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Minimally invasive surgical atrial fibrillation ablation: Patient selection and results
Minimally invasive surgical atrial fibrillation ablation: Patient selection and results Frederick T. Han, MD, Vigneshwar Kasirajan, MD, Mark A. Wood, MD, FHRS, Kenneth A. Ellenbogen, MD, FHRS From the Division of Cardiology and Division of Cardiothoracic Surgery, Virginia Commonwealth University, Richmond, Virginia. Minimally invasive surgical atrial fibrillation ablation (MISAA) is an emerging alternative to catheter ablation and the full surgical maze procedure for nonpharmacologic treatment of atrial fibrillation. MISAA offers the potential to provide highly effective pulmonary vein isolation, exclusion of the left atrial appendage, and extensive ablation of the ganglionic plexuses and the ligament of Marshall in a single procedure. We review the safety and efficacy of MISAA, discuss considerations for optimal patient selection for MISAA, and review the advantages/disadvantages of MISAA compared with catheter ablation and the maze procedure.
KEYWORDS Atrial fibrillation; Surgical ablation; Catheter ablation
Introduction
For patients with pacemakers, we reviewed their pacemakers for evidence of atrial tachyarrhythmias at each 6-month device interrogation.
Catheter-based and surgical ablative approaches have been developed for patients with medically refractory symptomatic atrial fibrillation (AF). The Cox maze III procedure uses a series of atrial incisions to prevent the maintenance of AF, but it is associated with significant morbidity and requires a median sternotomy with cardiopulmonary bypass.1 This has prevented widespread use of this procedure. Nevertheless, the maze III procedure is considered the gold standard for surgical treatment of AF by restoring sinus rhythm in up to 97% of patients.1 Surgeons have been interested in replicating these results using a less invasive and less morbid procedure.
Minimally invasive surgical AF ablation The procedure is described in detail elsewhere in this supplement. At our institution, the chest is entered thorascopically or using a non–rib-spreading minithoracotomy.2 We incorporate ganglionic plexuses mapping/ablation, radiofrequency ablation of the pulmonary vein (PV) antrum, ligament of Marshall ligation/ablation, and left atrial appendage (LAA) excision.2 After the procedure, all of our patients undergo 30-day continuous event monitoring with an automatic AF detection algorithm at 6 and 12 months, then yearly thereafter. Dr. Kasirajan and Dr. Wood have received honoraria and research support from AtriCure, Inc. Dr. Ellenbogen has received honoraria from AtriCure, Inc., Ablation Frontiers, and Biosense Webster. Dr Han has no conflicts of interest to disclose. Address reprint requests and correspondence: Dr. Kenneth A. Ellenbogen, Medical College of Virginia, P.O. Box 980053, Richmond, Virginia 23298-0053. E-mail address: kellenbogen@ pol.net.
ABBREVIATIONS AF ⫽ atrial fibrillation; BMI ⫽ body mass index; IVC ⫽ inferior vena cava; LAA ⫽ left atrial appendage; MISAA ⫽ minimally invasive surgical atrial fibrillation ablation; PV ⫽ pulmonary vein; PVI ⫽ pulmonary vein isolation (Heart Rhythm 2009;6:S71–S76) © 2009 Heart Rhythm Society. All rights reserved.
Outcomes Minimally invasive surgical AF ablation (MISAA) studies have reported variable success rates depending on the length of follow-up and methods for detection of recurrent AF. Tables 1 and 2 detail the outcomes and complications encountered in our experience and in the published series to date.2–7 At our institution, the single procedure success rate of MISAA in 43 patients is 65%, based on a minimum follow-up duration of 1 year and the application of the HRS/EHRA/ECAS consensus statement guidelines for AF ablation success (no atrial tachyarrhythmia ⬎30 seconds without antiarrhythmic drugs after a 90-day postprocedure blanking period).2 In accordance with these guidelines, we have used continuous 30-day transtelephonic event monitoring at 6 and 12 months to assess for recurrent atrial tachyarrhythmia.2 In the largest series to date, Edgerton et al5 found an overall success rate of 66% in 66 patients without antiarrhythmic drugs. There was a difference in the 6-month success rate between patients with paroxysmal AF (69.8% [N ⫽ 43]) and persistent AF (34.8% [N ⫽ 23]).5 This study defined recurrence as the presence of AF ⬎15 seconds on Holter, event monitor, or pacemaker interrogation.5 In an effort to improve on the success of MISAA with persistent AF, Sirak et al6 added a linear epicardial radiofrequency lesion set. Sinus rhythm was maintained without antiarrhythmic drugs in 21 (87.5%) of 24 patients.6 For these
1547-5271/$ -see front matter © 2009 Heart Rhythm Society. All rights reserved.
doi:10.1016/j.hrthm.2009.07.027
AAD ⫽ antiarrhythmic drug; AF ⫽ atrial fibrillation; AT ⫽ atrial tachyarrhythmia; MISAA ⫽ minimally invasive surgical atrial fibrillation ablation; PM ⫽ pacemaker. *One patient excluded. †Right-sided atrial tachycardias and atrial flutters were not considered a failure of surgical ablation.
38/66 (58%) 20/22 (91%) 15/20 (75%) 1 excluded,* 2 right atrial flutter† 28/43 (65%) No recurrence without AAD
No AF on ECG or transtelephonic event monitor Definition of success
Outpatient monitoring (no. of patients)
15/23 (65%)
No AF on ECG/end of study Holter No AF/ left AT without AAD after 90-day blank period†
ECG @ 1, 3, 6 months; PM (11); 14-to 21-day event monitor (31); 24-hour Holter (24) No AF ⬎15 seconds at 6 months ECG (10), 10-to 14-day event monitor (11)
ECG @ 3 months; Holter at end of study; questionnaire
Office visits (intervals not specified) ECG at office visits; 7 day continuous event monitor @ 3, 6, and 13 months No AT ⬎30 seconds without AAD after 90-day blank period 21/24 (88%) Office visits @ 1, 3, 6 months Office visits @ 3 and 6 months; yearly
Office visits @ 1, 2, 3, 6 weeks; 3 and 6 months; every 6 months thereafter ECG at follow-up; 24–48 Holter for symptoms only Office visits, telephone calls
Office visits @ 3, 6, 12 months; yearly; as needed ECG at office visits; 30day continuous event monitor @ 6 and 12 months; yearly No AT ⬎30 s without AAD after 90-day blank period
74 (46/28) 6 months 22 (14/8) 1 year 21 (11/9)* 1 year 27 (18/9) 3 months 45 (33/12) 1 year
N (paroxysmal/persistent) Minimum follow-up duration Follow-up
Edgerton et al5 (2008) Wudel et al7 (2008) McClelland et al4 (2007) Wolf et al3 (2005) Han et al2 (2009)
Comparison of MISAA studies Table 1
32 (0/32) 6 months
Heart Rhythm, Vol 6, No 12S, December Supplement 2009 Sirak et al6 (2008)
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patients, the follow-up protocol consisted of 1-week continuous event monitoring at 6 months for the detection of AF or atrial flutter lasting ⱖ30 seconds.6 Currently, there are no randomized comparisons among catheter ablation, MISAA, and the maze III procedure. Retrospective comparisons of MISAA results with catheter ablation or the full surgical maze are complicated by differing definitions of success, variable follow-up durations, different patient populations, and markedly disparate monitoring strategies for recurrences. For example, Prasad et al1 found that 97% of patients undergoing the maze III procedure were in sinus rhythm with the aid of antiarrhythmic drugs (76.4% in sinus rhythm without antiarrhythmic drugs) after a mean follow-up duration of 5.4 years. The follow-up protocol in this study consisted of questionnaires, telephone interviews, and a chart review of the referring physicians’ records.1 The estimated complication rate, length of stay, intensive care unit stay, and mortality of MISAA (7.7%, 5.9 ⫾ 2.6 days, 1.7 ⫾ 1.6 days, 0%, respectively) compare favorably with the maze III (19%, 9 days, 2 days, 1.8%, respectively; Figure 1). In comparison, catheter ablation has a 6% complication rate, with a single procedure success rate ranging from 46% to 89%.8 –13 Disadvantages of MISAA are length of stay, intensive care unit stay, intubation, and bilateral pleural chest tubes (removed in 6 – 8 hours for thorascopic approach or 12–24 hours with minithoracotomy; Figure 1 and Table 3). Thus, with the currently available data, MISAA does not supersede catheter ablation or the maze III procedure as a first-line approach for AF ablation; rather, it represents an alternative to those procedures in appropriately selected patients.
Patient selection for MISAA Patient characteristics from our experience and the five published series are given in Table 4.2–7 The optimal patient selection criteria for MISAA are unknown. In our series, patients were referred for MISAA because of failed catheter ablation (27%), contraindications to catheter ablation (4%), age older than 70 years (12%), morbid obesity (13%), or intolerance to warfarin (16%).2 Ideally, patient selection guidelines for MISAA will be established after randomized controlled trials. Until then, selecting patients for MISAA based on assessment of the potential advantages/disadvantages of the procedure seems reasonable. The advantages are (1) a potentially more effective single procedure pulmonary vein isolation (PVI), (2) elimination of the LAA to decrease embolic risk, (3) extensive mapping and ablation of the ganglionic plexuses and ligament of Marshall, and (4) avoidance of specific catheter ablation-related complications. These advantages must be weighed against (1) longer hospitalizations, (2) more patient discomfort, (3) longer recovery times, (4) necessity and risks of general anesthesia, and (5) potential for bleeding with LAA excision. At our institution, where we are experienced in both catheter ablation and MISAA, most patients prefer catheter ablation because of the disadvantages mentioned.
Han et al Table 2
Minimally Invasive Surgical Atrial Fibrillation Ablation
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MISAA complications from published series
Operative mortality Pleural effusion requiring drainage Pneumothorax Acute renal failure (transient) Diaphragmatic paralysis Sepsis Cerebrovascular accident/transient ischemic attack Embolic event Reoperation for bleeding Conversion to sternotomy Pacemaker Anemia requiring transfusion Hemothorax Pulmonary embolism Skin incision revision Brachial plexopathy (transient)
Han et al2 (2009)
Wolf et al3* (2005)
McClelland et al4 (2007)
Wudel et al7 (2008)
Edgerton et al5 (2008)
Sirak et al6 (2008)
0 2 1 0 1 0 2
0 0 1 (4%)† 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
1 (1.4%) 0 0 1 (1.4%)‡ 0 0 0
0 0 0 0 0 0 0
0 0 0 1 (4%) 0 0 0 0
0 0 0 0 1 (5%) 0 0 0
0 0 0 0 0 1 (4.5%) 1 (4.5%) 0
0 0 0 0 1 (1.4%) 0 0 1 (1.4%)
0 0 1 (3%) 0 0 0 0 0
(4%) (2%) (2%)§ (4%)
1 (2%) 0 0 0 0 0 0 0 0
MISAA ⫽ minimally invasive surgical atrial fibrillation ablation. *Two minor complications not included here are one right forearm phlebitis and one suspected pericarditis. †Pneumothorax resolved without treatment. ‡Episode of renal insufficiency did not require dialysis. §Right hemidiaphragmatic paralysis.
Effective PVI In our experience, failed catheter ablation accounts for 27% of patients referred for MISAA.2 Incomplete PVI is responsible for most AF recurrences after catheter ablation for PVI.14 –16 Pratola et al17 found that approximately 50% of patients had reversal of intraprocedural end-points at a mean of 6 months after catheter ablation. Verma et al16 reported that the majority of patients who were free of AF without antiarrhythmic drugs had no PV–left atrial reconnections, whereas atrial–PV conduction delay was seen in patients who were unable to maintain sinus rhythm. Prasad et al have demonstrated the consistent creation of acute and chronic transmural lesions in an animal model using a bipolar radiofrequency clamp (Figure 2). There may be some advantage
to MISAA after catheter ablation failure by pursuing epicardial PVI to achieve transmural lesions in patients with a previously demonstrated response to PVI.
Prevention of thromboembolic events Oral et al18 noted that 20% of patients continued taking warfarin after catheter-based ablation for AF. Because the LAA is the site of thrombus formation in 90% of patients with nonrheumatic AF, excision of the LAA may help to decrease the incidence of embolic events.19 Left atrial apTable 3 Advantages/disadvantages of catheter ablation, MISAA, and Cox maze III
Invasive Stepwise mapping/ablation Pulmonary vein isolation Left atrial appendage exclusion Ganglionic plexuses mapping/ablation Ligament of Marshall mapping/ablation Atrial tachyarrhythmia/atrial flutter mapping/ablation Radiation exposure Proarrhythmic Concomitant procedures Figure 1 Estimated complication rate, length of stay (LOS), and mortality of Cox maze III, minimally invasive surgical atrial fibrillation ablation (MISAA), and catheter ablation (CA).
Catheter ablation
MISAA
Cox maze III
⫹ Yes Good No
⫹⫹ No ? Excellent Yes
⫹⫹⫹⫹ No Excellent Yes
Equivocal Yes
Yes
Equivocal Yes
Yes
Yes
No
No
Yes Yes No
No Unknown No
No Minimal Yes
Invasive: percutaneous access for catheter ablation; intubation with bilateral thoracoscopic or minithoracotomy access for minimally invasive surgical atrial fibrillation ablation (MISAA); intubation, sternotomy, cardiopulmonary bypass for maze III.
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Heart Rhythm, Vol 6, No 12S, December Supplement 2009 MISAA patient characteristics from published series
Age (years) Male (%) Left ventricular ejection fraction (%) Structural heart disease (%) Left atrial diameter (cm) Paroxysmal atrial fibrillation (%) Nonparoxysmal atrial fibrillation (%) Previous failed catheter ablation (%) Intolerant of anticoagulants (%) BMI BMI ⬎40
Han et al2 (2009)
Wolf et al3* (2005)
McClelland et al4 (2007)
Wudel et al7 (2008)
Edgerton et al5 (2008)
Sirak et al6 (2008)
64 ⫾ 8.7 56 56 ⫾ 8 26 4.3 ⫾ 0.6 73 27 27 7* 31 ⫾ 6.8 BMI ⬎40
57 ⫾ 15 81 — 36 — 67 33 7 — — —
59 ⫾ 8 71 56 ⫾ 8 — 4.4 ⫾ 0.3 57 43 — — — —
63 ⫾ 9 68 55 ⫾ 4 13 3.5 ⫾ 1.1 100 — 32 27 — —
— 74 — — 5.2 62 38 27 — — —
62 ⫾ 10.1 64 — — 4.8 ⫾ 0.8 — 100 13 — — —
BMI ⫽ body mass index; MISAA ⫽ minimally invasive surgical atrial fibrillation ablation. *Reasons for intolerance with warfarin: 1 recurrent epistaxis, 1 history of intracranial hemorrhage with warfarin, 1 refused.
pendage removal at mitral valve replacement decreases the risk of late thromboembolic events by 2.5-fold.20 However, LAA excision does not completely eliminate the risk of embolic events. In our series, among patients with risk factors for stroke (CHADS2 score ⬎2 without anticoagulation), two patients had a transient ischemic attack and one patient had a lower extremity embolus. The two patients with a transient ischemic attack (in the first patient 24 months after surgery, in the second elderly patient 30 months after the procedure) were in sinus rhythm with complex atherosclerotic plaques and no left atrial thrombus noted on transesophageal echocardiography, These patients did not require thrombolytics. The only patient with disability is the patient with a lower extremity embolus requiring
thrombectomy. He was not taking warfarin and had AF. His CHADS2 score was 3. All three patients currently are anticoagulated with warfarin. Thus, although MISAA offers the potential benefit of reduced thromboembolic risk over catheter ablation in high-risk patients, it does not completely eliminate this risk. Whether or not percutaneous LAA occlusion devices deployed after catheter ablation offer a comparable reduction of thromboembolic events compared with MISAA will need to be determined in future trials.
Elimination of the ganglionic plexuses and ligament of Marshall Scherlag et al21 demonstrated that the parasympathetic and sympathetic efferent neurons present in epicardial ganglionic plexuses and the intrinsic cardiac autonomic nervous system may play an important role in triggering PV firing. The incidence of atrial premature beats from the PV was found to be higher in patients with a developed vein of Marshall.22 Methods for mapping and ablating the ligament of Marshall during catheter ablation have had limited success.23 With MISAA, this epicardial structure can be visualized, mapped, and ablated, thus eliminating possible triggers for AF that cannot be easily accessed with catheter ablation.
Avoidance of catheter ablation-related complications Elderly
Figure 2 Radiofrequency clamp lesion. Trichrome stain of left pulmonary vein in cross-section shows transmural linear ablation with bipolar radiofrequency clamp. Red stain indicates muscle, cytoplasm, and erythrocytes. Blue stain represents collagen. (Reproduced with permission from Prasad S, Maniar H, Diodato M, Schuessler R, Damiano R Jr. Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study. Ann Thorac Surg 2003;76:836 – 842.30)
Despite concern for the safety of catheter ablation in the elderly, the high prevalence of AF in the elderly and the evolution of catheter ablation have resulted in a rapidly increasing number of elderly patients being referred for this procedure. Spragg et al24 found that patients older than 70 years had nearly a fourfold greater risk (10%) of major complications than did patients younger than 70 years (P ⫽ .04). Multivariate analysis found age greater than 70 years to be predictive of major complications, including stroke, tamponade, and vascular injury (P ⬍.002).24 This 10% complication rate in patients older than 70 years contrasts
Han et al
Minimally Invasive Surgical Atrial Fibrillation Ablation
with the 2% to 4.4% complication rate found in four recent catheter ablation trials (mean age 56 ⫾ 4.8 years) and requires caution when evaluating elderly patients for catheter ablation.9 –11,13 With MISAA, the mean age of patients (61 ⫾ 2.9 years) across all studies is older than that with catheter ablation, with a procedural complication rate of 7.7%.2–7 The nature of complications may be different and more manageable for MISAA than for catheter ablation. For example, the incidence of acute stroke and pericardial tamponade appears extremely low for MISAA, but these are serious complications of catheter ablation.
Obesity Obesity results in a greater radiation dose during catheter ablation.25 A greater body mass index (BMI) also causes degradation of the fluoroscopic images. The difficulty in gaining femoral vascular access, achieving postprocedural hemostasis, and recognizing poor hemostasis increases the risk of groin complications in obese patients.26 By direct visualization of the ablation targets, MISAA avoids suboptimal fluoroscopic images, radiation burns, and vascular access complications associated with catheter ablation. The minithoracotomy and thorascopic approaches for MISAA use selective lung ventilation and controlled pneumothoraces, which provide uniform exposure and access to the heart across all BMI ranges. These approaches also provide the advantage of faster recovery and improved wound healing compared with the sternotomy required for the maze III procedure. In our MISAA series, six patients had a BMI ⬎40 (maximum BMI 54). Although the procedure is not technically more difficult in these patients, some of these patients may be prone to obesity hypoventilation syndrome
S75
and obstructive sleep apnea and thus may require a longer time to extubation.
Other catheter ablation-related complications Catheter ablation requires femoral vein access to perform transseptal puncture. At our institution, we have encountered two patients with impassable vascular anatomy (one inferior vena cava [IVC] filter, one IVC occlusion). These patients were preferentially referred for minimally invasive surgical ablation. Catheter ablation via the superior approach has recently been described in patients with IVC abnormalities. Although the cases described were successful, the procedures were technically demanding, and the long-term safety and efficacy remain unknown.27 Dong et al28 reported that circumferential PVI still poses a 3.8% risk of moderate to severe PV stenosis. No PV stenosis occurred in 12 of 21 patients at a minimum 3-month follow-up after MISAA.3 In our series, no changes in PV size have been noted in patients up to 24 months after surgery. Circumferential PVI has also been plagued by a proarrhythmic effect in up to 24% of patients.29 Chugh et al29 found that most atrial tachyarrhythmias were due to gaps in the index ablation lines. MISAA may preclude these gaps along the PV antrum with continuous transmural ablation lines (Figure 3). Atrio-esophageal fistula is a devastating complication of catheter ablation. The bipolar radiofrequency pen and clamp used in MISAA allow the creation of discrete lesions between the bipoles of the devices without collateral damage. Thus, MISAA studies in over thousands of patients using
Figure 3 Linear ablation created with Coolrail. Left: Coolrail device (AtriCure, Inc., Cincinnati, OH, USA) for epicardial use. The probe delivers 30 W of radiofrequency energy between two conducts on the surface of the probe. The electrodes are cooled by water irrigation through the head of the device. Top right: Coolrail epicardial lesion (32 ⫻ 9 mm) of 4-mm-thick ventricular myocardium preparation. Bottom right: Endocardial surface of the same ventricular myocardium preparation shows transmural extension (27 ⫻ 7 mm) of epicardial lesion above.
S76 radiofrequency energy have not yet reported this complication.3–7
Summary Currently, MISAA has demonstrated a 65% single procedure 12-month success rate. As we await guidelines on optimal patient selection, we favor MISAA when (1) patients are not considered suitable for catheter ablation due to age, body habitus, or anatomic considerations, (2) patients have multiple recurrences after initially successful catheter ablation, or (3) patients have a high embolic risk or are intolerant of warfarin. Future studies will need to evaluate the long-term efficacy and safety of this procedure in multicenter trials, the role of linear ablation lesion sets with MISAA for patients with persistent AF (Figure 3), and the efficacy of new devices devised for LAA exclusion. We will also need follow-up electrophysiology studies of asymptomatic patients in order to prove that our PVI lesions are transmural and that the electrophysiologic effects of ablation of the ganglionic plexuses/ligament of Marshall are maintained for the long term. As we accumulate data from these studies, we should be able to further refine guidelines for MISAA patient selection.
References 1. 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 2003;126:1822–1828. 2. Han F, Kasirajan V, Kowalski M, et al. Results of a minimally invasive surgical pulmonary vein isolation and ganglionic plexi ablation for atrial fibrillation: single center experience with 12-month follow-up. Circ Arrhythmia Electrophysiol 2009;2:370 –377. 3. 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 2005;130:797– 802. 4. McClelland JH, Duke D, Reddy R. Preliminary results of a limited thoracotomy: new approach to treat atrial fibrillation. J Cardiovasc Electrophysiol 2007;18: 1289 –1295. 5. Edgerton JR, Edgerton ZJ, Weaver T, et al. Minimally invasive pulmonary vein isolation and partial autonomic denervation for surgical treatment of atrial fibrillation. Ann Thorac Surg 2008;86:35–38. 6. Sirak J, Jones D, Sun B, Sai-Sudhakar C, Crestanelo J, Firstenberg M. Toward a definitive, totally thorascopic procedure for atrial fibrillation. Ann Thorac Surg 2008;86:1960 –1964. 7. Wudel JH, Chaudhuri P, Hiller JJ. Video-assisted epicardial ablation and left atrial appendage exclusion for atrial fibrillation: extended follow-up. Ann Thorac Surg 2008;85:34 –38. 8. Cappato R, Calkins H, Chen SA, et al. Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circulation 2005;111:1100 –1105. 9. Wazni O, Marrouche N, Martin D, et al. Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of symptomatic atrial fibrillation. JAMA 2005;293:2634 –2640. 10. Pappone C, Augello G, Sala S, et al. A randomized trial of circumferential pulmonary vein ablation versus antiarrhythmic drug therapy in paroxysmal atrial fibrillation: the APAF study. J Am Coll Cardiol 2006;48:2340 –347.
Heart Rhythm, Vol 6, No 12S, December Supplement 2009 11. Stabile G, Bertaglia E, Senatore G, et al. Catheter ablation treatment in patients with drug-refractory atrial fibrillation: a prospective, multi-centre, randomized, controlled study (catheter ablation for the cure of atrial fibrillation study). Eur Heart J 2006;27:216 –221. 12. Eloff B. Biosense Webster Navistar Thermocool catheter for the radiofrequency ablation of symptomatic paroxysmal atrial fibrillation. November 20, 2008. Available at: http://www.fda.gov/ohrms/dockets/AC/08/slides/2008-4393s1-01FDA%20team%20presentation%20FINAL%20%282%29.pdf. 13. Jais P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic drugs for atrial fibrillation; the A4 study. Circulation 2008;118:2498 –2505. 14. Nanthakumar K, Plumb VJ, Epstein AE, Veenhuyzen GD, Link D, Kay GN. Resumption of electrical conduction in previously isolated pulmonary veins: rationale for a different strategy? Circulation 2004;109:1226 –1229. 15. Ouyang F, Antz M, Ernst S, et al. Recovered pulmonary vein conduction as a dominant factor for recurrent atrial tachyarrhythmias after complete circular isolation of the pulmonary veins: lessons from double lasso technique. Circulation 2005;111:127–135. 16. Verma A, Kilicaslan F, Pisano E, et al. Response of atrial fibrillation to pulmonary vein antrum isolation is directly related to resumption and delay of pulmonary vein conduction. Circulation 2005;112:627– 635. 17. Pratola C, Baldo E, Notarstefano P, Toselli T, Ferrari R. Radiofrequency ablation of atrial fibrillation: Is the persistence of all intraprocedural targets necessary for longterm maintenance of sinus rhythm? Circulation 2007;117: 136 –143. 18. Oral H, Chugh A, Ozaydin M, et al. Risk of thromboembolic events after percutaneous left atrial radiofrequency ablation of atrial fibrillation. Circulation 2006;114:759 –765. 19. Blackshear J, Odell J. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996;61:755–759. 20. Garcia-Fernandez M, Perez-David E, Quiles J, et al. Role of left atrial appendage obliteration in stroke reduction in patients with mitral valve prosthesis. J Am Coll Cardiol 2003;42:1253–1258. 21. Scherlag BJ, Yamanashi W, Patel U, Lazzara R, Jackman WM. Autonomically induced conversion of pulmonary vein focal firing into atrial fibrillation. J Am Coll Cardiol 2005;45:1878 –1886. 22. Kurotobi T, Ito H, Inoue K, et al. Marshall vein as arrhythmogenic source in patients with atrial fibrillation: correlation between its anatomy and electrophysiological findings. J Cardiovasc Electrophysiol 2006;17:1062–1067. 23. Valderrabano M, Chen H, Sidhu J, Rao L, Ling Y, Khoury D. Retrograde ethanol infusion in the vein of Marshall: regional left atrial ablation, vagal denervation, and feasibility in humans. Circ Arrhythm Electrophysiol 2009;2: 50 –56. 24. Spragg D, Dalal D, Cheema A, et al. Complications of catheter ablation for atrial fibrillation: incidence and predictors. J Cardiovasc Electrophysiol 2008;19:627– 631. 25. Ector J, Dragusin O, Adriaenssens B, et al. Obesity is a major determinant of radiation dose in patients undergoing pulmonary vein isolation for atrial fibrillation. J Am Coll Cardiol 2007;50:234 –242. 26. Cox N, Resnic F, Popma J, Simon D, Eisenhauer A, Rogers C. Comparison of the risk of vascular complications associated with femoral and radial access coronary catheterization procedures in obese versus nonobese patients. Am J Cardiol 2004;94:1174 –1177. 27. Lim H, Pak H, Tse H, Lau C, Hwang C, Kim Y. Catheter ablation of atrial fibrillation via superior approach in patients with interruption of the inferior vena cava. Heart Rhythm 2009;6:174 –179. 28. Dong J, Vasamreddy C, Jayam V, et al. Incidence and predictors of pulmonary vein stenosis following catheter ablation of atrial fibrillation using the anatomic pulmonary vein ablation approach: results from paired magnetic resonance imaging. J Cardiovasc Electrophysiol 2005;16:845– 852. 29. Chugh A, Oral H, Lemola K, et al. Prevalence, mechanisms, and clinical significance of macroreentrant atrial tachycardia during and following left atrial ablation for atrial fibrillation. Heart Rhythm 2005;2:464 – 471. 30. Prasad S, Maniar H, Diodato M, Schuessler R, Damiano R Jr. Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study. Ann Thorac Surg 2003;76:836 – 842.
KEYWORDS Atrial fibrillation; Surgical ablation; Catheter ablation
Introduction
For patients with pacemakers, we reviewed their pacemakers for evidence of atrial tachyarrhythmias at each 6-month device interrogation.
Catheter-based and surgical ablative approaches have been developed for patients with medically refractory symptomatic atrial fibrillation (AF). The Cox maze III procedure uses a series of atrial incisions to prevent the maintenance of AF, but it is associated with significant morbidity and requires a median sternotomy with cardiopulmonary bypass.1 This has prevented widespread use of this procedure. Nevertheless, the maze III procedure is considered the gold standard for surgical treatment of AF by restoring sinus rhythm in up to 97% of patients.1 Surgeons have been interested in replicating these results using a less invasive and less morbid procedure.
Minimally invasive surgical AF ablation The procedure is described in detail elsewhere in this supplement. At our institution, the chest is entered thorascopically or using a non–rib-spreading minithoracotomy.2 We incorporate ganglionic plexuses mapping/ablation, radiofrequency ablation of the pulmonary vein (PV) antrum, ligament of Marshall ligation/ablation, and left atrial appendage (LAA) excision.2 After the procedure, all of our patients undergo 30-day continuous event monitoring with an automatic AF detection algorithm at 6 and 12 months, then yearly thereafter. Dr. Kasirajan and Dr. Wood have received honoraria and research support from AtriCure, Inc. Dr. Ellenbogen has received honoraria from AtriCure, Inc., Ablation Frontiers, and Biosense Webster. Dr Han has no conflicts of interest to disclose. Address reprint requests and correspondence: Dr. Kenneth A. Ellenbogen, Medical College of Virginia, P.O. Box 980053, Richmond, Virginia 23298-0053. E-mail address: kellenbogen@ pol.net.
ABBREVIATIONS AF ⫽ atrial fibrillation; BMI ⫽ body mass index; IVC ⫽ inferior vena cava; LAA ⫽ left atrial appendage; MISAA ⫽ minimally invasive surgical atrial fibrillation ablation; PV ⫽ pulmonary vein; PVI ⫽ pulmonary vein isolation (Heart Rhythm 2009;6:S71–S76) © 2009 Heart Rhythm Society. All rights reserved.
Outcomes Minimally invasive surgical AF ablation (MISAA) studies have reported variable success rates depending on the length of follow-up and methods for detection of recurrent AF. Tables 1 and 2 detail the outcomes and complications encountered in our experience and in the published series to date.2–7 At our institution, the single procedure success rate of MISAA in 43 patients is 65%, based on a minimum follow-up duration of 1 year and the application of the HRS/EHRA/ECAS consensus statement guidelines for AF ablation success (no atrial tachyarrhythmia ⬎30 seconds without antiarrhythmic drugs after a 90-day postprocedure blanking period).2 In accordance with these guidelines, we have used continuous 30-day transtelephonic event monitoring at 6 and 12 months to assess for recurrent atrial tachyarrhythmia.2 In the largest series to date, Edgerton et al5 found an overall success rate of 66% in 66 patients without antiarrhythmic drugs. There was a difference in the 6-month success rate between patients with paroxysmal AF (69.8% [N ⫽ 43]) and persistent AF (34.8% [N ⫽ 23]).5 This study defined recurrence as the presence of AF ⬎15 seconds on Holter, event monitor, or pacemaker interrogation.5 In an effort to improve on the success of MISAA with persistent AF, Sirak et al6 added a linear epicardial radiofrequency lesion set. Sinus rhythm was maintained without antiarrhythmic drugs in 21 (87.5%) of 24 patients.6 For these
1547-5271/$ -see front matter © 2009 Heart Rhythm Society. All rights reserved.
doi:10.1016/j.hrthm.2009.07.027
AAD ⫽ antiarrhythmic drug; AF ⫽ atrial fibrillation; AT ⫽ atrial tachyarrhythmia; MISAA ⫽ minimally invasive surgical atrial fibrillation ablation; PM ⫽ pacemaker. *One patient excluded. †Right-sided atrial tachycardias and atrial flutters were not considered a failure of surgical ablation.
38/66 (58%) 20/22 (91%) 15/20 (75%) 1 excluded,* 2 right atrial flutter† 28/43 (65%) No recurrence without AAD
No AF on ECG or transtelephonic event monitor Definition of success
Outpatient monitoring (no. of patients)
15/23 (65%)
No AF on ECG/end of study Holter No AF/ left AT without AAD after 90-day blank period†
ECG @ 1, 3, 6 months; PM (11); 14-to 21-day event monitor (31); 24-hour Holter (24) No AF ⬎15 seconds at 6 months ECG (10), 10-to 14-day event monitor (11)
ECG @ 3 months; Holter at end of study; questionnaire
Office visits (intervals not specified) ECG at office visits; 7 day continuous event monitor @ 3, 6, and 13 months No AT ⬎30 seconds without AAD after 90-day blank period 21/24 (88%) Office visits @ 1, 3, 6 months Office visits @ 3 and 6 months; yearly
Office visits @ 1, 2, 3, 6 weeks; 3 and 6 months; every 6 months thereafter ECG at follow-up; 24–48 Holter for symptoms only Office visits, telephone calls
Office visits @ 3, 6, 12 months; yearly; as needed ECG at office visits; 30day continuous event monitor @ 6 and 12 months; yearly No AT ⬎30 s without AAD after 90-day blank period
74 (46/28) 6 months 22 (14/8) 1 year 21 (11/9)* 1 year 27 (18/9) 3 months 45 (33/12) 1 year
N (paroxysmal/persistent) Minimum follow-up duration Follow-up
Edgerton et al5 (2008) Wudel et al7 (2008) McClelland et al4 (2007) Wolf et al3 (2005) Han et al2 (2009)
Comparison of MISAA studies Table 1
32 (0/32) 6 months
Heart Rhythm, Vol 6, No 12S, December Supplement 2009 Sirak et al6 (2008)
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patients, the follow-up protocol consisted of 1-week continuous event monitoring at 6 months for the detection of AF or atrial flutter lasting ⱖ30 seconds.6 Currently, there are no randomized comparisons among catheter ablation, MISAA, and the maze III procedure. Retrospective comparisons of MISAA results with catheter ablation or the full surgical maze are complicated by differing definitions of success, variable follow-up durations, different patient populations, and markedly disparate monitoring strategies for recurrences. For example, Prasad et al1 found that 97% of patients undergoing the maze III procedure were in sinus rhythm with the aid of antiarrhythmic drugs (76.4% in sinus rhythm without antiarrhythmic drugs) after a mean follow-up duration of 5.4 years. The follow-up protocol in this study consisted of questionnaires, telephone interviews, and a chart review of the referring physicians’ records.1 The estimated complication rate, length of stay, intensive care unit stay, and mortality of MISAA (7.7%, 5.9 ⫾ 2.6 days, 1.7 ⫾ 1.6 days, 0%, respectively) compare favorably with the maze III (19%, 9 days, 2 days, 1.8%, respectively; Figure 1). In comparison, catheter ablation has a 6% complication rate, with a single procedure success rate ranging from 46% to 89%.8 –13 Disadvantages of MISAA are length of stay, intensive care unit stay, intubation, and bilateral pleural chest tubes (removed in 6 – 8 hours for thorascopic approach or 12–24 hours with minithoracotomy; Figure 1 and Table 3). Thus, with the currently available data, MISAA does not supersede catheter ablation or the maze III procedure as a first-line approach for AF ablation; rather, it represents an alternative to those procedures in appropriately selected patients.
Patient selection for MISAA Patient characteristics from our experience and the five published series are given in Table 4.2–7 The optimal patient selection criteria for MISAA are unknown. In our series, patients were referred for MISAA because of failed catheter ablation (27%), contraindications to catheter ablation (4%), age older than 70 years (12%), morbid obesity (13%), or intolerance to warfarin (16%).2 Ideally, patient selection guidelines for MISAA will be established after randomized controlled trials. Until then, selecting patients for MISAA based on assessment of the potential advantages/disadvantages of the procedure seems reasonable. The advantages are (1) a potentially more effective single procedure pulmonary vein isolation (PVI), (2) elimination of the LAA to decrease embolic risk, (3) extensive mapping and ablation of the ganglionic plexuses and ligament of Marshall, and (4) avoidance of specific catheter ablation-related complications. These advantages must be weighed against (1) longer hospitalizations, (2) more patient discomfort, (3) longer recovery times, (4) necessity and risks of general anesthesia, and (5) potential for bleeding with LAA excision. At our institution, where we are experienced in both catheter ablation and MISAA, most patients prefer catheter ablation because of the disadvantages mentioned.
Han et al Table 2
Minimally Invasive Surgical Atrial Fibrillation Ablation
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MISAA complications from published series
Operative mortality Pleural effusion requiring drainage Pneumothorax Acute renal failure (transient) Diaphragmatic paralysis Sepsis Cerebrovascular accident/transient ischemic attack Embolic event Reoperation for bleeding Conversion to sternotomy Pacemaker Anemia requiring transfusion Hemothorax Pulmonary embolism Skin incision revision Brachial plexopathy (transient)
Han et al2 (2009)
Wolf et al3* (2005)
McClelland et al4 (2007)
Wudel et al7 (2008)
Edgerton et al5 (2008)
Sirak et al6 (2008)
0 2 1 0 1 0 2
0 0 1 (4%)† 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
1 (1.4%) 0 0 1 (1.4%)‡ 0 0 0
0 0 0 0 0 0 0
0 0 0 1 (4%) 0 0 0 0
0 0 0 0 1 (5%) 0 0 0
0 0 0 0 0 1 (4.5%) 1 (4.5%) 0
0 0 0 0 1 (1.4%) 0 0 1 (1.4%)
0 0 1 (3%) 0 0 0 0 0
(4%) (2%) (2%)§ (4%)
1 (2%) 0 0 0 0 0 0 0 0
MISAA ⫽ minimally invasive surgical atrial fibrillation ablation. *Two minor complications not included here are one right forearm phlebitis and one suspected pericarditis. †Pneumothorax resolved without treatment. ‡Episode of renal insufficiency did not require dialysis. §Right hemidiaphragmatic paralysis.
Effective PVI In our experience, failed catheter ablation accounts for 27% of patients referred for MISAA.2 Incomplete PVI is responsible for most AF recurrences after catheter ablation for PVI.14 –16 Pratola et al17 found that approximately 50% of patients had reversal of intraprocedural end-points at a mean of 6 months after catheter ablation. Verma et al16 reported that the majority of patients who were free of AF without antiarrhythmic drugs had no PV–left atrial reconnections, whereas atrial–PV conduction delay was seen in patients who were unable to maintain sinus rhythm. Prasad et al have demonstrated the consistent creation of acute and chronic transmural lesions in an animal model using a bipolar radiofrequency clamp (Figure 2). There may be some advantage
to MISAA after catheter ablation failure by pursuing epicardial PVI to achieve transmural lesions in patients with a previously demonstrated response to PVI.
Prevention of thromboembolic events Oral et al18 noted that 20% of patients continued taking warfarin after catheter-based ablation for AF. Because the LAA is the site of thrombus formation in 90% of patients with nonrheumatic AF, excision of the LAA may help to decrease the incidence of embolic events.19 Left atrial apTable 3 Advantages/disadvantages of catheter ablation, MISAA, and Cox maze III
Invasive Stepwise mapping/ablation Pulmonary vein isolation Left atrial appendage exclusion Ganglionic plexuses mapping/ablation Ligament of Marshall mapping/ablation Atrial tachyarrhythmia/atrial flutter mapping/ablation Radiation exposure Proarrhythmic Concomitant procedures Figure 1 Estimated complication rate, length of stay (LOS), and mortality of Cox maze III, minimally invasive surgical atrial fibrillation ablation (MISAA), and catheter ablation (CA).
Catheter ablation
MISAA
Cox maze III
⫹ Yes Good No
⫹⫹ No ? Excellent Yes
⫹⫹⫹⫹ No Excellent Yes
Equivocal Yes
Yes
Equivocal Yes
Yes
Yes
No
No
Yes Yes No
No Unknown No
No Minimal Yes
Invasive: percutaneous access for catheter ablation; intubation with bilateral thoracoscopic or minithoracotomy access for minimally invasive surgical atrial fibrillation ablation (MISAA); intubation, sternotomy, cardiopulmonary bypass for maze III.
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Heart Rhythm, Vol 6, No 12S, December Supplement 2009 MISAA patient characteristics from published series
Age (years) Male (%) Left ventricular ejection fraction (%) Structural heart disease (%) Left atrial diameter (cm) Paroxysmal atrial fibrillation (%) Nonparoxysmal atrial fibrillation (%) Previous failed catheter ablation (%) Intolerant of anticoagulants (%) BMI BMI ⬎40
Han et al2 (2009)
Wolf et al3* (2005)
McClelland et al4 (2007)
Wudel et al7 (2008)
Edgerton et al5 (2008)
Sirak et al6 (2008)
64 ⫾ 8.7 56 56 ⫾ 8 26 4.3 ⫾ 0.6 73 27 27 7* 31 ⫾ 6.8 BMI ⬎40
57 ⫾ 15 81 — 36 — 67 33 7 — — —
59 ⫾ 8 71 56 ⫾ 8 — 4.4 ⫾ 0.3 57 43 — — — —
63 ⫾ 9 68 55 ⫾ 4 13 3.5 ⫾ 1.1 100 — 32 27 — —
— 74 — — 5.2 62 38 27 — — —
62 ⫾ 10.1 64 — — 4.8 ⫾ 0.8 — 100 13 — — —
BMI ⫽ body mass index; MISAA ⫽ minimally invasive surgical atrial fibrillation ablation. *Reasons for intolerance with warfarin: 1 recurrent epistaxis, 1 history of intracranial hemorrhage with warfarin, 1 refused.
pendage removal at mitral valve replacement decreases the risk of late thromboembolic events by 2.5-fold.20 However, LAA excision does not completely eliminate the risk of embolic events. In our series, among patients with risk factors for stroke (CHADS2 score ⬎2 without anticoagulation), two patients had a transient ischemic attack and one patient had a lower extremity embolus. The two patients with a transient ischemic attack (in the first patient 24 months after surgery, in the second elderly patient 30 months after the procedure) were in sinus rhythm with complex atherosclerotic plaques and no left atrial thrombus noted on transesophageal echocardiography, These patients did not require thrombolytics. The only patient with disability is the patient with a lower extremity embolus requiring
thrombectomy. He was not taking warfarin and had AF. His CHADS2 score was 3. All three patients currently are anticoagulated with warfarin. Thus, although MISAA offers the potential benefit of reduced thromboembolic risk over catheter ablation in high-risk patients, it does not completely eliminate this risk. Whether or not percutaneous LAA occlusion devices deployed after catheter ablation offer a comparable reduction of thromboembolic events compared with MISAA will need to be determined in future trials.
Elimination of the ganglionic plexuses and ligament of Marshall Scherlag et al21 demonstrated that the parasympathetic and sympathetic efferent neurons present in epicardial ganglionic plexuses and the intrinsic cardiac autonomic nervous system may play an important role in triggering PV firing. The incidence of atrial premature beats from the PV was found to be higher in patients with a developed vein of Marshall.22 Methods for mapping and ablating the ligament of Marshall during catheter ablation have had limited success.23 With MISAA, this epicardial structure can be visualized, mapped, and ablated, thus eliminating possible triggers for AF that cannot be easily accessed with catheter ablation.
Avoidance of catheter ablation-related complications Elderly
Figure 2 Radiofrequency clamp lesion. Trichrome stain of left pulmonary vein in cross-section shows transmural linear ablation with bipolar radiofrequency clamp. Red stain indicates muscle, cytoplasm, and erythrocytes. Blue stain represents collagen. (Reproduced with permission from Prasad S, Maniar H, Diodato M, Schuessler R, Damiano R Jr. Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study. Ann Thorac Surg 2003;76:836 – 842.30)
Despite concern for the safety of catheter ablation in the elderly, the high prevalence of AF in the elderly and the evolution of catheter ablation have resulted in a rapidly increasing number of elderly patients being referred for this procedure. Spragg et al24 found that patients older than 70 years had nearly a fourfold greater risk (10%) of major complications than did patients younger than 70 years (P ⫽ .04). Multivariate analysis found age greater than 70 years to be predictive of major complications, including stroke, tamponade, and vascular injury (P ⬍.002).24 This 10% complication rate in patients older than 70 years contrasts
Han et al
Minimally Invasive Surgical Atrial Fibrillation Ablation
with the 2% to 4.4% complication rate found in four recent catheter ablation trials (mean age 56 ⫾ 4.8 years) and requires caution when evaluating elderly patients for catheter ablation.9 –11,13 With MISAA, the mean age of patients (61 ⫾ 2.9 years) across all studies is older than that with catheter ablation, with a procedural complication rate of 7.7%.2–7 The nature of complications may be different and more manageable for MISAA than for catheter ablation. For example, the incidence of acute stroke and pericardial tamponade appears extremely low for MISAA, but these are serious complications of catheter ablation.
Obesity Obesity results in a greater radiation dose during catheter ablation.25 A greater body mass index (BMI) also causes degradation of the fluoroscopic images. The difficulty in gaining femoral vascular access, achieving postprocedural hemostasis, and recognizing poor hemostasis increases the risk of groin complications in obese patients.26 By direct visualization of the ablation targets, MISAA avoids suboptimal fluoroscopic images, radiation burns, and vascular access complications associated with catheter ablation. The minithoracotomy and thorascopic approaches for MISAA use selective lung ventilation and controlled pneumothoraces, which provide uniform exposure and access to the heart across all BMI ranges. These approaches also provide the advantage of faster recovery and improved wound healing compared with the sternotomy required for the maze III procedure. In our MISAA series, six patients had a BMI ⬎40 (maximum BMI 54). Although the procedure is not technically more difficult in these patients, some of these patients may be prone to obesity hypoventilation syndrome
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and obstructive sleep apnea and thus may require a longer time to extubation.
Other catheter ablation-related complications Catheter ablation requires femoral vein access to perform transseptal puncture. At our institution, we have encountered two patients with impassable vascular anatomy (one inferior vena cava [IVC] filter, one IVC occlusion). These patients were preferentially referred for minimally invasive surgical ablation. Catheter ablation via the superior approach has recently been described in patients with IVC abnormalities. Although the cases described were successful, the procedures were technically demanding, and the long-term safety and efficacy remain unknown.27 Dong et al28 reported that circumferential PVI still poses a 3.8% risk of moderate to severe PV stenosis. No PV stenosis occurred in 12 of 21 patients at a minimum 3-month follow-up after MISAA.3 In our series, no changes in PV size have been noted in patients up to 24 months after surgery. Circumferential PVI has also been plagued by a proarrhythmic effect in up to 24% of patients.29 Chugh et al29 found that most atrial tachyarrhythmias were due to gaps in the index ablation lines. MISAA may preclude these gaps along the PV antrum with continuous transmural ablation lines (Figure 3). Atrio-esophageal fistula is a devastating complication of catheter ablation. The bipolar radiofrequency pen and clamp used in MISAA allow the creation of discrete lesions between the bipoles of the devices without collateral damage. Thus, MISAA studies in over thousands of patients using
Figure 3 Linear ablation created with Coolrail. Left: Coolrail device (AtriCure, Inc., Cincinnati, OH, USA) for epicardial use. The probe delivers 30 W of radiofrequency energy between two conducts on the surface of the probe. The electrodes are cooled by water irrigation through the head of the device. Top right: Coolrail epicardial lesion (32 ⫻ 9 mm) of 4-mm-thick ventricular myocardium preparation. Bottom right: Endocardial surface of the same ventricular myocardium preparation shows transmural extension (27 ⫻ 7 mm) of epicardial lesion above.
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Summary Currently, MISAA has demonstrated a 65% single procedure 12-month success rate. As we await guidelines on optimal patient selection, we favor MISAA when (1) patients are not considered suitable for catheter ablation due to age, body habitus, or anatomic considerations, (2) patients have multiple recurrences after initially successful catheter ablation, or (3) patients have a high embolic risk or are intolerant of warfarin. Future studies will need to evaluate the long-term efficacy and safety of this procedure in multicenter trials, the role of linear ablation lesion sets with MISAA for patients with persistent AF (Figure 3), and the efficacy of new devices devised for LAA exclusion. We will also need follow-up electrophysiology studies of asymptomatic patients in order to prove that our PVI lesions are transmural and that the electrophysiologic effects of ablation of the ganglionic plexuses/ligament of Marshall are maintained for the long term. As we accumulate data from these studies, we should be able to further refine guidelines for MISAA patient selection.
References 1. 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 2003;126:1822–1828. 2. Han F, Kasirajan V, Kowalski M, et al. Results of a minimally invasive surgical pulmonary vein isolation and ganglionic plexi ablation for atrial fibrillation: single center experience with 12-month follow-up. Circ Arrhythmia Electrophysiol 2009;2:370 –377. 3. 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 2005;130:797– 802. 4. McClelland JH, Duke D, Reddy R. Preliminary results of a limited thoracotomy: new approach to treat atrial fibrillation. J Cardiovasc Electrophysiol 2007;18: 1289 –1295. 5. Edgerton JR, Edgerton ZJ, Weaver T, et al. Minimally invasive pulmonary vein isolation and partial autonomic denervation for surgical treatment of atrial fibrillation. Ann Thorac Surg 2008;86:35–38. 6. Sirak J, Jones D, Sun B, Sai-Sudhakar C, Crestanelo J, Firstenberg M. Toward a definitive, totally thorascopic procedure for atrial fibrillation. Ann Thorac Surg 2008;86:1960 –1964. 7. Wudel JH, Chaudhuri P, Hiller JJ. Video-assisted epicardial ablation and left atrial appendage exclusion for atrial fibrillation: extended follow-up. Ann Thorac Surg 2008;85:34 –38. 8. Cappato R, Calkins H, Chen SA, et al. Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circulation 2005;111:1100 –1105. 9. Wazni O, Marrouche N, Martin D, et al. Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of symptomatic atrial fibrillation. JAMA 2005;293:2634 –2640. 10. Pappone C, Augello G, Sala S, et al. A randomized trial of circumferential pulmonary vein ablation versus antiarrhythmic drug therapy in paroxysmal atrial fibrillation: the APAF study. J Am Coll Cardiol 2006;48:2340 –347.
Heart Rhythm, Vol 6, No 12S, December Supplement 2009 11. Stabile G, Bertaglia E, Senatore G, et al. Catheter ablation treatment in patients with drug-refractory atrial fibrillation: a prospective, multi-centre, randomized, controlled study (catheter ablation for the cure of atrial fibrillation study). Eur Heart J 2006;27:216 –221. 12. Eloff B. Biosense Webster Navistar Thermocool catheter for the radiofrequency ablation of symptomatic paroxysmal atrial fibrillation. November 20, 2008. Available at: http://www.fda.gov/ohrms/dockets/AC/08/slides/2008-4393s1-01FDA%20team%20presentation%20FINAL%20%282%29.pdf. 13. Jais P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic drugs for atrial fibrillation; the A4 study. Circulation 2008;118:2498 –2505. 14. Nanthakumar K, Plumb VJ, Epstein AE, Veenhuyzen GD, Link D, Kay GN. Resumption of electrical conduction in previously isolated pulmonary veins: rationale for a different strategy? Circulation 2004;109:1226 –1229. 15. Ouyang F, Antz M, Ernst S, et al. Recovered pulmonary vein conduction as a dominant factor for recurrent atrial tachyarrhythmias after complete circular isolation of the pulmonary veins: lessons from double lasso technique. Circulation 2005;111:127–135. 16. Verma A, Kilicaslan F, Pisano E, et al. Response of atrial fibrillation to pulmonary vein antrum isolation is directly related to resumption and delay of pulmonary vein conduction. Circulation 2005;112:627– 635. 17. Pratola C, Baldo E, Notarstefano P, Toselli T, Ferrari R. Radiofrequency ablation of atrial fibrillation: Is the persistence of all intraprocedural targets necessary for longterm maintenance of sinus rhythm? Circulation 2007;117: 136 –143. 18. Oral H, Chugh A, Ozaydin M, et al. Risk of thromboembolic events after percutaneous left atrial radiofrequency ablation of atrial fibrillation. Circulation 2006;114:759 –765. 19. Blackshear J, Odell J. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996;61:755–759. 20. Garcia-Fernandez M, Perez-David E, Quiles J, et al. Role of left atrial appendage obliteration in stroke reduction in patients with mitral valve prosthesis. J Am Coll Cardiol 2003;42:1253–1258. 21. Scherlag BJ, Yamanashi W, Patel U, Lazzara R, Jackman WM. Autonomically induced conversion of pulmonary vein focal firing into atrial fibrillation. J Am Coll Cardiol 2005;45:1878 –1886. 22. Kurotobi T, Ito H, Inoue K, et al. Marshall vein as arrhythmogenic source in patients with atrial fibrillation: correlation between its anatomy and electrophysiological findings. J Cardiovasc Electrophysiol 2006;17:1062–1067. 23. Valderrabano M, Chen H, Sidhu J, Rao L, Ling Y, Khoury D. Retrograde ethanol infusion in the vein of Marshall: regional left atrial ablation, vagal denervation, and feasibility in humans. Circ Arrhythm Electrophysiol 2009;2: 50 –56. 24. Spragg D, Dalal D, Cheema A, et al. Complications of catheter ablation for atrial fibrillation: incidence and predictors. J Cardiovasc Electrophysiol 2008;19:627– 631. 25. Ector J, Dragusin O, Adriaenssens B, et al. Obesity is a major determinant of radiation dose in patients undergoing pulmonary vein isolation for atrial fibrillation. J Am Coll Cardiol 2007;50:234 –242. 26. Cox N, Resnic F, Popma J, Simon D, Eisenhauer A, Rogers C. Comparison of the risk of vascular complications associated with femoral and radial access coronary catheterization procedures in obese versus nonobese patients. Am J Cardiol 2004;94:1174 –1177. 27. Lim H, Pak H, Tse H, Lau C, Hwang C, Kim Y. Catheter ablation of atrial fibrillation via superior approach in patients with interruption of the inferior vena cava. Heart Rhythm 2009;6:174 –179. 28. Dong J, Vasamreddy C, Jayam V, et al. Incidence and predictors of pulmonary vein stenosis following catheter ablation of atrial fibrillation using the anatomic pulmonary vein ablation approach: results from paired magnetic resonance imaging. J Cardiovasc Electrophysiol 2005;16:845– 852. 29. Chugh A, Oral H, Lemola K, et al. Prevalence, mechanisms, and clinical significance of macroreentrant atrial tachycardia during and following left atrial ablation for atrial fibrillation. Heart Rhythm 2005;2:464 – 471. 30. Prasad S, Maniar H, Diodato M, Schuessler R, Damiano R Jr. Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study. Ann Thorac Surg 2003;76:836 – 842.