- Email: [email protected]
Current Role for Surgery in Treatment of Lone Atrial Fibrillation
STATE OF THE ART
Current Role for Surgery in Treatment of Lone Atrial Fibrillation Niv Ad, MD,* Linda Henry, PhD,† and Sharon Hunt, MBA† The Cox-Maze procedure has been performed successfully since 1987. The original surgery was performed by using the “cut and sew” technique and is considered quite complex and technically demanding; therefore, it never gained popularity among cardiac surgeons and referring cardiologists. As surgical ablation technology improved, the Cox-Maze procedure can now be performed by using new ablation devices that deliver different energy sources (radiofrequency, cryothermia, and others). The use of ablation technology simplified the technical aspects of the procedure and has led to decreased time on cardiopulmonary bypass, easier placement of ablation lines, and the development of various minimally invasive approaches to include off-pump techniques. The Heart Rhythm Society recommends surgical ablation for symptomatic patients, patients who are unable to take anticoagulation therapy, who have failed other therapies to include percutaneous catheter ablation, or by personal request. Therefore, with guidelines in place as to patient selection and newer, easier-to-use technology, more surgeons are tackling surgical ablation of atrial fibrillation, offering another treatment option for patients with lone atrial fibrillation. This article will review the current state of surgery for the ablation of lone atrial fibrillation. Semin Thoracic Surg 24:42-50 © 2012 Elsevier Inc. All rights reserved. Keywords: ablation, atrial fibrillation, catheter, hybrid, surgery Atrial fibrillation is the most common of all clinically sustained heart arrhythmias. According to recently published data, more than 2.3 million people in the United States are affected with this arrhythmia, and this number is expected to increase to 5.6 million people by 2050.1-3 The occurrence of atrial fibrillation is associated with age, race, and gender. The prevalence rate for people younger than 55 is 0.1%, but for those older than 80 the prevalence rate is 9%. Whites older than 50 are affected at a higher rate than blacks, and men have double the prevalence rate than women.1-3
Medical Treatment Medical treatment is the first line of treatment in most patients with atrial fibrillation. Patients might need to be treated with 1 or more types of medication. There are 2 main strategies for medical treatment rhythm and rate control.4-6 Most rhythm control regimens demonstrate fairly limited efficacy and might result in significant side effects.7-9 An appropriate anticoagulation treatment for patients with the appropriate indications is usually used to reduce the risk of embolic strokes.10,11
TREATMENT OPTIONS There are 3 clinical strategies for primary treatment of atrial fibrillation: medical treatment, percutaneous catheter ablation to either achieve rhythm or rate control, and surgical ablation with or without the use of cardiopulmonary bypass (Fig. 1).
Percutaneous Catheter Ablation Catheter-based techniques are being widely used in patients with atrial fibrillation. There are 2 different strategies. (1) With rate control, patients are being treated with an atrioventricular node ablation and pacemaker insertion to achieve rate control.12 (2) Catheter-based procedures are being performed routinely to achieve rhythm control and are the most commonly used nonpharmacological approach to treat atrial fibrillation.13 The procedures are done by using somewhat sophisticated mapping systems and different energy and catheters (radiofrequency, cryoballoons).13 Despite growing experience, the success rate of such procedures especially with a single application remains fairly limited, and
*Department of Cardiac Surgery, Inova Heart and Vascular Institute, Falls Church, Virginia. †Department of Cardiac Surgery Research, Inova Heart and Vascular Institute, Falls Church, Virginia. Address reprint requests to Niv Ad, MD, Department of Cardiac Surgery, Inova Heart and Vascular Institute, 3300 Gallows Road, Suite 3100, Falls Church, VA 22042. E-mail: [email protected]
42
1043-0679/$-see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.semtcvs.2012.04.007
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Figure 1. Algorithm of current state of treatment. AV, atrioventricular.
the risks associated with these procedures are stroke, pericardial tamponade, and vascular accidents.14-16 Surgical Ablation Surgical ablation for atrial fibrillation in general and Cox-Maze procedure in particular are highly effective in restoring sinus rhythm. Success rates vary by center but generally are reported in the range of 70%-100%. Most patients (about 80%) after the Cox-Maze procedure will be maintained in sinus rhythm without the need for any antiarrhythmic or anticoagulation medications. Most of the remaining patients will be able to manage their rhythm with a single antiarrhythmic medication, even if that medication did not control their rhythm preoperatively.17,18 Guidelines might consider sinus rhythm on antiarrhythmic drugs as a failure; however, we disagree with this approach because this group of patients will sustain a significantly lower risk of thromboembolic events, anticoagulation can be stopped with lower risk for bleeding, and they have much improved quality of life.19 Surgical Ablation for Atrial Fibrillation Over 25 Years The concept of the Cox-Maze procedure evolved around 4 principles: (1) ablate macro re-entrant circuits to reestablish sinus rhythm; (2) restore atrioventricular synchrony; (3) improve atrial transport function; and (4) eliminate the risk for thromboembolic events.20,21
The original Cox-Maze procedure involved cutting and sewing with multiple biatrial incisions to interrupt all macro re-entrant circuit options in the atria. The purpose was to allow the sinoatrial (SA) node to resume normal activity after surgery and direct the propagation of the sinus impulse through the atria.21,22 However, the Cox-Maze I procedure introduced 2 challenges. The first was significant chronotropic dysfunction in which the patient was unable to generate an increased heart rate in response to exercise because of a significant interruption to the blood supply to the sinus node complex as the lesions of the Cox-Maze 1 procedure almost isolated the sinus node complex. The second issue related to the Maze I was a significant conduction delay between the right and left atrium as one of the lesions was placed across the Bachmann bundle, which resulted in a long conduction delay (about 180 milliseconds) and for the right atrium to be activated first, followed by the other 3 heart chambers, which created an asynchronous beating of the heart.21 These significant issues led to modifications of the Maze I procedure. The initial modification was to move the surgical incision further away from the SA node by going to the back of the superior vena cava (Maze II procedure).22,23 However, this was technically challenging, so further modification was necessary. Additional changes moved the incision away from the SA node and toward the interatrial septum. These changes maintained the three-dimensional
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION concept of the Cox-Maze procedure and were less technically demanding to perform. In addition, the original problems of chronotropic dysfunction and conduction delay were no longer issues. Today this surgery is known as the Cox-Maze III procedure, and in its modern form, most of the surgical incisions were replaced by surgical ablation by using specially designed devices.24-26 The Cox-Maze III procedure has met with great success as reported by Washington University18,27 and has shown a significant reduction in cerebrovascular accidents and transient ischemic events because of the high success rate of ablating atrial fibrillation and amputating the left atrial appendage. In addition, fewer pacemakers were implanted, and improved atrial transport and sinus node function were seen.28,29 Different publications demonstrate that the cut and sew procedure as well as the use of other ablation devices when performed by an experienced surgeon result in very low morbidity and excellent long-term freedom from atrial fibrillation and thromboembolic events.30-32 In the past decade, several surgical ablation approaches to treat atrial fibrillation as a stand-alone or concomitantly with other cardiac surgical procedures were developed. The use of the heart-lung machine is required to perform the Cox-Maze procedure in its current form and with the available ablation devices. It can be performed as a full sternotomy or minimally invasive procedure.33 If other procedures such as valve repair/replacement or coronary bypass are to be performed concurrently with the Cox-Maze procedure, then the standard openchest approach is likely to be used; however, when an atrial septal defect closure, mitral valve repair or replacement, and tricuspid valve surgery are required, a minimally invasive right mini-thoracotomy can be applied.33,34 The overall operative risk is low in morbidity and mortality and might be impacted by the individual’s specific health conditions. In a recent publication, we reported the results of a study in which we investigated surgical ablation in patients with a low ejection fraction (⬍40%), heart failure, and atrial fibrillation. In this small series of patients we found that the results were excellent, with only 1 operative death and no strokes or transient ischemic attacks. Patients’ ejection fraction on average improved from 30% to 45%, the return to sinus rhythm rate at the time of their postprocedure echo was 86%, and their health-related quality of life physical functioning scores surpassed their age group norms. We concluded that patients such as these should not be excluded, and surgical ablation should be considered.35 In other work we have published, we have shown that when adding the Cox-Maze procedure to 44
patients who are older than 75, are undergoing a coronary artery bypass grafting or aortic valve surgery, or are considered high risk, the ablation procedure did not add operative risk, and patients had excellent outcome when compared with a similar group. Again, we concluded that these procedures and age should not be the only considerations when deciding whether to perform a surgical ablation procedure.36,37 Although the procedure is directed toward curing atrial fibrillation, there is some risk that the procedure might fail and that atrial arrhythmia will persist. Therefore, the definition of failure of the procedure per the Heart Rhythm Society is any monitored atrial arrhythmia (atrial fibrillation, atrial flutter, or atrial tachycardia) lasting ⬎30 seconds after the first 3 months after the procedure.38,39 In the early postoperative period, up to one-third of patients might have temporary atrial arrhythmia. Early arrhythmias should be addressed routinely by using clinical protocol and combine antiarrhythmic drugs and cardioversion; if it is addressed appropriately, most patients experiencing early atrial arrhythmia will regain sinus rhythm. Applying rate control strategies early after surgery (up to 6 months) should be considered inappropriate (Fig. 2).4 The further development of devices, mapping, and surgical ablation techniques has led to still another modification of the Maze procedure as well as allowing a minimally invasive surgical approach (minithoracotomy) in which the full Maze or less extensive lesions can be applied. The new modified procedure, Maze IV, replaces most of the prior incisions with linear ablation lines by using newer and easier technologies that include mainly radiofrequency energy and cryothermal energy. The Maze IV procedure follows the same concepts of the Maze III. The only difference between the 2 procedures is that in the Maze IV procedures, the box lesion around the pulmonary veins is accomplished after isolating the right and left pulmonary veins with a clamp (bipolar radiofrequency or cryoclamp) and only then connecting the upper and lower pulmonary veins. The addition of the term Maze IV added some confusion to the field, and surgeons should be aware that the results expected from the 2 procedures are the same because the electrophysiological concept is identical (Fig. 3).40 In the last few years there has been a growing interest in surgical ablation by using off-bypass techniques. This is done by using mainly radiofrequency and high-intensity focused ultrasound devices; however, there were reports about using microwave, laser, as well as cryothermal energy to try to achieve cure. Most off-bypass approaches in the initial expe-
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Figure 2. Protocol slide. AAD, antiarrythmic drug; DC, electric defibrillator using DC discharge. (Reprinted with permission from Ad et al.4) (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
rience were designed to isolate the pulmonary veins and later in the experience to ablate the left atrium and add some lesions to the right atrium.41-44 Furthermore, surgical pulmonary vein isolation can be performed without using cardiopulmonary bypass
for a subset of patients who meet specific criteria, mainly for those patients with short-term paroxysmal atrial fibrillation and a small left atrium.45-47 In a recent study, Atrial Fibrillation Catheter Ablation versus Surgical Ablation Treatment (FAST),
Figure 3. The Cox-Maze procedure: right and left atrial lesions. IVC, inferior vena cava; LLPV, left lower pulmonary vein; LUPV, left upper pulmonary vein; RLPV, right lower pulmonary vein; RULV, right upper pulmonary vein, SVC, superior vena cava. Seminars in Thoracic and Cardiovascular Surgery ● Volume 24, Number 1
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Figure 4. Pathway to surgery. AHA, American Heart Association; HRS, Heart Rhythm Society. (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
patients who failed conventional therapy were randomized to receive either a percutaneous pulmonary vein isolation (PVI) catheter ablation with optional additional lines or a surgical ablation procedure of PVI with bipolar radiofrequency, ganglionic plexus ablation, and left atrial appendage excision. There were 124 patients enrolled in the study. There was a significant difference in freedom from atrial arrhythmias off medication at 12 months, with surgical ablation being superior to catheter ablation (P ⫽ 0.0022). However, surgical ablation was found to have significantly more adverse events than catheter ablation (P ⫽ 0.027), most of which were very minor with no real impact on patient outcome. In the catheter ablation group 1 death was documented at 1 month.48 These results have helped to further the discussion with the electrophysiologists by using off-bypass techniques and a hybrid approach as a new way of ablating atrial fibrillation. These recent advances might allow more patients to be referred for surgical ablation in which atrial fibrillation is their only cardiac problem (lone atrial fibrillation; Fig. 4). Barnett and Ad49 performed a meta-analysis in 2006 on surgical ablation procedures and its role in the elimination of atrial fibrillation. Sixty-nine studies were included in their study. They determined that biatrial ablation surgical procedure was more effective in restoring sinus rhythm than procedures combined to the left atrium only. As part of the International Society for Minimally Invasive Car46
diothoracic Surgery consensus statement, Cheng et al50 followed up this meta-analysis with a metaanalysis study of their own in 2010. They compared surgical ablation patients with non-ablation patients with atrial fibrillation by using randomized and nonrandomized control studies. In the 33 studies that met their inclusion criteria, they concluded that patients with persistent or permanent atrial fibrillation at the time of surgery who underwent surgical ablation had a higher rate of return to sinus rhythm that persisted over time than those who did not undergo surgical ablation, with a trend for a reduction in embolic strokes and death in the ablation group. They concluded that atrial fibrillation surgery is beneficial, but patients should be counseled to the possibility of a pacemaker after surgery. They were unable to perform any subanalysis to determine what lesion set would be the best and in fact found that there was no consistency on the type of lesion set used. As noted in the International Society for Minimally Invasive Cardiothoracic Surgery consensus statement and meta-analysis,50 there are still a plethora of lesion sets performed that are being called a maze procedure. This has led to confusion and difficulty in comparing outcomes. Damiano and his group have studied the results of the surgical ablation extensively. In a recent study just published they reviewed the results of the Cox-Maze IV procedure (using the original lesion lines as described by
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION Dr. James Cox) for lone atrial fibrillation in 100 consecutive patients. They found that the simplified procedure of replacing the incision lesions with bipolar and crytothermia ablation linear lines was doable and allowed a shorter time on the bypass machine, with 84% of the patients in sinus rhythm and off antiarrhythmic drugs at 24 months.51 In another study in which they reviewed their results of the Cox-Maze procedure for lone atrial fibrillation during the last 2 decades, they concluded that the simplified Cox-Maze procedure maintained excellent results even with improved follow-up and stricter definitions of what constituted a successful procedure.52 In one of their most recent publications Damiano et al compared the Cox-Maze IV results for patients with lone atrial fibrillation versus concomitant mitral disease. They determined that by 12 months both groups, although different, had similar outcomes (77% success rate off antiarrhythmic drugs for the lone atrial fibrillation group) and that every patient should have the posterior left atrium isolated because they found that this was the only predictor of failure in either group.53 Edgerton et al46 have used a slightly different approach when performing surgical ablation for atrial fibrillation. One approach they use is the use of bilateral mini-thoracotomies in which they use video assistance to isolate the pulmonary veins with bipolar radiofrequency, as well as eliminate the ganglionic plexus and exclude the left atrial appendage. Their reported results at 6 months were that patients with paroxysmal atrial fibrillation fared better than patients with persistent or long-standing persistent atrial fibrillation (86.7% vs 56.3% vs 50%, respectively). They concluded that this approach might be appropriate for patients presenting with paroxysmal atrial fibrillation, but a more extensive lesion set is necessary for the patients with persistent or long-standing persistent atrial fibrillation. Another procedure that is used somewhat commonly is the Wolf procedure. The Wolf procedure, which was developed by Dr. Randall Wolf, uses bilateral video-assisted thoracoscopic surgery to isolate the pulmonary veins and antrums as well as a partial cardiac denervation and exclusion of the left atrial appendage.41 One of the other big advantages of the surgical ablation is the ability to gain control of the left atrial appendage by either excising or excluding it.54,55 The control of the atrial appendage is an essential addition to the improved outcome after surgical ablation, with a very low rate of thromboembolic events.29,56 Our work has also shown that the CHADS2 (congestive heart failure, hypertension, age, diabetes,
stroke) score is not an adequate indicator for managing anticoagulation after the ablation procedure. We found that the CHADS2 score had no predictive power in determining who was at risk for a stroke but did have significant power in predicting who would experience a major bleeding event. We found that the higher the CHADS score, the more likely the patient was to have a major bleed. Our results also demonstrated that our embolic stroke rate was very low and did not increase as the number of patients on Coumadin decreased. Therefore, we concluded that further study is needed to define anticoagulation strategies for patients after surgical ablation.19 Since the initiation of our institutional program in 2005, 175 patients were referred for surgery for stand-alone atrial fibrillation, of which 100 were performed minimally invasively through a small right thoracic cavity incision (approximately 4-6 cm). Most of our patients (76%) have long-standing persistent atrial fibrillation, with a mean length of time of 50.3 months and a mean left atrial size of 4.8 cm; none of our stand-alone patients had paroxysmal atrial fibrillation before surgery. Almost 50% of the patients had at least 1 prior percutaneous ablation, and the average additive EuroSCORE was 4.0. The return to sinus rhythm at 6, 12, and 24 months after surgery was 94%, 92%, and 91%, respectively, as verified by electrocardiogram and 24-hour Holter monitor. The return to sinus rhythm at 6 and 24 months as confirmed by long-term monitoring (5-7 days) was 92% and 100%, respectively. The return to sinus rhythm off antiarrhythmic medications at 6, 12, and 24 months was 85%, 85%, and 79%, respectively; however, up to 50% of the patients on antiarrhythmic medications had no indication for the medication (range, 25%-57%). The incidence of inappropriate antiarrhythmic drug treatment is trending down as our follow-up program is being disseminated and the clinical approach is being communicated with the referring physicians. All patients were discharged on Coumadin; by 12 months 60% were off anticoagulation, and by 24 months 90% were off anticoagulation with only one embolic stroke, which occurred at 12 months after procedure while in sinus rhythm and on aspirin. Patient health-related quality of life had also significantly improved by 6 months as measured by the Short-form health survey 12.57 Patients’ report of their symptom severity and frequency had significantly decreased at 6 months as reported by using the Atrial Fibrillation Symptom Severity and Frequency Checklist.58 The 3-year survival rate is 96% (confidence interval, 94%98%).
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION DISCUSSION The nonpharmacological treatment of atrial fibrillation is still evolving. Although the most common approach to treat patients is percutaneous catheter ablation, more patients are being referred for a standalone surgical ablation, with very low morbidity and high success rate. In a recent report released by the American Heart Association, Shah et al13 found that success of percutaneous catheter ablation for atrial fibrillation has been hampered by many complications after the procedure. The rate of complications was found to be particularly high in female and older patients and especially in those patients with multiple hospitalizations for atrial fibrillation in the year before ablation year. Vascular events, including hemorrhage and stroke, were the most common postprocedure complications. The researchers also reported readmission rates for atrial fibrillation at 1 year and 2 years of 22% and 30%, respectively, concluding that ablation has limited success in the long-term.13 These findings were supported by Weerasooriya et al14, who investigated catheter ablation results 5 years after procedure. They reported arrhythmia-free survival rates after a single catheter ablation procedure of 40%, 37%, and 29% at 1, 2, and 5 years, respectively. Most recurrences occurred within the first 6 months, and the median number of ablations performed per individual was 2. In addition, valvular heart disease and nonischemic dilated cardiomyopathy in patients were independent predictors of recurrence. As more studies are completed, there is beginning evidence to suggest that restoration and maintenance of sinus rhythm do convey a reverse in atrial remodeling that leads to better outcomes for patients.59 Through several trials catheter ablation has been shown to be more beneficial over antiarrhythmic drugs in restoring sinus rhythm with minimal side effects. The Cox-Maze procedure developed more than 20 years ago continues to demonstrate a very high return to sinus rhythm rate even in complex patients with multiple predictors for failure.31,32,51-53 It is clear that catheter ablation is not as effective in patients with atrial fibrillation other than paroxysmal or in patients with a larger left atrium and that most of the patients having catheter ablation will require more than one procedure. This entails increased cost and complications. The FAST study that compared the 2 approaches showed significantly better results for the surgical ablation.48 Therefore, surgical ablation should be offered to symptomatic patients either if they failed percutaneous catheter ablation or in some cases as the first line of therapy if the patients have long-term persistent atrial fibrillation and large (⬎5 cm) left atrium. The choice of surgical ablation should follow the same 48
rationale as limited ablation and off-bypass approach showed to be less effective in patients with more complex atrial fibrillation.36,37,46,60,61 A new and exciting approach that is currently being developed is the hybrid approach, in which percutaneous catheter ablation is combined with minimally invasive surgical ablation. These techniques are still in the early evolution and in constant adjustments. It can be done as a single stage or in 2 or more separate sessions. In our institution we have a dedicated hybrid operating room that is fully equipped with mapping equipment and electrophysiologist laboratory capabilities. In our approach we enroll patients for hybrid procedures through a local prospective randomized study to compare the 3 different modalities, catheter, hybrid, and a full Cox-Maze procedure, in different patients. As technology continues to advance and better mapping identifying abnormal atrial substrate is available, it has become imperative for electrophysiologists and cardiac surgeons to combine their skills to better individualize catheter-based treatment interventions for the restoration of sinus rhythm by using a hybrid approach. In the hybrid approach, the surgeon will begin the procedure and by using a total thoracoscopic approach will place lesions on the left and right atria on a beating heart. The electrophysiologist will then map the epicardial ablation lines and complete them by sealing the gaps and add some more lesions usually to the left and the right isthmuses. The big advantage of the hybrid approach over percutaneous catheter approaches is that through a small port placed on the left thoracic wall, the left atrial appendage is approached and excluded by a clip or other means. These patients should be followed as previously published by using a sophisticated follow-up system driven by a protocol that is necessary to attain and maintain the success of the hybrid procedure to include long-term monitoring or implantable devices. CONCLUSION Surgery for atrial fibrillation has changed over the years with the advent of newer technology. Others have tried variations of the original lesion set of the CoxMaze procedure but have not met with the same success. Patients with symptomatic lone atrial fibrillation should be approached with more invasive techniques to include surgical ablation off and on bypass. Surgery for lone atrial fibrillation when performed by using the full lesion set sinus rhythm has excellent outcome and can be performed by using minimally invasive approach in some centers. The hybrid procedure is still
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION untested but appears to combine the best of catheter and surgical ablation, which might improve the rate of return to sinus rhythm. The main challenge approaches
1. Miyasaka Y, Barnes ME, Gersh BJ, et al: Secular trends in incidence of atrial fibrillation in Olmsted county, Minnesota, 1980 to 2000, and implications on the projections for future prevalence. Circulation 114:119-125, 2006 2. Go AS, Hylek EM, Phillips KA, et al: Prevalence of diagnosed atrial fibrillation in adults: National implications for rhythm management and stroke prevention—The Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study. JAMA 285:2370-2375, 2001 3. Chugh SS, Blackshear JL, Shen WK, et al: Epidemiology and natural history of atrial fibrillation: Clinical implications. J Am Coll Cardiol 37:371-378, 2001 4. Ad N, Henry L, Hunt S, et al: The implementation of a comprehensive clinical protocol improves long-term success after surgical treatment of atrial fibrillation. J Thorac Cardiovasc Surg 139:1146-1152, 2010 5. Olshansky B, Rosenfeld L, Warner AL, et al: The Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study approaches to control rate in atrial fibrillation. J Am Coll Cardiol 43:1201-1208, 2004 6. Wyse DG, Anter E, Callans DJ: Cardioversion of atrial fibrillation for maintenance of sinus rhythm: A road to nowhere. Circulation 120: 1444-1452, 2009 7. Anter E, Callans DJ, Wyse DG: Pharmacological and electrical conversion of atrial fibrillation to sinus rhythm is worth the effort. Circulation 120:1436-1443, 2009 8. Cleland JG, Coletta AP, Buga L, et al: Clinical trials update from the American College of Cardiology meeting 2010: DOSE, ASPIRE, CONNECT, STICH, STOP-AF, CABANA, RACE II, EVEREST II, ACCORD, and NAVIGATOR. Eur J Heart Fail 12:623-629, 2010 9. Kim MH: Do the benefits of anti-arrhythmic drugs outweigh the associated risks? A tale of treatment goals in atrial fibrillation. Expert Rev Clin Pharmacol 5:163-171, 2012 10. Crandall MA, Horne BD, Day JD, et al: Atrial fibrillation significantly increases total mortality and stroke risk beyond that conveyed by the CHADS2 risk factors. Pacing Clin Electrophysiol 32:981-986, 2009 11. Trappe HJ: Atrial fibrillation: Established and innovative methods of evaluation and treatment. Dtsch Arztebl Int 109:1-7, 2012 12. Skanes AC, Healey JS, Cairns JA, et al: Focused 2012 update of the Canadian Cardiovascular Society atrial fibrillation guidelines: Recommendations for stroke prevention and rate/ rhythm control. Can J Cardiol 28:125-136, 2012 13. Shah RU, Freeman JV, Shilane D, et al: Procedural complications, rehospitalizations, and re-
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peat procedures after catheter ablation for atrial fibrillation. J Am Coll Cardiol 59:143-149, 2012 Weerasooriya R, Khairy P, Litalien J, et al: Catheter ablation for atrial fibrillation: Are results maintained at 5 years of follow-up? J Am Coll Cardiol 57:160-166, 2011 Deneke T, Shin D, Balta O, et al: Postablation asymptomatic cerebral lesions: Long-term follow-up using magnetic resonance imaging. Heart Rhythm 8:1705-1711, 2011 Bohnen M, Stevenson WG, Tedrow UB, et al: Incidence and predictors of major complications from contemporary catheter ablation to treat cardiac arrhythmias. Heart Rhythm 8:1661-1666, 2011 Ad N, Henry L: Historical summary and current state of the maze surgical procedure, 2010. Available at: http://www.cvtsa.com/ MediaServer/MediaItems/MediaItem_321.pdf. Accessed April 4, 2012 Prasad SM, Maniar HS, Camillo CJ, et al: The Cox Maze III procedure for atrial fibrillation: Long term efficacy in patients undergoing lone versus concomitant procedures. J Thorac Cardiovasc Surg 126:1822-1828, 2003 Ad N, Henry L, Schlauch K, et al: The CHADS score role in managing anticoagulation after surgical ablation for atrial fibrillation. Ann Thorac Surg 90:1257-1262, 2010 Ad N: The Maze procedure: Past, present, and future, in Sie HT, D’Ancona G, Bartolozzi F, et al (eds): Manual of Surgical Treatment of Atrial Fibrillation. Oxford, UK, Blackwell Publishing Ltd, 2008 Cox JL, Schuessler RB, D’Agostino HJ Jr, et al: The surgical treatment of atrial fibrillation III: Development of a definite surgical procedure. J Thorac Cardiovasc Surg 101:569-583, 1991 Cox JL: The surgical treatment of atrial fibrillation IV: Surgical technique. J Thorac Cardiovasc Surg 101:584-592, 1991 Cox JL, Boineau JP, Schuessler RB, et al: Modifications of the Maze procedure for atrial flutter and atrial fibrillation: I—Rationale and surgical results. J Thorac Cardiovasc Surg 110: 473-483, 1995 Cox JL, Jaquiss RD, Schuessler RB, et al: Modifications of the Maze procedure for atrial flutter and atrial fibrillation: II—Surgical technique of the Maze III procedure. J Thorac Cardiovasc Surg 110:485-495, 1995 Cox JL: The standard Maze-III procedure. Oper Tech Thorac Cardiovasc Surg 5:2-22, 2000 Cox JL: Cardiac surgery for arrhythmias. J Cardiovasc Electrophysiol 15:250-262, 2004 Damiano RJ Jr, Gaynor SL, Bailey M, et al: The long-term outcome of patients with coronary disease and atrial fibrillation undergoing the
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Cox Maze procedure. J Thorac Cardiovasc Surg 126:2016-2021, 2003 Ad N, Cox JL, Palazzo T, et al: Stroke prevention as an indication for the Maze procedure in the treatment of atrial fibrillation. Semin Thorac Cardiovasc Surg 12:56-62, 2000 Cox JL, Ad N, Palazzo T: Impact of the Maze procedure on the stroke rate in patients with atrial fibrillation. J Thorac Cardiovasc Surg 118:833-840, 1999 Schaff HV, Dearani JA, Daly RC, et al: CoxMaze procedure for atrial fibrillation: Mayo Clinic experience. Semin Thorac Cardiovasc Surg 12:30-37, 2000 Arcidi JM Jr, Doty DB, Millar RC: The Maze procedure: The LDS Hospital experience. Semin Thorac Cardiovasc Surg 12:38-43, 2000 Gaynor SL, Schuessler RB, Bailey MS, et al: Surgical treatment of atrial fibrillation: Predictors of late recurrence. J Thorac Cardiovasc Surg 129:104-111, 2005 Ad N, Cox JL: The Maze procedure for the treatment of atrial fibrillation: A minimally invasive approach. J Cardiothorac Surg 19:196200, 2004 Moten SC, Rodriguez E, Cook RC, et al: New ablation techniques for atrial fibrillation and the minimally invasive cryo-maze procedure in patients with lone atrial fibrillation. Heart Lung Circ 16:S88-S93, 2007 (suppl 3) Ad N, Henry L, Hunt S: The impact of surgical ablation in patients with low ejection fraction, heart failure, and atrial fibrillation. Eur J Cardiothorac Surg 40:70-76, 2011 Ad N, Henry L, Hunt S, et al: The results of the Cox Maze III/IV procedure in patients over 75 years old who present for cardiac surgery with a history of atrial fibrillation. J Cardiovasc Surg (in press) Ad N, Henry L, Hunt S, et al: Do we increase the operative risk by adding the Cox Maze III procedure to aortic valve replacement and coronary artery bypass surgery? J Thorac Cardiovasc Surg 143:936-944, 2012 A report of the Heart Rhythm Society (HRS) Task Force on Catheter Ablation of Atrial Fibrillation developed in partnership with European Heart Rhythm Association (EHRA) and the European Cardiac Arrhythmia (ECAS); in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). HRS/EHRA/ECAS Expert consensus statement on catheter and surgical ablation of atrial fibrillation: Recommendations for personnel, policy, procedures and follow-up. Heart Rhythm 4:1-46, 2007 Calkins H, Kuck KH, Cappato R, et al: HRS/EHRA/ ECAS expert consensus statement on catheter and
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surgical ablation of atrial fibrillation: Recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design—A report of the heart Rhythm Society (HRS) Task Force on Catheter and Surgical ablation of atrial fibrillation, Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS): Endorsed by the Governing Bodies of the American College of Cardiology Foundation, American Heart Association, the European Cardiac Arrhythmia Society, European Heart Rhythm Association, the Society of Thoracic Surgeons, Asia Pacific Heart Rhythm Society and the Heart Rhythm Society. Europace 14:528-606, 2012 Weimar T, Bailey MS, Watanabe Y, et al: The Cox maze IV procedure for lone atrial fibrillation: A single center experience in 100 consecutive patients. J Interv Card Electrophysiol 31: 47-54, 2011 Wolf RK, Schneeberger EW, Osterday R, et al: Video-assisted bilateral pulmonary vein isolation and left atrial appendage exclusion for atrial fibrillation. J Thorac Cardiovasc Surg 130:797-802, 2005 Kiser AC, Wimmer-Greinecker G, Chitwood WR: Totally extracardiac Maze procedure performed on the beating heart. Ann Thorac Surg 84:1783-1785, 2007 Edgerton JR, Jackman WM, Mahoney C, et al: Totally thorascopic surgical ablation of persis-
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tent AF and long-standing persistent atrial fibrillation using the “Dallas” lesion set. Heart Rhythm 6:S64-S70, 2009 (suppl) Ninet J, Roques X, Seitelberger R, et al: Surgical ablation of atrial fibrillation with off-pump, epicardial, high-intensity focused ultrasound: Results of a multicenter trial. J Thorac Cardiovasc Surg 130:803-809, 2005 Edgerton JR: Surgical therapy for atrial fibrillation. J Cardiovasc Med 13:125-130, 2012 Edgerton JR, McClelland JH, Duke D, et al: Minimally invasive surgical ablation of atrial fibrillation: Six-month results. J Thorac Cardiovasc Surg 138:109-114, 2009 Edgerton JR, Brinkman WT, Weaver T, et al: Pulmonary vein isolation and autoimmune denervation for the management of paroxysmal atrial fibrillation by a minimally invasive surgical approach. J Thorac Cardiovasc Surg 140:823-828, 2009 Yilmaz A, Nadal M, Sandoval E, et al: Atrial Fibrillation Catheter Ablation versus Surgical Ablation Treatment (FAST): A 2-center randomized clinical trial. Circulation 125:23-30, 2012 Barnett S, Ad N: Surgical ablation as treatment for the elimination of atrial fibrillation: A meta-analysis. J Thorac Cardiovasc Surg 131: 1029-1035, 2006 Cheng DC, Ad N, Martin J, et al. Surgical ablation for atrial fibrillation in cardiac surgery. Innovations 5:84-96, 2010 Weimar T, Schena S, Bailey MS, et al: The cox-maze procedure for lone atrial fibrillation: A single-center experience over 2 decades. Circ Arrhythm Electrophysiol 5:8-14, 2012 Weimar T, Bailey MS, Watanabe Y, et al: The Cox-maze IV procedure for lone atrial fibrilla-
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tion: A single center experience in 100 consecutive patients. J Interv Card Electrophysiol 31:47-54, 2011 Saint LL, Bailey MS, Prasad S, et al: Cox-Maze IV results for patients with lone atrial fibrillation versus concomitant mitral disease. Ann Thorac Surg 93:789-795, 2012 Gillinov AM, McCarthy PM: Atricure bipolar radiofrequency clamp for intraoperative ablation of atrial fibrillation. Ann Thorac Surg 74: 2165-2168, 2002 Salzberg SP, Gillinov AM, Anyanwu A, et al: Surgical left atrial appendage occlusion: Evaluation of a novel device with magnetic resonance imaging. Eur J Cardiothorac Surg 34: 766-770, 2008 Bando K, Kasegawa H, Okada Y, et al: Impact of preoperative and postoperative atrial fibrillation on outcome after mitral valvuloplasty for nonischemic mitral regurgitation. J Thorac Cardiovasc Surg 129:1032-1040, 2005 Ware J, Kosinski M, Turner-Bowker D, et al: How to score version 2 of the SF-12 health survey. Lincoln, RI, Quality Metric Inc, 2002 Jenkins LS: Test-specifications for the Bubien and Kay (Revised Jenkins) symptom checklist: Frequency and severity. Baltimore, MD, University of Maryland Press, 1993 Anter E, Callans DJ: Can ablation prevent the excess mortality of atrial fibrillation? Curr Cardiol Rep 12:389-392, 2010 Ad N, Henry L, Holmes S, et al: The impact of surgical ablation for atrial fibrillation in high risk patients. Ann Thorac Surg (in press) Ad N, Henry L, Hunt S, et al: The outcome of the Cox Maze procedure in patients with previous percutaneous catheter ablation to treat atrial fibrillation. Ann Thorac Surg 91:1371-1377, 2011
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Current Role for Surgery in Treatment of Lone Atrial Fibrillation Niv Ad, MD,* Linda Henry, PhD,† and Sharon Hunt, MBA† The Cox-Maze procedure has been performed successfully since 1987. The original surgery was performed by using the “cut and sew” technique and is considered quite complex and technically demanding; therefore, it never gained popularity among cardiac surgeons and referring cardiologists. As surgical ablation technology improved, the Cox-Maze procedure can now be performed by using new ablation devices that deliver different energy sources (radiofrequency, cryothermia, and others). The use of ablation technology simplified the technical aspects of the procedure and has led to decreased time on cardiopulmonary bypass, easier placement of ablation lines, and the development of various minimally invasive approaches to include off-pump techniques. The Heart Rhythm Society recommends surgical ablation for symptomatic patients, patients who are unable to take anticoagulation therapy, who have failed other therapies to include percutaneous catheter ablation, or by personal request. Therefore, with guidelines in place as to patient selection and newer, easier-to-use technology, more surgeons are tackling surgical ablation of atrial fibrillation, offering another treatment option for patients with lone atrial fibrillation. This article will review the current state of surgery for the ablation of lone atrial fibrillation. Semin Thoracic Surg 24:42-50 © 2012 Elsevier Inc. All rights reserved. Keywords: ablation, atrial fibrillation, catheter, hybrid, surgery Atrial fibrillation is the most common of all clinically sustained heart arrhythmias. According to recently published data, more than 2.3 million people in the United States are affected with this arrhythmia, and this number is expected to increase to 5.6 million people by 2050.1-3 The occurrence of atrial fibrillation is associated with age, race, and gender. The prevalence rate for people younger than 55 is 0.1%, but for those older than 80 the prevalence rate is 9%. Whites older than 50 are affected at a higher rate than blacks, and men have double the prevalence rate than women.1-3
Medical Treatment Medical treatment is the first line of treatment in most patients with atrial fibrillation. Patients might need to be treated with 1 or more types of medication. There are 2 main strategies for medical treatment rhythm and rate control.4-6 Most rhythm control regimens demonstrate fairly limited efficacy and might result in significant side effects.7-9 An appropriate anticoagulation treatment for patients with the appropriate indications is usually used to reduce the risk of embolic strokes.10,11
TREATMENT OPTIONS There are 3 clinical strategies for primary treatment of atrial fibrillation: medical treatment, percutaneous catheter ablation to either achieve rhythm or rate control, and surgical ablation with or without the use of cardiopulmonary bypass (Fig. 1).
Percutaneous Catheter Ablation Catheter-based techniques are being widely used in patients with atrial fibrillation. There are 2 different strategies. (1) With rate control, patients are being treated with an atrioventricular node ablation and pacemaker insertion to achieve rate control.12 (2) Catheter-based procedures are being performed routinely to achieve rhythm control and are the most commonly used nonpharmacological approach to treat atrial fibrillation.13 The procedures are done by using somewhat sophisticated mapping systems and different energy and catheters (radiofrequency, cryoballoons).13 Despite growing experience, the success rate of such procedures especially with a single application remains fairly limited, and
*Department of Cardiac Surgery, Inova Heart and Vascular Institute, Falls Church, Virginia. †Department of Cardiac Surgery Research, Inova Heart and Vascular Institute, Falls Church, Virginia. Address reprint requests to Niv Ad, MD, Department of Cardiac Surgery, Inova Heart and Vascular Institute, 3300 Gallows Road, Suite 3100, Falls Church, VA 22042. E-mail: [email protected]
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1043-0679/$-see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.semtcvs.2012.04.007
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Figure 1. Algorithm of current state of treatment. AV, atrioventricular.
the risks associated with these procedures are stroke, pericardial tamponade, and vascular accidents.14-16 Surgical Ablation Surgical ablation for atrial fibrillation in general and Cox-Maze procedure in particular are highly effective in restoring sinus rhythm. Success rates vary by center but generally are reported in the range of 70%-100%. Most patients (about 80%) after the Cox-Maze procedure will be maintained in sinus rhythm without the need for any antiarrhythmic or anticoagulation medications. Most of the remaining patients will be able to manage their rhythm with a single antiarrhythmic medication, even if that medication did not control their rhythm preoperatively.17,18 Guidelines might consider sinus rhythm on antiarrhythmic drugs as a failure; however, we disagree with this approach because this group of patients will sustain a significantly lower risk of thromboembolic events, anticoagulation can be stopped with lower risk for bleeding, and they have much improved quality of life.19 Surgical Ablation for Atrial Fibrillation Over 25 Years The concept of the Cox-Maze procedure evolved around 4 principles: (1) ablate macro re-entrant circuits to reestablish sinus rhythm; (2) restore atrioventricular synchrony; (3) improve atrial transport function; and (4) eliminate the risk for thromboembolic events.20,21
The original Cox-Maze procedure involved cutting and sewing with multiple biatrial incisions to interrupt all macro re-entrant circuit options in the atria. The purpose was to allow the sinoatrial (SA) node to resume normal activity after surgery and direct the propagation of the sinus impulse through the atria.21,22 However, the Cox-Maze I procedure introduced 2 challenges. The first was significant chronotropic dysfunction in which the patient was unable to generate an increased heart rate in response to exercise because of a significant interruption to the blood supply to the sinus node complex as the lesions of the Cox-Maze 1 procedure almost isolated the sinus node complex. The second issue related to the Maze I was a significant conduction delay between the right and left atrium as one of the lesions was placed across the Bachmann bundle, which resulted in a long conduction delay (about 180 milliseconds) and for the right atrium to be activated first, followed by the other 3 heart chambers, which created an asynchronous beating of the heart.21 These significant issues led to modifications of the Maze I procedure. The initial modification was to move the surgical incision further away from the SA node by going to the back of the superior vena cava (Maze II procedure).22,23 However, this was technically challenging, so further modification was necessary. Additional changes moved the incision away from the SA node and toward the interatrial septum. These changes maintained the three-dimensional
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION concept of the Cox-Maze procedure and were less technically demanding to perform. In addition, the original problems of chronotropic dysfunction and conduction delay were no longer issues. Today this surgery is known as the Cox-Maze III procedure, and in its modern form, most of the surgical incisions were replaced by surgical ablation by using specially designed devices.24-26 The Cox-Maze III procedure has met with great success as reported by Washington University18,27 and has shown a significant reduction in cerebrovascular accidents and transient ischemic events because of the high success rate of ablating atrial fibrillation and amputating the left atrial appendage. In addition, fewer pacemakers were implanted, and improved atrial transport and sinus node function were seen.28,29 Different publications demonstrate that the cut and sew procedure as well as the use of other ablation devices when performed by an experienced surgeon result in very low morbidity and excellent long-term freedom from atrial fibrillation and thromboembolic events.30-32 In the past decade, several surgical ablation approaches to treat atrial fibrillation as a stand-alone or concomitantly with other cardiac surgical procedures were developed. The use of the heart-lung machine is required to perform the Cox-Maze procedure in its current form and with the available ablation devices. It can be performed as a full sternotomy or minimally invasive procedure.33 If other procedures such as valve repair/replacement or coronary bypass are to be performed concurrently with the Cox-Maze procedure, then the standard openchest approach is likely to be used; however, when an atrial septal defect closure, mitral valve repair or replacement, and tricuspid valve surgery are required, a minimally invasive right mini-thoracotomy can be applied.33,34 The overall operative risk is low in morbidity and mortality and might be impacted by the individual’s specific health conditions. In a recent publication, we reported the results of a study in which we investigated surgical ablation in patients with a low ejection fraction (⬍40%), heart failure, and atrial fibrillation. In this small series of patients we found that the results were excellent, with only 1 operative death and no strokes or transient ischemic attacks. Patients’ ejection fraction on average improved from 30% to 45%, the return to sinus rhythm rate at the time of their postprocedure echo was 86%, and their health-related quality of life physical functioning scores surpassed their age group norms. We concluded that patients such as these should not be excluded, and surgical ablation should be considered.35 In other work we have published, we have shown that when adding the Cox-Maze procedure to 44
patients who are older than 75, are undergoing a coronary artery bypass grafting or aortic valve surgery, or are considered high risk, the ablation procedure did not add operative risk, and patients had excellent outcome when compared with a similar group. Again, we concluded that these procedures and age should not be the only considerations when deciding whether to perform a surgical ablation procedure.36,37 Although the procedure is directed toward curing atrial fibrillation, there is some risk that the procedure might fail and that atrial arrhythmia will persist. Therefore, the definition of failure of the procedure per the Heart Rhythm Society is any monitored atrial arrhythmia (atrial fibrillation, atrial flutter, or atrial tachycardia) lasting ⬎30 seconds after the first 3 months after the procedure.38,39 In the early postoperative period, up to one-third of patients might have temporary atrial arrhythmia. Early arrhythmias should be addressed routinely by using clinical protocol and combine antiarrhythmic drugs and cardioversion; if it is addressed appropriately, most patients experiencing early atrial arrhythmia will regain sinus rhythm. Applying rate control strategies early after surgery (up to 6 months) should be considered inappropriate (Fig. 2).4 The further development of devices, mapping, and surgical ablation techniques has led to still another modification of the Maze procedure as well as allowing a minimally invasive surgical approach (minithoracotomy) in which the full Maze or less extensive lesions can be applied. The new modified procedure, Maze IV, replaces most of the prior incisions with linear ablation lines by using newer and easier technologies that include mainly radiofrequency energy and cryothermal energy. The Maze IV procedure follows the same concepts of the Maze III. The only difference between the 2 procedures is that in the Maze IV procedures, the box lesion around the pulmonary veins is accomplished after isolating the right and left pulmonary veins with a clamp (bipolar radiofrequency or cryoclamp) and only then connecting the upper and lower pulmonary veins. The addition of the term Maze IV added some confusion to the field, and surgeons should be aware that the results expected from the 2 procedures are the same because the electrophysiological concept is identical (Fig. 3).40 In the last few years there has been a growing interest in surgical ablation by using off-bypass techniques. This is done by using mainly radiofrequency and high-intensity focused ultrasound devices; however, there were reports about using microwave, laser, as well as cryothermal energy to try to achieve cure. Most off-bypass approaches in the initial expe-
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Figure 2. Protocol slide. AAD, antiarrythmic drug; DC, electric defibrillator using DC discharge. (Reprinted with permission from Ad et al.4) (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
rience were designed to isolate the pulmonary veins and later in the experience to ablate the left atrium and add some lesions to the right atrium.41-44 Furthermore, surgical pulmonary vein isolation can be performed without using cardiopulmonary bypass
for a subset of patients who meet specific criteria, mainly for those patients with short-term paroxysmal atrial fibrillation and a small left atrium.45-47 In a recent study, Atrial Fibrillation Catheter Ablation versus Surgical Ablation Treatment (FAST),
Figure 3. The Cox-Maze procedure: right and left atrial lesions. IVC, inferior vena cava; LLPV, left lower pulmonary vein; LUPV, left upper pulmonary vein; RLPV, right lower pulmonary vein; RULV, right upper pulmonary vein, SVC, superior vena cava. Seminars in Thoracic and Cardiovascular Surgery ● Volume 24, Number 1
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Figure 4. Pathway to surgery. AHA, American Heart Association; HRS, Heart Rhythm Society. (Color version of figure is available online at http://www.semthorcardiovascsurg.com.)
patients who failed conventional therapy were randomized to receive either a percutaneous pulmonary vein isolation (PVI) catheter ablation with optional additional lines or a surgical ablation procedure of PVI with bipolar radiofrequency, ganglionic plexus ablation, and left atrial appendage excision. There were 124 patients enrolled in the study. There was a significant difference in freedom from atrial arrhythmias off medication at 12 months, with surgical ablation being superior to catheter ablation (P ⫽ 0.0022). However, surgical ablation was found to have significantly more adverse events than catheter ablation (P ⫽ 0.027), most of which were very minor with no real impact on patient outcome. In the catheter ablation group 1 death was documented at 1 month.48 These results have helped to further the discussion with the electrophysiologists by using off-bypass techniques and a hybrid approach as a new way of ablating atrial fibrillation. These recent advances might allow more patients to be referred for surgical ablation in which atrial fibrillation is their only cardiac problem (lone atrial fibrillation; Fig. 4). Barnett and Ad49 performed a meta-analysis in 2006 on surgical ablation procedures and its role in the elimination of atrial fibrillation. Sixty-nine studies were included in their study. They determined that biatrial ablation surgical procedure was more effective in restoring sinus rhythm than procedures combined to the left atrium only. As part of the International Society for Minimally Invasive Car46
diothoracic Surgery consensus statement, Cheng et al50 followed up this meta-analysis with a metaanalysis study of their own in 2010. They compared surgical ablation patients with non-ablation patients with atrial fibrillation by using randomized and nonrandomized control studies. In the 33 studies that met their inclusion criteria, they concluded that patients with persistent or permanent atrial fibrillation at the time of surgery who underwent surgical ablation had a higher rate of return to sinus rhythm that persisted over time than those who did not undergo surgical ablation, with a trend for a reduction in embolic strokes and death in the ablation group. They concluded that atrial fibrillation surgery is beneficial, but patients should be counseled to the possibility of a pacemaker after surgery. They were unable to perform any subanalysis to determine what lesion set would be the best and in fact found that there was no consistency on the type of lesion set used. As noted in the International Society for Minimally Invasive Cardiothoracic Surgery consensus statement and meta-analysis,50 there are still a plethora of lesion sets performed that are being called a maze procedure. This has led to confusion and difficulty in comparing outcomes. Damiano and his group have studied the results of the surgical ablation extensively. In a recent study just published they reviewed the results of the Cox-Maze IV procedure (using the original lesion lines as described by
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION Dr. James Cox) for lone atrial fibrillation in 100 consecutive patients. They found that the simplified procedure of replacing the incision lesions with bipolar and crytothermia ablation linear lines was doable and allowed a shorter time on the bypass machine, with 84% of the patients in sinus rhythm and off antiarrhythmic drugs at 24 months.51 In another study in which they reviewed their results of the Cox-Maze procedure for lone atrial fibrillation during the last 2 decades, they concluded that the simplified Cox-Maze procedure maintained excellent results even with improved follow-up and stricter definitions of what constituted a successful procedure.52 In one of their most recent publications Damiano et al compared the Cox-Maze IV results for patients with lone atrial fibrillation versus concomitant mitral disease. They determined that by 12 months both groups, although different, had similar outcomes (77% success rate off antiarrhythmic drugs for the lone atrial fibrillation group) and that every patient should have the posterior left atrium isolated because they found that this was the only predictor of failure in either group.53 Edgerton et al46 have used a slightly different approach when performing surgical ablation for atrial fibrillation. One approach they use is the use of bilateral mini-thoracotomies in which they use video assistance to isolate the pulmonary veins with bipolar radiofrequency, as well as eliminate the ganglionic plexus and exclude the left atrial appendage. Their reported results at 6 months were that patients with paroxysmal atrial fibrillation fared better than patients with persistent or long-standing persistent atrial fibrillation (86.7% vs 56.3% vs 50%, respectively). They concluded that this approach might be appropriate for patients presenting with paroxysmal atrial fibrillation, but a more extensive lesion set is necessary for the patients with persistent or long-standing persistent atrial fibrillation. Another procedure that is used somewhat commonly is the Wolf procedure. The Wolf procedure, which was developed by Dr. Randall Wolf, uses bilateral video-assisted thoracoscopic surgery to isolate the pulmonary veins and antrums as well as a partial cardiac denervation and exclusion of the left atrial appendage.41 One of the other big advantages of the surgical ablation is the ability to gain control of the left atrial appendage by either excising or excluding it.54,55 The control of the atrial appendage is an essential addition to the improved outcome after surgical ablation, with a very low rate of thromboembolic events.29,56 Our work has also shown that the CHADS2 (congestive heart failure, hypertension, age, diabetes,
stroke) score is not an adequate indicator for managing anticoagulation after the ablation procedure. We found that the CHADS2 score had no predictive power in determining who was at risk for a stroke but did have significant power in predicting who would experience a major bleeding event. We found that the higher the CHADS score, the more likely the patient was to have a major bleed. Our results also demonstrated that our embolic stroke rate was very low and did not increase as the number of patients on Coumadin decreased. Therefore, we concluded that further study is needed to define anticoagulation strategies for patients after surgical ablation.19 Since the initiation of our institutional program in 2005, 175 patients were referred for surgery for stand-alone atrial fibrillation, of which 100 were performed minimally invasively through a small right thoracic cavity incision (approximately 4-6 cm). Most of our patients (76%) have long-standing persistent atrial fibrillation, with a mean length of time of 50.3 months and a mean left atrial size of 4.8 cm; none of our stand-alone patients had paroxysmal atrial fibrillation before surgery. Almost 50% of the patients had at least 1 prior percutaneous ablation, and the average additive EuroSCORE was 4.0. The return to sinus rhythm at 6, 12, and 24 months after surgery was 94%, 92%, and 91%, respectively, as verified by electrocardiogram and 24-hour Holter monitor. The return to sinus rhythm at 6 and 24 months as confirmed by long-term monitoring (5-7 days) was 92% and 100%, respectively. The return to sinus rhythm off antiarrhythmic medications at 6, 12, and 24 months was 85%, 85%, and 79%, respectively; however, up to 50% of the patients on antiarrhythmic medications had no indication for the medication (range, 25%-57%). The incidence of inappropriate antiarrhythmic drug treatment is trending down as our follow-up program is being disseminated and the clinical approach is being communicated with the referring physicians. All patients were discharged on Coumadin; by 12 months 60% were off anticoagulation, and by 24 months 90% were off anticoagulation with only one embolic stroke, which occurred at 12 months after procedure while in sinus rhythm and on aspirin. Patient health-related quality of life had also significantly improved by 6 months as measured by the Short-form health survey 12.57 Patients’ report of their symptom severity and frequency had significantly decreased at 6 months as reported by using the Atrial Fibrillation Symptom Severity and Frequency Checklist.58 The 3-year survival rate is 96% (confidence interval, 94%98%).
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SURGERY’S ROLE IN LONE ATRIAL FIBRILLATION DISCUSSION The nonpharmacological treatment of atrial fibrillation is still evolving. Although the most common approach to treat patients is percutaneous catheter ablation, more patients are being referred for a standalone surgical ablation, with very low morbidity and high success rate. In a recent report released by the American Heart Association, Shah et al13 found that success of percutaneous catheter ablation for atrial fibrillation has been hampered by many complications after the procedure. The rate of complications was found to be particularly high in female and older patients and especially in those patients with multiple hospitalizations for atrial fibrillation in the year before ablation year. Vascular events, including hemorrhage and stroke, were the most common postprocedure complications. The researchers also reported readmission rates for atrial fibrillation at 1 year and 2 years of 22% and 30%, respectively, concluding that ablation has limited success in the long-term.13 These findings were supported by Weerasooriya et al14, who investigated catheter ablation results 5 years after procedure. They reported arrhythmia-free survival rates after a single catheter ablation procedure of 40%, 37%, and 29% at 1, 2, and 5 years, respectively. Most recurrences occurred within the first 6 months, and the median number of ablations performed per individual was 2. In addition, valvular heart disease and nonischemic dilated cardiomyopathy in patients were independent predictors of recurrence. As more studies are completed, there is beginning evidence to suggest that restoration and maintenance of sinus rhythm do convey a reverse in atrial remodeling that leads to better outcomes for patients.59 Through several trials catheter ablation has been shown to be more beneficial over antiarrhythmic drugs in restoring sinus rhythm with minimal side effects. The Cox-Maze procedure developed more than 20 years ago continues to demonstrate a very high return to sinus rhythm rate even in complex patients with multiple predictors for failure.31,32,51-53 It is clear that catheter ablation is not as effective in patients with atrial fibrillation other than paroxysmal or in patients with a larger left atrium and that most of the patients having catheter ablation will require more than one procedure. This entails increased cost and complications. The FAST study that compared the 2 approaches showed significantly better results for the surgical ablation.48 Therefore, surgical ablation should be offered to symptomatic patients either if they failed percutaneous catheter ablation or in some cases as the first line of therapy if the patients have long-term persistent atrial fibrillation and large (⬎5 cm) left atrium. The choice of surgical ablation should follow the same 48
rationale as limited ablation and off-bypass approach showed to be less effective in patients with more complex atrial fibrillation.36,37,46,60,61 A new and exciting approach that is currently being developed is the hybrid approach, in which percutaneous catheter ablation is combined with minimally invasive surgical ablation. These techniques are still in the early evolution and in constant adjustments. It can be done as a single stage or in 2 or more separate sessions. In our institution we have a dedicated hybrid operating room that is fully equipped with mapping equipment and electrophysiologist laboratory capabilities. In our approach we enroll patients for hybrid procedures through a local prospective randomized study to compare the 3 different modalities, catheter, hybrid, and a full Cox-Maze procedure, in different patients. As technology continues to advance and better mapping identifying abnormal atrial substrate is available, it has become imperative for electrophysiologists and cardiac surgeons to combine their skills to better individualize catheter-based treatment interventions for the restoration of sinus rhythm by using a hybrid approach. In the hybrid approach, the surgeon will begin the procedure and by using a total thoracoscopic approach will place lesions on the left and right atria on a beating heart. The electrophysiologist will then map the epicardial ablation lines and complete them by sealing the gaps and add some more lesions usually to the left and the right isthmuses. The big advantage of the hybrid approach over percutaneous catheter approaches is that through a small port placed on the left thoracic wall, the left atrial appendage is approached and excluded by a clip or other means. These patients should be followed as previously published by using a sophisticated follow-up system driven by a protocol that is necessary to attain and maintain the success of the hybrid procedure to include long-term monitoring or implantable devices. CONCLUSION Surgery for atrial fibrillation has changed over the years with the advent of newer technology. Others have tried variations of the original lesion set of the CoxMaze procedure but have not met with the same success. Patients with symptomatic lone atrial fibrillation should be approached with more invasive techniques to include surgical ablation off and on bypass. Surgery for lone atrial fibrillation when performed by using the full lesion set sinus rhythm has excellent outcome and can be performed by using minimally invasive approach in some centers. The hybrid procedure is still
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1. Miyasaka Y, Barnes ME, Gersh BJ, et al: Secular trends in incidence of atrial fibrillation in Olmsted county, Minnesota, 1980 to 2000, and implications on the projections for future prevalence. Circulation 114:119-125, 2006 2. Go AS, Hylek EM, Phillips KA, et al: Prevalence of diagnosed atrial fibrillation in adults: National implications for rhythm management and stroke prevention—The Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study. JAMA 285:2370-2375, 2001 3. Chugh SS, Blackshear JL, Shen WK, et al: Epidemiology and natural history of atrial fibrillation: Clinical implications. J Am Coll Cardiol 37:371-378, 2001 4. Ad N, Henry L, Hunt S, et al: The implementation of a comprehensive clinical protocol improves long-term success after surgical treatment of atrial fibrillation. J Thorac Cardiovasc Surg 139:1146-1152, 2010 5. Olshansky B, Rosenfeld L, Warner AL, et al: The Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study approaches to control rate in atrial fibrillation. J Am Coll Cardiol 43:1201-1208, 2004 6. Wyse DG, Anter E, Callans DJ: Cardioversion of atrial fibrillation for maintenance of sinus rhythm: A road to nowhere. Circulation 120: 1444-1452, 2009 7. Anter E, Callans DJ, Wyse DG: Pharmacological and electrical conversion of atrial fibrillation to sinus rhythm is worth the effort. Circulation 120:1436-1443, 2009 8. Cleland JG, Coletta AP, Buga L, et al: Clinical trials update from the American College of Cardiology meeting 2010: DOSE, ASPIRE, CONNECT, STICH, STOP-AF, CABANA, RACE II, EVEREST II, ACCORD, and NAVIGATOR. Eur J Heart Fail 12:623-629, 2010 9. Kim MH: Do the benefits of anti-arrhythmic drugs outweigh the associated risks? A tale of treatment goals in atrial fibrillation. Expert Rev Clin Pharmacol 5:163-171, 2012 10. Crandall MA, Horne BD, Day JD, et al: Atrial fibrillation significantly increases total mortality and stroke risk beyond that conveyed by the CHADS2 risk factors. Pacing Clin Electrophysiol 32:981-986, 2009 11. Trappe HJ: Atrial fibrillation: Established and innovative methods of evaluation and treatment. Dtsch Arztebl Int 109:1-7, 2012 12. Skanes AC, Healey JS, Cairns JA, et al: Focused 2012 update of the Canadian Cardiovascular Society atrial fibrillation guidelines: Recommendations for stroke prevention and rate/ rhythm control. Can J Cardiol 28:125-136, 2012 13. Shah RU, Freeman JV, Shilane D, et al: Procedural complications, rehospitalizations, and re-
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involving beating heart techniques is the ablation technology that does not yet reliably deliver continuous and transmural lesions that are so essential to achieve cure.
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