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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 32  |  Issue : 2  |  Page : 581-586

Left atrial maze efficacy for treatment of concomitant atrial fibrillation with mitral valve disease


1 Department of Cardiothoracic Surgery, Menoufia University, Menoufia, Egypt
2 Department of Cardiothoracic Surgery, National Heart Institute, Cairo, Egypt
3 Department of Cardiothoracic Surgery, Aswan Heart Centre, Aswan, Egypt

Date of Submission08-Sep-2017
Date of Acceptance05-Nov-2017
Date of Web Publication25-Jun-2019

Correspondence Address:
Walid KA Simry
Elkobri Elelwy Street, Birket Elsabaa, Menoufia
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_586_17

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  Abstract 

Objective
This study aims to compare the efficacy of mitral valve surgery with left atrial maze versus isolated mitral valve surgery.
Background
Atrial fibrillation (AF) is the most common arrhythmia in clinical practice, especially with mitral valve disease. It represents a significant health burden especially with the associated thromboembolic complications. Several surgical approaches have been developed. The most effective one is Cox-Maze III procedure using cut-and-sew technique. Recently, surgical ablation has been transformed into an easier and faster procedure using radiofrequency, microwave, and cryothermal energy.
Patients and methods
This is a prospective cohort study conducted after the approval of the Human Ethics Committee of Faculty of Medicine, Menoufia University. A total of 100 patients with permanent AF and concomitant mitral valve disease have been recruited. The patients were allocated into two equal groups. Group A included mitral valve surgery and left atrial maze procedure, whereas group B included mitral valve surgery without left atrial maze.
Results
Group A had significant longer bypass and clamp times than group B (P < 0.001). Group A had significant less postoperative AF as assessed at '1 week, 1 months, 3 months, and 6 months'. At 6 months, 74% of patients in group A were in sinus rhythm as compared with 20% of patients in group B (P < 0.0001). Moreover, it was noticed that 74% of patients in group A had atrial kick postoperatively as opposed to only 20% of patients in group B (P < 0.0001).
Conclusion
Left atrial maze with mitral valve surgery results in a better outcome in terms of myocardial function and dimensions. In addition, sinus rhythm restoration has the potential benefit of reducing the incidence of thromboembolic complications.

Keywords: atrial fibrillation, Cox Maze, left atrial maze, rheumatic mitral, thromboembolism


How to cite this article:
Dokhan AL, Taher AH, Allama AM, Ayanah AH, Simry WK. Left atrial maze efficacy for treatment of concomitant atrial fibrillation with mitral valve disease. Menoufia Med J 2019;32:581-6

How to cite this URL:
Dokhan AL, Taher AH, Allama AM, Ayanah AH, Simry WK. Left atrial maze efficacy for treatment of concomitant atrial fibrillation with mitral valve disease. Menoufia Med J [serial online] 2019 [cited 2019 Sep 20];32:581-6. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/581/260901




  Introduction Top


Atrial fibrillation (AF) is the most common arrhythmia in clinical practice, occurring in 1–2% of the population. It increases with age and is responsible for 15–20% of strokes, representing a significant health burden. It is associated with less favorable quality of life relative to sinus rhythm (SR)[1].

AF is present in up to one-third of patients undergoing mitral valve (MV) procedures. Although common, the mechanistic relationship between mitral valve disease and AF is poorly understood. The left atrial appendage (LAA) is a culprit of thromboembolic complications in the AF setting[2].

AF is present in two forms: paroxysmal or intermittent and persistent or chronic. Consideration of antithrombotic and antiarrhythmic therapies is one of the treatment approaches. Anti-arrhythmic agents are the first-line therapy[3].

Surgical ablation represents a nonpharmacological treatment in patients undergoing concomitant cardiac surgery. Several surgical approaches were developed, including left atrial isolation[4], corridor procedure, atrial transection procedure, maze procedure[5], and radial procedure[6].

The first two were designed to isolate the arrhythmia to one particular region of the atrium rather than to ablate the AF. The last three were designed to ablate the arrhythmia itself. However, only the maze procedure proved to be successful over time[7].

The ideal ablation strategy would (i) result in a long-lasting isolation of the pulmonary veins, (ii) tailor the subsequent ablation approach to the patient by delineating the underlying atrial electrical substrate, (iii) always generate totally transmural lesions, and (iv) be minimally invasive[8].

The first effective surgical procedure was introduced by James Cox in 1987 after extensive animal investigations. Unfortunately, the first version was complicated by late incompetence and a high rate of pacemaker implantation[9].

To address the problem, the procedure was modified, eventually resulting in the Cox-Maze III in 1992. This lesion set became the gold standard for surgery of AF[10].

It used a 'cut-and-sew' technique to guide the native sinus impulse to atria and the atrioventricular (AV) node while blocking all macro-re-entrant circuits. By restoring SR and atrioventricular synchrony while maintaining atrial transport function, the Cox-Maze procedure reduced the risk of thromboembolism, stroke, and hemodynamic compromise[11].

However, this technique is limited by an associated increase in operative times, morbidity, and technical complexity[12].

Recent advances gave rise to newer surgical ablation techniques. The discovery by Haïssaguerre et al.[13] that pulmonary veins are the source of ectopic activity in paroxysmal AF led to development of pulmonary vein isolation approach, which employs a minimal left atrial lesions.

Furthermore, the advent of alternative energy sources simplified 'cut and sew' technique. Because radiofrequency, microwave, and cryothermal energy can create lines of transmural necrosis, surgical ablation has become an easier and faster procedure with reduced morbidity[14].


  Patients and Methods Top


Patients ethical considerations

After approval of Menoufia Ethics committee for the study proposal and between December 2014 and December 2016, this prospective cohort study was conducted for 100 patients. Informed consents were obtained from all patients.

Selection criteria and methods of sampling

All patients had rheumatic mitral valve disease and permanent AF which was defined as continuous long-standing AF that lasts for a period more than 12 months without responding to electrical or medical cardioversion. The patients were divided into two groups; group A and group B (control group), with 50 patients per each group. Group A included patients who had valve surgery and a left-sided maze procedure using either cut and sew technique or radiofrequency ablation. Group B included patients who had valve surgery only without maze procedure.

Inclusion criteria

All patients between 18 and 65 years of age having permanent AF and underwent mitral valve surgeries either by replacement or repair were included.

Exclusion criteria

The exclusion criteria were as follows: paroxysmal and persistent AF, emergency or redosurgery, ischemic patients, chronic renal failure, chronic liver dysfunction, advanced parenchymal lung disease, documented history of arrhythmias other than AF, previous catheter ablation for AF, thyrotoxicosis or other primary causes of AF, and structural heart diseases that require intervention.

The following data were collected from both groups

Demographic data with a full personal history was obtained. Routine preoperative investigations were performed such as a 12-lead ECG strip, a transthoracic echocardiography, and a chest radiography.

Operative procedure in both groups

All patients had mitral valve surgery. A median sternotomy was employed in all cases. A conventional aortobicaval cannulation for cardiopulmonary by-pass was established. Systemic cooling to around 28–30°C was done. Cardioplegia was intermittent antegrade cold blood, and topical cooling was used. Mean time between cardioplegia doses was 20 min. The mitral valve was repaired or replaced using a metallic or biological prosthesis in all cases.

All patients in group A had a left atrial maze procedure either by cut and sew technique or by radiofrequency ablation using monopolar saline-irrigated cooled tip radiofrequency ablation (SICTRA) using the Medtronic Radiofrequency Generator Model 68000 as an energy source (Medtronic company in Coolidge, Arizona, USA). As a routine, the maze procedure was accompanied by amputation of the left atrial appendage.

Follow-up of patients from both groups

Twelve-leads ECG was recorded on all four predetermined times using the SCHILLER CARDIOVIT AT-101 ECG. Rhythm strip assessment was done at 1 week, 1 month, 3 months, and 6 months.

A transthoracic echocardiography was performed by two experienced investigators using the GE VIVID 3 (General Electric) ultrasound device (Absolute Medical Services company in Stony Point, New York, USA) at 6 months postoperatively.

Statistical analysis

Data were analyzed using Statistical Program for Social Science, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean ± SD. Qualitative data were expressed as frequency and percentage.

Independent-samples t-test of significance was used when comparing between two means.

χ2 test of significance was used to compare proportions between two qualitative parameters.

P value of less than 0.05 was considered significant.

P value of less than 0.001 was considered as highly significant.

P value of more than 0.05 was considered insignificant.


  Results Top


There was no statistically significance difference in the baseline characteristics of both groups concerning age, sex, AF duration, rheumatic etiology, and preoperative echo findings (left atrial size and ejection fraction), as shown in [Table 1].
Table 1: Preoperative demographic and patient characteristics

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The mean duration of by-pass time was statistically highly significant, as it was 106.93 ± 12.25 min in group A and 89.4 ± 12.94 min in group B, and also the mean duration of cross-clamp time was statistically highly significant, as it was 78.13 ± 12.84 min in group A and 61.53 ± 12.87 min in group B, as shown in [Table 2]. At the beginning, the maze procedure was more time consuming than later on during the study. There was a learning curve as with any novel procedure.
Table 2: Operative data of both groups

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The maze procedure was highly effective in regaining the SR at specified timings (1 week, 1 month, 3 months and 6 months), and the details are illustrated in [Table 3].
Table 3: Proportion of patients in sinus rhythm at specified timings

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The maze procedure had a great effect on regaining atrial contractility, as 74% of patients in group A did whereas only 20% of patients in group B, as shown in [Table 4].
Table 4: Bi-atrial contractility in relation to total number of patients in both groups

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The decrease in left atrial volume in both groups was significant. The mean left atrial volume preoperatively in group A was 125.9 ml and decreased to 105.76 at 6 months. In group B, the mean left atrial volume preoperatively was 122.1 ml, and it decreased to 108.6 ml at 6 months, as shown in [Table 5]. Moreover, there was a statistical significant difference between the left atrial volume preoperatively and the restoration of SR. In group A, mean left atrial volume was 108.5 ml in patients in SR at 6 months whereas it was 151.2 ml in patients who were in AF at 6 months.
Table 5: Difference in preoperative and postoperative left atrial volumes in both groups

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There was a statistical significance between preoperative fibrillation duration and SR restoration as shown in [Table 6]. In group A, mean AF duration in patients that regained SR at 6 months was 58.33 months and in patients who were still in AF was 79.69 months. In our study, we could not determine a specific AF duration over which sinus conversion would be unsuccessful.
Table 6: The relation between preoperative atrial fibrillation duration and restoration of sinus rhythm in both groups

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There was an increased incidence of failure of the procedure when the left atrial dimension was over 6 cm but not to a degree where ablation should not be attempted. We would further like to point out that one of our patients in which ablation was successful at 6 months had an anteroposterior diameter of more than 8 cm.

No short-term or long-term complications resulted from the maze procedure.

ECG strips of group A done during the first day of ICU showed a picture of nodal rhythm in four patients and picture of first-degree heart block in three patients. All of these reverted to SR before discharge from the hospital or at 1 month postoperatively.

Direct current cardioversion was attempted in seven patients in group A reverting to AF from SR or who were discharged from the operative theatre in AF. It was successful in four of the patients, but it failed to maintain in the other three in SR during ICU stay.

Direct current cardioversion was attempted in five patients in group B for patients in AF during early ICU stay, but this was discontinued during the rest of the study owing to failure in maintaining the patient in SR. We relied on medical cardioversion instead.

In group B, intravenous amiodarone infusion in the ICU did not seem to be particularly helpful in maintaining the patients in SR when the results are compared with that of patients not receiving amiodarone. However, another study in the cardiology department must be done to accurately compare between groups receiving amiodarone and groups that are not.

Stroke was recorded in one patient in group B around 3 months postoperatively. There was no incidence of stroke in group A.

There was no need for permanent pacemaker implantation in both groups.

One patient in group A presented with supraventricular tachycardia at 6 months. He was subsequently given propafenone.

Eventually, the presence of multiple negative prognostic factors will reduce success rates but not preclude success.


  Discussion Top


The maze operation designed and developed by James L. Cox in the years 1987–1991 used to be a gold standard of surgical AF treatment. Evidence of the importance of pulmonary vein ostia and the posterior atrial wall in the initiation and maintenance of AF together with technological advances led to abandoning the time-consuming, technically difficult Cox-Maze operation despite reported high efficacy of such treatment.

The development of alternative energy sources that can ablate atrial tissue by topical application has been a requisite advancement in the evolution toward faster, less-invasive procedures for AF. The ideal energy source would be fast, reliable, yield a full-thickness lesion, would not damage surrounding tissues, and would be amenable to off-pump and minimally invasive application.

At the beginning, a biatrial approach appeared preferable to either isolated left or right atrial ablation, because the success rate was 85% in patients with biatrial ablation. The left atrial only approach was considered, based on the study findings of Haïssaguerre and colleagues, who documented focal ectopies arising from the pulmonary veins, thus inducing paroxysmal AF. Sueda and colleagues proposed a minimized left atrial approach for patients with mitral valve disease and documented left atrial foci during intraoperative mapping, with promising results in 86%.

These findings led to the concept of approaching the left atrium only during antiarrhythmic surgery. Additional benefits of maze are that it may reduce postoperative troublesome brady arrhythmias, and is well suited to minimally invasive cardiac surgery. Left atrium maze is typically recommended for patients with recent onset of paroxysmal AF who are undergoing elective surgery with no reason to open the right atrium. The success rates of these procedures range between 74 and 82% at variable follow-up. The critical condition of successful maze seems to be transmural scar formation, which causes complete conduction block. Only during the cut and sew maze operation was the surgeon sure the scar would be transmural as the whole thickness of the atrial wall was cut.

Unfortunately in the case of radiofrequency ablation there is no way to check for the completeness of transmurality. We are only capable of setting up appropriate parameters of the ablating device but cannot interfere with the patient substrate – the atrial wall. Mean thickness of the left atrium wall in healthy individuals is reported not to exceed 3 mm. However, atrial wall thickness and proportions of endocardium, myocardium, and epicardium may vary between people. Left atrium dilatation and thickening are especially pronounced in the course of mitral valve disease, and left atrium wall thickness may reach even 5–6 mm.

However, bipolar and cryoenergy were used. The 'box' was not closed so that the posterior wall of the left atrium benefits from the procedure as well (if the posterior wall is left fibrillating it can form a nidus for thrombus formation and its contribution to biatrial contractility is lost). Box closure was part of the original Cox-Maze III in which the four pulmonary veins were isolated together in one island.

This is similar to most studies; for example, in a study on 99 patients, Chen et al.[15] claimed that sinus conversion rate was significantly lower in patients with a left atrial diameter over 56.8 mm. According to Zacà et al.,[16] a left atrial dimension of 5.1–6 cm was not associated with a lower rate of sinus conversion if compared with left atrial diameters below 5 cm, but atrial dimensions of more than 6 cm were associated with a nine-fold higher risk of failure at 1-year follow-up.


  Conclusion Top


Many patients with mitral valve disease have experienced AF, which results in a variety of morbidities including hemodynamics compromise, syncope, dizziness, fatigue, palpitations, chest pain, and an increased probability of a thromboembolic event.

At the time of mitral valve surgery, the incidence of concomitant AF can reach up to 50%. Mitral valve surgery alone usually does not abolish the AF, and its persistence after surgery increases postoperative morbidity and mortality, hence the need for an additional intervention to target AF itself.

Surgery for the treatment of atrial fibrillation culminated in the development of the Cox-Maze III, the gold standard of treatment and still, the procedure with the highest success rate (≤98% according to some studies). Intraoperative endocardial radiofrequency ablation to the pulmonary veins for AF is a promising new treatment option for patients with AF undergoing cardiac surgery or patients with highly symptomatic AF not responding to other therapies.

It is important to note that achieving a transmural scar is of paramount importance.

Predictors of failure were preoperative left atrial volume and preoperative AF duration.

Continuous postoperative ECG monitoring for 6 months or more would be a useful investigation to determine whether the patient in SR enters into paroxysms of AF and, if so, for how long.

So according to what we got from our study, we highly recommend association of left atrial maze procedure with mitral valve surgery for the treatment of rheumatic mitral valve diseases with permanent AF. This can potentially allow mitral valve repair patients to stop taking oral anticoagulation in the future, hence all benefits of elimination of atrial fibrillation will be achieved (improved hemodynamics, no palpitations, improvement of symptoms, and avoiding complications of both thromboembolic manifestations and the use of anticoagulants).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Ad N, Henry L, Massimiano P, Pritchard G, Holmes SD. The state of surgical ablation for atrial fibrillation in patients with mitral valve disease. Curr Opin Cardiol 2013; 28:170–180.  Back to cited text no. 14
    
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Chen M, Chang J, Chang H, Chen Ch, Yang Ch, Chen Y, et al. Clinical Determinants of sinus conversion by radiofrequency maze procedure for persistent atrial fibrillation in patients undergoing concomitant mitral valvular surgery. Am J Cardiol 2005; 96;1553–1557.  Back to cited text no. 15
    
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Zacà V, Galderisi M, Mondillo S, Focardi M, Ballo P, Guerrin F. Left atrial enlargement as a predictor of recurrences in lone paroxysmal atrial fibrillation. Can J Cardiol 2007; 23:869–872.  Back to cited text no. 16
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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