Chronic obstructive pulmonary disease effect on the prevalence and postoperative outcome of abdominal aortic aneurysms: A meta-analysis

The 5-Factor Modified Frailty Index is a Succinct yet Effective Predictor of Adverse Outcomes in Patients Undergoing Open Surgery for Abdominal Aortic Aneurysm

BACKGROUND

Frailty is an age-related, clinically recognizable state marked by increased susceptibility. The 5-item Modified Frailty Index (mFI-5) offers a concise assessment of frailty and has demonstrated its efficacy in various surgical fields. While the mFI-5 has been validated for endovascular aneurysm repair for abdominal aortic aneurysm (AAA), its applicability in open surgical repair (OSR) for AAA remains largely unexplored. This study sought to evaluate the utility of mFI-5 in predicting 30-day outcomes following OSR for AAA.

METHODS

Patients underwent OSR for AAA were identified in American College of Surgeons National Surgical Quality Improvement Program-targeted database from 2012 to 2021. Patients were stratified into 3 cohorts: mFI-5 score of 0 (control), 1, and 2+. Multivariable logistic regression was used to compare 30-day perioperative outcomes between frail patients and controls adjusting preoperative variables with P value <0.1.

RESULTS

Of the 5,249 patients who underwent OSR for AAA, 1,043 were controls, 2,938 had an mFI-5 score of 1 and 1,268 had an mFI-5 score of 2+. When compared to the control group, patients with an mFI-5 = 1 were more likely to have pulmonary events (adjusted odds ratio (aOR) = 1.452, P < 0.01), bleeding events (aOR = 1.33, P < 0.01), wound complications (aOR = 2.214, P < 0.01), ischemic colitis (aOR = 1.616, P = 0.01), and unplanned reoperation (aOR = 1.292, P = 0.04). Those with an mFI-5 = 2+ demonstrated higher risks of mortality (aOR = 1.709, P < 0.01), major adverse cardiovascular events (aOR = 1.347, P = 0.04), pulmonary events (aOR = 2.045, P < 0.01), renal dysfunction (aOR = 1.568, P < 0.01), sepsis (aOR = 1.587, P = 0.01), bleeding events (aOR = 1.429, P < 0.01), wound complications (aOR = 2.338, P < 0.01), ischemic colitis (aOR = 1.775, P = 0.01), unplanned reoperation (aOR = 1.445, P = 0.01), operation over 4 hours (aOR = 1.34, P < 0.01), length of stay over 7 days (aOR = 1.324, <0.01), discharge not to home (aOR = 1.547, P < 0.01), 30-day readmission (aOR = 1.657, P = 0.01).

CONCLUSIONS

The mFI-5 emerges as a succinct yet effective indicator of frailty for patients undergoing OSR for AAA. Especially, an mFI-5 score of 2+ is linked with increased 30-day mortality and complications. As such, mFI-5 can be used as a valuable screening tool for frailty in patients undergoing OSR for AAA.

A prospective longitudinal study of risk factors for abdominal aortic aneurysm

The aim of this study was to identify risk factors for abdominal aortic aneurysm (AAA) from the largest Welsh screening cohort to date. Patients were recruited from 1993 (to 2015) as part of the South East Wales AAA screening programme through general practitioners. Demographic data and risk factors were collected by means of a self-report questionnaire. Statistical tests were performed to determine whether associations could be observed between AAA and potential risk factors. Odds ratios (OR) were also calculated for each of the risk factors identified. A total of 6879 patients were included in the study. Two hundred and seventy-five patients (4.0%) presented with AAA, of which 16% were female and 84% were male. Patients with AAA were older than the (no AAA) control group (p < 0.0001). The following risk factors were identified for AAA: family history of AAA (p < 0.0001); history of vascular surgery (p < 0.0001), cerebrovascular accident (p < 0.0001), coronary heart disease (p < 0.0001), diabetes (p < 0.0001), medication (p = 0.0018), claudication (p < 0.0001), smoking history (p = 0.0001) and chronic obstructive pulmonary disorder (p = 0.0007). AAA is associated with classical vascular risk factors, in addition to other less-well-documented risk factors including previous vascular surgery. These findings have practical implications with the potential to improve future clinical screening of patients in order to reduce AAA mortality.

Utility of Continuous Paravertebral Block After Retroperitoneal Abdominal Aortic Aneurysm Repair

BACKGROUND

Open abdominal aortic aneurysm (AAA) repairs can be associated with significant pain and morbidity. Previous studies have demonstrated utility of adjunctive epidural analgesia (EA) in addition to general anesthesia (GA) to reduce pain and blunt the maladaptive surgical stress response. However, EA may be complicated by epidural hematomas and severe hypotension. Recently, we started using continuous paravertebral block (PVB) for perioperative analgesia after retroperitoneal AAA repair. PVB has some distinct advantages over EA such as unilateral localization, reduced risk of hypotension, and minimal risk of epidural hematoma in the setting of systemic heparinization. This study aimed to examine the utility of PVB by comparing total opioid consumption in the postoperative period among patients who received GA + PVB and those who received GA alone.

METHODS

This retrospective matched cohort study included 62 patients who underwent elective retroperitoneal AAA repair between January 2019 and August 2022. Thirty-one subjects managed with GA + PVB were compared with 31 control subjects treated with GA alone, matched on following criteria: age, sex, and cross-clamp location. Outcome measures included total opioid analgesics administered during their inhospital postoperative course, time to extubation, time to return to baseline activity, time to normal bowel function, and length of stay. Opioid doses were converted to morphine milligram equivalents (MMEs).

RESULTS

The GA + PVB group required significantly less opioid analgesics (81 ± 53 MME) than the GA group (171 ± 121 MME) (P < 0.001). Compared to GA alone, GA + PVB was superior in every clinical metric examined: time to extubation (3 vs. 1 hr, P < 0.001), recovery of bowel function (3 vs. 2 days, P = 0.002), recovery of baseline physical activity (4 vs. 2 days, P = 0.019), and length of stay (5 vs. 3 days, P < 0.001).

CONCLUSIONS

Continuous paravertebral block provides better pain management with significantly decreased opioid requirements in the postoperative period compared to GA-alone for patients undergoing elective retroperitoneal AAA repair.

Development and validation of a machine-learning prediction model to improve abdominal aortic aneurysm screening

OBJECTIVE

Despite recommendations by the United States Preventive Services Task Force and the Society for Vascular Surgery, adoption of screening for abdominal aortic aneurysms (AAAs) remains low. One challenge is the low prevalence of AAAs in the unscreened population, and therefore a low detection rate for AAA screenings. We sought to use machine learning to identify factors associated with the presence of AAAs and create a model to identify individuals at highest risk for AAAs, with the aim of increasing the detection rate of AAA screenings.

METHODS

A machine-learning model was trained using longitudinal medical records containing lab results, medications, and other data from our institutional database. A retrospective cohort study was performed identifying current or past smoking in patients aged 65 to 75 years and stratifying the patients by sex and smoking status as well as determining which patients had a confirmed diagnosis of AAA. The model was then adjusted to maximize fairness between sexes without significantly reducing precision and validated using six-fold cross validation.

RESULTS

Validation of the algorithm on the single-center institutional data utilized 18,660 selected patients over 2 years and identified 314 AAAs. There were 41 factors identified in the medical record included in the machine-learning algorithm, with several factors never having been previously identified to be associated with AAAs. With an estimated 100 screening ultrasounds completed monthly, detection of AAAs is increased with a lift of 200% using the algorithm as compared with screening based on guidelines. The increased detection of AAAs in the model-selected individuals is statistically significant across all cutoff points.

CONCLUSIONS

By utilizing a machine-learning model, we created a novel algorithm to detect patients who are at high risk for AAAs. By selecting individuals at greatest risk for targeted screening, this algorithm resulted in a 200% lift in the detection of AAAs when compared with standard screening guidelines. Using machine learning, we also identified several new factors associated with the presence of AAAs. This automated process has been integrated into our current workflows to improve screening rates and yield of high-risk individuals for AAAs.

Development of a comorbidity index for patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Endovascular aneurysm repair (EVAR) and open surgical repair (OSR) are two modalities to treat patients with abdominal aortic aneurysm (AAA). Alternative to individual comorbidity adjustment, a summary comorbidity index is a weighted composite score of all comorbidities that can be used as standard metric to control for comorbidity burden in clinical studies. This study aimed to develop summary comorbidity indices for patients who underwent AAA repair.

METHODS

Patients who went under EVAR or OSR were identified in National Inpatient Sample (NIS) between the last quarter of 2015 to 2020. In each group, patients were randomly sampled into experimental (2/3) and validation (1/3) groups. The weights of Elixhauser comorbidities were determined from a multivariable logistic regression and single comorbidity indices were developed for EVAR and OAR groups, respectively.

RESULTS

There were 34,668 patients underwent EVAR (2.19% mortality) and 4792 underwent OSR (10.98% mortality). Both comorbidity indices had moderate discriminative power (EVAR c-statistic, 0.641; 95% confidence interval [CI], 0.616-0.665; OSR c-statistic, 0.600; 95% CI, 0.563-0.630) and good calibration (EVAR Brier score, 0.021; OSR Brier score, 0.096). The indices had significantly better discriminative power (DeLong P <.001) than the Elixhauser Comorbidity Index (ECI) (EVAR c-statistic, 0.572; 95% CI, 0.546-0.597; OSR c-statistic, 0.502; 95% CI, 0.472-0.533). For internal validation, both indices had similar performance compared with individual comorbidity adjustment (EVAR DeLong P = .650; OSR DeLong P = .431). These indices demonstrated good external validation, exhibiting comparable performance to their respective validation groups (EVAR DeLong P = .891; OSR DeLong P = .757).

CONCLUSIONS

ECI, the comorbidity index formulated for the general population, exhibited suboptimal performance in patients who underwent AAA repair. In response, we developed summary comorbidity indices for both EVAR and OSR for AAA repair, which were internally and externally validated. The EVAR and OSR comorbidity indices outperformed the ECI in discriminating in-hospital mortality rates. They can standardize comorbidity measurement for clinical studies in AAA repair, especially for studies with small samples such as single-institute data sources to facilitate replication and comparison of results across studies.

Linking single nucleotide polymorphisms to signaling blueprints in abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) is a multifactorial complex disease with life-threatening consequences. While Genome-wide association studies (GWAS) have revealed several single nucleotide polymorphisms (SNPs) located in the genome of individuals with AAA, the link between SNPs with the associated pathological signals, the influence of risk factors on their distribution and their combined analysis is not fully understood. We integrated 86 AAA SNPs from GWAS and clinical cohorts from the literature to determine their phenotypical vulnerabilities and association with AAA risk factors. The SNPs were annotated using snpXplorer AnnotateMe tool to identify their chromosomal position, minor allele frequency, CADD (Combined Annotation Dependent Depletion), annotation-based pathogenicity score, variant consequence, and their associated gene. Gene enrichment analysis was performed using Gene Ontology and clustered using REVIGO. The plug-in GeneMANIA in Cytoscape was applied to identify network integration with associated genes and functions. 15 SNPs affecting 20 genes with a CADD score above ten were identified. AAA SNPs were predominantly located on chromosome 3 and 9. Stop-gained rs5516 SNP obtained high frequency in AAA and associated with proinflammatory and vascular remodeling phenotypes. SNPs presence positively correlated with hypertension, dyslipidemia and smoking history. GO showed that AAA SNPs and their associated genes could regulate lipid metabolism, extracellular matrix organization, smooth muscle cell proliferation, and oxidative stress, suggesting that part of these AAA traits could stem from genetic abnormalities. We show a library of inborn SNPs and associated genes that manifest in AAA. We uncover their pathological signaling trajectories that likely fuel AAA development.

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.

Pulmonary complications and survival after elective infrarenal endovascular abdominal aneurysm repair in patients with documented chronic obstructive pulmonary disease

BACKGROUND

Elective abdominal aortic aneurysm (AAA) repair is advocated in patients where risk of rupture exceeds the risks of peri-procedural morbidity and mortality. Chronic obstructive pulmonary disease (COPD) is a known risk factor for AAA and increased operative morbidity in general. Since literature on the correlation between the clinical classification of COPD and morbidity following endovascular infrarenal AAA repair (EVAR) is scarce, assessment per individual remains a challenge.

OBJECTIVE

To analyse the pulmonary and all-cause morbidity and mortality in patients with documented COPD and relate this to their GOLD classification.

METHODS

Sixty-eight patients with COPD, documented by a lung function test, who underwent elective EVAR between July 2002 and July 2018 were retrospectively reviewed. The primary endpoint was the incidence of 30-day pulmonary adverse events. Procedural characteristics, length of hospital stay, pulmonary and all-cause morbidity including major adverse events (MAEs) during follow-up and five-year survival divided per GOLD classification were the secondary endpoints.

RESULTS

There was no statistically significant difference in the incidence of pulmonary adverse events between GOLD I/II and GOLD III/IV patients. There was neither procedural nor 30-day mortality in either group. Through 30 days and 1 year, there was no difference in pulmonary and all-cause morbidity between groups. Three MAEs occurred in the GOLD I/II group versus 2 MAE in the GOLD III/IV group during the first postoperative year. The five-year survival was 66.0%, 60.9% and 61.9% for patients with GOLD I, GOLD II and GOLD III, respectively. Three of four GOLD IV died within the first year after EVAR.

CONCLUSION

EVAR can be safely performed in patients with COPD, with low 30-day morbidity and mortality rates. Although severe co-morbidity should be taken into account, EVAR seems to be justified in patients with COPD with a GOLD classification I, II or III. Further research should focus on optimising the pulmonary condition in patients selected for EVAR.

Spinal Cord Ischemia after Endovascular Aortic Repair of a Unilateral Iliac Artery Dissecting Aneurysm: A Case Report

PURPOSE

Spinal cord ischemia (SCI) is a rare complication of endovascular repair of abdominal aortic aneurysm that is attributed to the variable anatomy of the artery of Adamkiewicz, embolization of the collateral circulation, or hypoperfusion of cord structures secondary to hypotension.

CASE REPORT

A hypertensive 83-year-old male with chronic obstructive pulmonary disease presented with a 2.3-cm right iliac artery dissecting aneurysm. Paraplegia occurred on the first day after endovascular repair of iliac artery aneurysm. Postoperative magnetic resonance imaging showed multiple foci of spinal cord ischemia involvement from T10 to L1. Neither arterial pressure augmentation nor steroid therapy was effective. We hypothesized that the compromised blood flow from the artery of Adamkiewicz, combined with the transient hypotension and embolism, resulted in spinal cord infarction. The patient was eventually transferred to a nursing facility, with no improvement in his neurological status.

CONCLUSIONS

SCI after endovascular aortic repair is an extremely rare and unpredictable complication. Physicians should pay more attention to the patients with comorbidities of atherosclerosis, chronic obstructive pulmonary disease, or peripheral artery occlusive disease.

An anatomic risk model to screen post endovascular aneurysm repair patients for aneurysm sac enlargement

BACKGROUND

Follow-up computed tomography angiography (CTA) scans add considerable postimplantation costs to endovascular aneurysm repairs (EVARs) of abdominal aortic aneurysms (AAAs). By building a risk model, we hope to identify patients at low risk for aneurysm sac enlargement to minimize unnecessary CTAs.

METHODS

895 consecutive patients who underwent EVAR for AAA were reviewed, of which 556 met inclusion criteria. A Probit model was created for aneurysm sac enlargement, with preoperative aneurysm morphology, patient demographics, and operative details as variables.

RESULTS

Our final model included 287 patients and had a sensitivity of 100%, a specificity of 68.9%, and an accuracy of 70.4%. Ninety-nine (35%) of patients were assigned to the high-risk group, whereas 188 (65%) of patients were assigned to the low-risk group. Notably, regarding anatomic variables, our model reported that age, pulmonary comorbidities, aortic neck diameter, iliac artery length, and aneurysms were independent predictors of post-EVAR sac enlargement. With the exception of age, all statistically significant variables were qualitatively supported by prior literature. With regards to secondary outcomes, the high-risk group had significantly higher proportions of AAA-related deaths (5.1% versus 1.1%, P = 0.037) and Type 1 endoleaks (9.1% versus 3.2%, P = 0.033).

CONCLUSIONS

Our model is a decent predictor of patients at low risk for post AAA EVAR aneurysm sac enlargement and associated complications. With additional validation and refinement, it could be applied to practices to cut down on the overall need for postimplantation CTA.