Surgical treatment of atrial fibrillation using radiofrequency ablation - Chapter 6 Left Atrial Versus Bi-atrial MAZE Surgery Using Intraoperatively Cooled-Tip Radiofrequency Ablation in Patients Undergoing Open Hear

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Surgical treatment of atrial fibrillation using radiofrequency ablation

Khargi, K.

Publication date

2005

Link to publication

Citation for published version (APA):

Khargi, K. (2005). Surgical treatment of atrial fibrillation using radiofrequency ablation.

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C H A P T E R 6

Left Atrial Versus Biatrial MAZE Surgery Using

Intraoperatively Cooled-Tip Radiofrequency

Ablation in Patients Undergoing Open Heart

Surgery. Safety and Efficacy

10

Thomas Deneke', Krishna Khargi", Peter Hubert Grewe', Stefan von Dryander",

Frank Kuschkowitz", Thomas Lawo", Klaus-Michael Muller"", Axel Laczkovics", Bernd Lemke"

"' Published in part in the Journal of American College of Cardiology (ACC 2002; 39: 1644-50. * Department of Cardiology/Angiology, Bergmannsheil, University Hospital Bochum, Germany.

" Clinic of Cardio-Thoracic Surgery, Bergmannsheil, University Hospital Bochum, Germany.

L E F T A T R I A L V E R S U S B I - A T R I A L M A Z E S U R G E R Y U S I N G I N T R A O P E R A T I V E L Y C O O L E D T I P R A D I O F R E Q U E N C Y A B L A T I O N I N P A T I E N T S U N D E R G O I N G O P E N H E A R T S U R G E R Y . S A F E T Y A N D E F F I C A C Y

Journal 01 the American College of Cardiology © 2002 bv the American College of Cardiology Foundation Published' bv Elsevier Science Inc.

Vol. 39, N o . 10, 2002 ISSN 0735-1097/02/622.00 PII S0735-1097(02)01836-3

Atrial Fibrillation

Left Atrial Versus Bi-Atrial M a z e Operation

Using Intraoperatively Cooled-Tip Radiofrequency

Ablation in Patients Undergoing O p e n - H e a r t Surgery

Safety and Efficacy

Thomas Deneke, MD,* Krishna Khargi, M D , f Peter Hubert Grewe, MD,* Stefan von Dryander, MD,*

Frank Kuschkowitz, M D , t Thomas Lawo, MD,* Klaus-Michael Muller, M D , t Axel Laczkovics, M D , f

Bernd Lemke, MD*

Bo chum

Germany

OBJECTIVES W e sought to determine whether limited left atrial M a z e surgery encircling each of the pulmonary veins, using cooled-tip radiofrequency (RF) ablation, is as effective as t h e bi-atrial approach?

BACKGROUND T h e original C o x / M a z e operation effectively restores sinus r h y t h m (SR) in patients with atrial fibrillation (AF). Ablation procedures aimed a t eliminating pulmonary vein foci have produced promising short-term success.

METHODS T h i s was a prospective analysis of patients with chronic A F undergoing open-heart surgery in addition to t h e M a z e operation, using intraoperatively cooled-tip R F ablation either in the left atrium alone (group A) or in both atria (group B),

RESULTS Patients in group A (n = 21) and group B (n = 49) did not differ in terms of their baseline characteristics. C o n c o m i t a n t o p e n - h e a r t surgical procedures included mitral valve replace-m e n t (3 vs. 25), replace-mitral valve plasty (0 vs. 2), replace-mitral a n d aortic valve replacereplace-ment (1 vs. 1), aortic valve replacement (4 vs. 6) a n d coronary artery bypass grafting (13 vs. 15) in groups A and B, respectively. Follow-up ranged from 1 to 5 0 m o n t h s . T h e overall cumulative rates of SR were 8 2 % in group A a n d 7 5 % in g r o u p B, w i t h o u t a statistically significant difference (p = 0.571). Bi-atrial contraction was revealed in 9 2 . 3 % of patients in S R in group A a n d in 79.2% in group B. T h e cumulative survival rates were 9 0 . 5 % in group A and 77.9% in group B (p = 0^880).

CONCLUSIONS A left or bi-atrial M a z e operation using intraoperatively cooled-tip R F ablation can safely be combined with open-heart surgery. A left atrial M a z e procedure seems to be as effective as t h e bi-atrial procedure a n d restores S R in 8 2 % o f patients. (J A m Coll Cardiol 2002;39: 1 6 4 4 - 5 0 ) © 2002 by the American College of Cardiology Foundation

A t r i a l f i b r i l l a t i o n ( A F ) is o f t e n a s s o c i a t e d w i t h o t h e r c a r d i a c d i s e a s e s , t h u s c o m p r o m i s i n g t h e p a t i e n t ' s clinical o u t c o m e . R e s t o r a t i o n o f s i n u s r h y t h m ( S R ) w i t h a t r i o v e n t r i c u l a r r e s y n c h r o n i z a t i o n m a y b e difficult i n p a t i e n t s w i t h c h r o n i c o r p e r m a n e n t A F o r o t h e r r i s k factors for A F ( 1 - 3 ) . T h e M a z e p r o c e d u r e as a n o p e n - h e a r t surgical a p p r o a c h , e s t a b l i s h e d b y J a m e s C o x a n d a s s o c i a t e s , w a s f o u n d t o effectively r e s t o r e S R a n d atrial c o n t r a c t i o n i n p a t i e n t s w i t h i n t e r m i t t e n t o r c h r o n i c A F . D u r i n g t h e o r i g i n a l p r o c e d u r e , l i n e a r l e s i o n s in t h e right a n d left a t r i a w e r e p r o d u c e d t o p r e v e n t t h e o c c u r r e n c e o f m u l t i p l e r e e n t r a n t w a v e l e t s i d e n -tified d u r i n g A F ( 4 - 1 2 ) . T h i s o r i g i n a l M a z e o p e r a t i o n is e x t e n s i v e a n d t i m e - c o n s u m i n g a n d r e q u i r e s g r e a t s u r g i c a l skill. I n c o n t r a s t , m o r e r e c e n t l y , H a ï s s a g u c r r e e t al. ( 1 3 ) a n d C h e n e t al. ( 1 4 ) s h o w e d t h a t t h e o r i g i n o f A F m a y b e c o n f i n e d t o r a p i d l y firing foci o f t h e p u l m o n a r y v e i n s .

From the "Department of Cardiolojry/Anjriolo^y, fCIinic of Cardiothoracic Sur-gery' and ^Institute of Pathology, "Bergmannsheii," University HospitaJ, Bochum, German v.

Manuscript received June 18, 2001; revised manuscript received February 2 1 , 2002, accepted February 25, 2002.

Transvenous catheter ablation techniques have shown promising short-term results when ablating or isolating the pulmonary vein foci (15-17).

In our study, we employed two major modifications to facilitate the original Maze procedure: cooled-tip radiofre-quency (RF) ablation was used to perform electrophysi-ologically transmural linear lesions, and the number of lesions was minimized by confining the procedure to the left atrium only. T h e efficacy of augmenting open-heart surgery with the modified Maze procedure only in the left atrium, using cooled-tip R F ablation, in patients with A F was evaluated, and the outcomes were compared with those of patients who had bi-atrial Maze surgery.

METHODS

T h i s study was conducted as a prospective, nonrandomized analysis. T h e primary end point of our study was the occurrence of SR during postoperative follow-up. T h e secondary end points included survival, adverse events and atrial transport function.

JACC Vol. 39, No. 10, 2002 May 15. 2002:1644-50

Deneke et al. Left vs. Bi-Atrial Maze Operation

1645

Abbreviations and Acronyms AF = RF SR -atrial fibrillation radio frequency sinus rhythm

Patients. Between March 1997 and February 2001, all

patients undergoing a combination of open-heart surgery' and the modified Maze procedure, using intraoperativcly cooled-rip R F ablation, were included. Written, informed consent was given by all patients before their inclusion into the study. All patients had at least one year of chronic or permanent A F or unsuccessful direct-current shock cardio-version six months before inclusion.

Surgical procedure. All surgical procedures were

per-formed in the Clinic of Cardiothoracic Surgery, "Bcrg-mannsheil" University Hospital, Bochum, Germany. T h e additional Maze procedure was performed using coolcd-tip R F ablation. According to the site of ablation, patients were prospectively assigned to one of two groups: group A had left atrial ablation only, with ablation lines around each pulmonary vein's ostium, interconnections between the ostial lines and connecting lines to the mitral valve annulus and left atrial appendage; and group B bad bi-atrial R F ablation, as previously described by Khargi et al. (18), with ablation lines in the right and left atria. Ablation lines in the left atrium did not differ between groups A and B (Fig. 1).

Follow-up. Postoperative follow-up was performed in the

Department of Cardiology, "Bergmannsheil" University Hospital. Follow-up was performed on postoperative days 1 and 12 and after 3, 6 and 12 months, and then yearly. Some patients were also seen one month postoperatively. T h e anti-arrhythmic drug was sotalol (80 mg twice daily) for at least six months, up to April 1999. T h e n , drug treatment was switched to metoprolol succinate in an equipotent dosage (at least 47.5 to 95 mg/day).

At each follow-up visit, a clinical history and electrocar-diogram were obtained. Sinus rhythm was defined as a supraventricular rhythm with P waves detectable on the standard 12-lead electrocardiogram. Holter monitoring was performed six months postoperatively.

After six months, echocardiography was performed, in-cluding transmittal and transtricuspid Doppler echocardi-ography. Detection of E and A waves was considered as atrial contraction.

All data were collected between March 1997 and Febru-ary 2001.

Statistical analysis. Continuous variables are expressed as

the mean value ± SD. T h e Student unpaired t test was used for comparison of variables between the two groups. Dif-ferences were considered statistically significant at p < 0.05.

T h e survival rates and cumulative rates of SR were calculated according to the Kaplan-Meier method, and the groups were compared using the log-rank test, with a statistically significant difference assumed at p < 0.05.

\

LA

surgical

access

RSPV

(O)

* • . . . • *

. • • - • .

*s~—x*

•v J*

RIPV

L$PV

•C > "

** LIPV

MV

Figure 1. Schematic view of the ablation pattern (dotted black lines) in the left atrium; surgical access was through the Waterstone Grove. The encircling

ablation lesions around each pulmonary vein's ostium and the interconnecting lines, as well as additional lines to the mitral valve (MV) annulus and the excision of the left auricle (LA), are shown. LIPV = left inferior pulmonary vein; LSPV = left superior pulmonary vein; RIVP = right inferior pulmonary vein; RSPV — right superior pulmonary vein.

LEFT ATRIAL VERSUS BIATRIAL MAZE SURGERY USING INTRAOPERATIVELY C O O L E D - T I P RADIOFREQUENCY

ABLATION IN PATIENTS UNDERGOING OPEN HEART SURGERY. SAFETY AND EFFICACY

1646 Deneke et al.

Left vs. Bi-Atrial Maze Operation

JACC Vol. 39. No. 10. 2002 May 15, 2002:1644-50

Table 1. Baseline Patient Characteristics and Surgica]

Procedures Age (yrs) LA dimension (mm) Ejection fraction (%) AF duration (yrs) Range Follow-up (months) Range MVR MVP MVR + AVR AVR ACB (+ MVR) Group A [.eft Atrial Maze*

(n = 21) 69 ± 9 47 ± 8 56 ± 10 13 ± 17 1-25 11 ± 10 4-20 3 0 1 4 13(4) Group B Bi-Atrial Maze* (n = 49) 65 ± 9 51 ± 10 59 i 10 9 ± 8 1-15 18 ± 14 1-50 25 2 1 6 15(2) p Value 0.118 0.224 0.453 0.538 0.046

'In addition to anti-arrhythmic surgery. Data are presented as the mean value ± SD or number of patients.

ACB = aorto-coronary' bypass surgery; A F — atrial fibrillation; AVR = aortic valve replacement; LA = left atrial; M V P = mitral valve plasty; M V R - mitral valve replacement.

RESULTS

Seventy patients were included during the study period and had completed at least one month of follow-up. Group A consisted of 21 patients and group B of 49 patients. T h e patients did not diifer in terms of their baseline character-istics (age, duration of A F before surgery, left atrial dimen-sions and preoperative ejection fraction) (Table 1). All patients had an indication for open-heart surgery, indepen-dent A F . Concomitant procedures performed in groups A

and B included mitral valve replacement (3 vs. 25), mitral valve plasty (0 vs. 2), combined mitral and aortic valve replacement (1 vs. 1), combined mitral valve replacement (4 vs. 2), aortic valve replacement (4 vs. 6) and aorto-coronary bypass grafting (13 vs. 15) (Table 1).

Follow-up. All 70 patients completed at least one month

ot follow-up. T h e duration of follow-up ranged from 4 to 20 months (mean 11 ± 10) in group A and 1 to 50 months (mean 18 ± 14) in group B, with statistically significant longer follow-up durations in group B (p < 0.05).

In group A, 19 patients completed three months of follow-up; 17 patients completed six months; and 7 patients completed 12 months. In group B, 39 patients completed three months of follow-up; 36 patients completed six months; 29 patients completed 12 months; 21 patients completed 24 months; 7 patients completed 36 months; and 2 completed 48 months.

Cardiac rhythm. T h e cumulative rates of SR for complete

follow-up were 82% (17 of 21 patients) for group A and 75% (34 of 49 patients) for group B, without a statistically significant difference (p — 0.571). T h e cumulative rates of SR evolved during follow-up in the two groups (group A vs. group B): at one month, 6 3 % vs. 55%; at three months, 82% (16 of 19 patients) vs. 65% (26 of 39 patients); and at six months, 82% (14 of 17 patients) vs. 68% (24 of 36 patients). Only one patient in group B converted to SR more than six months after the procedure (at 24 months) (Fig. 2).

W i t h completed follow-up in groups A and B, 16 of 21 patients and 34 of 49 patients, respectively, were in SR. T h e

1.0 0 0

group A (0.816)

p = 0.571

group B (0.745)

follow-up (months)

Figure 2. Cumulative rates of sinus rhythm during postoperative follow-up (group A = left atrial Maze procedure; group B = bi-atrial Maze proce-dure).

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JACC Vol. 39. No. 10, 2002 May 15, 2002:1644-50

mode of conversion to SR was spontaneous in all patients in group A and in all but one patient (who had long-term success after direct-current shock cardioversion) in group B in SR (97% of all patients). Of the 15 patients still in A F in group B, 12 were electrically cardiovcrted (direct-current shock), with an immediate success rate of 27% (3 of 11 patients were in SR immediately after cardioversion); long-term success (SR at next follow-up visit) was achieved in only one patient (9.1% of cardioverted patients). N o patient from group A was converted using direct-current shock. Overall, only 1 of the 12 patients who were cardioverted was converted to prolonged SR (8%).

O n e patient from group B converted from SR to A F 12 months postoperatively, when sotalol was replaced by meto-prolol. After re-institution of sotalol, medication-stable SR was re-established.

T w o patients from group B demonstrated atypical atrial flutter between one and three months of follow-up: one patient was converted to SR while increasing the sotalol dosage from 80 to 160 mg twice daily. In the other patient, catheter ablation was performed in the right atrium, closing a gap between the intercaval intraoperative ablation line and the upper caval vein. Long-term, stable SR was found after the procedure in both patients.

Holter monitoring revealed short runs of atrial tachycar-dia ( < 1 5 % of the Holter interval) in two patients in SR in group A (12.5%) and 5 patients in group B (14.7%).

Doppler echocardiography. In groups A and B, 13

(81.3%) of 16 patients and 24 (70.6%) of 34 patients in SR, respectively, underwent Doppler echocardiography. Bi-atrial contraction was documented during transthoracic Doppler echocardiography in 12 of 13 patients in SR in group A (92.3%) and in 19 of 24 patients in SR in group B (79.2%). In group A, all of the patients in SR had docu-mented right atrial contraction (100%). In group B, two patients (1 patient after 3 months and 1 patient after 6 months) had no detectable right atrial contraction on the transthoracic echocardiogram (92% with right atrial contraction).

Pacemaker indication and complications. T w o patients

in group B (4%) had permanent pacemakers implanted because of postoperative bradycardia (1 patient with D D D and 1 with W I pacemaker). Implantation was performed during one to three months postoperatively. N o patient in group A had an indication for postoperative pacemaker implantation.

Bleeding requiring transfusion occurred in three patients (1 in group A after aorto-coronary bypass grafting plus mitral valve replacement; 2 in group B [1 had renal bleeding with a lethal outcome after mitral valve replacement and 1 had gastrointestinal bleeding after aortic valve replace-ment]), all under standard anticoagulative therapy, as used after valve replacement. Pericardial effusion occurred in one patient in group A and in two patients in group B, without the need for further invasive therapy. T w o patients in each group (1 after aorto-coronary bypass grafting and 1 after aortic valve replacement in group A and 2 after mitral valve

Deneke et al. 1647 Left vs. Bi-Atrial Maze Operation

replacement in group B) had transitory neurologic symp-toms in the first days after the surgical procedure.

Duration of the surgical procedure. T h e mean bypass

duration was 146 ± 34 min in group A and 179 ± 35 min in group B (p < 0.05). T h e mean aortic clamp duration was 98 ± 24 min in group A and 101 ± 20 min in group B (p = 0.53), showing a shorter duration in the group of patients with only the left atrial Maze operation.

Survival. T h e cumulative survival rates were not

statisti-cally significant different between the two groups (90% in group A vs. 78% in group B; p = 0.880)' (Fig. 3). Two patients in group A died within 30 days after the operation: 1 patient died of mediastinitis 21 days postoperatively, and 1 died of postoperative severe pyoderma with sepsis after 28 days. In group B, six patients died during follow-up: one patient died 40 days postoperatively, due to renal bleeding; one died after 45 days, due to mediastinitis; one had sudden cardiac death after four months; one had progressive respi-ratory insufficiency at seven months; one had respirespi-ratory insufficiency at 16 months; and one died of an unknown cause (noncardiac or cerebral ischemia) after 33 months.

DISCUSSION

T o the best of our knowledge, this study is a first analysis of data obtained in patients undergoing a modified Maze procedure in addition to another open-heart surgical pro-cedure, comparing the left atrial approach with the bi-atrial Maze operation.

Background. T h e left atrial only approach was considered,

based on the study findings of Haïssaguerre et al. (13), who documented focal ectopies arising from the pulmonary veins, thus inducing paroxysmal A F . This mechanism was also considered to maintain permanent and/or persistent A F and may be stopped when ablating or isolating foci of the pulmonary veins. Sueda et al. (19) proposed a minimized left atrial approach for patients with mitral valve disease and documented left atrial foci during intraoperative A F mapping, with promising results regarding SR in 86% ( 1 3 -16,19-21).

These findings lead to the concept of approaching the left atrium only during anti-arrhythmic surgery. In addition to isolating each of the four pulmonary vein's ostia, an inter-connection of the ablation line circles was performed, including additional ablation lines connecting the mitral valve annulus to the left atrial appendage.

Efficacy of the limited left atrial anti-arrhythmic proce-dure. This study was conducted to evaluate the efficacy and

safety of the left atrial only approach during anti-arrhythmic surgery. In our experience with 70 patients, we retrospec-tively compared the outcomes of patients undergoing left atrial—only Maze surgery, using intraoperatively cooled-tip R F ablation, with the outcomes of patients undergoing bi-atrial Maze surgery, again using the RF ablation tech-nique. Restoration of SR was documented in these patients, with a long duration of A F before the operation and large

LEFT ATRIAL VERSUS BI ATRIAL MAZE SURGERY USING INTRAOPERATIVELY C O O L E D - T I P RADIOFREQUENCY ABLATION IN PATIENTS UNDERGOING OPEN HEART SURGERY. SAFETY AND EFFICACY

1648 Deneke et al.

Left vs. Bi-Atrial Maze Operation

JACC Vol. 39, No. 10, 2002 May 15. 2002:1644-50 I.U • .8. . 7 . . 6 . .5. .4, .3, . 2 . .1 . 0.0 1

group A (0.905)

group B (0.779)

follow-up (months)

Figure 3. Cumulative survival of patients during postoperative follow-up (group A = left atrial Maze procedure; group B = bi-atrial Maze procedure).

left atrial dimensions in 81.6% of patients after the left atrial—only ablation procedure. Compared with patients undergoing bi-atrial ablation, who obtained SR at a rate of 74.5%, there was no statistically significant difference. These data are comparable to the results documented by different groups (5,7,8-11,22,23), who found restoration of SR between 72% and 99%, depending on the surgical procedure used and the patient cohort (e.g., concomitant underlying heart disease, idiopathic AF). Mclo et al. (22) proposed a pulmonary vein isolation technique with one incision encir-cling the four pulmonary veins, producing SR with bi-atrial contraction in only 33% of the patients after one year. One-third of the patients remained in A F after this proce-dure. T h e left atrial approach we proposed, encircling each of the four pulmonary vein ostium, seems to produce a higher rate of SR.

Failure of the anti-arrhythmic procedure. T h e

mecha-nisms for failure of the left atrial-onlv procedure still need to be investigated. O n the one hand, there may be gaps in the ablation lines, causing recurrent reentry circles, or on the other hand, the origin of the arrhythmia was not in the left atrium, as proposed to be the case in 9% to 19% of patients with underlying mitral valve disease. T h e mechanism of A F may be different in terms of the underlying heart disease. Patients with right atrial foci should benefit from the bi-atrial approach, even though there is no higher rate of SR in these patients, as documented in our study. Further evaluation using modern electroanatomic mapping systems may be helpful in understanding the mechanisms in patients with failure (19,20,24).

Atrial function after anti-arrhythmic surgery. An

impor-tant aim of restoring SR is to produce atrial contraction of both atria, to restore atrioventricular electromechanical synchrony and to decrease the risk of cardiac thromboem-bolism. In our study, bi-atrial contraction was restored in 92.3% of patients in SR after the left atrial approach and in 79.2% of patients in SR after the bi-atrial Maze operation. T h e outcome of these patients can be defined as complete success (score 4), when applying the Santa Cruz scoring system initiated by Melo et al. (22). T h e difference between the two groups may be the result of the fewer patients with mitral valve disease in the group undergoing left atrial incisions only, who seem to have a poorer prognosis ior SR restoration and larger atrial dimensions. In contrast, the higher rate of effective bi-atrial contraction may be attrib-uted to the minimized procedure itself. A smaller atrial area was isolated (preventing contraction), which may lead to more completely contracting atrial tissue (22). The left atrial inci-sions and ablation lines were the same in both groups. Our data are equivalent to the published data that document the occur-rence of bi-atrial contraction in 66.7% to 99% of patients. Again, the results differ in terms of the applied surgical procedure and the baseline characteristics of the patients (22).

T h e rates of left atrial contraction m a y b e underestimated by transthoracic echocardiography. Cox (4) proposed that left atrial contraction can more often be demonstrated by transesophageal echocardiography, compared with trans-thoracic echocardiography. T h e question remaining is whether patients without documented left atrial contraction (during transthoracic or transesophageal echocardiography)

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should be anticoagulated, and to what extent (anticoagula-tion plus antithrombotic medica(anticoagula-tion?).

Safety of intraoperatively cooled-tip R F ablation. T h e safety of adding the modified Maze operation (either left atrial or bi-atrial), as proposed in our study, can be derived from the low 30-day mortality and low complication rates. T w o patients died within the first 30 days after the operation, and another death due to mediastinitis after 45 days might be associated with the anti-arrhythmic proce-dure added to the surgical proceproce-dure. Although these mortality rates are not higher than those associated with open-heart surgery, without additional anti-arrhythmic pro-cedures, a mediastinal infection might become an acute postoperative complication. Antibiotic treatment and repeat operations have a high rate of failure, so that prevention by minimizing the procedure's duration (or limiting the num-ber of ablation lines) should be anticipated.

Our data are comparable to those published by different investigators, but again, the differing patient characteristics must be accounted for ( 5 , 7 1 1 ) . A d d i n g the a n t i -arrhythmic procedure to another open-heart operation may lead to higher mortality, even though there was no signifi-cant difference seen in a randomized study of patients undergoing mitral valve replacement with or without the Maze procedure (Denekc et al. [25]). This needs to be analyzed in further prospective, randomized studies includ-ing larger patient cohorts.

W e found a shorter bypass time and aortic clamp duration in patients who received ablation in the left atrium only, which can be attributed to the shorter procedure, as it was restricted to one atrium. The bypass time was not significantly different between the two groups, because of the need for cardiopulmo-nary bypass for blood-free access to the left atrium.

W e did not find any adverse events related to the postoperative care after the left atrial Maze procedure; in particular, there were no cases of pulmonary vein stenosis and no indication for pacemaker implantation. Pulmonary vein stenosis may occur when ablation is done inside the veins, which is one major drawback of focal catheter ablation of A F . T h e approach of encircling each of the pulmonary vein's ostia diminishes the risk of this compli-cation. During our whole experience, two patients received a permanent pacemaker due to postoperative bradycardia, which has been reported previously (5,8). Whether the requirement for pacemaker therapy was due to the Maze procedure or preoperative sinus node dysfunction cannot be evaluated. Some of the patients may demonstrate late stages of sick sinus syndrome, with an indication for pacemaker therapy, due to this disease itself (5).

Anti-arrhythmic medication after anti-arrhythmic sur-gery. Still under debate is the appropriate anti-arrhythmic medication after open-heart surgery and especially after anti-arrhythmic surgical procedures. Although Cox et al. (5) studied a high number of patients who received no anti-arrhythmic drug therapy postoperatively (94%), this may only be possible in patients with idiopathic A F . It has been

Deneke ef al. 1649 Left vs. Bi Atrial Maze Operation

widely established that sotalol should be administered in the early postoperative period, but it is less clear what to do in the long term. In the beginning of our experience, we treated patients with sotalol for at least six months (26). Cardioversion after anti-arrhythmic surgery. Another descriptive finding is the low long-term efficacy of electric cardioversion in patients who have undergone anti-arrhythmic surgery. Only 50% of overall patients with A F agreed to direct-current cardioversion in the first six months after the operation. Only one patient had long-term success (9%), despite a rather aggressive cardioversion protocol. From this finding, we derived a stepwise action plan for these patients: all patients were put on metoprolol therapy, and spontaneous conversion was awaited during the first six months after the operation. Only if patients were still in A F for more than six months after the anti-arrhythmic surgery' was direct-current shock cardioversion anticipated once during follow-up. Study limitations. Our study was a retrospective analysis of a rather small number of patients. Randomization was not performed, but the two groups showed no statistically significant difference in terms of their baseline characteris-tics. This analysis was performed in patients over almost four years, during which time the device used to perform the cooled-tip R F ablation lines was changed twice, even though the pattern of the ablation lines was kept the same. This may have effects on the efficacy of the procedure, especially when considering that patients in group A were underwent the operation in the later phase of the observa-tional period.

Conclusions

1. A left atrial anti-arrhythmic procedure establishing linear lesions encircling each ostium of the pulmonary vein, using cooled-tip R F ablation, can restore SR in patients with chronic A F .

2. Left atrial Maze surgery using intraoperative R F ablation can safely be combined with other open-heart surgical procedures and restores SR as effectively as the bi-atrial approach (in 81.6% of patients in chronic AF). . 3. Bi-atrial contraction can be restored after the left atrial

Maze procedure in 92.3% of patients in SR.

4. Direct-current shock cardioversion seems to show low long-term efficacy in patients who have undergone the Maze operation.

Larger prospective, randomized trials that can evaluate the left atrial-only approach for anti-arrhythmic surgery, as well as detect patients with a poorer prognosis for stable SR, are needed before this procedure can be universally accepted. Reprint requests and correspondence: Dr. Thomas Deneke, Department of Cardiology, Berutsgenossenschaftliche KJiniken Bergmannsheil, University of Bochum, Bürklc-de-la-Camp-Platz 1, 44789 Bochum, Germany. E-mail: thomas.deneke@ruhr-uni-bochum.de.

LEFT ATRIAL VERSUS BI-ATRIAL MAZE SURGERY USING INTRAOPERATIVEI.Y C O O L E D - T I P RADIOFREQUENCY ABLATION IN PATIENTS UNDERGOING OPEN' HEART SURGERY. SAFETY AND EFFICACY

1650 Deneke et al. JACC Vol. 39, No. 10. 2002 Left vs. Bi-Atrial Maze Operation May 15, 2002:1644-50

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