Concomitant bipolar radiofrequency ablation for atrial fibrillation in patients undergoing surgery for rheumatic Valvular disease in Sub-Saharan Africa

Jonathan O Nwiloh; Philip A Adebola; Mobolaji A Oludara

CASE REPORT

Year : 2016 | Volume : 1 | Issue : 1 | Page : 20-22

Concomitant bipolar radiofrequency ablation for atrial fibrillation in patients undergoing surgery for rheumatic Valvular disease in Sub-Saharan Africa

Jonathan O Nwiloh¹, Philip A Adebola², Mobolaji A Oludara³
¹ Dr. Joe Nwiloh Heart Center, St. Joseph's Hospital, Adazi Nnukwu, Anambra State, Lagos, Nigeria
² Department of Medicine, Lagos State University Teaching Hospital, Lagos, Nigeria
³ Department of Surgery, Lagos State University Teaching Hospital, Lagos, Nigeria

Date of Web Publication

25-Jul-2016

Correspondence Address:
Jonathan O Nwiloh
Dr. Joe Nwiloh Heart Center, St. Joseph's Hospital,Adazi Nnukwu, Anambra State
Nigeria

Source of Support: None, Conflict of Interest: None

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Abstract

The rhythm after valve surgery has been shown to impact on long-term outcome with increased thromboembolic risk in patients with persistent atrial fibrillation (AF) despite anticoagulation. Concomitant Cox maze IV (CMPIV) or pulmonary vein isolation using bipolar radiofrequency ablation has been demonstrated to reduce stroke risk when successful in restoring stable sinus rhythm. We report the case of a 27-year-old male with rheumatic mitral stenosis, persistent AF, and left atrial thrombus who underwent concomitant CMPIV radiofrequency ablation during mechanical mitral valve replacement and has subsequently remained in sinus rhythm and free from thromboembolism 10 years postoperatively. Strategies aimed at addressing AF and the left atrial appendage at the time of valve surgery may be beneficial in reducing embolic stroke and should be part of the contemporary surgeons armamentarium. Concomitant ablation when the capacity and expertise is locally available should therefore be considered in low-risk patients without severe left ventricular dysfunction or severe pulmonary hypertension during valve surgery in patients with persistent AF. When ablation is not feasible or equipment unavailable, consideration should then be given at a minimum to excision or exclusion of the left atrial appendage which is the most common source of emboli in AF as an alternative stroke reduction strategy.

Keywords: Ablation, atrial fibrillation, valvular disease

How to cite this article:
Nwiloh JO, Adebola PA, Oludara MA. Concomitant bipolar radiofrequency ablation for atrial fibrillation in patients undergoing surgery for rheumatic Valvular disease in Sub-Saharan Africa . Niger J Cardiovasc Thorac Surg 2016;1:20-2

How to cite this URL:
Nwiloh JO, Adebola PA, Oludara MA. Concomitant bipolar radiofrequency ablation for atrial fibrillation in patients undergoing surgery for rheumatic Valvular disease in Sub-Saharan Africa . Niger J Cardiovasc Thorac Surg [serial online] 2016 [cited 2023 Oct 3];1:20-2. Available from: https://journals.lww.com/njct/pages/default.aspx/text.asp?2016/1/1/20/186850

Introduction

Rheumatic valvular disease (RHD) is a major cause of heart failure in Sub-Saharan Africa (SSA) due usually to either late presentation, unavailability, or limited access to open heart surgery locally. As a consequence of this delayed presentation with heart chambers enlargement, a substantial percentage of these patients at the time of surgery has developed atrial fibrillation (AF). Concomitant bipolar radiofrequency ablation when feasible in this setting has been shown to increase chances of restoring sinus rhythm postoperatively and with a consequent reduction in risk of thromboembolic stroke.

Case Report

A 27-year-old male presented with exertional dyspnea, easy fatigability, persistent AF, and in New York Heart Association (NYHA) Class 4. Transthoracic echocardiogram showed severe mitral stenosis, moderate pulmonary hypertension with a left ventricular ejection fraction of 45%. Logistic EuroSCORE was 4.77. The patient underwent surgery through a mediastinotomy with cardiopulmonary bypass, systemic hypothermia at 30°C, and cold blood cardioplegia for myocardial protection during ischemic arrest. The mitral valve was exposed through left atriotomy, and after carefully removing a large organized thrombus, the valve was replaced with a 25 mm ATS mechanical valve. Concomitant Cox Maze IV (CMPIV) bipolar radiofrequency ablation with AtriCure clamp (AtriCure Inc., Cincinnati, OH, USA) was performed, excluding the endocardial cryoablation component to connect to the posterior mitral annulus [Figure 1]a and b. Patient's postoperative course was uneventful, and he was discharged home 2 weeks later in sinus rhythm on warfarin. Patient has remained in sinus rhythm, on warfarin for his mechanical valve, and in NYHA Class 1, 10 years postsurgery without any thromboembolic events.

Figure 1: (a and b) Left atrial radiofrequency ablation lesion sets.

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Discussion

AF is the most common arrhythmia and the prevalence in the population known to increase with age. In a review on the global burden of disease, Chugh et al. ^[1] estimated that 33.5 million patients approximately 0.5% of the world population had AF, whereas others estimate AF affects about 6% of the population older than 65 years. ^[2] The exact prevalence in Africa is unknown, but it is thought to be lower, however it is expected to rise as the risk factors increase with an aging population. ^[3] Moran et al. ^[4] in review of cardiovascular disease burden in SSA found that AF accounted for the largest relative increase between 1990 and 2010. Because RHD accounts for the majority of AF in SSA, it tends to occur in younger age groups compared to developed countries. AF is estimated to occur in about 30-50% of patients undergoing surgery for mitral valvular disease, ^[5] with most of these patients remaining in AF if no concomitant AF ablative procedure is performed. In our own surgical series from Nigeria, 38.5% of mitral valve disease patients had AF preoperatively. ^[6]

The first AF surgery was performed in 1987 by Cox. ^[7] The original operation was a complex surgical technique of cut and sew of both right and left atria that created a maze based on mapping patterns of activation during normal sinus rhythm. The maze prevented macro-reentry anywhere in either atrium while allowing impulses to activate all of the atria except the encircled pulmonary veins and excised atrial appendages. Subsequent iterations resulted in the Cox Maze III, which had a high success rate for both lone and concomitant AF. However, due to technical challenges with increased operating time associated with the Cox Maze III, alternate techniques utilizing energy sources such as radiofrequency ablation and cryoablation were developed to create the transmural lesions of the Cox Maze III. The CMPIV through a combination of cryoablation and bipolar radiofrequency ablation creates the lesion sets thus decreasing cardiopulmonary bypass and ischemic times with reduction in morbidity and mortality. ^[8] The CMPIV is now used for stand-alone AF and as an adjunct in patients with AF undergoing other cardiac surgical procedures. Many authors have reported benefits of concomitant ablation in patients with AF and valvular heart disease. Bando et al. ^[9] in a 24-year review of stroke after mechanical valve replacement found persistent AF postsurgery to be the most significant risk factor for stroke despite anticoagulation. Restoring sinus rhythm nearly eliminated this risk with an 8 year freedom from stroke in mitral valve replacement plus maze of 99% compared to 89% for valve replacement only cohort (P < 0.001). Other nonrandomized studies have shown 1 year freedom from AF postoperatively in the range of 80-90% although a recent randomized multi-institutional study reported a lower 1 year success rate. Two hundred and sixty patients with persistent or long-standing persistent AF were randomized with one group of 133 undergoing mitral valve surgery plus ablation and the other group of 127 mitral valve surgery without ablation. One year freedom from AF was 63.2% versus 29.4% (P < 0.001), respectively. One year mortality in both groups was however similar 6.8% versus 8.7% (P < 0.55), respectively. Surprisingly, in the ablation cohort, there was no difference between CMPIV versus pulmonary veins isolation with 1-year freedom from AF of 61.0% versus 66.0% (P < 0.60), respectively. ^[5] Over 50% of the randomized study, patients undergoing ablation were over 70 years, with a mean age of 69.7 ± 10.4 compared to the younger age of AF patients in SSA undergoing surgery, with a mean age of 26.7 ± 9.8 year in our series. ^[6] The cumulative benefit of concomitant ablation during valve surgery in this young RHD population could be enormous over their lifetime with restoration of a sinus rhythm and the associated stroke reduction risk. Patients undergoing valve repairs or bioprosthetic valve replacement converted to sinus rhythm postsurgery could be completely free of long-term anticoagulation and its attendant complications. Eliminating the usually encountered anticoagulant compliance challenges in our mostly indigent SSA population afflicted with RHD will help reduce the incidence of recurrent abortions in females during pregnancy and stroke risk in both sexes. ^[6] Even patients with mechanical valves needing lifelong anticoagulation do also obtain benefit from restoration of stable sinus rhythm postsurgery as this too has been shown to improve survival and freedom from thromboembolic stroke. ^[9] Although some advocate for only LA ablation, the addition of a right atrial lesion set (CMPIV) may increase effectiveness by 10-15%. ^[10] Heart block requiring permanent pacemaker occurs in 5% of patients after CMPIV; however, this rate is similar to AF patients without surgery. This study is limited by being a single case report, and our rhythm surveillance was only through isolated electrocardiograms, and there was no monitoring of the patient with either Holter or loop recorder which might have identified the episodes of paroxysmal AF. The results with a larger number of patients would obviously have more failures with persistent AF postablation.

Conclusion

According to American Heart Association/American College of Cardiology/Heart Rhythm Society 2014 guidelines, concomitant ablation is recommended in symptomatic paroxysmal, persistent and long-standing AF patients undergoing heart surgery (Class IIA, level of evidence C). Given the high burden of AF in rheumatic valvular patients in SSA, consideration should be given in low-risk patients for concomitant ablation when there are local capacity and expertise. If not feasible to consider exclusion or excision of the left atrial appendage which is the most common source of thromboembolism.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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