Why Does the Bicuspid Aortic Valve Keep Eluding Us?

The bicuspid aortic valve (BAV) is, by far, the most common congenital cardiovascular defect encountered by cardiovascular specialists. In the United States, the number of subjects alive is estimated to be 3 million, with an approximate 1% prevalence, more than 10 times higher than the second most common congenital lesion, ventricular septal defect. BAV is subjected to early degeneration and valve dysfunction, requiring surgical intervention in the course of a lifetime for most patients. BAV is also associated with ascending aortic dilatation, also known as BAV aortopathy. Surgical indications for a dysfunctional BAV are relatively straightforward and well established; the same as those for tricuspid aortic valve (TAV), usually triggered by symptoms or ventricular dysfunction. On the other hand, while sharing the same ultimate goal of preventing life-threatening consequences, such as aortic dissection and rupture, surgical thresholds for a dilated ascending aorta are different in the setting of BAV versus TAV; generally lower in BAV. Recently, the incidence of aortic dissection was reported to be much lower than believed, and the idea of more aggressive preemptive intervention on BAV aortopathy has become controversial. Instead, the importance of a more individualized approach is being highlighted. This article will provide a comprehensive review of (1) the typical clinical course of patients with BAV under contemporary management, (2) new risk-stratifying parameters proposed to make an individualized approach possible, and (3) practical challenges all cardiovascular specialists need to know when implementing and interpreting future BAV-related studies.