Poor concordance between definitions of type III arch and implications for risk prediction and assessment for carotid artery stenting

Aortic arch type, a novel morphological indicator and the risk for acute type B aortic dissection

 

OBJECTIVES

Aortic arch type is a readily recognizable and obtainable morphological feature of the aorta that does not require complex measurements. The goal of this study was to evaluate whether aortic arch type is a comparable and alternative morphological parameter for predicting acute type B aortic dissection (aTBAD) by comparing the prognostic value of the aortic arch type with that of other morphological parameters such as aortic length, angulation and tortuosity index.

METHODS

The patients with aTBAD (n = 216) were matched 1:1 with a control group (n = 263) by propensity score matching. The morphological data of the ascending aorta and the aortic arch, which included diameter, length, angulation and tortuosity index, were collected on a three-dimensional aortic model using 3mensio Vascular software. The aortic arch type was identified by the vertical distance from the origin of the brachiocephalic trunk to the top of the arch. The binary logistic regression models were analysed to determine the independent geometric variables related to the aTBAD. The nonparametric approach was performed to assess whether there were statistical differences between the area under the receiver operating characteristic curves (AUC) of the models.

RESULTS

After propensity score matching, 151 matched pairs of patients were selected. The diameters at the sinotubular junction and the mid-ascending aorta, the ascending aorta length and the ascending aorta angulation in the aTBAD group were significantly greater than those of the controls. Compared with the control group, the diameters at the proximal aortic arch, mid-aortic arch and distal aortic arch, the angulation and the tortuosity index of the aortic arch were significantly greater in the aTBAD group. The proportion of the type III arch in the patients with aTBAD is higher than that of the type I arch and the type II arch (χ² = 70.187; P < 0.001). Binary logistic regression analysis showed that the diameter at the mid-aortic arch, the ascending aorta length, the aortic arch angulation and the tortuosity index were independently related to the aTBAD with an AUC value of 0.887. Another binary logistic regression analysis indicated that the diameter at the mid-aortic arch and the aortic arch type were independent correlative variables associated with the aTBAD with an AUC of 0.874. No significant difference was observed in the prognostic value of receiver operating characteristic curves between the 2 models (P = 0.716).

CONCLUSIONS

The type III arch, which has the characteristics of aortic elongation, incremental angulation and tortuosity index, is a comparable and alternative identifier for patients at high risk for aTBAD.

Aortic Geometric Alteration Associated With Acute Type B Aortic Dissection: Angulation, Tortuosity, and Arch Type

Background: Acute type B aortic dissection is a highly serious aortic pathology. Aortic geometric parameters may be useful variables related to the occurrence of acute type B aortic dissection (aTBAD). The aim of the study is to delineate the alteration in aortic geometric parameters and analyze the specific geometric factors associated with aTBAD.

Methods: The propensity score matching method was applied to control confounding factors. The aortic diameter, length, angulation, tortuosity, and type of aortic arch of the aTBAD and control group were retrospectively analyzed via three-dimensional computed tomography imaging created by the 3mensio software (version 10.0, Maastricht, The Netherlands). The geometric variables of true lumen and false lumen in the descending aorta were measured to estimate the severity of aortic dissection. Multivariable logistic regression models were used to investigate the significant and specific factors associated with aTBAD occurrence. The area under the receiver operating characteristic curve (AUC) was used to estimate the performance of the model.

Results: After propensity score matching, 168 matched pairs of patients were selected. The ascending aorta and aortic arch diameters were dilated, and the ascending aorta and total aorta lengths were elongated in aTBAD group significantly (P < 0.001). The ascending aorta and aortic arch angulations in the aTBAD group were sharper than those of the controls (P = 0.01, P < 0.001, respectively). The aortic arch and total aorta tortuosities were significantly higher in the aTBAD group (P = 0.001, P < 0.001, respectively). There were more type III arch patients in the aTBAD group than the controls (67.9 vs. 22.6%). The true lumen angulation was sharper than that in the false lumen (P < 0.01). The true lumen tortuosity was significantly lower than that in the false lumen (P < 0.001). The multivariable models identified that aortic arch angulation, tortuosity, and type III arch were independent and specific geometric factors associated with aTBAD occurrence. The AUC of the multivariable models 1, 2, 3 were 0.945, 0.953, and 0.96, respectively.

Conclusions: The sharper angulation and higher tortuosity of aortic arch and type III arch were the geometric factors associated with aTBAD in addition to the ascending aorta elongation and aortic arch dilation. The angulation and tortuosity of the true and false lumens may carry significant clinical implications for the treatment and prognosis of aTBAD.

Implications of different definitions for aortic arch classification provided by contemporary guidelines on thoracic aortic repair

Contemporary guidelines on thoracic aortic repair provide inconsistent reporting standards for the definition of aortic arch classification in Types I, II and III. The different reported criteria cannot be used interchangeably, due to a very low level of concordance, and this finding has relevant implications for the comparisons between studies using different classifications, and between different datasets of multicentre trials, which are not consistently analyzed with the same criteria. Also, the reported definitions, which were originally proposed for predicting difficult carotid stenting and therefore were conceived for healthy aortic arches, can be influenced by the pathological derangements of the aortic wall, including aneurysms and dissections. In this respect, the Madhwal's classification, which is based on the diameter of the left common carotid artery, appears to be the more suitable one for aortic arch classification in patients with thoracic aortic disease because it provides relevant clinical information along with an adequate reproducibility.