Sexual dimorphism of abdominal aortic aneurysms: a striking example of "male disadvantage" in cardiovascular disease.

The abdominal aortic aneurysm (AAA) is a permanent, localised, dilation of the abdominal aorta that causes death in 80% of patients if left untreated. An apparent male predominance in AAA has been observed in most studies, with a male: female gender ratio of ∼6:1 between the ages 60 years-64 years. The majority of risk factors for AAA exhibit sexual dimorphism but no single risk factor shows a higher magnitude of "male disadvantage" than AAA itself. This in turn suggests that the additive effects of risk factors may better explain the higher prevalence of AAA in men than women compared to each individual factor. Amongst others, sex steroids and sex chromosomes have been hypothesised to act as the drivers of this sexual dimorphism. Future research should focus on the major biological differences between the sexes identifying why men are at more risk of AAA than women.