Convergent “Plus” Approach for Atrial Fibrillation

The CONVERGE IDE trial results were a major step forward for the treatment of nonparoxysmal atrial fibrillation (AF).¹ Despite the promising results of this trial showing a significant improvement in rhythm control for patients treated with a hybrid team ablation approach when compared to stand-alone endocardial catheter ablation (Figure 1), it begs the question: can we do better? Is a 67% freedom from AF without the use of new antiarrhythmic drugs the ceiling for a hybrid team approach? If the on-pump Cox-Maze surgery can consistently achieve rhythm control in >80% of patients over the mid and long term,^2,3 can we modify the original trial Convergent procedure to more closely approach the Cox-Maze surgery, and in doing so, achieve better patient outcomes? We believe we can. Herein we share an evolved iteration of the Convergent procedure, also known as Convergent “Plus.”

As a reminder, the trial Convergent procedure included epicardial posterior wall ablation, bilateral pulmonary vein isolation (PVI) (epicardial and endocardial), cavotricuspid isthmus isolation (endocardial), and, on rare occasions, mitral isthmus line (2%) endocardial ablation. When compared to the Cox-Maze IV,⁴ remaining potential lesions include management of the left atrial appendage (LAA), mitral isthmus ablation, coronary sinus (CS) ablation, superior vena cava (SVC) and inferior vena cava (IVC) (intracaval SVC-IVC) ablation, right atrial free wall ablation (“T”-lesion”), and further isolation of the posterior LA wall beyond the pericardial reflections (ie, outside of the transverse  pericardial sinus) (Figure 2). Of these lesions, it is important to prioritize which provide the best yield while also maintaining an appropriate safety profile. The Convergent “Plus” should expand its current “sweet spot” of effectiveness without compromising patient safety.

Convergent “Plus” Technique

In our opinion (as no published studies currently exist), the most obvious and likely greatest contribution to the trial Convergent procedure is the addition of managing the LAA. The LAAOS III trial indisputably demonstrated that concomitant management of the LAA during open cardiac surgery improves postcardiac surgical AF-related cerebrovascular accident.⁵ Thus, it would seem logical to apply this to the nonparoxysmal AF patient undergoing an epicardial surgical ablation. We have previously reported a >90% success rate with the management of the LAA using a video-assisted thoracoscopic surgery (VATS) approach with an epicardial occlusion device(s), and believe that with mentorship and proctoring, many current Convergent operators can also safely perform VATS epicardial occlusion (Figure 3 and Video 1).^6,7 Importantly, we have also reported that epicardial occlusion does not result in device migration or leak, and rare pouches do not appear to result in device-related thrombus.⁷ The critical steps in effective LAA management include: (1) safe entry into the left chest via port access (we prefer 4 ports) (Figure 4); (2) blunt manipulation of the device onto the base of the LAA to minimize the risk of inadvertent appendage puncture or tear with resultant bleeding; and (3) simultaneous direct epicardial surgical and endocardial transesophageal confirmation of complete LAA exclusion.

Video 1. VATS LAA epicardial exclusion with the AtriClip (AtriCure, Inc).

An added benefit of epicardial mechanical exclusion of the LA base is simultaneous electrical isolation of the LAA.^8,9 We also recommend, as a matter of workflow, that the VATS LAA be occluded prior to the subxiphoid ablation to minimize the number of times the transesophageal echocardiogram (TEE) and esophageal temperature probe are exchanged, and to allow for patient cardioversion prior to subxiphoid ablation to enhance the ability to confirm exit block.

Additional lesions in a Convergent “Plus” may include division of the ligament of Marshall (LOM) and extension of a partial roof line (beyond the anterior pericardial reflection). The LOM continues to gain support as a potential target for AF.¹⁰ During a left VATS approach for LAA management, the LOM can be directly identified as an epicardial structure between the left pulmonary artery and the dome of the LA (Figure 5 and Video 2). The ligament can be readily divided using electrocautery (unipolar or bipolar) with relative ease. Interestingly, it appears that the epicardial LOM viewed by surgeons is a unique structure than what is identified endocardially as a vein of Marshall by electrophysiologists. The direct contribution of epicardial division of the LOM is currently unknown, as there are no published studies that have compared Convergent cohorts with or without LOM division.

Video 2. Left VATS LOM identification and division. 

Finally, the addition of a partial roof life beyond the anterior pericardial reflection with the Convergent unipolar suction ablation catheter can also be easily and safely performed with the same left VATS approach. The catheter is introduced via the 12-mm sixth intercostal port and guided with an endoscopic grasper and positioned on the dome of the LA, extending from the left superior PV across the native transverse sinus up to the adipose tissue, which lies between the SVC superiorly, the right pulmonary artery (surgeon’s right), and the dome of the LA (surgeon’s left) (Figure 6). The efficiency of which this roof line can be extended and completed endocardially across the transverse sinus to right PVI is significantly improved (Figure 7). Partial mitral isthmus, CS, and epicardial bilateral PVIs, as well as right atrial epicardial lesions, can be performed. However, each of these lesions require a significant increase in thoracoscopic expertise and should not be performed by the surgeon until at least 50 Convergent “Plus” procedures have been safely executed.

Expanding Patient Selection Criteria

The discussion regarding Convergent “Plus” would be incomplete if we only focused on the possible technical additions to the trial Convergent procedure. Convergent “Plus” should also extend beyond the strict patient selection criteria of the CONVERGE IDE trial. The trial limited the patient study population to 18- to 80-year-olds with a LA no greater than 6 cm, no prior cardiac surgery or catheter ablation, and a left ventricular ejection fraction (LVEF) no less than 40%.¹ Although these limitations were expected for a trial, it is important to expand the patient population. Multiple catheter and surgical studies have now demonstrated the beneficial effect of ablation in patients with reduced EF in heart failure.^11-17 Specifically, Adademir et al reported that in patients with tachycardia-induced cardiomyopathy (TIC) and AF, surgical ablation with a Cox-Maze IV procedure can significantly improve New York Heart Association classification and LVEF%, and in some cases, even reverse LV dysfunction completely back to normal (LVEF >55%).¹⁶ Therefore, providing a Convergent “Plus” approach to include these patients seems like a natural extension of these promising data. At our center, we have also shown that a hybrid approach can significantly improve LVEF and even halt LA dilatation in the setting of TIC.¹⁸ Therefore, expansion of the procedure to include patients with depressed LVEF should be considered.

Patients with an enlarged LA >6 cm should also be seriously entertained for a Convergent “Plus” approach. Surgical ablation studies using a Cox-Maze III lesion set have demonstrated high rhythm success rates with an average LA size of 5.5 cm or greater.^19,20 Therefore, even though the expected rhythm success maybe lower with larger atria, enlarged atria should not be avoided, as rhythm success with posterior wall debulking may still be possible.

Finally, nearly 30% of patients who have undergone prior transcatheter aortic valve replacement (TAVR) for aortic stenosis (AS) have AF.²¹ It is unknown what the ultimate fate of the treatment of AF is in this TAVR population; however, we do know that patients who undergo TAVR with concomitant AF have worse outcomes when compared to those who do not have AF.²² This creates a population of what we call “pseudo” stand-alone AF, as these patients have been converted from concomitant AS and AF to TAVR with AF patients. Convergent “Plus” may offer a unique opportunity to treat these patients in a nonsternotomy fashion in a hybrid team approach. Surgeons often have access to these patients via TAVR clinics and the TAVR team approach, and should maintain their relationships with these patients to ensure appropriate care of AF after TAVR placement.

Summary

The CONVERGE IDE trial has laid the foundation for us to consider expanding both the technical and patient selection boundaries for patients with nonparoxysmal AF. We believe a Convergent “Plus” approach as outlined here may improve patient outcomes while maintaining an excellent safety profile. 

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Kiankhooy and Dunnington report support for attending meetings and/or travel from AtriCure. Drs Kiankhooy, Eisenberg, and Dunnington report consulting fees from AtriCure and payment for teaching ablation courses for AtriCure. Ms Daw reports that as a research assistant, she is indirectly compensated via a research grant by AtriCure to their institution.

Videos will be available shortly!

References

1. DeLurgio DB, Crossen KJ, Gill J, et al. Hybrid Convergent procedure for the treatment of persistent and long standing persistent atrial fibrillation: results of CONVERGE clinical trial. Circ Arrhythm Electrophysiol. 2020;13(12):e009288. doi:10.1161/CIRCEP.120.009288

2. Khiabani AJ, MacGregor RM, Bakir NH, et al. The long-term outcomes and durability of the Cox-Maze IV procedure for atrial fibrillation. J Thorac Cardiovasc Surg. 2022;163(2):629-641.e7. doi:10.1016/j.jtcvs.2020.04.100

3. Ad N, Henry L, Friehling T, Wish M, Holmes SD. Minimally invasive stand-alone Cox-maze procedure for patients with nonparoxysmal atrial fibrillation. Ann Thorac Surg. 2013;96(3):792-799. doi:10.1016/j.athoracsur.2013.05.007

4. Ruaengsri C, Schill MR, Khiabani AJ, et al. The Cox-maze IV procedure in its second decade: still the gold standard? Eur J Cardiothorac Surg. 2018;53(suppl_1):i19-i25. doi:10.1093/ejcts/ezx326

5. Whitlock RP, Belley-Cote EP, Paparella D, et al. Left atrial appendage occlusion during cardiac surgery to prevent stroke. N Engl J Med. 2021;384(22):2081-2091. doi:10.1056/NEJMoa2101897

6. Dunnington GH, Pierce CL, Eisenberg S, et al. A heart-team hybrid approach for atrial fibrillation: a single-centre long-term clinical outcome cohort study. Eur J Cardiothorac Surg. 2021;60(6):1343-1350. doi:10.1093/ejcts/ezab197

7. Kiankhooy A, Liem B, Dunnington GH, et al. Left atrial appendage ligation using the AtriClip device: single-center study of device safety and efficacy. Innovations (Phila). 2022;17(3):209-216. doi:10.1177/15569845221091998

8. Benussi S, Mazzone P, Maccabelli G, et al. Thoracoscopic appendage exclusion with an AtriClip device as a solo treatment for focal atrial tachycardia. Circulation. 2011;123(14):1575-1578. doi:10.1161/CIRCULATIONAHA.110.005652

9. Starck CT, Steffel J, Emmert MY, et al. Epicardial left atrial appendage clip occlusion also provides the electrical isolation of the left atrial appendage. Interact Cardiovasc Thorac Surg. 2012;15(3):416-418. doi:10.1093/icvts/ivs136

10. Valderrábano M, Peterson LE, Swarup V, et al. Effect of catheter ablation with vein of Marshall ethanol infusion vs catheter ablation alone on persistent atrial fibrillation: the VENUS Randomized clinical trial. JAMA. 2020;324(16):1620-1628. doi:10.1001/jama.2020.16195

11. Marrouche NF, Brachmann J, Andresen D, et al; CASTLE-AF Investigators. Catheter ablation for atrial fibrillation with heart failure. N Engl J Med. 2018;378(5):417-427. doi:10.1056/NEJMoa1707855

12. Prabhu S, Taylor AJ, Costello BT, et al. Catheter ablation versus medical rate control in atrial fibrillation and systolic dysfunction: the CAMERA-MRI Study. J Am Coll Cardiol. 2017;70(16):1949-1961. doi:10.1016/j.jacc.2017.08.041

13. Pozzoli A, Taramasso M, Coppola G, et al. Maze surgery normalizes left ventricular function in patients with persistent lone atrial fibrillation. Eur J Cardiothorac Surg. 2014;46(5):871-876. doi:10.1093/ejcts/ezu034

14. Pecha S, Ahmadzade T, Schäfer T, et al. Safety and feasibility of concomitant surgical ablation of atrial fibrillation in patients with severely reduced left ventricular ejection fraction. Eur J Cardiothorac Surg. 2014;46(1):67-71. doi:10.1093/ejcts/ezt602

15. 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. 2011;40(1):70-76. doi:10.1016/j.ejcts.2010.11.016

16. Adademir T, Khiabani AJ, Schill MR, et al. Surgical ablation of atrial fibrillation in patients with tachycardia-induced cardiomyopathy. Ann Thorac Surg. 2019;108(2):443-450. doi:10.1016/j.athoracsur.2019.01.088

17. Khiabani AJ, Schuessler RB, Damiano RJ Jr. Surgical ablation of atrial fibrillation in patients with heart failure. J Thorac Cardiovasc Surg. 2021;162(4):1100-1105. doi:10.1016/j.jtcvs.2020.05.125

18. Southern Thoracic Surgical Association (STSA) 68th annual meeting conference program. November 2021. Accessed July 27, 2022. https://stsa.org/wp-content/uploads/2021/11/STSA_ProgramBook_2021_vF.pdf

19. Ad N, Henry L, Hunt S, Holmes SD. Should surgical ablation for atrial fibrillation be performed in patients with a significantly enlarged left atrium? J Thorac Cardiovasc Surg. 2014;147(1):236-241. doi:10.1016/j.jtcvs.2013.09.037

20. Ad N, Holmes SD, Shuman DJ, Pritchard G. Impact of atrial fibrillation duration on the success of first-time concomitant cox maze procedures. Ann Thorac Surg. 2015;100(5):1613-1619. doi:10.1016/j.athoracsur.2015.04.105

21. Leon MB, Smith CR, Mack M, et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med. 2010;363(17):1597-1607. doi:10.1056/NEJMoa1008232

22. Shahim B, Malaisrie SC, George I, et al. Atrial fibrillation and outcomes after transcatheter or surgical aortic valve replacement (from the PARTNER 3 trial). Am J Cardiol. 2021;148:116-123. doi:10.1016/j.amjcard.2021.02.040