Stephan Geidel, Michael Lass and Jörg
Ostermeyer
Dept. Cardiac Surgery, AK St. Georg, Hamburg, Germany
Address for
correspondence: Dr. med. Stephan Geidel, Dept. Cardiac Surgery, AK St.
Georg Hamburg, Lohmuehlenstraße 5
20099 Hamburg, Germany. E-mail: StGeidel@aol.com
Abstract
Background: Even if permanent atrial fibrillation (pAF) is a
frequent concomitant problem in patients undergoing open heart surgery
and particularly in those with advanced age, data of pAF ablation
surgery in older
aged patients are scarce. This study was performed to assess early and
late
results of combined open heart surgery and pAF ablation procedures in
patients
with advanced aged, compared to young patients.
Material and Methods: A selective group of 126 patients
(Group A: age ≥70 [76.4±4.8] years, n=70; Group B: age <70
[62.0±6.2] years: n=56) with pAF (≥6 months) underwent either
monopolar (Group A, B: n=51 vs. n=44) or bipolar (Group A, B: n=19 vs.
n=12) radiofrequency (RF) ablation procedures concomitant to open heart
surgery. Regular follow-up
was performed 3 to 36 months after surgery to assess survival, New York
Heart Association (NYHA) class and conversion rate to stable sinus
rhythm (SR).
Results: Early mortality (<30 days) was 2.9% in Group A
(Group B: 0%), cumulative survival at long-term follow up was 0.78 vs.
0.98 (p=0.03) and NYHA-class improved significantly in both groups,
particularly in cases with stable SR. At 12-months follow-up 73% of
Group A patients were in stable SR (Group B 78%).
Conclusions: Concomitant mono- and bipolar RF ablation
surgery represents a safe option to cure pAF during open heart surgery
with a very low risk, even in patients with advanced age.
Key words: Atrial fibrillation; atrial fibrillation surgery;
radiofrequency ablation; arrhythmia surgery; bipolar radiofrequency
ablation.
Introduction
Permanent
atrial fibrillation (pAF) is a serious concomitant problem in many
patients undergoing open heart surgery, particularly in those with
advanced age: a prospective analysis among 4590 patients, which were
scheduled for open heart surgery in our institution between February
2001 and December 2004, revealed a prevalence of pAF (persisting for at
least 6 months) of 4.6% in older aged patients
(70-99 years), compared to only 2.9% in young patients (p<0.001;
Table
1.); the prevalence was particularly high in elderly women (7.2%
[58
of 809], compared to 3.1% [43 of 1381] in older aged men;
p<0.001).
As pAF
significantly deteriorates the prognosis particularly at advanced age
1, reliable ablation concepts are required
to eradicate pAF during open heart surgery in these patients. This
study was performed to assess early and late results (survival,
improvement of New
York Heart Association [NYHA] class and SR conversion rate) of combined
open
heart surgery and pAF ablation procedures using monopolar and bipolar
radiofrequency (RF) energy in patients with advanced aged, compared to
young patients.
*ration male/female: 67.6% (n=3103) vs.
32.4%
(n=1487); pAF among men and women: 88 of 3103 (2.8%) vs. 83 of 1487
(5.6%),
p<0.001;
**male: n=88, female: n=83;
†male: n=65, female: n=61;
‡pAF in older aged (70-99 years) vs. young (<70 years) patients: 101
of
2190 [4.6%] vs. 70 of 2400 [2.9%].
Patients
The population
existed of a selective group of 126 patients (Group A: age ≥70
[76.4±4.8] years, n=70; Group B: age <70 [62.0±6.2]
years: n=56) with pAF
(≥6months) which were scheduled for open heart surgery in our
department
between February 2001 and December 2004. Exclusion criteria for
ablation
surgery were: emergency operation, Euro-score >12
(Euro-score:
established
score to evaluate the predicted risk of cardiac operations [low
risk:
1-2 points; moderate risk: 3-5 points; high risk: ≥6 points]),
severe
reduced left ventricular function (LVEF ≤25%), acute endocarditis or
myocardial
infarction (≤7days), considerable cachexia (Body Mass Index ≤18),
intracardiac
thrombosis with one or more large (>20mm) floating thrombus, left
atrial
(LA) enlargement with an LA-diameter of
≥72mm in the
transthoracic
echocardiography (parasternal M-mode acquisition) or any other form of
AF
(intermittent or permanent lasting less than 6 months). All relevant
data
of patient characteristics are given in
Table 2. There was no
significant
difference of NYHA class, left ventricular (LV) ejection fraction (EF)
or
LA-size between Group A and B, but Group A patients had a significantly
higher
Euro-score and a shorter duration of pAF duration. In contrast to Group
B,
most Group A patients were female. All patients were managed medically
before
and after surgery with standard heart failure medications, 6 of Group A
patients
had beta-blockers (Group B: n=4), 6 patients were on amiodarone (Group
B:
n=6).
Mono- and bipolar RF ablation surgery, perioperative
management and follow-up
The
monopolar endocardial procedure has been described before
2. From February 2001 to February 2003 all
patients scheduled for combined heart valve and pAF ablation surgery
underwent monopolar RF ablation (Group A: n=20; Group B: n=75); with
the beginning of a bipolar RF approach (see below) since March 2003 the
monopolar ablation concept
was applied during mitral valve (MV) surgery only (when the left atrium
has to be opened anyhow). To create endocardial RF ablation lesions
either
the Thermaline® device (2001) or the Cobra® device (2002-2004)
were
used (both Boston Scientific Corporation, San Jose, USA). Monopolar RF
ablation
was performed with 100W RF power for two minutes (local temperature:
70°C).
The first lesion completed the isolation of the right pulmonary veins
(RPVs)
from the inferior to the superior RPV using the left atriotomy.
Isolation
of the left pulmonary veins (LPVs) was performed with a semicircular
ablation
line close to the inferior, and another one around the superior LPV.
These
were connected by a transverse lesion across the posterior LA wall. The
left atrial appendage (LAA) was sutured from the endocardial side in
cases
with LA enlargement (LA-diameter ≥56mm). Arrangements to avoid thermic
esophageal
injury were: (1) the ablation procedure was performed under direct view
during
conventional open heart valve surgery only, (2) the transesophageal
echocardiogram
(TEE) probe was removed during ablation, (3) local temperature was set
at
only 70°C (4) a dry compress was passed behind the LA before energy
delivery,
(5) the flexible ablation probe was adapted to the tissue without
pressure
and (6) cachectic patients were excluded.
The
bipolar
RF ablation procedure has been described previously
3,4; a similar surgical
concept using microbipolar RF coagulation to replace incisions of maze
surgery has been reported before by Patwardhan et al.
5. Since March 2003 bipolar RF ablation
surgery was performed using the bipolar Atricure® device (Atricure
Inc., Cincinnati, USA) combined with CABG
and since October 2003 concomitant to aortic valve replacement (Group
A,
B: n=19 vs. n=12). After start of cardiopulmonary bypass (CPB)
isolation
of the RPVs and the LPVs was performed by impacting the atrial tissue
between
the jaws of the Atricure® hand piece and then energy was delivered
(local
temperature 40-55°C). The procedure was terminated when the
ablation
and sensing unit (ASU) indicated that the tissue conductance was at
least
10 sec below 2.5 Millisiemens. Then a purse-string suture was set at
the
posterior LA wall. The distal jaw was inserted through an incision in
direction
of the LPVs and ablation was performed after clamp-closure. Finally the
distal
jaw was inserted in direction of the RPVs and the connection line was
completed. The LAA was sutured from the epicardial side in cases with
LA enlargement (see previous).
Transthoracic
echocardiogram (TTE) and standard 12-lead electrocardiogram (ECG) were
routinely
performed on admission and before discharge. TTE was performed by an
experienced
cardiologist. The preoperative LA size was determined from parasternal
M-mode
acquisitions at end systole using a Vingmed Vivid 5 (General
Electric-Vingmed)
system. Amiodarone administration was started with an intravenous 300
mg
bolus before CPB termination followed by an infusion of 900mg/day for 3
days; after that, oral administration of 5x200 mg up to 7-10 g was
begun
(dependent of body weight), 1x200 mg/day followed for 3 months. In
cases
of amiodarone contraindication (e.g. amiodarone imcompatibility,
thyroid
disease), sotalol was given alternatively (first intravenous bolus of
10
mg, then 1 mg/kg for 24 hours; oral administration of 2-3x40-80 mg
dependent
of body weight for 3 months). An indication for amiodarone/sotalol
termination
was persisting bradycardia for ≥10 days. An indication for pacemaker
implantation
was persisting bradycardia for ≥2 weeks. Early recurrence of AF
was
DC cardioverted after antiarrhythmic drug saturation and after
exclusion
of intracardiac thrombosis by TEE. During initial therapy and
particularly
in case of AF recurrence or bradycardia, patients were observed with
continuous
monitoring on the intensive or intermediate care unit (ICU). Heparin
was
given after resolution of postoperative bleeding. Patients with CABG,
MV
repair or bioprosthesis got cumarine for 3 months, patients with
mechanical
valves lifelong anticoagulation. All patients were restudied
3,
6, 9, 12, 18, 24 and 36 months after
surgery
by standard 12-lead ECG and clinical
examination.
To confirm stability of SR one 24-hour-ECG registry was performed
within
the first 6 months.
Statistical analysis
Quantitative
data were normally distributed and described by arithmetic mean
± SD,
qualitative distributed data were presented as absolute frequencies;
for
pAF and SR the relative frequency among all patients and some subgroups
were calculated. Comparison of proportions was performed using exact
Fisher
Chi-Square-Test. Survival time was analyzed by the method of
Kaplan-Meier,
comparison of cumulative survival was performed using Log Rank Test.
P-values
<0.05 were considered to be statistically significant; analysis was
performed
with SPSS for Windows 11.5.1.
Results
All relevant
operative and postoperative data are outlined in
Table 3-5. All
126 patients left the OR either in regular SR or externally paced in
DDD-mode. In general, Group B patients had a slightly faster recovery
than Group A patients. Thirty-seven percent of Group A patients kept SR
during hospital stay (Group B: 50%),
63% had early AF recurrence (Group B: 50%). DC cardioversion was
performed
with success in 16 of 32 Group A patients (Group B: 9 of 23 patients),
2
patients of Group A converted to SR spontaneously. At discharge 63% of
patients
of Group A (n=43) had SR (Group B: 66 %; n=37) (
Table 5). No
case
of left atrial flutter was observed. Early mortality (<30 days) was
2.9%
in Group A (n=2: one severe sepsis, one sudden cardiac death) and 0% in
Group B. Autopsy was performed in both cases to exclude ablation
related complications. Other complications were 9 cases of transient
pulmonary malfunction (acute pneumonia: Group A n=3, Group B n=2; acute
obstructive ventilation disorder: Group A n=3, Group B n=1), 2 cases of
enteropathy (one each group), 2 transient strokes and 2 slight wound
infections (Group A).
ASD, atrial septal defect; AVR, aortic valve
replacement;
CABG, coronary artery bypass grafting; MVR, mitral valve replacement;
TV,
tricuspid valve
ACC, aortic cross clamping; CPB, cardiopulmonary
bypass;
ICU, intensive/intermediate care unit; *including adjustment of the
equipment
and a precise adaption of the probe to the tissue (Thermaline®
/Cobra®)
and preparation of the PVs (Atricure®); ** exact Fisher
Chi-Square-Test
All patients
were
regularly restudied with follow-up of 18.5±12.0 months in Group
A
(Group B: 15.2±11.0 months). Administration of
amiodarone/sotalol was stopped after 3 months in all patients. Late
mortality occurred in eight cases (Group A, B: n=7 vs. n=1), which was
related to 2 cardiac and 6 non-cardiac deaths. Cumulative survival at
long-term follow up was 0.78 vs. 0.98 (p=0.03;
Fig. 1),
NYHA-class improved from 3.0±0.5 to 1.4±0.5
(Group A) and from 3.0±0.5 to 1.5±0.5 (Group B;
p<0.01).
In general at 6 months follow-up patients with stable SR (71 of 94) had
a significantly higher NYHA-class improvement (78% NYHA 1, 22% NYHA 2),
than patients with persisting pAF (13% NYHA 1, 87% NYHA 2; p<0.001).
At 12-months follow-up 73% patients of Group A patients presented
stable
SR (Group B 78%;
Table 4).
Figure 1. Kaplan-Meier cumulative survival
curves
of 126 patients, demonstrating a 78% cumulative survival after combined
open
heart and pAF ablation surgery of older aged patients (n=70) and a 98%
survival
in patients <70 years (n=56).
Discussion
Besides other
variables cardiac disease and particularly age highly predisposes
atrial
musculature to develop and maintain atrial fibrillation
1; thus mid- and long-term results of
surgical
AF treatment may also depend on age and cardiac disease. The presented
study
data describe our experience with RF ablation surgery in a selective
group
of older aged patients and the effects on survival, functional class
and
SR conversion rate. In the current literature reliable data on this
subject
are scarce. However, as in Germany and other countries the number of
open
heart procedures in older aged patients is increasing dramatically,
this
topic is of progressive importance; in 2003 notably 40% of all patients
hospitalized
for open heart surgery in Germany were 70 years or older, with a 5-fold
increase
of procedures in the 7th decade and a 14-fold increase in patients
older
than 80 years, compared to 1990
6.
It must be anticipated, that this trend is influencing directly the
number
of older aged patients scheduled for open heart surgery with
concomitant
atrial fibrillation, because AF is predominantly found at advanced age,
affecting
approximately 5-10% of people in the 7th decade and 10-15% of people
older
than 80 years
1. Particularly
permanent
AF, which is normally the final mode in which non-permanent AF cumulates
7, deteriorates the prognosis of old
people:
it doubles the mortality rate and increases dramatically the morbidity,
as
(1) a loss of rapid ventricular rate without adequate
“AV-synchronization” and atrial contraction results in reduced cardiac
output and potential heart failure, (2) the risk of stroke by blood
pooling in the atria is increased, and (3) stroke prevention forces
systemic anticoagulation with the risk
of bleeding
1. For that
reasons
concomitant treatment of pAF during open heart surgery in aged patients
has become a great challenge and reliable concepts are required, which
can
be applied during open heart surgery particularly in the older aged
with
low risk, satisfactory success-rates regarding SR conversion rate and
secondary
survival.
Compared with
the literature our data confirm the experience that longstanding pAF is
predominantly a disease of the elderly, particularly of older aged
women.
In the literature a gender difference has been described, but the
etiology
of this finding is still unclear
1.
Normally men develop AF at 1.5 times the rate of women. However,
possibly
because of the greater longevity in women, the minority of AF cases is
found
in men. It is estimated that 53% of all people affected by AF are female
8. Among patients scheduled for open heart
surgery,
men are more often hospitalized with isolated coronary artery disease,
which
is not frequently combined with pAF
2,4; in contrast a high ratio of women is
hospitalized
with severe heart valve disease, in which a higher occurrence of pAF
has
been described
2,4.
We interpret
the clinical results of ablation surgery particularly on the basis of
researches of others: AF wavelets sustained by foci located inside the
PVs were blocked by the created lesions
9-13. The antiarrhythmic drug protection
using amiodarone or sotalol supported
SR during the unstable initial stage, which was approximately 3 months;
amiodarone was given as first choice antiarrhythmic drug to reduce
postoperative recurrence of AF according to the data of Roy at al.
14 and the clinical experience of others
15. However, AF recurred soon after
surgery in more than half of the patients because the refractory period
of the atrium was still shortened.
Our data
further indicate that the described concepts (including a monopolar
endocardial
RF ablation technique during mitral valve surgery and a bipolar
approach
in non-mitral valve cases) can be performed in a selective group of
older
aged patients with low risk and satisfactory success-rates regarding
survival,
improvement of NYHA class and conversion rate to SR after surgery. Even
if
young patients had a slightly faster recovery than older aged patients,
the
postoperative SR conversion rate was of no significant difference;
perioperative
complications were low and postoperative management including
antiarrhythmic
drug administration and early DC cardioversion under anticoagulation
were
tolerated well. We therefore suppose that the described strategies are
effective
and can be recommended as reliable treatment strategies to cure pAF
during
open heart surgery in patients with advanced age.
Limitations
This study
consists of a heterogeneous patients group regarding the type of
pathology and the type of RF ablation technique, what limits the
evidence. The data were not evaluated under randomized conditions,
further the groups were not matched. For rhythm evaluation no 7-days
Holter-monitoring and only one 24-hour-ECG registry was performed
within 6 months, at long-term follow-up (6-36 months) only 12-lead ECG
was used. Patients with severe reduced left ventricular
function were excluded, which explains the good LVEF in both groups
despite
structural heart disease and pAF.
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