The Rupture Risk of Aneurysm in the Anterior Communicating Artery: A Single Center Study

Associations between morphological parameters and ruptured anterior communicating artery aneurysm: A propensity score-matched, single center, case-control study

BACKGROUND

To identify an association between morphological parameters and the rupture risk of anterior communicating artery (ACoA) aneurysms using propensity score matching (PSM).

METHODS

Data for 109 patients with ACoA aneurysms treated from January 2018 to October 2021 were reviewed; 94 patients were enrolled. The geometrical parameters of the ACoA aneurysms were measured and calculated using three-dimensional reconstructed digital subtraction angiography images. The aneurysms' morphological parameters were analyzed using a propensity score for six factors (age, sex, excess alcohol intake, smoking, hypertension, diabetes mellitus). Univariate logistic regression was used to analyze the relationship between the aneurysms' morphological parameters and rupture risk.

RESULTS

Twenty-five patients each with or without ruptured aneurysms were selected. After matching, no statistically significant differences were seen between the groups in their baseline characteristics. Aneurysm neck size (p = 0.038) was higher in the unruptured group than that in the ruptured group, and the dome-to-neck ratio (D/N; p = 0.009) and aspect ratio (AR; p = 0.003) were higher in the ruptured group than those in the unruptured group. Univariable logistic regression analysis demonstrated that ACoA aneurysm rupture was associated with AR (odds ratio: 8.047; 95% confidence interval: 1.569-41.213; p = 0.012) and D/N (odds ratio: 4.253; 95% confidence interval: 1.228-14.731; p = 0.022). The areas under the receiver operating characteristic curves for AR and D/N were 0.746 and 0.715, respectively.

CONCLUSIONS

After PSM, ACoA aneurysms with higher AR and D/N, and smaller neck size were more likely to rupture. AR may be a much more important predictor of aneurysm rupture than other predictors.

Clinical and Morphological Factors for Ruptured Anterior Communicating Artery Aneurysms

Introduction

The anterior communicating artery (ACoA) aneurysm, the most frequent cerebral aneurysm to rupture, carries a significant clinical burden, yet the factors influencing its rupture are limited in Indonesia. This study aims to determine the clinical and morphological features associated with ruptured ACoA compared to non-AcoA aneurysms among Indonesians.

Patients and Methods

We retrospectively reviewed our center's aneurysm patient registry from January 2019 to December 2022, and compared the clinical and morphological features between ruptured ACoA aneurysms and ruptured aneurysms elsewhere with univariate and multivariate analyses.

Results

Of the 292 patients with 325 ruptured aneurysms, 89 were from ACoA. The mean age of patients was 54.99 years, with female preponderance in the non-ACoA group (non-ACoA: 73.31%, ACoA: 46.07%). On univariate analysis, ages ≥60 [ages 60-69: OR = 0.311 (0.111-0.869), p=0.026; ages ≥70: OR = 0.215 (0.056-0.819), p=0.024], female gender [OR = 0.311 (0.182-0.533), p<0.001], and smoking [OR=2.069 (1.036-4.057), p=0.022] exhibited significant association with ruptured ACoA aneurysm. On multivariate analysis, only the female gender was independently associated with ruptured ACoA aneurysm (aOR 0.355 [0.436-1.961], p=0.001).

Conclusion

In our study, ruptured ACoA aneurysm was inversely associated with advanced age, female gender, presence of daughter aneurysm, and directly associated with smoking. After multivariate adjustment, the female gender showed an independent association with ruptured ACoA aneurysm.

CLINICAL CHARACTERISTICS AND MORPHOLOGICAL PARAMETERS ASSOCIATED WITH RUPTURE OF ANTERIOR COMMUNICATING ARTERY ANEURYSMS

We analyzed aneurysm morphology, demographic and clinical characteristics in patients with anterior communicating artery (ACoA) aneurysms to investigate the risk factors contributing to aneurysm rupture. A total of 219 patients with ACoA aneurysms were admitted to our hospital between January 2016 and December 2020, and morphological and clinical characteristics were analyzed retrospectively in 153 patients (112 ruptured and 41 unruptured). Medical records were reviewed to obtain demographic and clinical data on age, gender, presence of hemorrhage, history of hypertension, diabetes, heart disease, and kidney disease. Morphological parameters examined on 3-dimensional digital subtraction angiography included aneurysm size, neck diameter, aspect ratio, size ratio, bottleneck ratio, height/width ratio, aneurysm angle, (in)flow angle, branching angle, number of aneurysms per patient, shape of the aneurysm, aneurysm wall morphology, variation of the A1 segment, and direction of the aneurysm. Male gender, aspect ratio, height/width ratio, non-spherical and irregular shape were associated with higher odds of rupture, whilst controlled hypertension was associated with lower odds of rupture, when tested using univariate logistic regression model. In multivariate model, controlled hypertension, presence of multiple aneurysms, and larger neck diameter reduced the odds of rupture, while irregular wall morphology increased the risk of rupture. Regulated hypertension represented a significant protective factor from ACoA aneurysm rupture. We found that ACoA aneurysms in male patients and those with greater aspect ratios and height/width ratios, larger aneurysm angles, presence of daughter sacs and irregular and non-spherical shapes were at a higher risk of rupture.

Relationship between peroxisome proliferator-activated receptor-γ mRNA expression and intracranial aneurysm rupture

It has been reported that the normal adults can suffer from an intracranial aneurysm (IA) that might present the risk of rupture and cause the subarachnoid hemorrhage. Peroxisome proliferator-activated receptor-γ (PPAR-γ) as a nuclear hormone receptor has been identified to involve in the progress of the formation and rupture of IAs. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect PPAR-γmRNA expression in the macrophages of the patients with IAs. The information including fasting blood glucose (FBG), interleukin-6 (IL-6), and systolic blood pressure (SBP) were collected. The aneurysm parameters of all the participants were obtained through the cerebral angiography. Establishing the receiver-operating characteristic curve (ROC curve) evaluated the clinical significances of PPAR-γmRNA for IAs rupture. In this study, we observed that the rupture of IAs was caused by the maximum height of aneurysm ⩾7 mm, the location of aneurysm in posterior communicating artery (PCOM) or anterior communicating artery (ACOM), and the increase of aneurysm size ratio (SR). The levels of SBP and IL-6 in the rupture group were higher than those in the unrupture group, and PPAR-γmRNA expression in the rupture group was also significantly reduced. In addition, heavy drinking was statistically significant between the ruptured and unruptured groups. There was no significant difference in serum FBG level between the two groups. The evidences of this study showed that PPAR-γmRNA was negatively correlated with SBP, SR, and IL-6 levels in rupture group, respectively. The AUC of PPAR-γmRNA in ROC curve was 0.867, indicating that the change of PPAR-γmRNA level had obvious effect on IAs rupture. The aim of this study was to evaluate the potential of PPAR-γ in macrophages to prevent IAs rupture.

Tobacco use and age are associated with different morphologic features of anterior communicating artery aneurysms

We present a cohort of patients with anterior communicating artery (ACoA) aneurysms to investigate morphological characteristics and clinical factors associated with rupture of the aneurysms. 505 patients with ACoA aneurysms were identified at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016, with available CT angiography (CTA). Three-dimensional (3D) reconstructions were performed to evaluate aneurysmal morphologic features, including location, projection, irregularity, the presence of daughter dome, height, height/width ratio, and relationships between surrounding vessels. Patient risk factors assessed included patient age, sex, tobacco use, alcohol use, and family history of aneurysms and aneurysmal subarachnoid hemorrhage. Logistic regression was used to build a predictive ACoA score for rupture. Morphologic features associated with ruptured ACoA aneurysms were the presence of a daughter dome (OR 21.4, 95% CI 10.6-43.1), smaller neck diameter (OR 0.55, 95% CI 0.42-0.71), larger aspect ratio (OR 3.57, 95% CI 2.05-6.24), larger flow angle (OR 1.03, 95% CI 1.02-1.05), and smaller ipsilateral A2-ACoA angle (OR 0.98, 95% CI 0.97-1.00). Tobacco use was predominantly associated with morphological factors intrinsic to the aneurysm that were associated with rupture while younger age was also associated with morphologic features extrinsic to the aneurysm that were associated with rupture. The ACoA score had good predictive capacity for rupture with AUC = 0.92 using the 0.632 bootstrap cross-validation for correction of overfitting bias. Ruptured ACoA aneurysms were associated with morphological features that are simple to assess using a simple scoring system. Tobacco use and younger age were predominantly associated with intrinsic and extrinsic morphological features characteristic of rupture, respectively.

Treatment allocation of ruptured anterior communicating artery aneurysms: The influence of aneurysm morphology

OBJECTIVES

Since publication of the ISAT study, the majority of neurovascular centers adhere to "coil first" policy for patients with subarachnoid hemorrhage (SAH). However, final allocation in favor of coiling or clipping is based on anatomic features of ruptured intracranial aneurysms with respect to clinical characteristics of SAH. In this study, we analyzed the parameters relevant for treatment allocation of ruptured anterior communicating artery aneurysms (AComAA).

PATIENTS AND METHODS

From our institutional SAH database, all cases with ruptured AComAA, which underwent diagnostic subtraction angiography (DSA) with subsequent treatment allocation, were included. The radiographic features of AComAA were collected from pre-treatment DSA. In addition, demographic, clinical and radiographic parameters of SAH were recorded. The variables selected through univariate analyses were subsequently evaluated using multivariate regression analysis.

RESULTS

Of 300 SAH patients in the final analysis, the majority of the cases underwent endovascular coiling (n = 221, 73.7%). The following aneurysm features were associated with treatment modality in the univariate analysis: maximal sack size (p = 0.034), perpendicular height (p = 0.007), aspect ratio (p < 0.001) and sack/neck-ratio (p = 0.001). Accordingly, the following cutoffs for these variables were defined upon the receiver operating characteristics curves: 5 mm for sack size, 6 mm for perpendicular height, 1.6 for aspect ratio and sack/neck-ratio. In the multivariate analysis, aspect ratio of 1.6 was the only independent predictor of treatment allocation (p = 0.005; aOR = 2.57; 95% CI 1.33-4.96), which remained significant (p = 0.003; aOR = 2.77; 95% CI 1.41-5.45) after adjusting for patients' age, WFNS & Fisher grades, as well as intracerebral hematoma volume.

CONCLUSION

Although not-routinely assessed during initial allocation treatment, our retrospective analysis proved that aspect ratio is a reliable predictor of treatment allocation of ruptured AComAA. Except for large space-occupying ICH commonly obligating the microsurgical treatment, other clinical and radiographic characteristics of SAH do not seem to be of clinical relevance for the selection of treatment modality.

A Simple Scoring Model for Prediction of Rupture Risk of Anterior Communicating Artery Aneurysms

Background: The rupture risk of anterior communicating artery aneurysms (ACoAAs) has been known to be higher than that of aneurysms at other locations. Thus, the aim of this study is to investigate the clinical and morphological characteristics associated with risk factors for the rupture of ACoAAs.

Methods: In total, 361 consecutive patients with 361 ACoAAs between August 2011 and December 2017 were retrospectively reviewed. Patients and ACoAAs were divided into ruptured and unruptured groups. In addition to clinical characteristics, ACoAA characteristics were evaluated by CT angiography (CTA). A multiple logistic regression analysis was used to identify the independent risk factors associated with ACoAA rupture. The assignment score of these variables depends on the β coefficient. A receiver operating characteristic (ROC) curve analysis was used to calculate the optimal thresholds.

Results: The multiple logistic regression model revealed that A1 dominance [odds ratio (OR) 3.034], an irregular shape (OR 3.358), and an aspect ratio ≥1.19 (AR; OR 3.163) increased the risk of rupture, while cerebral atherosclerosis (OR 0.080), and mean diameters ≥2.48 mm (OR 0.474) were negatively correlated with ACoAA rupture. Incorporating these five factors, the ROC analysis revealed that the threshold value of the multifactors was one, the sensitivity was 88.3%, and the specificity was 66.0%.

Conclusions: The scoring model is a simple method that is based on A1 dominance, irregular shape, aspect ratio, cerebral atherosclerosis, and mean diameters from CTA and is of great value in the prediction of the rupture risk of ACoAAs.

Correlation of flow complexity parameter with aneurysm rupture status

Ruptured aneurysms are known to have complex flow patterns and concentrated inflow jet, but a quantifiable measure for the degree of flow complexity in patient-specific geometries has not been established. Previously, we proposed a flow complexity parameter that provides a quantitative description of the complexity of flow patterns through calculated curvature and torsion of the flow field. The purpose of the current study was to provide an analytic solution of the flow complexity parameter and assess a possible correlation with the rupture status of cerebral aneurysms by analyzing the parameter on five ruptured and five unruptured aneurysms from anterior communicating artery. We analyzed the flow complexity parameter in jet and non-jet regions in order to measure the concentration of the jet flow and the complexity of the non-jet flow. We found that on average, in a ruptured case the jet region is significantly less complex (4.5 times) than the jet region in an unruptured case, while the non-jet region is significantly more complex (3.5 times) than the non-jet region in an unruptured case. We also found a strong positive correlation of the non-jet complexity with dome volume in ruptured cases, but no correlation of jet complexity with dome volume. These findings suggest that a ruptured aneurysm has more than 4 times more concentrated inflow jet and more than 3 times more complex flow patterns in non-jet region than an unruptured aneurysm. This newly implemented kinematic parameter provides a measurable degree of complexity of flow patterns in cerebral aneurysms that can better assess aneurysm rupture risk.

Difference in aneurysm characteristics between ruptured and unruptured aneurysms in patients with multiple intracranial aneurysms

Background:

The risk of aneurysmal rupture is dependent upon numerous factors, however, there are inconsistencies in the results between studies, which may be due to confounding factors. This can be avoided by comparing the characteristics of ruptured and unruptured aneurysms within the same patient. We sought to analyze the aneurysm characteristics of patients with acute aneurysmal subarachnoid hemorrhage (SAH) and multiple intracranial aneurysms.

Methods:

We reviewed our prospectively maintained institutional database, between 01/10/2007 and 01/01/2017, for all patients with confirmed SAH and >1 aneurysm. We recorded the size, location, and morphology and calculated secondary geometric indices such as bottleneck factor and aspect ratio.

Results:

During the study period, a total of 694 patients with aneurysmal SAH were admitted to our institution. We identified 113 patients (74.3% female, average age 51.7 ± 12.3). The majority of patients had only one associate unruptured aneurysm (79.6%). The average unruptured aneurysm was 3.1 ± 1.5 mm and the average ruptured aneurysm was 5.7 ± 2.7 mm (P < 0.001). In the multivariate analysis, aneurysm location, aneurysm morphology, and size were independently associated with rupture. A complex aneurysm morphology was the strongest risk factor for rupture (OR, 29.27; 95% CI 14.33–59.78; P < 0.001) with size >7 mm (OR, 17.74; 95% CI 4.07–77.35; P < 0.001), and AcomA location also showing a strong independent association.

Conclusion:

Size plays an important part in determining rupture risk, however, other factors such as location and in particular morphology must also be considered. We believe that the introduction of vessel wall imaging will help to risk stratify aneurysms.