Multidisciplinary Collaboration for the Treatment of Atrial Fibrillation: Convergent Procedure Outcomes from a Single Center

DOI: 10.19102/icrm.2013.041002

DAVID M. GILLIGAN, MD, FACC, CHARLES A. JOYNER, MD, FACC and GRAHAM M. BUNDY, MD

Levinson Heart Hospital at Chippenham and Johnston Willis Medical Center, Richmond, Virginia, USA

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ABSTRACT.  Background: The convergent procedure is a multidisciplinary, closed-chest atrial fibrillation (AF) treatment. Transdiaphragmatic access allows the endoscopic creation of linear epicardial lesions throughout the posterior left atrium (PLA). Epicardial lesions are connected endocardially to ensure pulmonary vein isolation (PVI) and PLA segmentation. Objective: To evaluate the perioperative safety and 1-year efficacy after treating AF with the convergent epicardial and endocardial ablation procedure. Methods: This prospective study evaluated safety and 1-year efficacy for the convergent procedure. Rhythm status, required interventions, and antiarrhythmic drug (AAD) therapy were quantified at 6 and 12 months post procedure. Results: A total of 42 patients (81% persistent AF or longstanding persistent AF) were enrolled. There was no operative or perioperative mortality; 30-day major adverse cardiac event (MACE) rate was 4.7% including one pericarditis and one transfusion ≥2 units of blood. At 6 months, 97% of patients were free of AF, 86% were in sinus rhythm (SR), and 3% had repeat ablations. At 12 months, 95% were in SR, and 81% were in SR without requiring new AAD therapy from baseline or discharge. Conclusion: The convergent procedure safely treated persistent and longstanding persistent AF with excellent 1-year efficacy and a very low need for repeat interventions.

KEYWORDS. ablation, arrhythmia therapy, atrial fibrillation, convergent.

Dr. Gilligan, Dr. Joyner, and Dr. Bundy report they have consulted for nContact, Inc.
Manuscript received August 11, 2013, Final version accepted September 15, 2013.

Address correspondence to: David M. Gilligan, MD, FACC, 7401 Beaufont Springs, Drive, Suite 100, Richmond, VA 23225, USA. E-mail: dgilligan@vacardio.com

Introduction

Atrial fibrillation (AF) is a burden to the healthcare system and needs long-term treatment and management to address the rapidly increasing prevalence, projected to exceed 15 million by 2050.¹ Considering AF care costs nearly $15,000 annually in incremental direct and indirect costs per patient, the economic drain on society will become untenable.²

AF is commonly associated with other comorbidities, either as a cause or an effect, which accelerate disease progression, persistence of AF, and atrial enlargement, increasing stroke, heart failure, and mortality rates.³ As AF becomes permanent, the annual mortality exceeds 8% compared with 3% for paroxysmal AF.⁴ The average annual direct cost for patients with a CHADS2 score ≥2 dramatically exceeds that for patients with a CHADS2 ≤1.⁵

To reduce healthcare costs and improve quality of life, definitive treatment solutions must reduce hospitalization rates and facilitate management of AF without relying on repeat treatments such as ablations and cardioversions, or continued adjustment of medications. Catheter ablation involving pulmonary vein (PV) isolation has demonstrated efficacy at managing patients with lone, paroxysmal AF, but efficacy decreases dramatically when patients have structural heart disease and enlarged atria.⁶ Technology limitations and increased disease complexity have prevented effective treatment of persistent patients, especially those having risk factors.⁷

A philosophy that treating all patients with lone, paroxysmal AF will prevent progression to persistent AF is flawed when studies have shown that 50% of permanent AF occurs at first onset.⁸ These patients need a comprehensive bi-atrial lesion pattern, complete with PV isolation and segmentation of the posterior left atrium.^9,10 Catheter ablation is unable to safely create a comprehensive pattern of linear lesions without leaving gaps that are proarrhythmic; surgical ablation is too invasive and complex, requiring painful chest incisions or ports, lung deflation, and dissection of the pericardial reflections.

The convergent procedure is a multidisciplinary, closed chest, endoscopic approach that augments the ability to create linear lesions epicardially with endocardial mapping and ablation to avoid dissecting the pericardial reflections.¹¹ The endoscopic approach allows epicardial access and ablation to be accomplished without violating the chest or deflating the lungs. This closed chest approach enables a single setting procedure to be performed in the electrophysiology (EP) laboratory, potentially reducing post-procedure pain, decreasing hospital stay, and improving patient recovery. The multidisciplinary treatment creates a comprehensive bi-atrial lesion pattern that isolates the PVs and segments the posterior left atrium. Outcomes for the convergent procedure are presented for a largely persistent AF patient population.

Methods

Patients who received the convergent procedure beginning with the first case performed at our institution in August 2009 through December 2011 were consented and enrolled in this prospective study. Hospital Institute Review Board approval for the conduct of this study was obtained. AF classification adhered to the Heart Rhythm Society definitions.¹²

Multidisciplinary convergent procedure

The multidisciplinary convergent procedure was performed in the EP laboratory as a single-setting procedure for all patients. Epicardial linear lesions were created under general anesthesia prior to endocardial mapping and ablation that connected epicardial lesions into a comprehensive bi-atrial pattern, and ensured PV isolation and segmentation of the posterior left atrium.

After induction of anesthesia the cardiac surgical team undertook the epicardial ablation portion of the procedure. All procedures were performed by one surgeon (GB). A pericardial window through the central tendon of the diaphragm was created endoscopically with CO₂ insufflation used to create space to visualize the diaphragm. The window allowed insertion of a pericardioscopic cannula to access the epicardial surface of the posterior left atrium without any chest incisions or ports, or deflation of the lungs.¹³ The cannula was sized to facilitate passage of the epicardial ablation device and an endoscope to visualize the pericardial space and atrial surface during epicardial lesion creation. Linear epicardial lesions were created along the posterior left atrium and adjacent to the pulmonary vein antra without any dissections of attachments between the atrium and pericardium.¹³

Epicardial lesions were created with the vacuum contact, saline perfused, unipolar radiofrequency (RF) Numeris® Guided Coagulation System (nContact, Inc., Morrisville, NC) (Figure 1), utilizing the preset RF generator settings for power (30 W) and time (90 s). Vacuum produces consistent contact force against the epicardium while saline is pulled along the device and ablated epicardium to cool the device, direct heating into target tissue, and increase lesion depth ensuring full thickness, complete linear lesions.¹⁴ Figure 2 shows the lesion pattern during epicardial ablation and the relationship of lesions to the pericardial reflections.

After creating epicardial lesions, a pericardial drain was left in place and the abdominal access sites were closed. While the patient remained under general anesthetic the room was “turned over” and the EP team undertook the endocardial ablation. All procedures were performed by one of two electrophysiologists (DG and CJ). Multiple venous access sites were obtained and multipolar recording catheters were placed to the coronary sinus, the His bundle, and the right atrium and ventricle. Intracardiac was used to guide two transseptal punctures. Heparin was administered throughout left-sided catheterization to ensure ACTs exceeded 300 s. The EnSite NavX™ Navigation System (St. Jude Medical, St. Paul, MN) was used to generate navigation maps and direct endocardial connection of epicardial linear lesions. Endocardial ablation was performed utilizing irrigated tip catheters (Navistar Thermocool®, Biosense Webster, Diamond Bar, CA, or Coolpath St. Jude Medical). Figure 2 shows the endocardial creation strategy and relationship to previously created epicardial lesions. During and after endocardial ablation, EP testing was used to interrogate lesion completeness and PV isolation by demonstrating entrance and/or exit block. In all procedures PV isolation was targeted, further linear ablation in the left and right atria was at the discretion of the electrophysiologist (Figure 2).

Postoperative management

The pericardial drain was left in place for 36–48 hours. Patients were observed in hospital for a further 24 hours post drain removal. Heparin was used to bridge patients from anticoagulant discontinuation pre-procedure through restoring therapeutic anticoagulation levels with warfarin post procedure. The majority of patients were discharged on antiarrhythmic drugs (AADs), which were managed by the referring physician. There was no defined protocol to eliminate AADs at a specific follow-up period but the AAD status was recorded at each follow-up. Adhering to the Heart Rhythm Society (HRS) recommendations, anticoagulants were instituted post procedure and continued for at least 3 months. Discontinuation of anticoagulants during follow-up was managed by the referring physician.

Follow-up monitoring

Patients were evaluated with electrocardiograms (ECGs) and/or 72-h Holters at 6, 12, and 12+ months’ follow-up visits. AAD therapy, required interventions (repeat catheter ablation and cardioversion), and anticoagulation therapy were also recorded at each follow-up visit.

Statistical analysis

Baseline and follow-up values are reported as mean±standard deviation (SD) for numeric measures, and counts and percentages for categorical measures. Kaplan–Meier survival analyses were derived for freedom from AF recurrence and maintenance of sinus rhythm (SR) without AADs, repeat ablation procedures, or cardioversion.

Results

Forty-two patients receiving the convergent procedure were included in the study. The mean age was 60 years, and 76% (32/42) of the patients were male. Eighty-one percent (34/42) of patients presented with persistent or longstanding persistent AF. The average left atrial size based on a transthoracic echocardiography (TTE) parasternal view was 4.5 cm. Patient demographics are detailed in Table 1.

Figure 2 shows the percentage of patients who received each epicardial lesion. All patients received posterior and anterior pulmonary vein orifice epicardial ablation; 93% received a superior crossing lesion that connected right to left pulmonary veins posterior to the pericardial reflection; 64% received an inferior PV connecting lesion, and 50% received a lesion that extended from the left PV to the coronary sinus.

Endocardial lesions intended to connect epicardial lesions along the reflections are shown in Figure 2. All patients had PV lesions connected to complete PV isolation. Only 3% received endocardial ablation to connect the epicardial coronary sinus lesion to the mitral valve isthmus. No ablation within the left or right atrial appendages was performed. Fifty-four percent received a cavotricuspid isthmus lesion prophylactically.

All procedures were performed in the EP laboratory in a single setting. The average and median epicardial procedure time was 142.3±28.3 min and 38.2 min with an average and median epicardial ablation time of 38.4±7.6 min and 38.2 min. The average and median endocardial procedure time was 253.7±82.0 min and 242.5 min, with an average and median RF time of 31.1±18.0 min and 25.9 min, and an average and median fluoro time of 51.7±16.9 min and 48.9 min. The average and median length of stay was 3.7±1.5 days and 4 days respectively. All patients were discharged on anticoagulants with 83% on class I or III AADs (amiodarone, 34%; dofetilide, 10%; sotalol, 12%; multaq, 12%; flecainide, 10%; amiodarone and sotalol, 2%; flecainide and multaq, 2%; flecainide and sotalol, 2%).

Safety data for the study is described in Table 2. There was no operative or perioperative mortality. The total MACE was 4.7% (2/42) and included one pericarditis and one acute blood loss anemia requiring transfusion of ≥2 units of packed red blood cells. MACE greater than 30 days post procedure included three pericardial effusions. Three patients required pacemakers, at 31 days, 155 days, and 372 days post procedure. There was one late mortality greater than 6 months post procedure due to pulmonary causes unrelated to the procedure; this 75 year-old female with a 6-cm left atrium pre-procedure was in SR at the 6-month follow-up visit but remained on amiodarone. There were no operative, perioperative, or late embolic events, PV stenosis, esophageal injury, phrenic nerve palsy, or tamponade.

Six- and/or 12-month follow-up was available for all patients in the study. Eighty-three percent (83%) of patients had rhythm monitored with Holters or implanted pacemakers; the remaining 17% of patients had serial ECGs.

Efficacy outcomes are detailed in Table 3. Ninety-seven percent of patients receiving the convergent epicardial and endocardial procedure were free from AF at 6 months post procedure, with 86% in SR. One patient (3%) required a repeat catheter ablation for atypical atrial flutter at 27 days post procedure but was still in atypical flutter at the 6-month follow-up visit.

At 12-month follow-up, 95% of patients were in sinus rhythm with 65% in sinus rhythm without class I/III AADs, repeat ablation, or cardioversion. A total of three patients (9%) required one repeat catheter ablation procedure during 1-year follow-up (at 27 days mentioned above, 196 days, and 322 days); all remained on AADs at the 12-month follow-up. Two patients were cardioverted post 6-month follow-up, with one patient still in atypical flutter and one patient in sinus rhythm but remaining on AADs.

Figure 3 shows freedom from AF Kaplan–Meier survival analysis over 24 months utilizing a 3-month blanking period. Figure 4 shows arrhythmia and intervention-free Kaplan–Meier survival analysis over the same period. Any repeat catheter ablation, even within the blanking period, and any cardioversion were deemed a failure whether or not monitoring showed arrhythmia recurrence.

As shown in Table 3, all patients (n = 42) had at least 6-month follow-up with an average of 381±115 days (range 176–700 days). Ninety-three percent of patients were in sinus rhythm, with 81% (34/42) in sinus rhythm without requiring new AAD therapy from baseline or discharge; 74% (31/42) remained in sinus rhythm without requiring new AAD therapy, repeat catheter ablation, or cardioversion. Sixty-two percent (62%) of patients remained in SR off all AADs without any intervention (repeat catheter ablation or cardioversion). In addition, 64% of patients had anticoagulation discontinued, although most were kept on an aspirin regimen.

Discussion

The deficiencies of current AF ablation approaches stem from the inadequacy of ablation catheters in creating complete linear lesions and the invasiveness of surgical ablation, even so-called minimally invasive surgery.

The concern of injuring the phrenic nerve, lungs, and esophagus hamper the ability to create full-thickness lesions during endocardial catheter ablation, especially along the posterior left atrium. There is a fine line between creating endocardial lesions that extend to the epicardium and avoiding damage to anatomy that abuts the epicardial surface. In addition, technical constraints of remotely manipulating steerable catheters hinder connecting spot lesions into a continuous line without leaving proarrhythmic gaps. These limitations illustrate why the efficacy in persistent and longstanding persistent populations which, debatably, require several long, linear lesions is extremely low.^7,15 In addition, outcomes for catheter ablation consistently decline and depend on repeat catheter ablations for patient management due to high recurrence rates of AF and the proarrhythmic nature of trying to create linear lesions endocardially.^15–18

Surgical ablation of AF involving median sternotomy, or chest incisions or ports is highly invasive and is usually performed concomitantly with another valve or bypass procedure. The challenges in performing surgical ablation as a stand-alone option include long hospital stays, pain associated with damaging the intercostals nerves, lengthy recovery, and the morbidity reported in the literature. According to the STS database, on-pump stand-alone surgical ablation has a 28% major complication rate including 1.7% operative mortality, and an 11% readmission rate within 30 days postoperatively; the off-pump major complication rate was 14% with 0.5% operative mortality, and an 11% readmission rate.¹⁹ In a randomized comparison between catheter and surgical ablation in a largely paroxysmal patient population where nearly 50% of patients did not observe AF on their pre-procedure Holter, the procedural serious adverse events totaled 3.2% in the catheter arm versus 23.0% in the surgical arm.²⁰ Despite the improved efficacy in the surgical arm over catheter ablation, the morbidity associated with penetrating the chest wall prevents widespread adoption for a disease escalating in prevalence and needing viable treatment options.

To provide a viable procedure that provides the efficacy demonstrated by surgery with the safety inherent in catheterization, a multidisciplinary approach was envisioned to take advantage of direct visualization and linear lesion creation available with epicardial access, the diagnostic capabilities of catheter mapping to ensure procedure completeness, and the reduced invasiveness from avoiding any violation of the chest wall. This convergent procedure is enticing in that it is an EP procedure performed in a single setting within the EP laboratory, can fit within the normal practice and procedure requirements of catheter ablation, and avoids the downfalls of surgical procedures, including the pain associated with chest incisions or ports.

This study showed excellent safety and efficacy for the convergent procedure in a largely persistent AF patient population. The multidisciplinary procedure was durable in terms of maintaining SR throughout follow-up, allowing discontinuation of antiarrhythmic drugs, and eliminating dependence on repeat ablation procedures or cardioversion.

One explanation for the demonstrated efficacy is the access to and ablation of the posterior epicardium, enabling segmentation of the posterior left atrium in conjunction with PV isolation. Prior surgical studies suggest a correlation between long-term outcomes and the ability to definitively isolate the posterior left atrium.¹⁰ Another facet of epicardial ablation is the inherent ability to ablate the ganglionated plexi, which have been suggested as potential substrates for inducing AF. No matter what the basis for treatment, the multidisciplinary, closed chest epicardial and endocardial approach allows the creation of linear lesions that can be interrogated and completed through EP mapping and ablation techniques to create a comprehensive, bi-atrial lesion pattern.

Limitations

This observational study did not include epicardial mapping of CFAEs, ganglionated plexi, or other potential AF substrate markers. So the effect of each epicardial linear lesion, created in an anatomic pattern, on substrate modification was not evaluated. Endocardial mapping was performed to interrogate lesion completeness and PV isolation but, due to logistical reasons, voltage or activation maps were not created before lesion creation, after epicardial ablation, and at procedure completion post-endocardial ablation. Therefore, the clinical impact of individual components of the multidisciplinary procedure cannot be separated.

This observational prospective study also did not have information for the AF burden at baseline. Persistent AF is a complex disease and management of symptoms and prevention of recurrence should be the goal versus claiming a treatment cure.¹⁸ In addition, any real-world study endures the inability to mandate post-procedure patient management, including prescribing and discontinuing antiarrhythmic drugs and consistent methodologies for patient rhythm management, because of the dependence on referring physicians for continued patient care. Prolonged event recording was therefore not available in follow-up so shorter episodes of AF could have been missed and thus the success rate of the single procedure may be overestimated. Patients may be left on AADs, not because they had a recurrence but because patients are content with their current rhythm management. Multicenter studies with defined rhythm management protocols are needed to evaluate the treatment outcomes of the convergent procedure.

Conclusions

Outcomes from this prospective evaluation demonstrated the ability of the convergent procedure to treat persistent and longstanding persistent AF in a single procedure. Randomized clinical trials in the persistent patient population need to compare the multidisciplinary approach to real world catheter ablation techniques based on the reduction in AF burden without dependency on AADs or cardioversion after a single procedure. In addition, improvement in quality of life, exercise capacity, and heart function need to be quantified and related to long-term event-free survival in patients with structural heart disease who may benefit the most from AF treatment. Finally, the reduction in hospitalizations long-term should be determined along with other metrics that affect cost effectiveness in the current managed care environment to demonstrate whether treatment can reduce the economic burden on the healthcare system.

Acknowledgment

The contribution of F. Anne Adams, CMA, CCRC, for her assistance in compiling the data is greatly appreciated.

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