The cardiovascular and prognostic significance of the infrarenal aortic diameter

The normal aortic diameter in adults usually ranges from 16 to 18 mm in women and 19 to 21 mm in men. Individuals with diameters outside this range seem to be at increased risk of other cardiovascular disease. There is a graded association between increasing aortic diameter and both cardiovascular mortality and peripheral arterial disease. The magnitude of increased risk of cardiovascular death seems to be about 4% to 6% per mm increase over a diameter of about 23 mm. To a lesser extent, these outcomes are also increased in individuals with aortic diameters below the normal range. While the threshold of 3 cm is useful in the diagnosis of abdominal aortic aneurysm (AAA), it is arbitrary in terms of the vascular biology and pathophysiology of the abdominal aorta. This review examines the risk factors for aortic enlargement and the cardiovascular implications of this enlargement in patients with and without AAAs. The mechanisms underlying the association between aortic diameter and cardiovascular risk and the relevance to screening are also discussed.