| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2006;82:1758-1764
© 2006 The Society of Thoracic Surgeons
Cardiac Surgical Associates MAZE Investigators, Tampa-St. Petersburg, Florida
Accepted for publication May 11, 2006.
* Address correspondence to Dr Badhwar, Cardiac Surgical Associates, Tampa Bay Heart Institute, 6006 49th St N, Suite 310, St. Petersburg, FL 33701 (Email: vbadhwar{at}heartsurgery-csa.com).
Presented at Fifty-second Annual Meeting of the Southern Thoracic Surgical Association, Orlando, FL, Nov 10–12, 2005.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
METHODS: From January 2003 to July 2005, 71 consecutive drug-resistant patients with permanent atrial fibrillation and left atrial enlargement who required mitral valve surgery underwent aggressive left atrial reduction combined with left-sided only irrigated radiofrequency unipolar maze. Left atrial dimensions were measured by transesophageal echo anterior-to-posterior leading edge-to-edge standardized protocol. There were 39 men (54.9%) and 32 women (45.1%), and their mean age was 71.9 ± 9.5 years. Mean duration of atrial fibrillation was 49.3 ± 58.0 months.
RESULTS: All patients underwent left atrial reduction with identical Cox-maze III pulmonary vein and appendage isolation including mitral annular connection, followed by appendage suture closure. Left atrial size was reduced from 6.7 ± 1.2 cm to 4.3 ± 0.6 cm (p = 0.001). Mitral valve repair was performed in 55 patients (76.1%) and replacement in 17 (23.9%). The 30-day mortality was 4.2% (3/71). Postoperative length of stay was 8.8 ± 5.7 days, with 56 (82.4%) of 68 patients discharged in normal sinus rhythm. P-wave sinus rhythm was 93.8% between 7 and 12 months and 92.0% for patients with 1 year or more of follow-up.
CONCLUSIONS: Left atrial reduction combined with a left atrial only single energy-source radiofrequency maze procedure is an effective treatment for patients with permanent atrial fibrillation undergoing concomitant mitral operations.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
The traditional cut-and-sew Cox-maze III operation serves as the benchmark in treatment, providing 90% to 97% freedom from AF [3, 4]. However, concerns about procedural complexity have limited the acceptance of this surgical technique [3–6]. Recent modifications in the operation that include the use of ablative therapies and limiting the approach to the left atrium have increased the application of the maze procedure with concomitant mitral valve surgery. Despite some groups achieving acceptable early results, few have been able to replicate those obtained with the traditional Cox-maze III operation. Most reports describe the use of single or even combined energy sources applied to a heterogeneous AF population, resulting in rates of freedom from AF of 60% to 80% [7–10].
Unlike paroxysmal or persistent AF, patients with permanent AF tend to have larger left atria and are more resistant to spontaneous size reduction or rhythm conversion after isolated mitral valve surgery [2]. The foci of AF in this cohort of patients may be from the remodeled left atrium in addition to the pulmonary veins. Because permanent AF and large left atria have both been implicated in modified maze operation failures, it has been postulated that a reduction of left atrium size may improve patient outcomes [10–17].
The purpose of this report is to discern the efficacy of combined left atrial reduction (LAR) with a left atrium only, modified Cox-maze III lesion set performed with a single radiofrequency energy source applied in patients with permanent AF and large left atria during concomitant mitral valve surgery. The objective was also to assess the early outcomes of this simplified technique.
|
Material and Methods |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
The study comprised 39 men (54.9%) and 32 women (45.1%) with a mean age of 71.9 ± 9.5 years (range, 45 to 87 years). Mean duration of AF in the series was 49.3 ± 58.0 months (range, 3 to 300 months). The preoperative mean atrial size was 6.7 ± 1.2 cm. Preoperative functional class was ranked according to the New York Heart Association (NYHA) classification system. Seven patients (9.9%) were in class II, 45 (63.4%) in class III, and 19 (26.8%) in class IV. In 8 patients (11.3%), the current procedure represented a reoperation. Patient clinical characteristics are presented in Table 1.
|
Operative Technique
Median sternotomy was performed and patients were placed on cardiopulmonary bypass with bicaval cannulation and cooled to 34°C. Antegrade and retrograde blood cardioplegic arrest was established. Dissection of the interatrial groove was extended to the interatrial septum, and the roof of the left atrium was entered. Routine atriotomy was performed to enhance mitral valve exposure involving extension slightly inferior and posterior to the right inferior pulmonary vein. The required mitral valve repair or replacement procedure was then performed.
In all patients, an irrigated unipolar radiofrequency device (Cardioblate Surgical Ablation Pen, Medtronic, Inc, Minneapolis, MN) was used to perform linear ablative lesions that isolated the pulmonary veins, the left atrial appendage orifice, and connected the pulmonary vein box lesion to the mitral annulus. This approach is consistent with the Cox-maze III lesion set [10] (Fig 1A).
|
Operative Data
All 71 patients underwent LAR with identical Cox-maze III radiofrequency lesions, including left atrial appendage suture closure as shown in Figure 1. The mean left atrium size was reduced from 6.7 ± 1.2 cm preoperatively to 4.3 ± 0.6 cm postoperatively (p = 0.001). Mitral valve repair was done in 54 patients and mitral valve replacement in 17. There were 30 valves implanted, 17 in the mitral position and 13 in the aortic position. In the mitral position, seven mechanical valves and 10 bioprostheses were implanted. All 13 aortic valves replaced were bioprostheses.
Additional concomitant procedures were required in 42 patients (59.2%). For the 29 patients (40.8%) who underwent CABG, the mean number of grafts per patient was 1.8 ± 0.9 (range, 1 to 4 grafts). Addition of the complete left-sided only modified maze procedure including LAR and left atrial closure added approximately 25 to 30 minutes of cross-clamp time to the operation.
The mean cardiopulmonary bypass time was 178.3 ± 63.7 minutes (range, 89 to 358 minutes). The mean duration of aortic cross-clamping time was 142.8 ± 61.1 minutes (range, 0 to 310 minutes). In 3 patients (4.2%), the procedure was a reoperation and was performed through a right thoracotomy on cardiopulmonary bypass without the use of aortic cross-clamping. Right-sided maze lesions were not performed in the 13 patients (18.3%) who required a tricuspid valve repair. The distribution of operative procedures is summarized in Table 2.
|
Anticoagulation therapy was determined by the mitral operation performed. If a mechanical prosthesis was implanted, warfarin therapy was initiated on the third postoperative day and continued permanently. If a bioprosthesis was inserted, then low-dose warfarin was generally prescribed on the third postoperative day and continued for the first month. If mitral valve repair was performed, then generally no warfarin was prescribed and patients were administered antiplatelet therapy only.
Data Collection and Statistical Analysis
Data were collected prospectively by in-patient evaluation, telemetry monitoring, and serial ECG. Upon discharge, ECG monitoring and clinical parameters were recorded during follow-up periods at 1 month, every 3 months until 2 years, and every 6 months thereafter. A MAZE Surgery Patient Registration Form was completed for each patient in the study at the time of operation and a Patient Follow-up Form was completed at each follow-up. Data were entered into a MAZE Surgery Clinical Database and subsequently retrieved for analysis. Follow-up was complete through August 2005. Information was obtained through direct contact with the patient or with the patient's referring or current physician when geographically remote.
Data are presented as frequency distributions and simple percentages. Values of continuous variables are expressed as mean ± standard deviation. Analysis of discrete variables was accomplished by 
2 the continuity-adjusted 2 analysis or a two-tailed Fisher exact test. Comparison of atrial size before and after the procedure was conducted using a paired t test. Data collected were analyzed using the Number Cruncher Statistical Systems software (NCSS, Kaysville, UT). A significant difference between measurements was defined as p 
0.05.
|
Results |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
Of the 71 study patients, 30 (42.3%) underwent cardioversion, all of which occurred within the first postoperative month. Four were cardioverted for postoperative atrial flutter, which represents a 5.6% incidence of readily treatable atrial flutter in this series.
Hospital mortality was defined as death that occurred during the hospitalization in which the procedure was performed or death after discharge from the hospital but within 30 days of the surgical procedure, unless the cause was unrelated to the operation. Three patients died in the hospital (4.2%; 95% confidence interval [CI], 3.6% to 5.3%). The first patient was a 70-year-old man who had end-stage ischemic cardiomyopathy, an ejection fraction of 15% with left ventricular dyskinesia, chronic renal failure, severe mitral regurgitation, permanent AF, and refractory NYHA IV congestive heart failure (CHF). He underwent two-vessel CABG, mitral valve repair, modified maze, and left ventricular restoration. His initial postoperative progress was uneventful. Worsening renal dysfunction and an ileus developed on postoperative day 5, followed by ischemic colitis and multisystem organ dysfunction. The patient died on postoperative day 26.
The second patient was a 76-year-old man with refractory NYHA IV CHF, chronic renal dysfunction, ischemic cardiomyopathy, mitral regurgitation, and permanent AF. He underwent mitral valve repair, modified maze, and CABG. The patient progressed well until postoperative day 6, when acute worsening renal insufficiency developed, followed by hepatic dysfunction and eventually multisystem organ failure. He died on postoperative day 15.
The third patient was a 50 year-old man who presented with multiple comorbidities including a history of morbid obesity, hepatitis C cirrhosis, diabetes mellitus, permanent AF, and progressive CHF. This patient had been previously turned down for cardiac transplantation. He underwent mitral and tricuspid valve repair and modified maze without complication and was discharged on postoperative day 6. The patient was readmitted for acute hepatic dysfunction on postoperative day 25 and was diagnosed with splenic and portal vein thromboses. He died on postoperative day 30 awaiting liver transplantation.
The mean EuroSCORE [20] for the total cohort was 7.2 ± 2.4 (range, 3 to 13). This EuroSCORE was predictive of a mortality rate of 11.2%. The average postoperative length of stay was 8.8 ± 5.7 days.
Rhythm Monitoring and Patient Follow-up
Data were collected in 70 patients (98.6%) with 1 patient (1.4%) lost to late follow-up. The mean follow-up was 10.7 ± 8.4 months (range, 1 to 31.0 months). The cumulative follow-up for the series was 730.0 patient-months. Of the 68 patients discharged from the hospital, there were 8 (11.3%) late deaths. Of the hospital survivors, 56 (82.4%; 95% CI: 71.2% to 90.5%) of 68 patients were discharged in NSR. The proportion of patients in NSR was 25 (92.6%) of 27 at 0 to 6 months follow-up, 15 (93.8%) of 16 patients between 7 and 12 months follow-up, and 23 (92.0%) of 25 patients with more than 1 year of follow-up, with 95% CIs of 89.9% to 94.1%, 89.3% to 96.1%, and 89.1% to 93.7%, respectively. Patient rhythm status at varying time intervals during the follow-up is displayed in Figure 2. For current survivors with at least 12 months of follow-up, 12.5% (3/24) were on antiarrhythmic agents compared to 95.8% (23/24) at hospital discharge (p = 0.001). This represents a significant reduction in postoperative modified maze antiarrhythmic therapy.
|
|
Comment |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
The success of the maze procedure after mitral valve surgery in patients with large left atria and permanent AF currently remains suboptimal. Despite the 90% to 97% success rate with the traditional cut-and-sew Cox-maze III operation, its complexity has limited its universal acceptance [3–6]. The multitude of surgical technique modifications and energy source variations now available tend to obscure the surgical decision-making algorithm when this challenging cohort of patients is managed. Several reports discuss the use of one or occasionally two energy sources, and many combine data from patients with paroxysmal, persistent, and permanent AF with results of 60% to 80% freedom from AF [7–10].
Unlike paroxysmal or recent-onset AF, permanent AF does not revert spontaneously after mitral valve surgery, and its persistence postoperatively has been implicated as a predictor of late stroke and mortality [2]. Large left atria are commonly associated with permanent AF and mitral valve disease. Additional AF foci in the wall of the enlarged remodeled left atrium may contribute to failures of simple pulmonary vein isolation and other modified maze procedures in patients with permanent AF and large left atria. Reduction in left atrial size has been suggested to play a central role in improving maze procedure outcomes [10–17]. Scherer and colleagues [22] reported that when left atrial plication alone was performed with a mitral valve operation, 63.0% (17/27) patients with permanent AF were in NSR at 1 year.
Our primary focus in this study was to control for the lesion set, operative technique, and AF type. Each patient underwent an identical left atrium–only Cox-maze III lesion set using one radiofrequency energy source, combined with left atrial reduction and left atrial appendage linear suture closure, as illustrated in Figure 1. We further chose to examine this treatment paradigm on a homogeneous cohort of patients presenting with only permanent AF and undergoing mitral valve surgery.
All patients in this series had corrective mitral valve surgery. This was a consecutive unselected series of high-risk patients who had advanced cardiovascular disease, with 90.1% (64/71) being in end-stage NYHA class III-IV heart failure at the time of operation, and 59.2% (42/71) requiring concomitant major cardiovascular procedures. Furthermore, the cohort had a mean calculated EuroSCORE [20] of 7.2. Despite a predictive operative mortality of 11.2% with a EuroSCORE of 6.0 or greater, the observed mortality rate in this series was 4.2%. Moreover, minimal morbidity was observed with no esophageal injuries and no early or late cerebrovascular events. There were eight late deaths. Among survivors the total freedom from AF beyond 6 months was 92.7% (38/41) and beyond 1 year, 92.0 % (23/25). Yuda and associates [23] suggest that improvements in exercise capacity and peak oxygen uptake may have more to do with a reduction in left atrium size than in restoring NSR and atrial contraction after mitral valve surgery with a concomitant maze procedure. This may explain why 98.3% (58/59) of our patients reported they were "somewhat better" or "much better" than before their operation.
It has been suggested that a left atrium–only maze procedure results in an increased incidence of right-sided atrial flutter and that the addition of right-sided lesions and biatrial reduction is necessary to avoid this complication while optimizing outcomes [24]. Conversely, electrophysiology studies have recently revealed that in patients experiencing atrial flutter after left atrial radiofrequency lesions were created during mitral valve surgery, the flutter is predominantly of left-sided origin [25]. This argues against routine ablation of the cavotricuspid isthmus during AF surgery. Furthermore, routine excision of the left and right atrial appendage during the maze operation has been associated with an elevation in circulating arginine vasopressin and aldosterone levels, presumably due to alterations in atrial baroreceptor response, thus resulting in excessive postoperative fluid retention [26]. With the isolated left atrial approach examined in this study, no patient underwent right-sided ablation or excision of either atrial appendage. This may explain the negligible postoperative fluid retention and the relatively low incidence of cardioversion-responsive atrial flutter (5.6%, 4/71) found in this series.
Left atrial reduction can be safely and effectively combined with isolated left atrium–only radiofrequency ablation to treat permanent AF during concomitant mitral valve operations. Results of 1-year 92.0% freedom from AF by this modified technique may be comparable with those obtained from the traditional Cox-maze III operation. Continued clinical evaluation and further follow-up remains essential to confirm long-term outcomes.
Study Limitations
Despite the valuable information obtained from this study, it was conceived as an observational, nonrandomized investigation conducted by retrospective analysis of data. Limitations of this study also include the limited sample size, the lack of a non-atrial-reduction control group, and the short duration of follow-up. Although the operative technique was standardized by a single surgeon experience (VB), electrocardiographic measurements, but not Holter recordings, were used for postoperative rhythm follow-up. As a result, episodic postoperative AF may not have been detected. Prudence should therefore be exercised in the interpretation of these encouraging early results until such time as confirmation can be achieved by further long-term follow-up.
|
Discussion |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
DR BADHWAR: Thank you, Dr Hammon, for your kind comments. On the issue of transmurality, there are multiple different devices around, with varied options of technique. We tried to set out to determine an answer of simplicity using something that is fairly rapid. The procedure, as you see here, takes about 25 to 30 minutes of clamp time, including reduction. Furthermore, our reasons to proceed with the irrigated radiofrequency option involve three-month transmurality shown in patients that have had unipolar lesions with this device. I do not believe there is a lot of human histologic data out there providing confidence that when you use a bipolar device that, despite operative feedback, you know it is transmural and this equates to success. From troponin staining of atrial specimens analyzed from patients three months after irrigated unipolar surgery, you could see that there is actually a good transmural result. With this information combined with trying to keep the procedure simple, we wanted to proceed with this type of device. However your point is well taken on the varying different options available. Thank you.
DR KEVIN D. ACCOLA (Orlando, FL): Very nice presentation and your group is to be congratulated as you are doing outstanding work on surgical treatment options with atrial fibrillation. I have a couple of questions in regards to the "massive" left atriums. We have done left atrial reductions for the atriums that are 7 or 8 centimeters, the ones that at the end of the procedure you see a normal sinus rhythm complex on the screen but you look at your TEE and you just see smoke. I would be interested if you have followed this subset-up independently, and if with your follow-up echoes you demonstrate an increase in left atrial contractility, which I think is important. As Dr Hammon had mentioned with Dr Cox's follow-up, that he has shown increased left atrial activity in the majority of his patients?
One other comment in regards to anticoagulation, I think it is somewhat risky without anticoagulating these patients. They have a lot of suture lines, and especially in the massive left atriums. I think it is probably safer to put them on some anticoagulation, even if it is only for 6 or 8 weeks to also demonstrate sustained sinus rhythm.
Again, congratulations on a very nice study and we look forward to seeing further follow-up on these patients.
DR BADHWAR: Thank you, Dr Accola, for your kind comments and questions. To answer your questions in order, there has been some literature revealing VO2 improvements and exercise tolerance improvements with left atrial reduction alone, exclusive of maintenance of normal sinus rhythm in terms of long-term post-procedural benefit to patients. We have noticed in our series that over 98 percent of our patients have reported quality-of-life improvements in follow-up, and I think that left atrial reduction is part of that.
In terms of contractility, we have been looking at echocardiographic follow-up and that information is pending, but we have noticed more regular return of contractility often, as has been reported, at around three months.
Regarding the issue of anticoagulation, we know that it is somewhat controversial not to put patients on anticoagulation following mitral valve repair, but there is no true data in the literature indicating that you cannot. I feel that with the smooth surface we are able to create with this maze technique and the fact that we have not had any cerebrovascular events in this series, we feel that the risks of warfarin in our very elderly population, of which I know you are familiar being here in Florida, is something that I can think we avoid effectively and safely.
DR CLIFF K. CHOONG (Cambridge, United Kingdom): Congratulations to you and your team for the excellent clinical results and presentation. Two quick questions. In your presentation, there was no mention of the definition for a very large atrium. In your clinical practice, what do you define as a very large atrium and at what size would you perform left atrial reduction? Question two is, have you compared results in your patients where you have done AF surgery without having done the left atrial reduction (ie, patients with smaller left atrial size) and have you been able to get such similar excellent clinical results? Once again, congratulations on the excellent clinical work and presentation.
DR BADHWAR: Thank you for your questions. With regards to defining left atrial size enlargement, we defined those that were over 5.5 centimeters. In our series, most had massive left atrial sizes, as Dr Accola had commented, in the area of 7 to 8 centimeters. Still in our region, our cardiologists have not quite understood the Mayo data that early referral for mitral valve repair is good, so we see many patients with large atria with longstanding mitral disease. For the purposes of this study we defined large atria as 5.5 centimeters.
In comparing it to patients who have normal left atria, our maze results are about similar, but most of those patients, however, were not chronic permanent as defined by the ACC/AHA/European community guidelines as permanent atrial fibrillation, and the majority were in fact paroxysmal, as you might expect. Therefore we did not include these patients in this analysis for the homogeneity of the data and analysis.
DR A. DAVID SLATER (Louisville, KY): I wonder if you could comment on what percentage of your patients are free of anti-arrhythmic therapy in your 1- and 2-year follow-up?
DR BADHWAR: Thank you for your question, Dr. Slater. In reviewing the long-term data, of the entire 71 that were studied, only 3 in the late follow-up, over a year, were maintained on anti-arrhythmic therapy. Now, these are spot follow-ups, so some may have been off and then restarted, for whatever reason, by the patient's physicians at late follow-up. Thank you.
|
Acknowledgments |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
|
References |
|---|
|
TopAbstractIntroductionMaterial and MethodsResultsCommentDiscussionAcknowledgmentsReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  S. Chaiyaroj, T. Ngarmukos, and P. Lertsithichai Predictors of Sinus Rhythm after Radiofrequency Maze and Mitral Valve Surgery Asian Cardiovasc Thorac Ann, August 1, 2008; 16(4): 292 - 297. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Marui, Y. Saji, T. Nishina, E. Tadamura, S. Kanao, T. Shimamoto, N. Sasahashi, T. Ikeda, and M. Komeda Impact of left atrial volume reduction concomitant with atrial fibrillation surgery on left atrial geometry and mechanical function. J. Thorac. Cardiovasc. Surg., June 1, 2008; 135(6): 1297 - 1305. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Gillinov Choice of Surgical Lesion Set: Answers From the Data Ann. Thorac. Surg., November 1, 2007; 84(5): 1786 - 1792. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Marui, K. Tambara, E. Tadamura, Y. Saji, N. Sasahashi, T. Ikeda, T. Nishina, and M. Komeda A novel approach to restore atrial function after the maze procedure in patients with an enlarged left atrium Eur. J. Cardiothorac. Surg., August 1, 2007; 32(2): 308 - 312. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Villa, A. Messina, M. Cirillo, and G. Troise Size matters in atrial fibrillation surgery Eur. J. Cardiothorac. Surg., August 1, 2007; 32(2): 398 - 399. [Full Text] [PDF]
|
|
|
|
|
|
G. D'Ancona, G. Santise, S. Sciacca, F. Pirone, and M. Pilato Simplified Left Atrial Volume Reduction and Modified Maze Procedure as Treatment for Permanent Atrial Fibrillation During Concomitant Mitral Surgery Ann. Thorac. Surg., July 1, 2007; 84(1): 357 - 357. [Full Text] [PDF]
|
|
|
|
|
|
V. Badhwar Reply Ann. Thorac. Surg., July 1, 2007; 84(1): 357 - 358. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
