AAA growth. Data on the association with rupture are insufficient. Based on the currently available evidence, neither (18)F-FDG PET-CT nor USPIO-MRI can be implemented as growth or rupture prediction tools in daily practice. The heterogeneous results reflect the complex and partially unclear relationship between inflammatory processes and AAA progression.

Evaluation of preoperative geriatric assessment of elderly patients with colorectal carcinoma. A retrospective study

AIMS

Elderly patients with colorectal carcinoma are screened with the Identification of Seniors at Risk (ISAR) questionnaire to identify frail patients. These patients are more at risk for mortality and morbidity and are referred to the geriatric specialist for assessment (Dutch acronym: DOG). The DOG assessment aims to preoperatively optimize the patient in order to improve postoperative outcomes. This study evaluates if the DOG assessment influences postoperative outcome after colorectal surgery.

METHODS

Retrospective cohort and match-control study. Elderly patients who underwent elective resection between 01-01-2008 and 01-08-2013 in the Medical Centre Alkmaar were included. Patients with a positive ISAR score were referred to the geriatric specialists for DOG assessment (DOG patients). DOG assessment encompassed comprehensive geriatric assessment and interventions.

PRIMARY OUTCOMES

Mortality, delirium and length of hospital stay.

SECONDARY OUTCOMES

postoperative complications.

COHORT COMPARISON

Cohort ISAR- (2008-2010, no ISAR questionnaire) is compared with cohort ISAR+ (2011-2013, ISAR questionnaire). Match-control comparison: DOG patients are compared with matched controls from cohort ISAR-.

RESULTS

Compared to their matched controls, DOG patients were older and had a higher prevalence of certain risk factors for postoperative delirium. In both comparisons, no statistical significant differences were found between the groups in mortality and postoperative delirium. Length of stay was significantly shorter in cohort ISAR+.

CONCLUSIONS

While the DOG patients were significantly more at risk for postoperative complications, the DOG patients had comparable postoperative outcomes as their matched controls. We therefore conclude that the DOG assessment has a positive influence on the postoperative outcomes after colorectal surgery.