Discussion
UAV is a rare congenital malformation, resulted from the abnormal fusion ot the three tubercles. The true prevalence of UAV is unknown and likely underestimated, since it is often difficult to differentiate between other anomalies like BAV by cardiac imaging3,4. Further, >50% of UAV cases are only confirmed by intraoperative surgery or autopsy5. Two phenotypes of UAV have been described in the literature, the unicommisural type with a single leaflet from the aortic wall and one being the pinhole-shaped acomissural UAV6,7. Four echocardiographic criteria are used to improve the differential diagnosis8: (i) single commissural attachment zone, (ii) rounded leaflet-free edge on the opposite side of the commissural attachment zone, (iii) eccentric valvular orifice during systole and (iv) age <20 years and mean transvalvular gradient >15mmHg. When three of them are met, they have 97% specificity for diagnosing of UAV (Figure 1B; Videos 1-4). Clinically, UAV presents a more aggressive evolution during follow-up than BAV—the valve is rarely normofunctional and generates earlier significant aortic stenosis and more aortic valve intervention associated with ascending aortic aneurysm repair via the Bentall procedure than in BAV patients5,9.
Recently, BAV has been associated with IE, especially when aortic valve function shows significant stenosis10. This new evidence challenges the recommendations of antibiotic prophylaxis in BAV patients undergoing dental procedures. The high-risk profile of UAV for developing aortic complications highlight the differential diagnosis between both entities and the potential risk of IE should raise the question if antibiotic prophylaxis may be also recommended in these patients.