Clinical Data

CONVERGE IDE Study Design

The CONVERGE IDE trial enrolled 153 patients (88 persistent and 65 long-standing persistent patients) at 27 locations (25 in the United States and 2 in the United Kingdom). Patients were randomized at a rate of 2:1 and received either Hybrid AF Convergent therapy or endocardial RF catheter ablation alone. David DeLurgio, MD, of Emory St. Joseph’s Hospital in Atlanta, Georgia, was the trial’s national principal investigator.

CONVERGE IDE Trial Findings

The Hybrid AF Convergent procedure is the only proven therapy to treat patients who have been in AF for more than one year.^1,2 Both 12-month (Table 1) and 18-month (Table 2) data from the CONVERGE IDE trial show that the Hybrid AF Convergent procedure provides durable, long-lasting efficacy.

Data based on the post-hoc analysis of long-standing persistent AF sub-groups (N=65).

Hybrid AF Convergent Procedure in Electroanatomic Heterogeneous Cohort³

Maclean, E., et al. 2020

In this challenging cohort of patients with refractory, long-standing persistent atrial fibrillation (LSPAF), the probability of long-term arrhythmia-free survival was significantly higher with Hybrid AF Convergent ablation (p=0.003).

The study by Maclean, et al., enrolled 43 consecutive patients with LSPAF, who were treated with the Hybrid AF Therapy. Outcomes were compared with a matched group of 43 patients who had catheter ablation alone. Both groups underwent multiple catheter ablations as needed.

• Severe left ventricular systolic dysfunction
• Cardiomyopathy
• Pacemakers
• Prior unsuccessful rhythm control in over one-third of cases

While the Hybrid AF Convergent group had an increased incidence of atrial tachycardia (AT, 32.6%) none of these arrhythmias originated from the posterior wall. Instead, the origin of the AT prompted the authors to suggest consideration of empirical cavotricuspid isthmus (CTI) lines.

This study reveals that in patients with LSPAF, the Hybrid AF Convergent procedure is associated with increased freedom from AF at one year—and improved arrhythmia-free survival long term—versus endocardial catheter ablation alone.

AADs: anti-arrhythmic drugs

Hybrid AF CryoConvergent Therapy⁴

Makati, K. J., et al. 2020

This study by Makati, et al., showed that using endocardial cryothermy in Hybrid AF Convergent procedures achieved marked reductions in AF burden, even in long-standing persistent AF (LSPAF). Most Hybrid AF Convergent studies use radiofrequency as the endocardial and epicardial energy. This study reports the safety and efficacy of the Hybrid AF Convergent procedure using endocardial cryothermy.

Method: Retrospective analysis of 226 TRAC-AF Registry patients (2011-2018) who underwent epicardial RF ablation and endocardial cryothermy.

Results indicate Hybrid AF Convergent using cryo energy provides a promising solution for treatment of persistent AF and LSPAF, evidenced by relatively low AF recurrence rates and marked AF burden reduction after treatment—even in LSPAF patients.

AF: atrial fibrillation; AFL: atrial flutter; AT: atrial tachycardia; AADs: anti-arrhythmic drugs

Outcomes of Convergent Atrial Fibrillation Ablation with Continuous Rhythm Monitoring⁵

Larson, J., et al. 2020

The study involved 113 consecutive patients at one institution who underwent the Hybrid AF Convergent procedure. Among the patient characteristics: 88% had either persistent AF or long-standing persistent (LSP) AF; mean duration of AF before the procedure was 5.1 ± 4.6 years; 45% had undergone at least one prior catheter ablation; 31% had impaired LVEF; 62% had moderate or severe LA enlargement.

During follow-up, most patients (n = 92) had continuous rhythm monitoring. During the mean follow-up of 501 days, results were as follows.

Procedural complications decreased significantly following the transition from transdiaphragmatic to subxiphoid surgical access: 23% vs 3.8% (p = 0.005). Other results included: 9% of patients had elective cardioversion outside the blanking period, and 9.7% of patients underwent repeat ablation at a mean of 229 ± 178 days post procedure.

As noted in the Discussion, the data “highlight the potential shortcomings of conventional definitions of AF ablation success which have utilized a definition of recurrence including any AF/AT episode lasting >30 seconds ... [with most study results therefore showing] very modest success rates at approximately 50% to 60% at 1 year.”

The authors noted that recent study results, such as those from CASTLE-AF, suggest AF burden may be more reflective of ablation efficacy than conventional freedom from recurrence. In the current study, the authors found nearly 95% of their continuously monitored patients with recurrences remained free from an arrhythmia burden >5%.

In summary, more than half of the patients were AF/AT-free, and among patients who did experience an AF recurrence, the Hybrid AF Convergent procedure was able to reduce AF burden to very low mean levels of <5%, a level which appeared consistent over time.

At time of study completion, it was noted that future trials will be necessary to best define which patients are most likely to benefit from the Convergent approach.

Convergent Ablation for Persistent Atrial Fibrillation: Single Center Experience⁶

Gulkarov, I. et al. 2019

This retrospective study examined 31 symptomatic patients—with persistent AF (n =16) or long-standing persistent (LSP, n = 15) AF—who were treated with the Convergent procedure. All patients underwent surgical epicardial ablation via subxiphoid approach, followed by radiofrequency endocardial ablations on the same day. Median LA size was 4.3 cm. All but 4 patients, who were lost to follow-up, completed 2-year follow-up.

Interestingly, there was no statistical significance in AF/AFL recurrence in patients with or without AADs. Perioperatively, there was a 12.9% (4/31 patients) complication rate, but “some of these complications occurred early in our experience and steps were taken to avoid” these complications in the future. Of the 3 mortalities, 2 were from noncardiac causes within 18 months, and one was from cardiac arrest due to unknown causes at 4 months post intervention.

It is important to point out that 16.1% of this patient cohort had hypertrophic cardiomyopathy, and these patients are known to have much higher AF recurrence rates.

The Convergent procedure emphasizes the importance of silencing the posterior LA, which is an important area of arrhythmogenicity. This study demonstrates that the Convergent approach can be a reasonable alternative for treating patients with advanced stages of AF and severely dilated LA.

The authors concluded the hybrid procedure is a relatively safe and effective option for patients with PAF. Further studies are needed to better determine its long-term outcomes.

Short and Intermediate Term Outcomes of the Convergent Procedure: Initial Experience in a Tertiary Referral Center⁷

Tonks, R. et. al., 2020

This retrospective study examined 36 patients treated with the Hybrid AF™ Convergent procedure— 89% of whom had persistent AF or long-standing persistent (LSP) AF, and 58% of whom had LA enlargement > 4 cm. Findings are as follows.

During the procedure, 36% had LAA management using the AtriClip device. None of these patients had AF recurrence after the 90-day blanking period, supporting the theory that LAA exclusion augments the success rates of ablation alone.

The authors reported good outcomes, but also a learning curve for the first 10 patients. There were no peri-procedural deaths. Complications included 1 phrenic nerve palsy, 1 tamponade, 2 pericardial effusions requiring pericardiocentesis, and 2 severe pericarditis.

The authors concluded that the Hybrid Convergent the Hybrid Convergent procedure is a safe and effective treatment option that leverages the strengths of minimally invasive surgery and percutaneous endocardial catheter approaches to confer significant symptomatic relief from persistent and long-standing persistent AF. Such a multidisciplinary, hybrid approach may be the key to optimizing outcomes for this difficult patient population and should be considered as part of the armamentarium in a comprehensive AF treatment program.

Staged Hybrid Ablation for Persistent and Longstanding Persistent Atrial Fibrillation Effectively Restores Sinus Rhythm in Long-Term Observation⁸

Zembala, M. et. al., 2017

While catheter ablation is effective in terminating paroxysmal AF, it lacks efficacy in patients with persistent AF and especially long-standing persistent (LSP) AF. Historically, surgical epicardial ablation was not commonly recommended for such patients.

This study enrolled 90 patients with persistent AF (n = 39, 43%) or LSPAF (n = 51, 57%) to undergo a Hybrid AF™ Convergent procedure. Of the 39 patients who had previously had a catheter ablation, 56.4% had two or more prior ablations. Outcomes are presented for the 70 consecutive patients who had completed the 12-month post-procedure follow-up (the remaining patients had shorter follow-up durations). The 1-year results revealed the following.

The fact that only 62.3% of patients were in SR and free of AADs reflects the authors’ “philosophy of cautious AAD withdrawal,” since in many LSPAF cases they prefer to perform AAD withdrawal over 18-24 months rather than 1 year.

During follow-up, only one patient required a repeat ablation for AFL. There were 4 serious adverse events over the study duration: death of unknown cause, bleeding requiring sternotomy, cardiac tamponade, and transient ischemic attack. Three minor, reversible complications occurred: transient ischemic attack, pericardial effusion, and temporary phrenic nerve palsy.

The authors concluded a combination of epicardial and endocardial RF ablation should be considered as a treatment option for patients with persistent and long-standing persistent atrial fibrillation as it is safe and effective in restoring sinus rhythm.

Simultaneous Catheter and Epicardial Ablations Enable a Comprehensive Atrial Fibrillation Procedure⁹

Kiser, A. C., et al. (2011)

A simultaneous endocardial and epicardial ablation procedure, the Convergent procedure, precludes the treatment limitations related to epicardial AF procedures alone. The procedure achieves a comprehensive and bilateral ablation.

The epicardial portion is performed via a 2-cm subxiphoid incision vs a chest incision. To assess the potential advantages of adding endocardial ablation, investigators compared two types of epicardial procedures to the Convergent procedure. Patients undergoing (1) the open-chest concomitant Ex-Maze procedure and (2) the thoracoscopic/pericardioscopic Ex-Maze procedure did not receive endocardial ablation therapy.

Most of the patients evaluated in all three groups had persistent or long-standing persistent (LSP) AF:

• 89% among open-chest concomitant Ex-Maze patients
• 100% among pericardioscopic /thoracoscopic Ex-Maze patients
• 92% among Convergent procedure patients

Results related to restoration of SR are as follows.

*Reveal = 19 (sinus rhythm >97%)

The authors concluded these results indicate that, compared with surgical ablation procedures alone, collaboration with electrophysiologists improves outcomes.

Safety data revealed that, of the patients undergoing the Convergent procedure, 2 patients developed a pericardial effusion 2 weeks post procedure requiring percutaneous drainage; both patients fully recovered and continued to be in sinus rhythm at 12 months. (After investigators added a pericardial drainage tube for 48 hours post procedure, the Convergent patients experienced no pericardial effusions.) One patient who was discharged on Dofetilide experienced SCD 7 days post procedure, presumably related to torsades de pointes since no other cause of death was discovered. Two patients developed atrial-esophageal fistulas which resulted in death.

The authors stated that by providing endocardial ablation and verifying lesion transmurality during the Convergent procedure, the authors felt confident that all had been done to fully address any potential arrhythmias.

The authors concluded that use of both epicardial and endocardial ablation improves outcomes for patients with persistent or longstanding persistent atrial fibrillation. The authors furthermore stated that the outcomes observed with this collaboration—cardiac surgeons and electrophysiologists both delivering ablation therapy—reveals that this is an important treatment option for patients with atrial enlargement and chronic atrial fibrillation

Low Rate of Atrial Fibrillation Recurrence Verified by Implantable Loop Recorder Monitoring Following a Convergent Epicardial and Endocardial Ablation of Atrial Fibrillation¹⁰

Gersak, B., et al. 2012

Since the initial diagnosis of AF is long-standing persistent (LSP) AF for 50% of patients, clinicians need more comprehensive approaches for this patient population. Endocardial ablation to achieve PVI does not treat reentrant circuits common in persistent and LSP patients, who often have developed structural heart disease and atrial enlargement.

The Convergent procedure (CP) targets persistent and LSP patients—who are at increased risk of heart failure, stroke, and mortality—by combining endoscopic creation of epicardial linear lesions followed by endocardial mapping and ablation. EP testing is performed to assure lesion transmurality, pattern completeness, and PV isolation. This article reports the results of a study in which a total of 50 patients were enrolled, with 94% having persistent AF or LSPAF; 78% of the patients had structural heart disease.

Investigators evaluated long-term outcomes in consecutive patients undergoing the CP. Mean duration of AF was 5.0 ± 4.7 years. The results revealed:

Two patients receiving the CP were in continuous AF beyond the blanking period, and both had LSPAF pre-procedure, as well as hypertension and enlarged left atria ≥ 5.0 cm. There were 2 atrioesophageal fistulas reported. In one patient, the fistula resulted in death at 33 days post procedure; in the second, the fistula was surgically repaired but the patient died 8 months post procedure from a CVI. Consequently, investigators introduced added safety measures and temporarily staged the procedure—after which no other serious events were observed.

The investigators determined that, given the results of continuous loop recording, the CP was successful in treating persistent AF and LSPAF. Given that 87% of patients continued to have a cumulative AF burden less than 3% at 24 months post procedure, the dual epicardial/endocardial ablation was able to maintain outcomes throughout follow-up. The authors noted that the durability achieved—in maintaining sinus rhythm and eliminating redo procedures—compares favorably to catheter ablation study data.

Hybrid Convergent Procedure for Persistent and Long-Standing Persistent Atrial Fibrillation: From an Electrophysiologist's Perspective¹¹

DeLurgio, D.B. 2022

This review by Dr. David B. De Lurgio (Emory Heart & Vascular Center at Saint Joseph's, Atlants, GA) summarized the Hybrid Convergent study findings and highlighted the pathophysiology behind Hybrid Convergent ablation, improved efficiency of the electrophysiology (EP) lab during the study, reduced endocardial ablation time, and the value of a collaborative heart team approach when treating difficult-to-treat patients with advanced HF.

As new therapeutic tools have become available to EPs and more advanced energy delivery systems such as RF and cryoablation are used, it would follow that cardiac ablation would, as a result, become more effective and efficient. Endocardial ablation time was reduced in the CONVERGE trial in the Hybrid Convergent arm. The addition of epicardial ablation resulted in a shorter mean endocardial ablation time by 36 minutes in the Hybrid Convergent arm versus endocardial catheter ablation (Figure 1).

AADs: anti-arrhythmic drugs
AF: atrial fibrillation
AT: atrial tachycardia
CP: Convergent procedure
CVI: cerebrovascular insult
LA: left atrial
LAA: left atrial appendage
LVEF: left ventricular ejection fraction
PV: pulmonary vein
SR: sinus rhythm
SCD: sudden cardiac death