Enlargement of the left atrium is associated with increased infiltration of immune cells in patients with atrial fibrillation who had undergone surgery.
BACKGROUND
Enlargement of the left atrium (LA) is a risk factor of atrial fibrillation (AF) recurrence after pharmacological and nonpharmacological interventions for AF. However, structural changes associated with LA enlargement have not been fully elucidated.


METHODS
To examine inflammation in the structural changes associated with LA enlargement, human left appendages obtained from 27 patients who underwent cardiac surgery by using the maze procedure were subjected to immunohistochemical analysis.


RESULTS
The extent of interstitial fibrosis increased according to the increase in LA dimension (LAD) as assessed by using ultrasound echocardiography. The extent of the infiltration of CD68-positive macrophages and CD3-positive T cells increased simultaneously according to the increments in LAD. The areas infiltrated by immune cells were positively and significantly correlated with LAD (r (2)=0.58, p<0.01 for CD68; r (2)=0.49, p<0.01 for CD3).


CONCLUSIONS
In the patients with AF, LA enlargement was associated not only with the increase in the extent of interstitial fibrosis but also with the changes in the LA component cells, including an increase in number of immune cells resident in tissues.
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Takeshi
T
Yamashita
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Akiko
A
Sekiguchi
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Shinya
S
Suzuki
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Takayuki
T
Ohtsuka
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Koichi
K
Sagara
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Hiroaki
H
Tanabe
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Takashi
T
Kunihara
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Hitoshi
H
Sawada
The Cardiovascular Institute, Nishiazabu 3-2-19, Minato-ku, Tokyo 1060031, Japan.
Tadanori
T
Aizawa
Atrial fibrillation; Inflammation; Left atrial dimension