Abdominal Aorta Dilatation and Cardiovascular Outcomes

Aortic aneurysm is defined as having a permanent localized dilatation of the aorta, with at least 50% increase in diameter compared with the expected normal diameter of that aortic segment.1 The same guidelines do not offer a definition for a localized aortic dilatation of <50% of the expected normal diameter, commonly referred to in clinical practice as mild aortic dilatation. Further, this definition does not specify what represents a normal diameter. It has been recognized that aortic diameters are affected by age, sex, body size, and imaging modality.1 Thus, without taking these factors into account, normal diameters can be misclassified as abnormal.See Article by Qazi et al The lack of standardized cutoffs for the aorta represented a challenge in which normal needed to be defined before defining what is abnormal but nonaneurysmal. Many smaller studies attempted to address this,1–4 but it was not until a landmark study using the Framingham Heart Study Offspring and Third Generation cohorts data took a comprehensive approach defining sex-specific normal diameters of the aorta at multiple segments stratified by age and body surface area, using noncontrasted multidetector computed tomography (CT) in a community-based cohort.5 However, the question remained, what is the clinical significance of having a dilated, nonaneurysmal aorta?Abdominal aortic aneurysm has been recognized to be associated with atherosclerotic risk factors, supported by an abundance of prospective studies from national screening programs which showed increased mortality in patients with mild aortic aneurysms.6–9 Years later, the Tromso study was published.10 This was a population-based study of 6295 men and women aged 25 to 84 years and followed up for 10 years who did not have aneurysmal abdominal aorta using ultrasonography. In the study, subjects with age- and sex-adjusted infrarenal aortic diameter 27 to …