Editor's Choice - Infective Native Aortic Aneurysms: A Delphi Consensus Document on Terminology, Definition, Classification, Diagnosis, and Reporting Standards

OBJECTIVE

There is no consensus regarding the terminology, definition, classification, diagnostic criteria, and algorithm, or reporting standards for the disease of infective native aortic aneurysm (INAA), previously known as mycotic aneurysm. The aim of this study was to establish this by performing a consensus study.

METHODS

The Delphi methodology was used. Thirty-seven international experts were invited via mail to participate. Four two week Delphi rounds were performed, using an online questionnaire, initially with 22 statements and nine reporting items. The panellists rated the statements on a five point Likert scale. Comments on statements were analysed, statements revised, and results presented in iterative rounds. Consensus was defined as ≥ 75% of the panel selecting "strongly agree" or "agree" on the Likert scale, and consensus on the final assessment was defined as Cronbach's alpha coefficient > .80.

RESULTS

All 38 panellists completed all four rounds, resulting in 100% participation and agreement that this study was necessary, and the term INAA was agreed to be optimal. Three more statements were added based on the results and comments of the panel, resulting in a final 25 statements and nine reporting items. All 25 statements reached an agreement of ≥ 87%, and all nine reporting items reached an agreement of 100%. The Cronbach's alpha increased for each consecutive round (round 1 = .84, round 2 = .87, round 3 = .90, and round 4 = .92). Thus, consensus was reached for all statements and reporting items.

CONCLUSION

This Delphi study established the first consensus document on INAA regarding terminology, definition, classification, diagnostic criteria, and algorithm, as well as reporting standards. The results of this study create essential conditions for scientific research on this disease. The presented consensus will need future amendments in accordance with newly acquired knowledge.

The value of 18F-FDG-PET-CT in the management of infective native aortic aneurysms

OBJECTIVE

The objective of this systematic literature review was to explore the value of positron emission tomography combined with low-dose computed tomography (18F-FDG-PET-CT) in the diagnostics of infective native aortic aneurysm (INAA).

METHODS

A systematic literature review was performed using the search terms mycotic- and infected aortic aneurysms in Medline and Sciencedirect databases, published between 1 January 2000 and 1 January 2020. Using the PRISMA statement, articles were scrutinized according to a predefined protocol including: timing of 18F-FDG-PET-CT examination, the maximum standardized uptake value (SUVmax), additional findings on examination, and findings on repeated scanning of 18F-FDG-PET-CT.

RESULTS

Four studies were included in the analysis, comprising a total of 11 patients. Two studies were single case reports, and two were small case series, all were graded to be of low quality with high risk of bias. All patients were examined with a preoperative 18F-FDG-PET-CT, and 10 (91%) had increased 18F-FDG uptakes. The median SUVmax value was 6.53, range 4.46-9.23. The mean duration of antibiotic therapy prior to 18F-FDG-PET-CT was not known. Two patients were examined with repeated 18F-FDG-PET-CT examinations after treatment, where a decrease in SUVmax values could be demonstrated after successful treatment.

CONCLUSION

The literature on 18F-FDF-PET/CT for diagnosing infective native aortic aneurysms is scarce. However, there might be a role for 18F-FDF-PET/CT in the management of the disease, in particular for patients with clinical suspicion of INAA without convincing findings on CT. SUVmax values ranging from 4.5 to 6.5 could be guiding and suggestive of metabolic activity in agreement of INAA. However, further conclusions on its usefulness, robustness and specific SUVmax values are premature, and a definitive cut-off value is probably not attainable.

Outcomes of patients with aortic vascular graft and endograft infections initially contra-indicated for complete graft explantation

OBJECTIVE

Complete excision in patients with aortic vascular graft and endograft infections (VGEIs) is a significant undertaking, and many patients never undergo definitive treatment. Knowing their fate is important to be able to assess the risks of graft excision vs alternative strategies. This study analyzed their life expectancy and sepsis-free survival.

METHODS

VGEIs were diagnosed according to the Aortic Graft Infection (MAGIC) criteria, and patients turned down for graft removal from November 2006 to December 2020 were included. Primary endpoints were aortic-related and sepsis-free survival estimated using the Kaplan-Meier method. A Cox proportional hazards regression analysis was used to compute the hazard ratio (HR) and 95% confidence interval (CI) as estimates of survival without sepsis.

RESULTS

Seventy-four patients were included, with a median age of 71 years (range, 63-79 years). The index aortic repair was either open (n = 33; 44.6%), endovascular (n = 19; 25.7%), or hybrid (n = 22; 29.7%). Causative organisms were identified in 56 patients (75.7%). At presentation, 26 patients (35.1%) required salvage surgery, open (n = 22; 29.7%) or endovascular (n = 8; 10.8%), and 17 radiological drainage (23.0%). During follow-up, eight required drainage and 11 (14.9%) graft removal (five complete). Infectious complications included pseudoaneurysms (n = 14; 18.9%), rupture (n = 9; 12.2%), gastro-intestinal bleeding (n = 13; 17.6%), septic embolisms (n = 4; 5.4%), and thrombosis (n = 12; 16.2%). In-hospital mortality was 20.3% (n = 15), freedom from aortic-related death and overall survival was 77.1% (95% CI, 65.2%-85.3%) and 70.4% (95% CI, 58.3%-79.7%) at 1 year, and 61.7% (95% CI, 46.1%-74.0%) and 43.1% (95% CI, 29.2%-56.3%) at 5 years. Sepsis recurrence occurred in 37 patients (50.0%). Seven (16.3%) developed acquired antimicrobial resistance. Malnutrition (HR, 3.3; 95% CI, 1.4-7.6; P = .005), hemorrhagic shock at presentation (HR, 2.9; 95% CI, 1.0-8.2; P = .048), aorto-enteric fistulae (HR, 3.3; 95% CI, 1.3-8.4; P = .011), fungal coinfection (HR, 3.5; 95% CI, 1.2-11.5; P = .030), and infection with resistant micro-organisms (HR, 3.1; 95% CI, 1.1-8.3; P = .023) were significantly associated with worse survival without sepsis.

CONCLUSIONS

In-hospital and aortic-related mortality were significant, but with salvage surgery and antibiotic therapy, the median survival was 3 years. Sepsis recurrence remained frequent, and further procedures were needed. These outcomes should be considered when graft excision is proposed. Known predictors of adverse outcomes should become important points for discussion in multidisciplinary team meetings.

Infective Native Aortic Aneurysm: a Delphi Consensus Document on Treatment, Follow Up, and Definition of Cure

OBJECTIVE

Evidence is lacking to guide the management of infective native aortic aneurysm (INAA). The aim of this study was to establish expert consensus on surgical and antimicrobial treatment and follow up, and to define when an INAA is considered cured.

METHODS

Delphi methodology was used. The principal investigators invited 47 international experts (specialists in infectious diseases, radiology, nuclear medicine, and vascular and cardiothoracic surgery) via email. Four Delphi rounds were performed, three weeks each, using an online questionnaire with initially 28 statements. The panellists rated the statements on a five point Likert scale. Comments on statements were analysed, statements were revised and added or deleted, and the results were presented in the iterative rounds. Consensus was defined as ≥ 75% of the panel rating a statement as strongly agree or agree on the Likert scale, and consensus on the final assessment was defined as Cronbach's alpha > 0.80.

RESULTS

All 49 panellists completed all four rounds, resulting in 100% participation. One statement was added based on the results and comments of the panel, resulting in 29 final statements: three on need for consensus, 20 on treatment, five on follow up, and one on definition of cure. All 29 statements reached agreement of ≥ 86%. Cronbach's alpha increased for each consecutive round; round 1, 0.85; round 2, 0.90; round 3, 0.91; and round 4, 0.94. Thus, consensus was reached for all statements.

CONCLUSION

INAAs are rare, and high level evidence to guide optimal management is lacking. This consensus document was established with the aim of helping clinicians manage these challenging patients, as a supplement to current guidelines. The presented consensus will need future amendments in accordance with newly acquired knowledge.

Reconstruction of primary and secondary aortic infections with an antimicrobial graft

INTRODUCTION

In situ reconstruction (ISR) with autologous veins is the preferred method in infectious native aortic aneurysms (INAAs) or vascular (endo)graft infection (VGEI). However, access to biological substitutes can prove difficult and lacks versatility. This study evaluates survival and freedom from reinfection after ISR of INAA/VGEI using the antimicrobial Intergard Synergy graft combining silver and triclosan.

METHODS

From February 2014 to April 2020, 86 antimicrobial grafts were implanted for aortic infection. The diagnosis of INAA/VGEI and reinfection was established based on the Management of Aortic Graft Infection Collaboration criteria. Survival was analyzed using the Kaplan-Meier method and log-rank P values.

RESULTS

The antimicrobial graft was implanted in 32 cases of INAA, 28 of VGI, and 26 of VEI. The median age was 69.0 (interquartile range: 62.0; 74.0), with a history of coronary artery disease (n = 21; 24.4%), chronic kidney disease (n = 11; 12.8%), cancer (n = 21; 24.4%), and immunosuppression (n = 27; 31.4%). Imaging showed infiltration (n = 14; 16.3%), air (n = 10; 11.6%), and rupture (n = 16; 18.6% including 22 aortoenteric fistulae [AEnF]). Symptoms included fever (n = 37; 43.0%), shock (n = 11; 12.8%), and pain (n = 47; 54.7%). Repair was undertaken through a midline laparotomy in 75 cases (87.2%) and coeliac cross-clamping in 19 (22.1%), suprarenal in 26 (30.2%), plus celiac trunk (n = 3), mesenteric (n = 5), renal (n = 13), or hypogastric (n = 4) artery reconstruction, and omental flap coverage (n = 41; 48.8%). For AEnF, the gastrointestinal tract was repaired using direct suture (n = 14; 16.3%) or resection anastomosis (n = 8; 9.3%). Causative organisms were identified in 74 patients (86.0%), with polymicrobial infection in 32 (37.2%) and fungal coinfection in 7 (8.1%). Thirty-day and in-hospital mortality were 14.0% and 22.1% (n = 12 and 19, respectively, 3 INAA [9.4%], 7 VGI [25.0%], and 9 VEI [34.6%]). Seventy patients (81.4%) had a postoperative complication, 44 (51.2%) of whom returned to the operative room. The 1- and 2-year survival rates were 74.0% (95% confidence interval [CI]: 63.3-82.1) and 69.8% (95% CI: 58.5-78.5), respectively. Survival was significantly better for INAA vs VGEI (P = .01) and worse for AEnF (P = .001). Freedom from reinfection was 97.2% (95% CI: 89.2-99.3) and 95.0% (95% CI: 84.8-98.4) with six reinfections (7.0%) requiring two radiological/six surgical drainage and two graft removals. Primary patency was 88.0% (95% CI: 78.1-93.6) and 79.9% (95% CI: 67.3-88.1) with no significant difference between INAA and VGEI (P = .16).

CONCLUSIONS

ISR of INAA or VGEI with the antimicrobial graft showed encouraging early mortality, comparable to the rates found in femoral vein (9%-16%) and arterial allograft (8%-28%) studies, as well as mid-term reinfection. The highest in-hospital mortality was noted for VEI including nearly 50% of AEnF.

Predicting Infection Related Complications After Endovascular Repair of Infective Native Aortic Aneurysms

OBJECTIVE

Endovascular aortic repair (EVAR) as surgical treatment for infective native aortic aneurysm (INAA) is associated with superior survival compared with open surgery, but with the risk of infection related complications (IRCs). This study aimed to assess the association between baseline clinical and computed tomography (CT) features and the risk of post-operative IRCs in patients treated with EVAR for INAA. It also sought to develop a model to predict long term IRCs in patients with abdominal INAA treated with EVAR.

METHODS

All initial clinical details and CT examinations of INAAs between 2005 and 2020 at a major referral hospital were reviewed retrospectively. The images were scrutinised according to aneurysm features, as well as peri-aortic and surrounding organ involvement. Data on post-operative IRCs were found in the patient records. Cox regression analysis was used to derive predictors for IRCs and develop a model to predict five year IRCs after EVAR in abdominal INAA.

RESULTS

Of 3 780 patients with the diagnosis of aortic aneurysm or aortitis, 98 (3%) patients were treated with EVAR for abdominal INAAs and were thus included. The mean follow up time was 52 months (range 0 ‒ 163). The mean transaxial diameter was 6.5 ± 2.4 cm (range 2.1 ‒14.7). In the enrolled patients, 38 (39%) presented with rupture. The five year IRC rate in abdominal INAAs was 26%. Female sex, renal insufficiency, positive blood culture, aneurysm diameter, and psoas muscle involvement were predictive of five year IRC in abdominal INAA after EVAR. The model had a C-index of 0.76 (95% CI 0.66 - 0.87).

CONCLUSION

Pre-operative clinical and CT features have the potential to predict IRC after endovascular aortic repair in INAA patients. These findings stress the importance of rigorous clinical, laboratory, and radiological follow up in these patients.

Features of infective native aortic aneurysms on computed tomography

Background

Infective native aortic aneurysm (INAA) is a rare clinical diagnosis. The purpose of this study was to describe the CT findings of INAAs in detail.

Methods

This was a retrospective single-center study of INAA patients at a major referral hospital between 2005 and 2020. All images were reviewed according to a protocol consisting of aneurysm features, periaortic findings, and associated surrounding structures.

Results

One hundred and fourteen patients (mean age, 66 years [standard deviation, 11 years]; 91 men) with 132 aneurysms were included. The most common locations were infrarenal (50.8%), aortoiliac (15.2%), and juxtarenal (12.9%). The mean transaxial diameter was 6.2 cm. Most INAAs were saccular (87.9%) and multilobulated (91.7%). Calcified aortic plaque was present in 93.2% and within the aneurysm in 51.5%. INAA instability was classified as contained rupture (27.3%), impending rupture (26.5%), and free rupture (3.8%). Rapid expansion was demonstrated in 13 of 14 (92.9%) aneurysms with sequential CT studies. Periaortic inflammation was demonstrated as periaortic enhancement (94.7%), fat stranding (93.9%), soft-tissue mass (92.4%), and lymphadenopathy (62.1%). Surrounding involvement included psoas muscle (17.8%), spondylitis (11.4%), and perinephric region (2.8%). Twelve patients demonstrated thoracic and abdominal INAA complications: fistulas to the esophagus (20%), bronchus (16%), bowel (1.9%), and inferior vena cava (IVC) (0.9%).

Conclusion

The most common CT features of INAA were saccular aneurysm, multilobulation, and calcified plaques. The most frequent periaortic findings were enhancement, fat stranding, and soft-tissue mass. Surrounding involvement, including psoas muscle, IVC, gastrointestinal tract, and bronchi, was infrequent but may develop as critical INAA complications.

A case of Infective Native (Abdominal) Aortic Aneurysm Caused by Streptococcus Agalactiae: An Updated Literature Review Based on New Nomenclature

The management of abdominal aortic aneurysms (AAA) has evolved significantly with the advent of endovascular strategies. Thus, there has been a decline in the number of open AAA repairs once an endovascular option is available. There have also been reports of successful endovascular management of infective native aortic aneurysms (INAA)¹, previously called mycotic aneurysms². The rarity of this condition makes its management a challenging one as there are no standard guidelines. The European Society of Vascular Surgery has suggested that the nomenclature be changed from mycotic aneurysms as this can be misleading to standardise reporting¹. The authors' present a case of a 67-year old male who presented during the peak of the Corona Virus pandemic with constitutional gastrointestinal symptoms. He was subsequently diagnosed with an INAA and successfully managed with open Neo-Aorto Iliac System reconstruction with a homograft³. The report highlights various strategies used in the surgical approach and their benefits in the management of INAA. Furthermore, a literature review of Streptococcus (Streptococcus agalactiae) species as a rare cause of INAA and how these cases were managed are also highlighted.

Analysis of antibiotic strategies to prevent vascular graft or endograft infection after surgical treatment for infective native aortic aneurysms: a systematic review

INTRODUCTION

Some patients with an infective native aortic aneurysm (INAA) develop an aortic vascular graft or endograft infection (VGEI) even after successful open surgical repair or endovascular intervention. The aim of the systematic review and meta-analysis performed herein was to compare the clinical outcomes of different surgical and antibiotic treatment strategies.

METHODS

We systematically searched PubMed, MEDLINE, EMBASE and Web of Science. The keywords used for the search were "mycotic aortic aneurysm", "infected aortic aneurysm", "infective native aortic aneurysm", "antibiotics", "surgery", and "endovascular". The search was limited to articles written in English and to studies involving humans. Articles published before 2000 were excluded. Case reports and review articles were excluded.

RESULTS

Of the 524 studies retrieved from our search of the databases, 47 articles were included in this study. Among the 47 articles (1546 patients, 72.8% of whom were male) retrieved, five articles were excluded from the subgroup analysis because the data concerning open surgical repair and endovascular intervention could not be separated. The remaining 42 articles included a total of 1179 patients who underwent open surgical repair (622 patients) or endovascular intervention (557 patients) for INAA. There was a statistically significant difference (p = 0.001) in the pooled in-hospital mortality rate between the open surgical repair group (13.2%, 82/622) and the endovascular intervention group (7.2%, 40/557). However, there was a statistically significant difference (p < 0.001) in the aortic VGEI rate between the open surgical repair group (5.4%). 29/540) and endovascular intervention (13.3%, 69/517) group. For patients who underwent open surgical repair, a lower rate of aortic vascular graft infection was associated with long-term antibiotic use (p = 0.005). For patients who underwent endovascular intervention, there was a trend of association (p = 0.071) between the lower rate of aortic endograft infection and lifelong antibiotic use.

CONCLUSION

Infective native aortic aneurysms are life-threatening. The pooled in-hospital mortality rate of the open surgical repair group was significantly higher than that of the endovascular intervention group, whereas the rate of the aortic VGEI in the open surgical repair group was significantly lower than that in the endovascular intervention group. Regardless of whether open surgical repair or endovascular intervention is performed, better long-term outcomes can be achieved with aggressive antibiotic treatment, which is especially important for patients who undergo endovascular intervention.

Danish Nationwide Study on Surgical Treatment of Infective Native Abdominal Aortic Aneurysms

OBJECTIVE

This study aimed to describe surgical trends, survival, and infection related complications (IRC) in a Danish cohort of patients with infective native aortic aneurysms (INAAs).

METHODS

A retrospective nationwide cohort study including all patients in Denmark who were surgically treated for abdominal INAA between 2000 and 2020 was conducted. Patients were identified through the Danish vascular registry, Karbase, which is a database registering all patients treated with vascular surgery in Denmark. Subsequent data on clinical presentation, treatment, all cause mortality, and complications were obtained from the electronic patient charts.

RESULTS

Seventy-five patients were included in the study, of whom 60 (80%) were male, with a median age of 69 (IQR 64, 75) years. Open surgical repair (OSR) was performed in 54 (72%) patients and endovascular aortic repair (EVAR) in 21 (28%). Median follow up was 52 (IQR 32, 103) months. Open repair was consistently the most frequent treatment modality throughout the study period, but EVAR became more frequent over time. The 30 day survival of the total cohort was 97% (94 - 100%). Kaplan-Meier survival estimates for the cohort were 92% (95% CI 85 - 98%), 80% (95% CI 71 - 91%), 63% (95% CI 52 - 78%), and 48% (95% CI 35 - 66%) at one, three, five and 10 years, respectively. Patients treated by EVAR had comparable long term survival to patients treated by OSR, with a hazard ratio of 0.35 (95% CI 0.10 - 1.22), but was associated with better short term survival up to five years. The most common cause of death was sepsis. Five (9%) OSR patients had IRC compared with one (5%) EVAR patient.

CONCLUSION

In this nationwide study of patients treated for abdominal INAA, an increasing number of patients were surgically treated during the study period. Patients treated by EVAR demonstrated long term survival comparable to OSR. The incidence of post-operative IRC was low. These results should be interpreted with caution and prospective registries are needed.