Why is aortic valve-preserving surgery not
popular?
One reason why surgeons have been reluctant to perform AVP may involve
the conservative nature of the guidelines over the last decade. The
current guidelines specify AVR as the standard surgical option in cases
of AR. Therefore, they recommend aortic valve surgery in symptomatic
patients or those with reduced left ventricular function as a class I
indication13, 14. However, cases with depressed left
ventricular function or advanced symptom are known to be associated with
elevated mortality even after AVR15, 16. In addition,
when AVP is planned, better quality of repair can be anticipated before
degeneration of the aortic cusps.
Of course, some researchers recognized these concerns and proposed
earlier indication for surgical intervention. The Mayo clinic reported
that patients with indexed left ventricular endosystolic dimension
(LVESD) ≥ 20 mm/m2 had poorer survival at 10 years
compared to those with indexed LVESD < 20
mm/m2 (Fig. 4A)17. The Cleveland
clinic also reported that patients with indexed LVESD between 20 and 25
mm/m2 had a survival benefit after AVR compared to
those without AVR3. Patients with LVEF ≥ 50% but
< 55% were reported to have poorer survival at 10 years
compared to those with LVEF ≥ 55% (Fig. 4B)18. Even
after AVR, patients treated in accordance with the guidelines for
earlier surgery showed better survival than those undergoing later
operation19. Therefore, the latest Japanese guidelines
recommend aortic valve surgery in patients with LVESD > 45
mm as a class IIa indication, taking Japanese body size into account
(English version will be available soon).
Another reason may be complexity of AVP. Compared with the mitral valve,
the aortic valve has smaller cusp volume, thinner cusp thickness, and
three coaptation planes20. There are many technical
alternatives for MVP, whereas there is no chordal replacement technique
in AVP. Thus, a long learning curve of approximately 40 – 60 cases is
estimated for AVP, which has made this a technique exclusively for
experienced surgeons21. Several technical/theoretical
modifications or refinements have been made to increase adoption of AVP,
which will be introduced in the following section.