Anemia Predicts Poor Clinical Outcome in Mechanical Thrombectomy Patients with Fair or Good Collateral Circulation

Prognostic Impact of Anemia and Blood Transfusions on Cardiovascular Outcomes in Patients Undergoing Vascular Surgery: A Scoping Review

OBJECTIVE

Prior studies suggest an association of anemia and blood transfusion with increased morbidity and mortality in patients undergoing cardiac surgery. However, the impact of perioperative anemia and blood transfusion on clinical outcomes in patients undergoing major vascular surgery has been poorly defined yet. The primary objectives of this scoping review were to determine the extent of the evidence base that links anemia and blood transfusions to mortality and cardiovascular outcomes in patients undergoing major vascular surgery, and identify recurring themes or gaps in the literature to guide future research.

METHODS

A scoping review of the literature from PubMed, Cochrane, and EMBASE databases was conducted up to December 2023 to identify articles related to the impact of anemia and blood transfusions on postoperative cardiovascular outcomes on patients undergoing vascular surgery. Methodology followed the PRISMA Protocols Extension for Scoping Reviews.

RESULTS

Twenty-two articles met the inclusion criteria, including 15 retrospective and 6 observational prospective studies. Anemia definition varied across studies, mainly based on hemoglobin cut-off levels. An association with older age, coronary artery disease, hypertension, diabetes, and other comorbidities was reported. Particularly in peripheral and endovascular aortic surgery, anemia was linked consistently with higher mortality, major adverse cardiac events, and other postoperative complications, such as respiratory and renal issues, surgical site infections, and longer hospital stays, depending on hemoglobin levels. Anemia itself is an important predictor of transfusions. Transfusions in anemic patients were associated with increased mortality, postoperative complications, and increased need for major amputation.

CONCLUSIONS

The weight of the evidence suggests that anemia carries a substantial burden of cardiovascular complications, mortality, and multiorgan complications, resulting in increased health care costs. Peripheral and endovascular aortic surgery are affected deeply by the impact of anemia. Anemia itself stands out as a crucial predictor for requiring transfusions. In turn, the effect of transfusion of blood products is associated with worse outcomes and complications.

Anemia and Optimal Transfusion Thresholds in Brain-Injured Patients: A Narrative Review of the Literature

Anemia is a highly prevalent condition that may compromise oxygen delivery to vital organs, especially among the critically ill. Although current evidence supports the adoption of a restrictive transfusion strategy and threshold among the nonbleeding critically ill patient, it remains unclear whether this practice should apply to the brain-injured patient, given the predisposition to cerebral ischemia in this patient population, in which even nonprofound anemia may exert a detrimental effect on clinical outcomes. The purpose of this review is to provide an overview of the pathophysiological changes related to impaired cerebral oxygenation in the brain-injured patient and to present the available evidence on the effect of anemia and varying transfusion thresholds on the clinical outcomes of patients with acute brain injury.

Hemoglobin in large vessel occlusion: Look further than collaterals

BACKGROUND

Abnormal hemoglobin (Hb) levels lead to poorer outcomes in ischemic stroke, though the mechanisms remain elusive. We aimed to study the role of Hb on imaging and clinical outcomes, namely on collaterals as it is a known mediator of infarct growth.

METHODS

Retrospective cohort study of patients with large vessel occlusion ischemic stroke admitted to our center. Demographics, clinical and imaging variables were collected, particularly baseline hemoglobin, presence of anemia and collateral score. Collaterals were scored from 0 to 3 and defined as poor if 0-1. Multivariable analyses were performed for collateral score and clinical outcomes (3-month mortality and good prognosis).

RESULTS

We included 811 patients, 215 (26.5 %) with anemia. Patients with anemia were older, had more comorbidities and more severe strokes. Hemoglobin levels and anemia were not associated with collateral score (OR 0.97, 95 % CI 0.89-1.05, p = 0.414 and OR 0.89, 95 % CI 0.64-1.24, p = 0.487, respectively) nor with poor collaterals (OR 0.96, 95 % CI 0.88-1.05, p = 0.398 and OR 0.86, 95 % CI 0.60-1.23, p = 0.406, respectively). Hb levels were associated with 3-month mortality (OR 0.85, 95 % CI 0.76-0.96, p = 0.008).

CONCLUSION

Hemoglobin or anemia were not found to be associated with collateral status. Our results raise further questions regarding the pathophysiology of anemia and outcomes in ischemic stroke, highlighting the need for future research.

Association Between Anemia and Clinical Outcome in Acute Ischemic Stroke Patients Treated With Endovascular Treatment

BACKGROUND AND PURPOSE

Endovascular treatment (EVT) is the preferred treatment option in eligible acute ischemic stroke (AIS) patients with a large vessel occlusion of the anterior circulation. Several comorbidities have been identified that can affect clinical outcomes. Various studies have investigated the association between anemia and clinical outcome and found conflicting.

RESULTS

. The aim is to investigate the association between pre-EVT anemia and clinical outcomes at different time points post-EVT, primarily focusing on the National Institutes of Health Stroke Scale (NIHSS) at 24-48 hours.

METHODS

We prospectively included 560 AIS patients who received EVT in the Maastricht University Medical Center+. Hemoglobin levels (Hb; g/dL) were determined on admission. Hb levels were also categorized into two groups: anemia (male: Hb ≤12.9 g/dL; female: Hb ≤11.9 g/dL) and no anemia. Multiple imputation was used to handle missing data. Multivariable regression was used to investigate the association between anemia or Hb levels and clinical outcomes.

RESULTS

Anemia was present in 26% of the patients. Multivariable regression did not show a significant association between anemia or Hb levels and NIHSS at 24-48 hours (adjusted β [aβ]anemia: 1.44, 95% confidence interval [CI]: -0.47 to 3.36; aβHb: -0.37, 95% CI: -0.88 to 0.13). However, multivariable regression showed significant associations with modified Rankin Scale (adjusted common odds ratio [acOR]anemia: 1.66, 95% CI: 1.12 to 2.48; acORHb: 0.83, 95% CI: 0.75 to 0.93) and poor functional outcome at 90 days (adjusted OR [aOR]anemia: 2.09, 95% CI: 1.21 to 3.63; aORHb: 0.80, 95% CI: 0.69 to 0.92).

CONCLUSION

Anemia was not independently associated with early neurological deficit (NIHSS) post-AIS, suggesting it is more suitable as a general frailty marker.

Association of clinical factors to functional outcomes in patients with stroke with large-vessel occlusion after endovascular thrombectomy

BACKGROUND/PURPOSE

Multiple clinical factors have been reported to be associated with functional outcomes in patients with stroke. However, little is known about prognostic predictors of functional independence in patients with stroke undergoing endovascular thrombectomy (EVT). Our study aimed to investigate the correlation between multiple prognostic variables (including EVT and rehabilitation-related parameters) and functional outcomes in patients post-EVT.

METHODS

This retrospective cohort study recruited patients hospitalized between December 2018 and March 2022. Patients with stroke with large-vessel occlusion who underwent EVT were eligible for inclusion in the study. Prognostic factors, including premorbid characteristics, laboratory data, EVT- and rehabilitation-related parameters, functional activity level, balance ability, swallowing, and sphincter function, were collected. Logistic regression and generalized linear models were used to analyze their correlations with functional outcomes.

RESULTS

A total of 148 patients were included. In the univariate logistic regression analysis, younger age, premorbid functional independence, higher hemoglobin (Hb) level, lower National Institute of Health Stroke Scale (NIHSS) score, absence of hemorrhagic transformation in 14 days, no nasogastric (NG) tube placement, earlier rehabilitation, frequent daily rehabilitation sessions, more out-of-bed rehabilitation, better ability of sitting up, better initial sitting balance, higher Barthel index (BI), absence of immobility, and neurological complications were associated with favorable outcomes at 3 months. In the stepwise regression model, the predictors of favorable function at 3 months included age, ability to sit up, and frequency of daily rehabilitation sessions; favorable outcomes at 6 months were associated with age, ability to sit up, and swallowing function.

CONCLUSION

In patients with stroke post-EVT, better functional outcomes were associated with prognostic variables, including younger age, better ability to sit up, normal swallowing function, and frequent daily rehabilitation sessions.

Interplay between anemia parameters and collateral status in patients who undergo mechanical thrombectomy

INTRODUCTION

Anemia is associated with higher morbidity and mortality, but its association with acute ischemic stroke (AIS) is not well established. We aim to determine the association of five-day anemia parameters with clinical outcomes in patients with an AIS, depending on their pre-mechanical thrombectomy (MT) collateral status.

METHODS

We performed a retrospective chart review of patients who underwent MT at a comprehensive stroke center from 7/2014 to 12/2020. The patients were divided into good and poor collateral groups depending on their pre-MT collateral status. A blinded board-certified neuroradiologist used collateral grading scale of Maas ≥ 3 to designate good collaterals on the pre-MT CT Angiogram. A binary logistic regression analysis was performed, controlling for the baseline parameters, with the five-day anemia parameters as predictors. The outcomes were functional independence (mRS 0-2), mortality, and early neurological improvement.

RESULTS

A total of 220 met the inclusion criteria. 94 (42.72 %) patients had good collaterals, while 126 (57.27 %) patients had poor collaterals. In the multivariable analysis, for patients with good collaterals, the higher values of five-day mean Hb (12.41 ± 1.87 vs 11.32 ± 1.95; OR, 0.72; 95 % CI, 0.54-0.95; P 0.018), five-day mean HCT (37.43 ± 5.1 vs 34.35 ± 5.5; OR, 0.89; 95 % CI, 0.81-0.98; P 0.018) and lower values of the difference between peak and trough values of Hb (1.75 ± 1.15 vs 2.41 ± 1.35; OR, 1.71; 95 % CI, 1.07-2.74; P 0.025) were associated with functional independence. For patients with poor collaterals, there was no association between five-day mean Hb, mean HCT parameters with functional independence, lower mortality, and early neurological improvement.

CONCLUSION

Our study was suggestive of an association between higher mean values of Hb and HCT over a five-day period and good clinical outcomes in patients with good collaterals who undergo MT for an anterior circulation LVO. This association was not found in the poor collateral group.

Vascular tortuosity in endovascular mechanical thrombectomy

Endovascular mechanical thrombectomy effectively removes occlusive thrombi from the arterial lumen; however, there is little literature supporting the relevance of vascular geometry on surgical outcomes. Critical vessel characteristics including the degree of angulation and tortuosity influence the ability to advance stent retriever devices toward the site of occlusion. Therefore, it is crucial to evaluate the impact of carotid artery catheter pathway accessibility on the thrombectomy outcomes in acute ischemic stroke (AIS) patients. Traditional imaging modalities generate incomplete pictures of the vascular tortuosity and are prone to clinical judgment errors. Recent three-dimensional computed tomography angiography image analysis techniques circumvent these limitations to calculate accurate tortuosity and angulation measurements. These novel images facilitate classifying common anatomical variant patients into groups that may be treated with specially designed catheter devices. Importantly, this image analysis method reveals significant angulation in the common carotid artery and extracranial internal carotid artery that correlates with delays in reaching the occlusion site. Increased age, which is associated with increased risk of stroke, also increases the incidence of severe tortuosity. The semi-automated measurements technique also demonstrate that full 360° arterial loops are present in nearly 3% of catheter pathways and that the overall degree of angulation differs bilaterally. In this review, we examine the utility of this novel image analysis procedure and evaluate the recent literature relevant to neuroendovascular thrombectomy in AIS patients. Three literature databases – PubMed, Embase, and Web of Science were queried for original articles investigating both preclinical and clinical thrombectomy applications.