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.