DISCUSSION
We showed that:
In AR patients over 65 years of age, aortic cusp bending was the most
frequent AR etiology. On the other hand, in the younger patients,
bicuspid AV was the most observed cause of AR.
Aging was the only significant factor to predict coexisting cusp
bending of AV.
Cusp bending could occur in any AV cusp, nevertheless, it was detected
on RCC by far the most frequently (45 out of 49 cusp-bending related
cases). This was consistent with the previous study, reporting that 70%
of the isolated cusp bending was seen on RCC (9). Roberts et al.
reported that the most frequent cause of AR was “unclear”, accounting
for 34% (3). The characteristics of the AR patients with “etiology
unclear” were higher age with atherosclerotic diseases, in common with
the cusp-bending group in this study. Higher age may also contribute to
the result that the patients in this group were shorter in height with
smaller body surface area. Recent improvement in TEE image quality has
helped to detect cusp-bending more clearly, which may have been included
in “etiology unclear”. Aging is associated with degenerative changes
in cusps in various signaling pathways of molecular levels (14). In this
study, however, there were no differences between those with and without
cusp-bending in terms of the prevalence of atherosclerotic factors such
as hypertension, diabetes, lipid disorder, CKD and smoking. Most of the
patients in this study had various atherosclerotic diseases originally,
and aging is considered the most influential contributor to occurrence
of cusp bending above all. Although the number of patients with mitral
prolapse was small (4 of 126 patients), they were detected only in cusp
bending group, which may be associated with valvular vulnerability in
patients with cusp bending.
There are several classifications of AR, and adaptation of the
Carpentier classification originally designed for the mitral valve have
been described for AR and can be helpful to understand the mechanism of
AR, to guide valve repair technique, and to predict recurrence of AR
(15). This scheme classifies dysfunction based on the aortic root and
leaflet morphology. Cusp bending belongs to type II, cusp prolapse, in
this category. As shown in this report, AV cusp bending may have
favorable surgical repairability and outcome such as freedom from
bleeding events caused by anti-coagulants or IE (9). Therefore, it is
important to detect cusp bending preoperatively.
There are some limitations in the present study. This is a single center
study and the number of patients enrolled in this study was relatively
small. Secondly, 10 cases (7.9%) were classified as
echocardiographically normal finding (Table 2). Even without any
abnormality on AV cusps, AR can be generated from imbalanced sizes of
aortic annulus, Valsalva sinus and ST junction (16) (17), which may be
beyond echocardiographic resolution capability. Further investigation
will be required for the validation of our study.