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.