4.1 Main findings
Our main findings were as follows: (1) female sex was more prevalent, BW
was lower, and the distance between the NCC and anterior LA wall was
less in the LVZ Group than in the No LVZ Group; (2) the size (area) of
LVZs on the anterior LA wall at LA-ascending aorta contact areas
correlated negatively with the aorta-LA angle and positively with the
aorta-LV angle and the NCC diameter; and (3) the aorta-LV angle
correlated negatively with BW and BMI, whereas the aorta-LA angle
correlated positively with BMI.
In general, LVZs are commonly seen in patients with AF. The incidence
among patients with persistent AF is 35%, and among patients with
paroxysmal AF, the incidence is 10%. LVZs have been shown to
independently predict AF recurrence after PVI,3,12 and
LVZs reflecting LA remodeling are frequently detected in the anterior LA
wall.6,10,11 With the ascending aorta being the
structure closest to the LA, we hypothesized that mechanical compression
caused by an anatomically deviated or expanded ascending aorta leads to
the development of LVZs on the anterior LA wall.6 The
aorta-LA angle was narrow and the aorta-LV angle was wide in our study
patients with anterior LA wall LVZs, suggesting that the ascending aorta
had sunk into the anterior LA wall due a deviation in its course and
distention of the NCC. These deformities might have been the result of
aortic root dilation due to aging and
hypertension.13,14 The NCC is adjacent to the anterior
LA wall, and, because of the relatively low LA pressure, it might easily
collapse against the LA. Our anatomical findings support our hypothesis.
The increased LA pressure in the LVZ Group also supports our hypothesis.
The anterior LA wall LVZs were more prevalent among female patients than
among male patients. Generally, the thoracic cavity is smaller in
females than in males. Deviation in the course of the ascending aorta
and a dilated sinus of Valsalva in patients with a relatively small
thoracic cavity might increase intrathoracic pressure. Mechanical
compression of the LA by the aorta might promote local myocardial
fibrosis and electrophysiologic remodeling. In such cases, the
intrathoracic space, which normally compensates for the pressure
gradient, would be limited.
We thus suggest that dilation of the aortic root leads to the
development of LVZs on the anterior LA wall. LA remodeling is generally
thought to be related to the arrhythmic substrate. However, in our
study, we found no association between LVZs on the anterior LA wall and
AF recurrence after ablation. Remodeling of the anterior LA wall may
contribute little to the arrhythmic substrate.