New Mouse Model of Abdominal Aortic Aneurysm: Put Out to Expand

Human abdominal aortic aneurysm (AAA) is typically defined as an enlargement of the luminal diameter of the abdominal aorta by >50% or to a diameter >3 cm.1,2 Virtually, all AAA are clinically silent and are detected either during radiological investigation of unrelated signs and symptoms or by surveillance programs aimed at high-risk populations (eg, older male smokers or all men aged ≥65 years).3 Once an AAA is discovered, management is dictated by the size and anatomy of the AAA, with consideration also given to individual patient comorbidities. In general, AAA <5.5 cm diameter are followed with serial imaging; whereas, AAA ≥5.5 cm are treated by either open surgery or endovascular repair.4,5 Treatment is aimed at preventing AAA rupture, which typically results in sudden death.1 However, both open and endovascular AAA repair are themselves associated with significant morbidity and mortality.1 See accompanying article on page 2171 AAA is not a rare disease. The prevalence of AAA is estimated at 5% to 8% in men between 65 and 80 years of age, with an annual incidence of 0.4% to 0.7%.1 Although most individuals with smaller AAA will die of other causes, AAA rupture is responsible for ≈7000 male deaths/year in the United States.1 Female deaths from AAA rupture are increasing, with women now accounting for ≈30% of all AAA ruptures.1 Risk factors for AAA include age, male sex, smoking (current or former), family history, central obesity, and high level of alcohol consumption.1 A common human genetic polymorphism also seems to confer increased risk for AAA, and variants at other loci may also contribute to risk.6,7 Because aggressive screening programs could identify the vast majority of AAA before they either rupture or enlarge to ≥5.5 cm, and …