Neutrophil-to-Lymphocyte Ratio Associated With Adverse Events After Endovascular Aneurysm Repair (EVAR)

A systematic review of the role of systemic inflammation-based prognostic scores in patients with abdominal aortic aneurysm

BACKGROUND AND AIMS

Activation of the systemic inflammatory response (SIR) is associated with inferior outcomes across a spectrum of disease. Routinely available measures of the SIR (neutrophil:lymphocyte ratio (NLR), platelet:lymphocyte ratio (PLR), systemic immune-inflammatory index (SII), systemic inflammatory grade (SIG)) have been shown to provide prognostic value in patients undergoing surgical intervention. The present study aimed to review the literature describing the prognostic association of NLR, PLR, SII and SIG in patients undergoing intervention for abdominal aortic aneurysm (AAA).

METHODS

This PRISMA guidelines were followed. The MEDLINE database was interrogated for relevant studies investigating the effect of peri-operative systemic inflammation-based prognostic systems on all-cause mortality in patients undergoing OSR and EVAR for AAA. Inter-study heterogeneity precluded meaningful meta-analysis; qualitative analysis was instead performed.

RESULTS

There were 9 studies included in the final review reporting outcomes on a total of 4571 patients; 1256 (27 %) patients underwent OSR, and 3315 (73 %) patients underwent EVAR. 4356 (95 %) patients underwent a procedure for unruptured AAA, 215 (5 %) patients underwent an emergency procedure for ruptured AAA0.5 studies reported early (inpatient or 30-day) mortality; 2 of these found that elevated NLR predicted inferior survival, however PLR did not provide prognostic value. 6 studies reported long-term mortality; elevated NLR (5 studies), PLR (1 study), and SIG (1 study) predicted inferior survival.

CONCLUSIONS

It appears that activation of the SIR is associated with inferior prognosis in patients undergoing intervention for AAA, however the evidence is limited by heterogenous methodology and lack of consensus regarding optimal cutoff.

PROSPERO DATABASE REGISTRATION NUMBER

CRD42022363765.

Inflammation in Abdominal Aortic Aneurysm: cause or co-morbidity?

Aortic aneurysm is a potentially deadly disease. It is chronic degeneration of the aortic wall that involves an inflammatory response and the immune system, aberrant remodeling of the extracellular matrix, and maladaptive transformation of the aortic cells. This review article focuses on the role of the inflammatory cells in abdominal aortic aneurysm. Studies in human aneurysmal specimens and animal models have identified various inflammatory cell types that could contribute to aneurysm formation and or expansion. These include the commonly studied leukocytes (neutrophils and macrophages) as well as the less commonly explored natural killer cells, dendritic cells, T- and B-cells. Despite the well-demonstrated contribution of inflammatory cells and the related signaling pathways to aneurysm development and expansion, anti-inflammatory therapy approaches have demonstrated limitations and may require additional considerations, such as a combinational approach in targeting multiple pathways for significant beneficial outcomes.

The Preoperative Lymphocyte-To-Monocyte Ratio Predicts Mortality Among Patients Undergoing Endovascular Aortic Repair for Abdominal Aortic Aneurysm

PURPOSE

The purpose of this study was to investigate the preoperative lymphocyte-to-monocyte ratio (LMR) as a potential surrogate biomarker predictive of overall mortality in patients undergoing endovascular aortic repair (EVAR) for abdominal aortic aneurysm (AAA).

METHODS

Data on patients with AAA treated by EVAR between March 2012 and December 2016 were obtained from a prospectively maintained EVAR database at Tokyo Medical University Hospital, Tokyo, Japan. The LMR was calculated by dividing the absolute lymphocyte count by the absolute monocyte count.

RESULTS

One hundred seventy-six patients were included in this study after selection based on the exclusion criteria. The subjects consisted of 148 males and 28 females with a mean age of 78.5 years (range, 51-89 years). The median follow-up period was 4.98 years (range, .03-9.28). A receiver operating characteristic curve analysis determined the optimal cut-off value of the preoperative LMR for predicting overall mortality with 3.21 (area under the curve, .71; 95% confidence interval [CI], .62-.79; sensitivity, 57.4%; specificity, 77.0%; P < .001). On univariable and multivariable analyses, octogenarian (hazard ratio [HR], 1.89; 95%CI, 1.10-3.22; P = .020), poor nutritional status (HR, 2.95; 95%CI, 1.73-5.03; P < .001), chronic obstructive pulmonary disease (HR, 1.79; 95%CI, 1.06-3.03; P = .031), active cancer (HR, 2.60; 95%CI, 1.53-4.41; P < .001), and low preoperative LMR (HR, 2.56; 95%CI, 1.53-4.30; P < .001) were identified as independent predictors for overall mortality.

CONCLUSION

This study showed that a low preoperative LMR (<3.21) is an independent predictor of overall mortality after EVAR for AAA. The LMR may help in decision-making regarding the prediction of poor prognosis after EVAR.

Predictors of 30-Day Postoperative Outcome after Elective Endovascular Abdominal Aortic Aneurysm Repair: A Tertiary Referral Center Experience

BACKGROUND

We evaluated the 30-day postoperative outcome after elective endovascular aneurysm repair (EVAR) and the possible predictors for the 30-day postoperative outcome.

MATERIALS

Demographics, medical history, laboratory values, intensive care unit (ICU) admission and 30-day complications classified as major (major adverse cardiovascular events (MACEs), acute kidney injury (AKI) and death of any cause) and minor (postimplantation syndrome (PIS), postoperative delirium (POD), urinary tract infection (UTI) and technical graft failure) were documented (March 2016 to February 2019).

RESULTS

We included 322 patients. The majority were managed under general anesthesia (83%) with femoral cutdown (98.1%). Overall, 121 (37.5%) complications, mostly minor (n = 103, 31.9%), were recorded. In total, 11 patients (3.4%) developed MACEs, 5 (1.6%) experienced AKI and 2 (0.6%) died in the ICU. Moreover, 77 patients (23.9%) suffered from PIS, 11 from POD, 11 from UTI and 4 from technical graft failure. The multivariate logistic regression analysis revealed that aneurysm diameter (p = 0.01) and past smoking (p = 0.003) were predictors for complications. PAD was an independent predictor of MACEs (p = 0.003), preoperative neutrophil to lymphocyte ratio (NLR) of AKI (p = 0.003) and past smoking of PIS (p = 0.008), respectively.

CONCLUSIONS

Our study showed that the 30-day morbidity after EVAR exceeded 35%. However, the majority of complications were minor, and the associated mortality was low. Aneurysm diameter and past smoking were independent predictors for postoperative outcome.

Residual Aneurysmal Sac Shrinkage Post-Endovascular Aneurysm Repair: The Role of Preoperative Inflammatory Markers

INTRODUCTION

In this study, we evaluated the role of preoperative inflammatory markers as Neutrophil-to-Lymphocyte (NLR) and Platelet-to-Lymphocyte (PLR) ratios in relation to post-endovascular aneurysm repair (EVAR) sac shrinkage, which is known to be an important factor for abdominal aortic aneurysm (AAA) healing.

METHODS

This was a single-center retrospective observational study. All patients who underwent the EVAR procedure from January 2017 to December 2020 were eligible for this study. Pre-operative blood samples of all patients admitted were used to calculate NLR and PLR. Sac shrinkage was defined as a decrease of ≥5 mm in the maximal sac diameter. The optimal NLR and PLR cut-offs for aneurysmal sac shrinkage were obtained from ROC curves. Stepwise multivariate analysis was performed in order to identify independent risk and protective factors for the absence of AAA shrinkage. Kaplan-Meier curves were used to evaluate survival rates with respect to the AAA shrinkage.

RESULTS

A total of 184 patients were finally enrolled. The mean age was 75.8 ± 8.3 years, and 85.9% were male (158/184). At a mean follow-up of 43 ± 18 months, sac shrinkage was registered in 107 patients (58.1%). No-shrinking AAA patients were more likely to be older, to have a higher level of NLR and PLR, and be an active smoker. Kaplan-Meier curves highlighted a higher rate of survival for shrinking AAA patients with respect to their counterparts (p < 0.03). Multivariate analysis outlined active smoking and NLR as independent risk factors for no-shrinking AAA.

CONCLUSIONS

Inflammation emerged as a possible causative factor for no-shrinking AAA, playing a role in aneurysmal sac remodeling. This study revealed that inflammatory biomarkers, such as NLR and PLR, can be used as a preoperative index of AAA sac behavior after EVAR procedures.

Neutrophil-to-Lymphocyte Ratio as a Predictive Tool for Post-Operative Outcomes in Patients Undergoing Open Lower Extremity Revascularization Procedures

INTRODUCTION

Elevated neutrophil-to-lymphocyte ratio (NLR), a marker of systemic inflammation, has been shown to correlate with worse outcomes in patients undergoing vascular surgery. Limited data exists on the association of NLR and outcomes in patients undergoing lower extremity vascular surgery. We sought to investigate whether preoperative NLR correlates with outcomes in patients undergoing open lower extremity revascularization procedures.

METHODS

We conducted a retrospective analysis of a prospectively maintained database of patients who underwent open lower extremity revascularization procedures from January 2011 to January 2017 (N=535). Preoperative NLR was calculated within six months of surgery. Primary outcomes were major adverse limb event (MALE) or death. The maximally-ranked statistic method was used to determine the NLR cut-off point. Kaplan-Meier analyses of death and MALE and NLR were used to compare the groups by NLR cut-off point. We conducted a multivariate analysis of the association between NLR and mortality using Cox proportional hazard models, including confounding variables such as age, smoking status, and diabetes. P-values <0.05 were considered statistically significant.

RESULTS

254 patients undergoing surgery from January 2011 to January 2013 were analyzed. The median NLR was 3.6 [IQR 2.5 - 6.7]. The analysis showed a negative correlation between elevated NLR and mortality (P<0.001), but not MALE (P=0.8). Controlling for multiple comorbidities including gender, age, smoking, BMI, diabetes, hyperlipidemia, hypertension, and infection, the NLR cut-off point was a significant independent predictor of mortality (P<0.0001), but not MALE (P=0.551). Elevated NLR was also correlated with statistically and clinically significant longer hospital stays (6.5 [IQR 3.0 - 12.8] days vs. 4.0 [IQR 2.0 - 8.0] days, P=0.027).

CONCLUSION

This study suggests that NLR is an independent predictor of mortality and hospital length of stay in patients undergoing open lower extremity revascularizations. Going forward, we plan to expand this study to include more patients and to compare NLR to other risk assessment tools.

Association of neutrophils, lymphocytes, and neutrophil-lymphocyte ratio to overall mortality after endovascular abdominal aortic aneurysm repair

BACKGROUND

The purpose of this study was to determine the predictive ability of neutrophilia, lymphocytopenia, and neutrophil-lymphocyte ratio (NLR) for overall mortality after EVAR for AAA.

METHODS

Data on patients with AAA treated by EVAR between March 2012 and December 2016 were obtained from a prospectively maintained EVAR database at Tokyo Medical University Hospital. The NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. A cut-off value of total WBC count, neutrophil count, lymphocyte count, and NLR was determined according to a receiver operating characteristic (ROC) curve. Univariate and multivariate analyses were performed using the Cox proportional hazard analyses to account for the time at risk.

RESULTS

178 patients were included in this study after selection based on the exclusion criteria. The subjects consisted of 150 men and 28 women with a mean age of 77.5 years (range, 51-89 years). A ROC curve analysis determined the optimal cut-off values of preoperative total WBC, neutrophils, lymphocytes, and NLR for predicting overall mortality with 7,050 /μL, 4,012 /μL, 1,312 /μL, and 3.19, respectively. On univariate analysis and multivariate analyses, octogenarian, obesity, COPD, active cancer, and lymphocytopenia or NLR were detected as independent predictors for overall mortality.

CONCLUSIONS

Specific leukocyte populations, such as lymphocyte count and NLR, are useful biomarkers to predict overall mortality in patients undergoing EVAR for AAA, suggesting that WBC count and its subsets, which are easy to perform a test, may be used to stratify patients at risk for poor prognosis following EVAR.

Biomarkers in EndoVascular Aneurysm Repair (EVAR) and Abdominal Aortic Aneurysm: Pathophysiology and Clinical Implications

Circulating biomarkers have been recently investigated among patients undergoing endovascular aortic aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA). Considering the plethora of small descriptive studies reporting potential associations between biomarkers and clinical outcomes, this review aims to summarize the current literature considering both the treated disease (post EVAR) and the untreated disease (AAA before EVAR). All studies describing outcomes of tissue biomarkers in patients undergoing EVAR and in patients with AAA were included, and references were checked for additional sources. In the EVAR scenario, circulating interleukin-6 (IL-6) is a marker of inflammatory reaction which might predict postoperative morbidity; cystatin C is a promising early marker of post-procedural acute kidney injury; plasma matrix metalloproteinase-9 (MMP-9) concentration after 3 months from EVAR might help in detecting post-procedural endoleak. This review also summarizes the current gaps in knowledge and future direction of this field of research. Among markers used in patients with AAA, galectin and granzyme appear to be promising and should be carefully investigated even in the EVAR setting. Larger prospective trials are required to establish and evaluate prognostic models with highest values with these markers.

Neutrophils as Regulators and Biomarkers of Cardiovascular Inflammation in the Context of Abdominal Aortic Aneurysms

Neutrophils represent up to 70% of circulating leukocytes in healthy humans and combat infection mostly by phagocytosis, degranulation and NETosis. It has been reported that neutrophils are centrally involved in abdominal aortic aneurysm (AAA) pathogenesis. The natural course of AAA is growth and rupture, if left undiagnosed or untreated. The rupture of AAA has a very high mortality and is currently among the leading causes of death worldwide. The use of noninvasive cardiovascular imaging techniques for patient screening, surveillance and postoperative follow-up is well established and recommended by the current guidelines. Neutrophil-derived biomarkers may offer clinical value to the monitoring and prognosis of AAA patients, allowing for potential early therapeutic intervention. Numerous promising biomarkers have been studied. In this review, we discuss neutrophils and neutrophil-derived molecules as regulators and biomarkers of AAA, and our aim was to specifically highlight diagnostic and prognostic markers. Neutrophil-derived biomarkers may potentially, in the future, assist in determining AAA presence, predict size, expansion rate, rupture risk, and postoperative outcome once validated in highly warranted future prospective clinical studies.