Background: Bicuspid aortic valves are associated with aortic dilation and dissection. There is a paucity of prospective studies evaluating changes in aortic size over time in adult subjects with bicuspid aortic valves.

Methods: A total of 115 subjects with asymptomatic bicuspid aortic valves were enrolled from 2003 to 2008 and followed prospectively over 5 years. Clinical and family histories, as well as transthoracic echocardiograms, were obtained at baseline, and echocardiograms were performed annually thereafter.

Results: The mean age of subjects was 41.8 ± 12.8 years, and 61% were male. Ascending aortic size at baseline averaged 35.5 ± 5.6 mm and increased in 71.1% of subjects (mean, 0.66 ± 0.05 mm/y; range, 0.2-2.3 mm/y) over an average of 4.8 years. In 15.6% of subjects, the rate of change exceeded 1 mm/y. The average rate of ascending aortic dilation for all subjects was 0.47 ± 0.05 mm/y (P < .001). A family history of aortic valve disease was associated with progression in both unadjusted (P = .029) and logistic regression analyses adjusted for age, gender, and body surface area (odds ratio, 13.7; P = .021). Multivariate analysis did not find leaflet orientation or moderate to severe aortic valve dysfunction as independent predictors of aortic dilation.

Conclusions: We found that in subjects with bicuspid aortic valve, studied prospectively, there was an annual rate of ascending aortic dilation of 0.47 mm/y. In contrast to previous reports, leaflet orientation and aortic valve dysfunction were not independent predictors of aortic dilation. A family history of aortic valve disease was associated with a significantly increased risk of increasing ascending aortic size.