Shinshu Med J, 69⑷：189～201, 2021

Association between Inter-atrial Septum Motion and PersistentAtrial Fibrillation Recurrence after Catheter Ablation
Hideki Kobayashi1）, Ayako Okada1）＊, Hiroaki Tabata1）, Wataru Shoin1）
Takahiro Okano1）, Koji Yoshie1）, Yasutaka Oguchi2）, Ken Kato3）
Hirohiko Motoki1）, Morio Shoda1）4） and Koichiro Kuwahara1）
1） Department of Cardiovascular Medicine, Shinshu University School of Medicine
2） Department of Cardiovascular Medicine, Aizawa Hospital3） Department of Cardiology, Tokyo Metropolitan Tama Medical Center
4） Clinical Research Division for Heart Rhythm Management, Department of Cardiology,
Tokyo Women’s Medical University

Background : Recently, several echocardiographic parameters have been proposed as predictors of the recurrenceof persistent atrial fibrillation (psAF) after catheter ablation (CA). This study aimed to evaluate whether a decrease
in inter-atrial septum (IAS) motion was associated with recurrence of psAF after CA.
Methods : A total of 103 consecutive patients who underwent CA for psAF were retrospectively reviewed. IAS
motion was measured 48-72 hours before CA using transesophageal echocardiography. The primary outcome
was AF recurrence beyond 3 months post-ablation. The follow-up period was 12 months after CA.
Results : PsAF recurrence after CA occurred in 29 (28.2 ％) patients. The median value of IAS motion was 4.1
mm (interquartile range 2.4, 5.4), and the decline in IAS motion was an independent predictor of AF recurrence
in a multivariate analysis of various models. Kaplan-Meier analysis showed that AF recurrence was significantly
higher in the low IAS motion group (IAS motion＜4.2, n＝47) than in the high IAS motion group (IAS motion ≥4.2, n＝52) (log-rank test, p＝0.001). A negative correlation was observed between IAS motion and left atrial
volume (LAV), and conversely, a positive correlation was found between IAS motion and left atrial appendage
flow velocity. The low IAS motion group had a higher left atrial pressure (LAP) than the high IAS motion group.
Conclusions : PsAF recurrence after CA was associated with reduced IAS motion. Decreased IAS motion could
be an important finding suggestive of left atrial remodeling as well as LAV enlargement and increasing LAP.
Shinshu Med J 69 : 189―201, 2021
(Received for publication January 12, 2021 ; accepted in revised form March 29, 2021)
Key words : atrial fibrillation, catheter ablation, inter-atrial septum, transesophageal echocardiography,
left atrial pressure

Ⅰ Introduction

mensional mapping and balloon ablation (BA), thesuccess rate of PVI has also increased in patients with

The effectiveness of pulmonary vein isolation (PVI)

persistent AF (psAF). Superior vena cava (SVC) iso­for atrial fibrillation (AF) has recently been estab­lation3）, creating block lines to the cavo-tricuspid

lished1）2）. Furthermore, with the advent of three-di­

isthmus (CTI), and complete isolation of the left atrial
wall (box isolation) are other options for catheter abla­＊

Corresponding author : Ayako Okada
Department of Cardiovascular Medicine,
Shinshu University School of Medicine,
3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
E-mail : aokada@shinshu-u.ac.jp

No. 4, 2021

tion (CA) for psAF4）5）. However, AF may recur evenafter an acutely successful CA6）. In particular, psAF,
in which remodeling of the left atrium is progressing,occurs more frequently after CA than paroxysmal
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Kobayashi・Okada・Tabata et al.

AF7）. In addition, several other factors have been8）-11）disease (Global Initiative for Chronic Obstructive. Electrical and struc­

Lung Disease class 2 or more), and those on hemodi­

tural remodeling of the left atrium is also thought toalysis were excluded. AF duration was defined asassociated with AF recurrence
10）

the period from the day when AF was first docu­

be involved .

In general, prior transthoracic echocardiographymented to CA. Oral administration of amiodarone(TTE) and transesophageal echocardiography (TEE)

was discontinued 1 month before CA, and other anti-

to assess cardiac function and morphology are im­arrhythmia drugs (AAD) were discontinued at 1 week

portant for safely performing CA. Recently, several

before CA. AAD were prescribed at discharge at

echocardiographic parameters have been proposed

the discretion of the attending cardiac electrophys­12）

as predictors of recurrence of psAF after CA . Left

iologist. IAS motion was examined in all patientsatrial diameter (LAD) and left atrial volume (LAV)

before CA, as described below. The study protocol

can be easily measured by TTE, and LAD and LAV

was approved by the ethics committee of Shinshu

enlargements may act as predictors of AF recur­

University Hospital (Apr 9, 2020, No.4705). Informed

rence after CA13）14）. TEE is required to ensure theconsent was obtained from as many patients as pos­absence of left atrial thrombi prior to CA

15）
16）

, and

sible, which was limited by the retrospective study

also provides a wide range of information. Determin­

design. However, the information pertaining to thising the thickness of the inter-atrial septum (IAS), thestudy was published on the homepage of our institu­

location of the fossa ovalis, and the presence of antion, and all study participants had the opportunity

atrial septal defect (ASD) or patent foramen ovale

to refuse participation.

(PFO) is essential for successful IAS puncture before

Ｂ Echocardiographic parameters and measure-

PVI. The IAS is often observed to move with the17）18）heartbeat during TEE

ment of IAS motion. This movement may be

All patients underwent TTE and TEE during theaffected by various factors, and Masai et al. have re­AF rhythm at 48 to 72 hours before CA. TTE wasported that a decline in this movement is correlated

performed using an iE 33 (Philips Medical Systems,

18）

with an increase in left atrial pressure (LAP) . The

Andover, MA) and X5-1 transducer probe (frequen­

elevation of LAP occurs as the LAD expands and thecy 1-5 MHz). TEE was performed using iE 33 with

LAV increases and the stretching stress may be aan 8-2t transducer probe (frequency 1-5 MHz). All

19）
20）

cause AF

. However, the direct relationship be­

tween IAS motion and psAF recurrence after CA isstill unknown.

evaluations were performed in a physiological labora­
tory.
Left ventricular ejection fraction (LVEF), LAD,

In this study, we observed and measured IAS mo­

LAV, LAV index (LAVI) and the peak transmitraltion on TEE performed before CA for psAF. We

velocity/peak lateral mitral annular velocity (lateral

aimed to evaluate whether a decrease in IAS motionE/e’) ratio were measured by TTE. LVEF was mea­

was associated with recurrence of AF after CA.

sured using Simpson’s method. LAV was determined

Ⅱ
Ａ

Materials and Methods

Patient populationaccording to the end-systolic maximum LAV before
mitral valve opening on the 4-chamber and 2-chamber
views using the biplane disc summation method.

Patients who underwent their first CA for psAF at

LAVI was determined by dividing the LAV by theShinshu University Hospital between August 2014

body surface area according to the DuBois equation21）.

and May 2018 were retrospectively reviewed. The

The lateral E/e’ ratio was measured in accordance

inclusion criterion was symptomatic, drug-refractorywith the guidelines of the American Society of Echo­

psAF. Patients with ASD, PFO, atrial septal aneu­

cardiography and the European Association of Car­rysm, moderate or more severe mitral valve disease,

diovascular Imaging22）. All values were calculated

any cancer, severe chronic obstructive pulmonary

using the average of 5 heartbeats.

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Shinshu Med J. 69

IAS motion and AF recurrence

Left atrial appendage (LAA) flow velocity and IAS

position to the most posterior position over 5 cardiac

motion were measured using TEE. LAA flow velocity

cycles (Fig. 1) due to the large variation in the am­

was measured at the LAA outlet using the pulse

plitude for each heartbeat during AF. All echocar­

Doppler method. The flow velocity was selected as

diographic measurements were performed by two

the maximum value among 5 heartbeats.

independent reviewers who were blinded to the ab­

Patients who were in sinus rhythm during mea­

lation methods and the clinical outcomes. The varia­

surement of IAS motion were excluded from thetion between reviewers was small, with an inter-study in order to focus on patients with true psAF.

class correlation coefficient for the average IAS motion

Accordingly, IAS motion was measured during AF

of 0.951 (95 ％ confidence interval [CI] : 0.944-0.975, p

rhythm in all patients. The IAS motion was defined＜0.001 ; Fig. 2). Due to the low variance among theas follows, with some modifications to the measure­reviewers, the quantitative data from one reviewer

18）: (1) Using a

was used for all figures and tables. Including thetwo-dimensional system, the IAS was visualized inanalyses performed by the other reviewers did not

the mid-esophageal bicaval view (90°-120°). At thisaffect the statistical significance or the overall magni­

time, patients with ASD, PFO, or atrial septal aneu­

tude of the observed changes.

rysm were excluded from this study. (2) An M-modeＣment method in the previous study

CA procedure and measurement of LAP

echocardiogram was drawn with the cursor passing

PVI was performed by radiofrequency CA (RFCA)

through the central portion of the IAS on the 2D

using an irrigated catheter with contact force (Thermo­

echocardiogram. (3) The amplitude of IAS motion was

Cool ; Biosense Webster, CA). A three-dimensional

measured using the M-mode. (4) The IAS motion

mapping system was used to simulate the geometry

was defined as the distance from the most anteriorof the left atrium and pulmonary veins. CTI block

Fig. 1 Measurement of IAS motion
IAS motion was observed in the mid-esophageal bicaval view (90°-120°
) with transesophageal echocardi­
ography. An M-mode echocardiogram was drawn with the cursor passing through the central part of the
IAS of the 2D echocardiogram. At this time, the IAS motion was depicted as the IAS amplitude. IAS motion
was defined as the distance from the most anterior to the most posterior position during 5 cardiac cycles.
IAS, inter-atrial septum.
No. 4, 2021

191

Kobayashi・Okada・Tabata et al.

Fig. 2 Inter-observer variance of IAS motion(a) Regression plot for determination of IAS motion by two echocardiographic observers blinded to the ablation methods
and clinical outcome. There is a high correlation coefficient (r＝0.951 ; p＜0.001) with a slope close to 1.0. (b) Bland andAltman analysis showed no difference in IAS motion between the two observers. The solid horizontal line represents themean difference between the two observers, and the dashed horizontal line represents the 95 ％ limits of agreement.
IAS, inter-atrial septum ; SD, standard deviation.

line ablation was performed if common atrial flutter

12 months.

was observed before or during CA. SVC isolation was

Ｄ

Follow-up and endpoint

performed if patients did not have sinus node dys­

All patients were monitored regularly for 12

function. Complete left atrial posterior wall isolation,months after CA. Data from 12-lead electrocardiog­

complex fractionated atrial electrogram ablation andraphy (ECG) or Holter monitoring were obtained atlinear ablation of the mitral isthmus were not per­follow-up visits every 3 months, or when the patient

formed.

came to the hospital complaining of palpitations. AF

The patient was sedated with dexmedetomidine

recurrence was defined as AF or atrial tachycardia

and thiopental, and respiratory management waslasting more than 30 seconds, as confirmed by 12-

performed using adaptive servoventilation (ASV).

lead ECG or Holter monitoring after CA. The three-During the CA procedure, defibrillation was per­month period immediately following the CA wasformed from the intra-cardiac electrode to restore

excluded as a blanking period.

sinus rhythm immediately before IAS puncture.

Ｅ

Statistics

After IAS puncture, a long sheath was inserted into

Normally distributed quantitative variables ac­

the left atrium and the LAP under sinus rhythm wascording to the Shapiro-Wilk test were presented asmeasured. Maximum LAP, minimum LAP and mean

the mean ±standard deviation (SD), while non-

LAP were recorded using CardioLab (General Elec­normally distributed variables were presented as thetric Medical Systems Inc., Milwaukee, WI).

median of the interquartile range (IQR). Quantitative

The procedural endpoints were defined as follows :variables were compared using either Student’s

the entrance and exit blocks between each pulmo­

t-test or the Mann-Whitney test, as appropriate.

nary vein and the left atrium were confirmed, noCategorical variables were compared using the chi-induction of sustained AF or atrial tachycardia bysquare test or Fisher’s exact test. A p-value of <0.05

rapid atrial pacing and 10 μg isoproterenol infusion

was considered statistically significant. Multiple logis­

after PVI, and no documented dormant conduction

tic regression analysis using the stepwise method

between the pulmonary vein and the left atrium,

was used to identify predictors of AF recurrence.

induced by adenosine triphosphate. All patients re­

Receiver-operating characteristic (ROC) curve analy­

ceived oral anticoagulation for at least 4 weeks before

sis was performed to assess the optimal cut-off value

CA, which was subsequently continued for at leastof IAS motion for predicting AF recurrence. The

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Shinshu Med J. 69

IAS motion and AF recurrence

Kaplan-Meier method was employed to estimate thedecreased IAS motion, increased maximum LAP, andcumulative event rates of AF recurrence. Spearman’s

increased mean LAP were significantly associatedrank correlation coefficient was calculated to deter­with AF recurrence. Low lateral E/e’ and increasedmine the relationship between IAS motion and other

LAVI tended to be higher in the patients that devel­

echocardiographic parameters and LAP. All analyses

oped AF recurrence. There was no relationship be­were performed using SPSS statistical software,

tween AF recurrence after CA and the type of anti­

version 24.0 (IBM Corp., Armonk, NY).

arrhythmic drugs prescribed at discharge or theⅢ
Ａ

Results

Patient characteristics and IAS motion

ablation methods. A multivariate analysis performed
using various models adjusted for BMI, LAV, systolic
LAP, and mean LAP showed that decreased IAS

A total of 103 patients were enrolled in this study.

motion was independently associated with AF recur­

AF recurrence after CA occurred in 29 patients (28.2

rence after CA. ROC curve analysis for IAS motion’s％) during the follow-up period. The median value ofability to predict AF recurrence was performed andIAS motion was 4.1 mm (IQR, 2.4, 5.4). Table 1 sum­compared with that of LAV (Fig. 3). This analysis

marizes the baseline characteristics. The cohort was

showed that the optimal cut-off value for IAS motion

divided into two groups (high IAS motion group ;was 4.2 mm (area under the curve [AUC] : 0.75, 95 ％IAS motion ≥ 4.2 mm, n＝47 and low IAS motion

CI 0.64-0.85, p＝0.001), with a specificity and sensitiv­

group ; IAS motion＜4.2 mm, n＝56) based on the

ity of 89.3 ％ and 56.1 ％, respectively. The AUC for

ROC curve analysis described later. Although the

IAS motion exceeded that for LAV (0.75 vs. 0.66).

CHA2DS2-Vasc score was significantly higher in theFig. 4 shows the AF recurrence-free curve for the

low IAS motion group, the presence of factors relat­high and low IAS motion groups. During follow-up,

ed to the CHA2DS2-Vasc score such as age, female

the high IAS motion group had fewer AF recurrenc­

sex, and diabetes mellitus, did not differ between thees than the low IAS motion group (p＝0.001, log rank

two groups. The brain natriuretic peptide and C-test).

reactive protein levels were significantly higher inＣ Relationship between IAS motion and otherthe low IAS motion group. LAV and LAVI was sig­

echocardiographic parameters and LAP

nificantly larger in the low IAS motion group, but

A comparison of IAS motion and parameters

LAD showed no significant difference. The differenc­

obtained by TTE and TEE was performed as shownes in lateral E/e’ and LAA flow velocity were statis­

in Fig. 5. IAS motion was not correlated with LAD

tically significant. Amiodarone, beta-blockers and(correlation coefficient ; r＝－0.11, p＝0.26), but showed

calcium antagonists were used during the periopera­

a negative correlation with LAV and lateral E/e’ (r＝tive period, but the rates of their use did not differ－0.26, p＝0.01 ; and r＝－0.24, p＝0.014, respectively).

between the two groups. There were no significant

Conversely, a positive correlation was found between

differences between the two groups in the number of

LAA flow velocity and IAS motion (r＝0.30, p＝0.002).

patients undergoing PVI alone or those undergoing

In addition, the relationship between IAS motion

additional SVC isolation and/or CTI block line. Meanand LAP measured during CA was also examined. Inarterial pressure, maximum LAP, and mean LAP

patients with reduced IAS motion, the mean LAP

were higher in the low IAS motion group while

was increased ; that is, IAS motion was negatively

there was no difference in minimum LAP values.

correlated with systolic LAP and mean LAP (r＝－Ｂ Association between IAS motion and AF

0.31, p＝0.016 ; and r＝－0.39, p＝0.002, respectively).

recurrence

The mean LAP in the low and high IAS motion

Logistic regression analysis was performed to de­groups were 12 mmHg (IQR, 9, 14) and 9 mmHg

termine the factors related to psAF recurrence(IQR, 5, 11), respectively, showing a significant inter-(Table 2). High body mass index (BMI), large LAV,

group difference (Fig. 6).

No. 4, 2021

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Kobayashi・Okada・Tabata et al.
Table 1Age (years)
Female sex
Body mass index (kg/m2)
Hypertension
Congestive heart failure
Diabetes mellitus
Previous cerebral infarction
Coronary artery disease
Peripheral artery disease
CHA2DS2-Vasc score
AF Duration (month)
BNP (pg/ml)
eGFR (ml/min/1.73m2)

C-reactive protein (mg/dl)
Left atrial diameter (mm)Left atrial volume (ml)Left atrial volume index (ml/m2)
LVEF (％)
Lateral E/e’
LAA flow velocity (cm/s)
IAS motion (mm)Ineffective AAD before CA
Amiodarone
Beta- blocker
Calcium antagonist
ACE-I/ARBAAD at discharge
Amiodarone
Beta-blocker
Calcium antagonist
ACE-I/ARB
Ablation method
PVI only
PVI＋SVCIPVI＋CTI block line
PVI＋SVCI＋CTI block line
Procedure findings
Mean arterial pressure (mmHg)
Heart rate (bpm)
Maximum LAP (mmHg)
Minimum LAP (mmHg)
Mean LAP (mmHg)

Baseline characteristics

All patients

IAS motion ≥ 4.2 mm

IAS motion＜4.2 mm(n＝103)(n＝47)(n＝56)

p-value

64 (58, 69)
15 (14.6)

61 (48, 69)
7 (14.9)

65 (61, 69)
8 (14.3)

0.066
1.00

24.7±3.4
55 (53.4)
14 (13.6)
19 (18.4)
10 (9.7)
6 (5.8)2 (1.9)24.1±3.8
20 (42.6)
6 (12.8)
5 (10.6)2 (6.9)3 (6.4)
1 (1.8)25.3±3.1
35 (62.5)
8 (14.3)
14 (25.0)
8 (10.8)
3 (5.4)1 (2.1)

0.20
0.053
1.00
1.00
0.21
0.83
1.00

1 (1, 2)36 (12, 72)
99.7 (54.6, 181)

1 (0, 2)24 (12, 60)
69.4 (34.3, 142)

2 (1, 3)36 (12, 72)
115 (66.1, 203)

0.005
0.76
0.012

66.0 (57.0, 72.0)
0.05 (0.03, 0.10)
42.0 (38.0, 45.0)
75.0 (52.1, 94.0)

64.0 (59.0, 73.0)
0.04 (0.02, 0.07)
39.5 (36.0, 44.5)
60.1 (47.0, 80.0)

66.5 (54.3, 71.5)
0.06 (0.04, 0.13)
42.5 (39.3, 45.3)
81.0 (59.7, 101)

0.98
0.012
0.099
0.001

40.7 (29.1, 51.2)
62.1±11.9
7.20 (5.70, 8.67)
35.7 (24.3, 56.9)
4.1 (2.4, 5.4)

31.3 (28.2, 47.8)
60.9±9.1
6.30 (5.20, 7.55)
43.6 (30.0, 68.5)
5.5 (4.6, 7.0)

44.1 (32.6, 53.3)
63.1±13.0
7.60 (6.43, 10.6)
31.0 (21.5, 41.0)
2.6 (1.7, 3.6)

0.002
0.41
0.001
0.006
＜0.00116 (15.5)
51 (49.5)
48 (46.6)
45 (43.7)

8 (17.0)23 (48.9)
18 (38.3)
17 (36.2)

8 (14.3)
28 (50.0)30 (53.6)
28 (50.0)

0.79
1.00
0.17
0.17

14 (13.6)
60 (58.3)
40 (38.8)
44 (42.7)

5 (10.6)
25 (53.2)
14 (29.8)
16 (34.0)

9 (16.1)
35 (62.5)
26 (46.4)
28 (50.0)

0.57
0.42
0.11
0.11

35 (34.0)
42 (40.8)8 (7.8)18 (17.5)

17 (36.2)
17 (36.2)
4 (8.5)9 (19.1)

18 (32.2)
25 (44.6)
4 (7.1)9 (16.1)

0.67
0.43
0.80
0.68

90 (80, 101)
62 (55, 71)
18 (15, 24)
3 (1, 5)10 (8, 13)

81 (75, 95)
58 (51, 66)
17 (13, 21)
2 (0, 4)9 (5, 11)92 (87, 101)
64 (59, 73)
19 (17, 24)
4 (2, 5)12 (9, 14)

0.017
0.082
0.045
0.089
0.010

IAS, interatrial septum ; AF, atrial fibrillation ; BNP, brain natriuretic peptide ; eGFR, estimated glomerular filtration
rate ; LVEF, left ventricular ejection fraction ; E/e’, early diastolic left ventricular filling velocity / peak early diastolicmitral annulus velocity ; LAA, left atrial appendage ; AAD, anti-arrhythmia drug ; ACE-I, angiotensin converting
enzyme-inhibitor ; ARB, angiotensin II receptor blocker ; PVI, pulmonary vein isolation ; SVCI, superior vena cava
isolation ; CTI, cavo tricuspid isthmus ; LAP, left atrial pressure.

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No. 4, 2021
0.21
0.63
0.045
0.83
0.55
0.84
0.55
0.15
0.56
0.59
0.12
0.35
0.020
0.061
0.13
0.053
0.24
0.003
0.20
0.69
0.74
0.54
0.32
0.20
0.25
0.83
0.017
0.13
0.038

1.03 (0.98-1.08)
1.33 (0.41-4.30)
1.14 (1.00-1.31)
1.10 (0.47-2.56)
1.52 (0.39-5.88)
1.12 (0.37-3.45)
1.64 (0.33-8.33)
1.32 (0.91-1.89)
1.03 (0.94-1.13)
1.00 (1.00-1.00)
1.03 (0.99-1.07)
1.37 (0.71-2.67)
1.02 (1.00-1.04)
1.03 (1.00-1.06)
1.03 (0.99-1.07)
0.82 (0.68-1.00)
0.99 (0.97-1.01)
0.69 (0.55-0.88)

0.47 (0.15-1.47)
0.84 (0.35-2.00)
1.16 (0.48-2.78)
0.76 (0.32-1.83)

1.57 (0.64-3.80)
0.57 (0.24-1.36)
0.53 (0.18-1.36)
0.83 (0.14-4.73)
1.12 (1.02-1.22)
1.16 (0.96-1.41)
1.16 (1.01-1.33)

p-value

0.12

0.17

0.005

1.01 (1.00-1.03)

0.66 (0.49-0.88)

p-value

1.13 (0.97-1.31)

OR (95 ％ CI)

Model 1

Logistic regression analysis

1.09 (0.97-1.22)

0.57 (0.36-0.88)

1.02 (0.99-1.05)

OR (95 ％ CI)

Model 2

0.15

0.012

0.21

p-value

Multivariate
Model 3

1.15 (0.96-1.37)

0.58 (0.37-0.91)

1.02 (0.99-1.05)

OR (95 ％ CI)

0.13

0.017

0.16

p-value

OR, Odds ratio ; CI, confidence interval ; BMI, Body mass index ; AF, atrial fibrillation ; BNP, brain natriuretic peptide ; eGFR, estimated glomerular filtration rate ; LVEF,
left ventricular ejection fraction ; E/e’, early diastolic left ventricular filling velocity / peak early diastolic mitral annulus velocity ; LAA, left atrial appendage ; IAS,
interatrial septum ; AAD, anti-arrhythmia drug ; ACE-I, angiotensin converting enzyme-inhibitor ; ARB, angiotensin II receptor blocker ; PVI, pulmonary vein isolation ; SVCI,
superior vena cava isolation ; CTI, cavo tricuspid isthmus ; LAP, left atrial pressure.

Age
Female sex
BMI
Hypertension
Congestive heart failure
Diabetic mellitus
Previous cerebral infarction
CHA2DS2-Vasc score
AF Duration
BNP
eGFR
Left atrial diameter
Left atrial volume
Left atrial volume Index
LVEF
Lateral E/e’
LAA flow velocity
IAS motion
AAD at discharge
Amiodarone
Beta-blocker
Calcium antagonist
ACE-I/ARB
Ablation method
PVI only
PVI＋SVCIPVI＋CTI block line
PVI＋SVCI＋CTI block line
Systolic LAP
Diastolic LAP
Mean LAPOR (95 ％ CI)

Univariate

Table 2

IAS motion and AF recurrence

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Kobayashi・Okada・Tabata et al.

Fig. 3 ROC curve analysis for IAS motion and LAV
The optimal cut-off value for IAS motion was 4.2 mm(the specificity and sensitivity were 89.3 ％ and 56.1 ％,respectively). The area under the curve (AUC) of IAS
motion was 0.75 (95 ％ CI 0.64-0.85, p＝0.001). The AUC
for IAS motion exceeded that for LAV (0.75 vs. 0.66).
ROC, receiver-operating characteristic ; IAS, inter-atrial
septum ; LAV, left atrial volume.

Fig. 4 Kaplan-Meier analysis for the probability of AF recurrence after CA according to IAS motion
The solid line represents the high IAS motion group, and the dashed line represents the low IAS motion group.
AF, atrial fibrillation ; CA, catheter ablation ; IAS, inter-atrial septum.

Ⅳ Discussion

motion also had a higher LAP measured during CA
than those with preserved IAS motion. Our results

This study showed that a decline in IAS motion

suggest that the decrease in IAS motion reflected

was independently associated with AF recurrence

the increase in LAP, which might increase the risk ofafter CA. In addition, IAS motion was significantly

AF recurrence following CA.

correlated with other echocardiographic parameters,

The IAS is a membrane-like structure that sepa­

such as LAV and E/e’, which are associated with AF

rates the left and right atria. TTE and TEE studies

recurrence. Moreover, patients with decreased IAS

have confirmed the amplitude movement of the IAS

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Shinshu Med J. 69

IAS motion and AF recurrence

Fig. 5 Associations between IAS motion and other echocardiographic parameters(a) IAS motion and LAD. (b) IAS motion and LAV. (c) IAS motion and lateral E/e’. (d) IAS motion and LAA
velocity flow. IAS motion had a negative correlation with LAV and lateral E/e’ (r＝－0.26, p＝0.01 ; and r＝－0.24,
p＝0.014, respectively), and a positive correlation with LAA flow velocity (r＝0.30, p＝0.002).
IAS, inter-atrial septum ; E/e’, early diastolic left ventricular filling velocity / peak early diastolic mitral annulus
velocity ; LAA, left atrial appendage ; LAD, left atrial diameter ; LAV, left atrial volume.

Fig. 6 Comparison of mean LAP according
to IAS motion
The mean LAP was significantly higher inthe low IAS motion group than in the high
IAS motion group (12 mmHg vs. 9 mmHg,
respectively). Horizontal lines represent themedian, boxed areas are the interquartile
range, and vertical whiskers represent the
10 ％-90 ％ range.
IAS, inter-atrial septum ; LAP, left atrial pre­ssure.

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Kobayashi・Okada・Tabata et al.

during the cardiac cycle23）. Previously, Tei et al. sug­were performed during CA in sedated patients andgested that there was a decrease in IAS activity in

could have been affected if the patient had sleep

17）

patients with atrial overload . IAS motion has been

apnea syndrome ; however, the use of ASV may mean

reported to be influenced by various factors andthat this is not an issue. Patients with reduced IAS

might reflect the compliance and pressure of the left

motion have reportedly higher LAP18）. Even in our

atrium6）. The normal values for IAS motion are notstudy, the average LAP values were significantly

clear ; Masai et al. have reported that IAS motion inincreased in patients with reduced IAS motion. Thus,

patients with AF rhythm was 7.6 mm to 12.2 mm,

the decrease in IAS motion may be an indicator of18）

and motion＜10 mm as low IAS motion . This study

LAP elevation.

defined IAS motion＜4.2 mm as a decrease in IAS

Cases of psAF with LAV enlargement and LAP

motion. This threshold was supported by an ROC

increase are often accompanied by such electricalcurve analysis for prediction of AF recurrence. In

remodeling as spreading of the low voltage area

addition, the Bland and Altman analysis showed little(LVA) of the left atrium30）-32）. Since left atrial LVA

difference in the values of IAS motion between thecan be the arrhythmogenic substrate and circuit of

two echocardiographic reviewers, suggesting thatatrial tachycardia, its expansion may lead to AF re­the IAS motion measurement had high inter-rater

currence after CA. To summarize, the following

reliability.

mechanism can be considered : (1) Persistence of AF.

Several reports have described the association be­(2) Enlargement of LAV. (3) Increase in LAP. (4) Prog­

tween echocardiographic parameters, including ex­

ress of structural and electrical remodeling of left

13）
24）

pansion of LAD and LAV, and recurrence of AF

atrium. (5) Increased possibility of AF recurrence.

12）

after CA . LAA flow velocity has been evaluated as

Since an enlargement of LAV and increase in LAP

a surrogate marker of left atrial function. Previous

were observed in the group with reduced IAS motion

studies have reported a higher rate of AF recur­in our study, decreased IAS motion might be consid­

rence after CA in patients with reduced LAA flow

ered to reflect the steps (2) and (3).

velocity

25）
26）. Studies have also shown that increased

Ａ

Clinical implications
Estimating the state of left atrial remodeling prior

E/e’ reflects decreased left ventricular diastolic func­
27）
28）. These parameters may

to CA is very important for predicting the likelihood

indirectly reflect left atrial structural remodeling andof recurrence, determining the appropriate ablation

LAP elevation. In this study, IAS motion was nega­

strategy, and managing patients post-ablation. Al­

tively correlated with LAD, LAV, and E/e’, and posi­though LAD and LAV measured by TTE are usefultively correlated with LAA flow velocity. These find­in estimating left atrial remodeling, we have shownings suggest that progression of left atrial structuralthat IAS motion was more useful for predicting AF

remodeling and an increase in LAP might indicate arecurrence. Elevated LAP is another useful indicator

decrease in IAS motion.

of left atrial remodeling, but its measurement musttion and increased LAP

LAP measured invasively via IAS puncture has

be made invasively during CA. IAS motion, con­been reported as an independent predictor of AF re­versely, can be easily measured with TEE before

29）

currence after PVI . Park et al. found that elevated

CA. In other words, measuring IAS motion may be

LAP was closely associated with electro-anatomical

useful for prediction of left atrial remodeling before

remodeling of the left atrium and was an independent

CA.

30）

predictor of AF recurrence after CA . Moreover,Ｂ

Limitations

LAP measured during trans-septal puncture has alsoThis study had several limitations. First, this was abeen shown to be an independent predictor of AF

small observational study ; therefore, sampling bias

recurrence after cryoablation with second-generation

may be present. Validation in prospective trials withcryoballoons19）. In this study, LAP measurements

larger cohorts is needed. Second, while TEE was198

Shinshu Med J. 69

IAS motion and AF recurrence

essential for measuring IAS motion, it is an invasive

ablation methods were used in this study ; neverthe­

procedure and its use is decreasing due to the devel­

less, in all cases, the same conditions were eventuallyopment of contrast-enhanced computed tomography

assessed at the end of the procedure, i.e., AF was not

33）

and the prevalence of direct oral anticoagulants .

induced by isoproterenol administration and atrial

However, the risk of thrombosis during oral antico­

burst pacing after ablation. No significant differences

34）

agulant therapy is reported to be about 0.6 ％ , andwere found between the ablation methods, such as

thrombosis of the left atrium is a contraindication for

performing additional SVC isolation and/or CTI block

CA of AF. Therefore TEE is still being performedlines, and the recurrence rate in this study.

prior to CA at many institutions. Being able to pre­Ⅴ Conclusions

dict the recurrence of psAF by simple TEE IAS mo­tion assessment would be of great clinical signifi­

This study showed that AF recurrence after CA

cance. Third, IAS motion and LAP could not be mea-­

was associated with lower IAS motion. Our results

sured simultaneously. If IAS motion were measured

indicate that the decrease in IAS motion may repre­

by TEE during the CA, the correlation with LAP

sent an important finding suggestive of left atrial

would have been more apparent. However perform­

remodeling as well as enlargement of LAV and in­ing TEE during the CA was difficult. Lastly, several

creasing LAP.

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