The surgical Maze procedure needs cardiopulmonary bypass and reveals high complication rate comparing to catheter technique. Minimally invasive surgical techniques find the similar effects of the Cox Maze procedure, but with less complications. The TTA approach adopts a circular atrial ablation lesion set around pulmonary veins.
Considering the risk–benefit ratio of surgical vs catheter ablation, thoracoscopic approach should be suggested for patients with previous failed catheter ablation or with a high risk of catheter-ablation failure. The advantage of surgical ablation could be the surgeon’s ability to gain direct access to the epicardial structures such as the ligament of Marshall and GP. Direct visualization enables to avoid complications of the phrenic nerve and the esophagus.
The hybrid approach
If permanent PVI is the ablation strategy, different techniques such as combined approach of surgical and catheter ablation might be needed to improve long-term efficacy, and hybrid approach could show better results [
23]. Surgical epicardial ablation has been shown to increase transmurality of the ablation lesions and to eliminate epicardial targets for AF, such as the LAA, the GP and the LOM. Theoretically combining the epicardial approach with endocardial ablation into a one-stop procedure that includes validation of the ablation lines and modification of the residual AF substrate may increase long-term procedural success rates. A hybrid approach of the sequential procedures of TTA and RFCA is an alternative strategy that supplements the limitations of endo- and epicardial ablations [
14].
We evaluated the effect of the hybrid ablation (a staged RFCA procedure during the same hospitalization after TTA) compared with RFCA alone. There was no significant difference in recurrence of any atrial arrhythmia during median 2.1-year follow-up between the hybrid and RFCA alone (32.5% vs. 35.7%). But the AF recurrence was lower in the hybrid group than in the RFCA alone group (29.6% vs 34.9%, HR: 0.53;
P = 0.046). [
14] The hybrid AF ablation strategy in our institution was not the procedure in a hybrid operating room in a single hospitalization.
The timing of the hybrid approach should be a topic of discussion. Performing the two procedures during a single session reduces repeated hospitalization, but prolongs the duration of procedure. We examined the effect of postprocedural electrophysiological study after TTA. Persistent AF patients were randomized into 2 groups, the hybrid group and the TTA only group. Electrophysiological confirmation was studied at 4 or 5 day after TTA. In hybrid group, additional ablation was performed in 23%. Normal sinus rhythm was noted similar in both groups at one year [
24]. Having a 1- to 3-month interval between the two stages leads the ablation lesions to recover, which could reveal gaps in ablation line.
Asmundis et al. [
25] reported the results of TTA followed by simultaneous RFCA. The success rate was 67.2% at a 23.1 months after hybrid procedure and the overall freedom from AF reached 79.7% after redo RF procedures.
Mahapatra et al. [
26] presented a sequential approach during the same hospitalization in patients with persistent or long-standing persistent AF and enlarged left atrium. After 20.7 months of follow-up, 86.7% of hybrid patients and 53.3% of catheter-alone patients, were free of any atrial arrhythmia without anti-arrhythmic drugs (AAD) (
p = 0.04). On AAD, 93.3% of hybrid patients showed free of any atrial arrhythmia recurrence, compared to 56.7% catheter-alone patients (
p = 0.01).
Another hybrid approach is the convergent trans-diaphragmatic procedure with standard laparoscopic techniques and endocardial RFCA [
27,
28]. The operator could not approach superior region of PVs and the inferior part of the right PVs thru trans-diaphragmatic approach because of the anatomy of pericardial reflections. So the endocardial RFCA is mandatory to complete the electrical isolation of pulmonary veins in a hybrid convergent procedure.
A convergent trial demonstrated the successful results in treating persistent and longstanding persistent AF patients [
28]. Endocardial mapping and RFCA with diagnostic confirmation of procedural success complemented the surgical creation of epicardial linear lesions. After convergent procedures, 88% of patients were in sinus rhythm at 12-month follow-up and 87% at 24 months. The median AF burden recorded with implantable loop recorder was 0.1% at 24 months with 87% of patients demonstrating AF burden less than 3%.
Gersak et al. [
29] reported that the convergent procedure was a safe and efficacious treatment option for persistent and long-standing persistent AF. The single-procedure maintenance of sinus rhythm was 76% at 12 months and 52% were in sinus rhythm without antiarrhythmic drugs.
A meta-analysis [
30] suggested that hybrid treatment using mini-thoracotomy access showed superior outcome in freedom of atrial arrhythmia after follow-up duration (odds ratio [OR] = 6.67).
But hybrid treatment through either mini-thoracotomy or trans-diaphragmatic/subxiphoid approach had limitation such as longer procedure time and duration of hospitalization than catheter ablation.
A systematic review in persistent or long-standing persistent AF found that a hybrid approach showed a higher success rate of freedom from arrhythmias at 12 months or longer compared with AF catheter ablation (70.7% vs 49.9%, P < 0.001). [
31] Hybrid ablations had higher rate of complications (13.8% vs 5.9%). Large-scale randomized controlled trials comparing both strategies are needed.
In a hybrid approach of thoracoscopic epicardial procedure with Cobra-Fusion system and transcatheter mapping with endocardial touch-up of gaps to persistent AF with dilated atria, [
32] 92% of patients underwent a second-stage endocardial procedure after a mean of 2.2 months and touch-up ablation of surgical lesions was performed in 54% of patients and a CTI ablation was applied in 17% of patients. At 2 years, 65% of patients were in sinus rhythm without the use of antiarrhythmic drugs or electrical cardioversion and 82% were in sinus rhythm allowing antiarrhythmic drugs or electrical cardioversion. The box was isolated during the endocardial procedure in less than half of the patients (46%), therefore, the Cobra-Fusion technique is not very effective in making durable transmural lesions but demonstrates the added value of a hybrid approach.
Electrophysiological follow-up 2–3 months after surgical TTA to deliver a circumferential lesion set anterior to the pulmonary veins in an attempt to isolate the posterior LA revealed that the box isolation was incomplete in 60% and box isolation was successfully achieved with additional catheter ablation in 89% of those patients [
33]. Typical gap locations were the anterior–superior part of the superior PVs and the roofline.
In our institution, EPS was performed for recurrent atrial tachyarrhythmia at least 3 months after the TTA procedure and 50% of the recurred patients revealed AF as recurrent form of arrhythmia. Non-PV related arrhythmias were confirmed in half of recurred patients. Gaps in right PVs were frequently noted at the posterior ridge [
34].
Tan et al. [
35] reported that subsequent endocardial mapping showed that 28% of the patients had incomplete isolation of the right superior PVs and 6% patients had incomplete ablation lesions at the roof of the left atrium. The left PVs were isolated in all patients. By closing the gaps along the designated surgical lines, sinus rhythm was restored in 3 additional patients.
The different outcome of the hybrid procedure comparing with catheter ablation could be explained by a long-lasting isolation of the PVs after bipolar radiofrequency clamping of the PVs, epicardial clipping of the LAA and the add-on possibility of an endocardial touch-up [
33].
A study characterizing the recurrence of arrhythmia after hybrid ablation for patients with persistent AF was reported. Persistent AF patients received hybrid procedures of endocardial catheter ablation and a small midline surgical approach of the posterior LA wall and were followed for a mean of 25 months. Of patients with recurrence of arrhythmia, 53% were in atrial flutter and 47% were in AF. Half of ablations for atrial flutter following the hybrid procedure ablated the mitral isthmus [
36].