J Cardiol 2004 Aug; 44（2）: 53 – 58

Predictors of Successful Catheter
Ablation for Atrial Fibrillation
Using the Pulmonary Vein Isolation
TechniqueTomoo

YASUDA, MD

Koichiro

KUMAGAI, MD,FJCC

Masahiro

OGAWA, MD

Hiroo

NOGUCHI, MD

Hideaki TOJO, MD
Naomichi

MATSUMOTO, MD

Keijiro

SAKU, MD, FJCC

Abstract ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
Objectives. Pulmonary vein isolation has been performed to cure atrial fibrillation（Af）. However, therecurrence rate of Af is relatively high, and additional sessions are sometimes required. The predictors ofsuccessful pulmonary vein isolation were evaluated.
Methods. The study population consisted of 52 patients（41 men, mean age 55 ± 9 years）
with Af who
underwent pulmonary vein isolation. A second session was required in 22 patients with recurrence of Af
after the first session. Pulmonary vein isolation eliminated Af in 38 patients after 1 or 2 sessions. Patientswith successful pulmonary vein isolation（n ＝ 39）
were compared with those with unsuccessful pulmonaryvein isolation despite 2 sessions（n ＝ 13）.
Results. The patients in the successful group had significantly higher incidence of paroxysmal Af（92%vs 46%, p ＜ 0.001）and lower incidence of mitral regurgitation（10% vs 46%, p ＜ 0.01）than those in theunsuccessful group. However, there was no significant difference between the two groups with regard toage, history of Af, cardiopulmonary ratio, dimension of left atrium, ejection fraction, pulmonary veindiameter, and pulmonary vein number.
Conclusions. Type of Af and presence of mitral regurgitation are significant predictors of successful
pulmonary vein isolation.
─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────J Cardiol 2004 Aug ; 44（2）: 53−58

Key Words
Atrial fibrillation pulmonary vein isolation
Mitral regurgitation

INTRODUCTION
Atrial fibrillation（Af）is the most common typeof arrhythmia in humans. Most cases of Af are initiated by premature beats from the orifices of thepulmonary veins or from the myocardial sleeves
inside the pulmonary veins, so radiofrequency
catheter ablation targeting pulmonary veins could

Ablation-catheter

cure Af 1−7）. Pulmonary vein isolation can beachieved by electrophysiological breakthroughsfrom the left atrium to the pulmonary vein5）. Morethan 90% of pulmonary veins were electrically disconnected from the left atrium by targeting only
certain segments of the ostial circumference, as
guided by pulmonary vein potential. These results
confirm that there are isolated fascicles that travel──────────────────────────────────────────────
福岡大学医学部附属病院 循環器科 : 〒 814−0180 福岡市城南区七隈 7−45−1
Department of Cardiology, Fukuoka University School of Medicine, Fukuoka
Address for correspondence : KUMAGAI K, MD, FJCC, Department of Cardiology, Fukuoka University School of Medicine,
Nanakuma 7−45−1, Jonan-ku, Fukuoka 814−0180
Manuscript received January 28, 2004 ; revised May 24, 2004 ; accepted May 24, 2004

53

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Yasuda, Kumagai, Ogawa et al

from the left atrium into the muscle sleeves thatsurround the pulmonary veins, and that ablation ofthese fascicles, as opposed to circumferential ablation at the ostium, is sufficient to isolate the veins.
Segmental pulmonary vein isolation resulted in significant reduction in the symptom severity andimprovement in the quality of life of patients withdrug refractory paroxysmal Af 8）. However, priorstudies of segmental pulmonary vein isolation
found a large percentage of patients required additional ablation procedures3,5）.
The present study evaluated the predictors ofsuccessful pulmonary vein isolation for Af.
SUBJECTS AND METHODS
Study population
The study population consisted of 52 patients（41
men, mean age 55 ± 9 years）
with paroxysmal（n ＝42）or persistent Af（ n ＝ 10）who underwent
pulmonary vein isolation or focal ablation.
Cardioversion was implemented in the early stage（＜ 24 hr）
, because many patients in the persistentgroup had severe symptoms. Therefore, paroxysmal
Af was defined as Af terminating spontaneously
within 24 hr, and persistent Af as Af lasting morethan 24 hr which required cardioversion to restore
sinus rhythm.
No structural heart disease was present in 35
patients. Hypertension was present in 14 patients,
mitral regurgitation in 10, coronary artery diseasein 8, and cardiomyopathy in 2. Significant mitral
regurgitation was defined as more than second
degree flow by Doppler echocardiography. All
antiarrhythmic drugs were discontinued for at least
five half-lives before the study. Informed consent
was obtained from all patients before the study.
Catheter positions
Three multipolar electrode catheters（Daig Corp.）
were positioned in the right atrial appendage, theHis bundle area, and the distal coronary sinus.
After an atrial transseptal procedure, a long sheath（8-French, Daig Corp. SL-1）was put into the left
atrium through the foramen ovale of the atrial septum from the right femoral vein. Pulmonary veinangiography was performed with an angiocatheter（6-French, Baxter）to determine the position of thecatheters relative to the ostium of the pulmonaryveins. A 7-French deflectable, quadripolar ablation
catheter（EPT）was inserted in the left atrium directly through the foramen ovale. Intravenous heparin

was administered at 1,000 U/hr after the atrial
transseptal procedure.
Electrophysiological study
Bipolar intracardiac electrograms were recorded
at a filter setting of 30 to 500 Hz and stored digitally on an EPMed system（EP MedSystems, Inc.）
simultaneously with the surface electrocardiography. A unipolar electrogram was recorded from the
distal electrode of the ablation catheter using a filter
ranging from 0.05 to 500 Hz. A programmed stimulator（SEC-3102, Nihon Koden）
was used to deliverelectrical stimuli at twice the diastolic threshold for
2 msec. If Af was not spontaneously present, burst
atrial pacing（10 to 20 beats）, isoproterenol, or bothwere used to facilitate spontaneous Af. If theepisode of induced Af was sustained for ＞ 10 min,external cardioversion（ with 100 to 300 J）was
attempted to defibrillate Af, and the spontaneous
re-initiation of Af was monitored.
Pulmonary vein isolation
All pulmonary veins with distinct and late pulmonary vein potentials were targeted for ablation.
After a targeted pulmonary vein was identified, abasket catheter（Constellation, EPT）or a circular
20-electrode catheter（ Lasso, Webster）was
deployed in the pulmonary vein through a transseptal sheath. Circumferential pulmonary vein electrograms were acquired simultaneously, and used to
guide the ablation at the ostial sites with the earliest
pulmonary vein potentials during sinus rhythm forthe right pulmonary veins or distal coronary sinus
pacing for the left pulmonary veins. The source ofectopy as well as the electrical inputs from the atria
to pulmonary vein were determined. Radiofrequency pulses were delivered with the temperature preset to 50 °C
（CABL-IT, Central Inc.）with apower limit of 30 W for 30 to 60 sec at ostial sites
with the earliest pulmonary vein potentials while
monitoring distal pulmonary vein potentials. If theactivation sequence around the pulmonary vein
ostium was changed, the bipole showing the new
shortest atrio-pulmonary vein conduction was targeted. The endpoint was determined as eliminationof atrio-pulmonary vein conduction based on abolition of distal pulmonary vein potentials.
Follow-up
Heparin（500 U/hr）was continuously administered for 24 hr, and oral coumadin was continued
J Cardiol 2004 Aug; 44（2）: 53 – 58

Predictors of Successful Pulmonary Vein Isolationfor 1 month with an international normalized ratio
level of about 2.0. Follow-up examinations were
performed at this institution, initially at 1 week, andsubsequently at 1-month intervals. Clinical examination, electrocardiography, and 24-hour Holter
recordings were made every 3 months and if symptoms suggested recurrence of the arrhythmia. Three
dimensional computer tomography was obtained at
3 and 6 months after ablation to assess stenosis of
the pulmonary veins. Ablation was considered successful if no recurrence of Af was present without
drug administration during the follow-up.
Comparison of parameters between successful
and unsuccessful groups
Age, history of Af, type of Af, incidence of
mitral regurgitation, cardiothoracic ratio, thedimension of the left atrium, the ejection fraction,
pulmonary vein number, and the pulmonary veindiameter were compared between the successful
and unsuccessful groups.
Statistical analysis
Data are presented as mean ± SD. Unpaired ttest was used for comparison of parameters
between the successful and unsuccessful groups.
p ＜ 0.05 was considered statistically significant.
RESULTS
Pulmonary venous isolation was performed in all
52 patients. One, 2, 3 and 4 pulmonary veins wereablated in 10, 12, 25 and 5 patients, respectively. A
total of 129 pulmonary veins, including 46 left
superior, 42 right superior, 33 left inferior, and 8
right inferior pulmonary veins were ablated. The
earliest pulmonary vein potentials were localized ina segment of the circumference of the ostium,
whereas the remaining perimeter was activatedsequentially later. Ablation limited to a single segment blocked atrio-pulmonary vein conduction andthe ablation of the secondary breakthrough eliminated all distal pulmonary vein potentials in 84 pulmonary veins（ 65%）. Multiple radiofrequency
applications to more than two segments wererequired to eliminate all distal pulmonary veinpotentials in 117 pulmonary veins（ 91%）.
Pulmonary vein disconnection could be achievedby less than 3 segmental ablations in 98% of all
pulmonary veins. The electrical breakthroughpoints were mainly located in the inferior well inthe superior pulmonary veins, and in the superior
J Cardiol 2004 Aug; 44（2）: 53 – 58

55

Fig. 1 Outcome of pulmonary vein isolation
After the first session, atrial fibrillation recurred in 22
patients, who underwent a second session. After thesecond session, atrial fibrillation recurred in 13 patients.
Pulmonary vein isolation with 1 or 2 sessions eliminated atrial fibrillation in 39 patients.
Af ＝ atrial fibrillation.

wall in the left inferior pulmonary vein.
Af recurred in 22 patients after the first session.
A second session was performed in 16 patients dueto the recovery of atrio-pulmonary vein conduction（including 2 other pulmonary vein foci and 1 nonpulmonary vein focus）, 3 patients with non-pulmonary vein foci（1 atrio-pulmonary vein conduction recurrence and 1 near ablated pulmonary vein
are implicated）, 2 patients with recurrence from
pulmonary vein ostia proximal to the previous pulmonary venous isolation（1 atrio-pulmonary veinrecurrence and 1 non-pulmonary vein）, and 3
patients with recurrence from a different pulmonaryvein（ including 2 atrio-pulmonary vein conduction）. Af recurred at a median of 3 days（range,
1 to 7 days）
after the first procedure. Af recurred in
13 patients after the second session. During a meanfollow up of 15 ± 8 months, pulmonary vein isolation with 1 or 2 sessions eliminated Af without
antiarrhythmic drugs in 39 patients（Fig. 1）. No
complications including pulmonary vein stenosis
were observed during follow-up.
Comparison of the successful and unsuccessful
groupsPatients with successful pulmonary vein isolation（n ＝ 39）
were compared with those with unsuccessful ablation（n ＝ 13）. The patients in the successful group had significantly higher incidence ofparoxysmal Af（92% vs 46%, p ＜ 0.001）
and lower
incidence of mitral regurgitation（10% vs 46%, p ＜0.01）than those in the unsuccessful group.

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Yasuda, Kumagai, Ogawa et al

Table 1 Comparison of parameters between successful and unsuccessful groups
Successful group（n＝39）

Unsuccessful group（n＝13）

Age（yr）

57±9

53±9

NS

Male/female

32/7

9/4

NS

Af history（months）

43±40

62±43

NS

Paroxysmal Af

36（92）

6（46）＜0.001

Persistent Af

3（ 8）

7（54）

＜0.001Hypertension

13（33）1（ 8）NS

p value

Mitral regurgitation

4（10）

6（46）

＜0.001

Coronary artery diseases

7（18）

1（ 8）

NS

Cardiomyopathy

1（ 2）

1（ 8）

NS

Cardiopulmonary ratio
（%）

49±5

47±4

NS

Left atrial dimension
（mm）

39±6

38±4

NS

Ejection fraction
（%）

66±10

62±11

NS

Pulmonary vein diameter（mm）

18±12

18±9

NS

Pulmonary vein number

2±0.9

3±0.7

NS

Continuous values are mean±SD.（
Abbreviation as in Fig. 1.

）: %.

However, there was no significant difference
between the two groups with regard to age, sex,
history of Af, incidence of other organic heart diseases, left atrium dimension, ejection fraction, pulmonary vein diameter, and pulmonary vein number（Table 1）.
DISCUSSION
This study found that in patients who required asecond procedure, recovery of conduction throughthe surrounding pulmonary veins was the mostcommon reason for recurrent Af after pulmonaryvein isolation. It is possible that some of the fascicles were too thick to be ablated with the conventional radiofrequency energy limited to 30 W. This
would explain why a saline-irrigated ablation
catheter, which creates deeper lesions than a conventional ablation catheter, was needed to isolate
about 10% of pulmonary veins5）. Recovery of atriopulmonary vein conduction may be prevented if thepower of the radiofrequency energy applications is
not limited to 30 W. However, a conservative
approach to ablation is favored to minimize the riskof pulmonary vein stenosis.
Another reason for recurrence of Af after pulmonary vein isolation is unmasked foci from thepulmonary vein ostial edge or atrial tissue. Previous
studies have demonstrated that the foci that trigger
paroxysmal Af arise from areas other than the pul-monary veins in 5% to 15% of patients 1,2）.
Pulmonary vein isolation should be supplemented
by some other type of ablation procedure directed
at the atrial tissue. The ideal catheter ablation strategy remains to be determined.
In the present study, the patients in the successful
group had significantly higher incidence of paroxysmal Af than those in the unsuccessful group. Thisfinding is consistent with a previous study which
reported that the efficacy of pulmonary vein isolation in patients with persistent Af was only 29%6）.
Pulmonary vein isolation performed intraoperatively under direct visualization in patients with chronic Af restored sinus rhythm in only about 33% of
patients9）. These results suggest that the pulmonaryveins are less critical in generating Af once the Af
has become persistent. Electrophysiological andanatomic remodeling may occur during persistent
Af and allow the atria to continue fibrillating independent of the pulmonary veins. Therefore, it may
be preferable to intervene with catheter ablation
before paroxysmal Af progresses to persistent Af.
In contrast to the findings of the present study,
another study reported that pulmonary vein isolation was equally effective in patients with paroxysmal and persistent Af, with about 60% of patients
being free of recurrent Af 9 months after circumferential ablation at the ostia of the pulmonaryveins10）. The explanation for this discrepancy is
J Cardiol 2004 Aug; 44（2）: 53 – 58

Predictors of Successful Pulmonary Vein Isolationunclear but may be related to differences in patient
selection or technique.
In the present study, the other significant predictor of successful pulmonary vein isolation was thepresence of mitral regurgitation. Atrial stretch
induced by increased volume overload may precipitate Af through some effect on atrial refractoriness.
Elevation of atrial pressure might cause electrical
remodeling, which may increase the stability of Af
and be involved in the transition of paroxysmal Af
to persistent Af. A limitation of this study is thatleft atrial dimension was only 39 ± 5 mm with all
要

57

patients, because the enrollment of patients withparoxysmal and persistent Af was intentionallyrestricted. Also, drugs including diuretics may haveinfluenced the results.
CONCLUSIONSThe present study demonstrated that the type of
Af and the presence of mitral regurgitation weresignificant predictors of successful pulmonary vein
isolation. Therefore, paroxysmal Af without mitral
regurgitation may be eligible for pulmonary vein
isolation.
約

肺静脈隔離術を用いた心房細動に対するカテーテルアブレーションの成功予測因子
安田

目

智生

熊谷浩一郎

小川

正浩

野口

東條

秀明

直道

朔

啓二郎

松本

博生

的 : 肺静脈隔離術は心房細動の治療目的に施行されている．しかし，心房細動は再発率が比較的高く，追加のセッションがしばしば必要とされる．我々は肺静脈隔離術の成功予測因子を評価した．
方法 : 対象は肺静脈隔離術を経験した発作性または持続性心房細動患者 52 例（男性 41 例，平均年齢 55 ± 9 歳）である．発作性心房細動は 24 時間以内に自然停止する心房細動，持続性心房細動は24 時間以上続く心房細動と定義した．最初のセッション後，22 例の患者で心房細動の再発がみら
れ，2 回目のセッションを施行した．39 例の患者で 1 または 2 回の肺静脈隔離術が施行された．肺静脈隔離術の成功群（39 例）と，2 回の肺静脈隔離術にもかかわらず不成功であった群（13 例）とを比較検討した．
結果 : 成功群では，不成功群より発作性心房細動の占める割合が有意に高く（92% vs 46%，p ＜0.001），僧帽弁閉鎖不全の頻度が有意に低かった（10% vs 46%，p ＜ 0.01）．しかし，両群間で，年齢，心房細動歴，他の基礎疾患，左房径，左室駆出率，心胸郭比に有意差はみられなかった．
結論 : 心房細動のタイプと心臓弁膜症の存在が，肺静脈隔離術の成功規定因子として重要と考えられた．

J Cardiol 2004 Aug; 44（2）: 53−58

References
1）Haissaguerre M, Jais P, Shah DC, Takahashi A, Hocini M,
Quiniou G, Garrigue S, Le Mouroux A, Le Metayer P,
Clementy J : Spontaneous initiation of atrial fibrillation byectopic beats originating in the pulmonary veins. N Engl J
Med 1998 ; 339 : 659−666
2）Chen SA, Hsieh MH, Tai CT, Tsai CF, Prakash VS, Yu
WC, Hsu TL, Ding YA, Chang MS : Initiation of atrial fibrillation by ectopic beats originating from the pulmonaryveins : Electrophysiological characteristics, pharmacological responses, and effects of radiofrequency ablation.
Circulation 1999 ; 100 : 1879−1886
3）Haissaguerre M, Jais P, Shah DC, Garrigue S, Takahashi A,

J Cardiol 2004 Aug; 44（2）: 53 – 58

Lavergne T, Hocini M, Peng JT, Roudaut R, Clementy J :Electrophysiological end point for catheter ablation of atrial
fibrillation initiated from multiple pulmonary venous foci.
Circulation 2000 ; 101 : 1409−14174）Kumagai K, Gondo N, Matsumoto N, Noguchi H, Tojo H,
Yasuda T, Nakashima H, Saku K : New technique forsimultaneous catheter mapping of pulmonary veins forcatheter ablation in focal atrial fibrillation. Cardiology
2000 ; 94 : 233−238
5）Haissaguerre M, Shah DC, Jais P, Hocini M, Yamane T,
Deisenhofer I, Chauvin M, Garrigue S, Clementy J :Electrophysiological breakthroughs from the left atrium tothe pulmonary veins. Circulation 2000 ; 102 : 2463−2465
6）Oral H, Knight BP, Tada H, Ozaydin M, Chugh A, Hassan

58

Yasuda, Kumagai, Ogawa et al

S, Scharf C, Lai SW, Greenstein R, Pelosi F Jr,
Strickberger SA, Morady F : Pulmonary vein isolation forparoxysmal and persistent atrial fibrillation. Circulation
2002 ; 105 : 1077−10817）Morady F : Treatment of paroxysmal atrial fibrillation bypulmonary vein isolation. Circ J 2003 ; 67 : 567−571
8）Tada H, Naito S, Kurosaki K, Ueda M, Ito S, Shinbo G,
Takahashi T, Hoshizaki H, Oshima S, Taniguchi K,
Nogami A : Segmental pulmonary vein isolation for paroxysmal atrial fibrillation improves quality of life and clinicaloutcomes. Circ J 2003 ; 67 : 861−8659）Melo J, Adragao P, Neves J, Ferreira MM, Pinto MM,
Rebocho MJ, Parreira L, Ramos T : Surgery for atrial fibrillation using radiofrequency catheter ablation : Assessmentof results at one year. Eur J Cardiothorac Surg 1999 ; 15:
851−854
10）Pappone C, Rosanio S, Oreto G, Tocchi M, Gugliotta F,
Vicedomini G, Salvati A, Dicandia C, Mazzone P,
Santinelli V, Gulletta S, Chierchia S : Circumferential
radiofrequency ablation of pulmonary vein ostia : A newanatomic approach for curing atrial fibrillation. Circulation
2000 ; 102 : 2619−2628

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