Outcome of stand-alone thoracoscopic epicardial left atrial posterior box isolation with bipolar radiofrequency energy for longstanding persistent atrial fibrillation

Hybrid Ablation of Atrial Fibrillation: A Contemporary Overview

Electrical isolation of pulmonary veins (PVI) is the cornerstone of invasive treatment of atrial fibrillation (AF). However, arrhythmia-free survival of a PVI only approach is suboptimal in patients with persistent and long-term persistent AF. Hybrid AF ablation has been developed with the aim of combining the advantages of a thoracoscopic surgical ablation (direct visualization of anatomical structures to be spared and the possibility to perform epicardial lesions) and endocardial ablation (possibility to check line block, confirm PVI, and possibility to perform cavotricuspid isthmus ablation). Patient selection is of utmost importance. In persistent and long-term persistent AF, hybrid AF ablation demonstrated promising results in terms of AF free survival. It has been associated with a relatively low complication rate if performed in centers with expertise in hybrid procedures and experience with both surgical and endocardial ablation. Different techniques have been described, with different approaches and lesion sets. The aim of this review is to provide a state-of-the-art overview of hybrid AF ablation.

A Novel Laser Energy Ablation Catheter for Endocardial Cavo-Tricuspid Isthmus Ablation and Epicardial Ventricular Lesion Formation: An in vivo Proof-of-Concept Study

Aim

This proof-of-concept study aimed to investigate atrial and ventricular lesion formation by a 20-mm linear laser ablation catheter, regarding lesion depth and tissue damage.

Methods

In total, 6 female swines underwent standard femoral vein access to introduce a novel 20-mm linear laser ablation catheter in the right atrium to perform endocardial cavotricuspid isthmus (CTI) ablations. The navigation took place under fluoroscopy with additional visualization by intracardiac echocardiograph. Via a sternotomy, epicardial ablations were performed on the surface of the left ventricle (LV), right ventricle (RV), and right atrial appendage (RAA). Procedural safety was assessed by registration of intraprocedural adverse events and by macroscopic examination of the excised hearts for the presence of charring or tissue disruption at the lesion site.

Results

Altogether 39 lesions were created, including 8 endocardial CTI (mean lesion length 20.6 ± 1.65 mm), 26 epicardial ventricle (mean lesion length LV: 25.3 ± 1.35 mm, RV: 24.9 ± 2.40 mm), and 5 epicardial appendage ablations (mean lesion length RAA: 26.0 ± 3.16 mm). Transmurality was achieved in all CTI and atrial appendage ablations, in 62% of the RV ablations and in none of the LV ablations. No perforation or steam pop occurred, and no animal died during the procedure.

Conclusion

In this porcine study, the 20-mm linear laser ablation catheter has shown excellent results for endocardial cavotricuspid isthmus ablation, and it resulted in acceptable lesion depth during atrial and ventricular epicardial ablation. The absence of tissue charring, steam pops, or microbubbles under the experimental conditions suggests a high degree of procedural safety.

Midterm results of stand-alone thoracoscopic epicardial ablation with box lesion for atrial fibrillation

OBJECTIVES

The short-term results of video-assisted thoracoscopic surgical ablation (VTSA) with box lesion have been highly variable, and the actual efficacy requires clarification through longer follow-ups. We aimed to report which patients might benefit more from VTSA with box lesion by longer follow-up.

METHODS

From September 2010 to November 2016, patients with atrial fibrillation (AF) who underwent VTSA with box lesion were screened. All enrolled patients visited the outpatient clinic and underwent 24-h Holter monitoring at 3, 6 and 12 months after surgery and annually thereafter.

RESULTS

A total of 91 consecutive patients [age, 58.0 (interquartile interval from 52.0 to 62.0) years; male, 71.4%] with paroxysmal (67%) or persistent/long-standing persistent (33%) AF were enrolled. After a median follow-up of 48 months (interquartile interval from 36 to 60 months), freedom from atrial tachyarrhythmias without antiarrhythmic drugs (AADs) was 76.5%, 66.0% and 66.0% for paroxysmal AF and 58.6%, 47.8% and 34.2% for persistent/long-standing persistent AF at 12, 36 and 60 months, respectively (P = 0.017). The preoperative left atrial diameter >40 mm (hazard ratio: 2.837, 95% confidence interval: 1.408-5.716; P = 0.004) and age >50 years (hazard ratio: 2.927, 95% confidence interval: 1.359-6.305; P = 0.006) were associated with recurrences of atrial tachyarrhythmias. In patients with paroxysmal AF and left atrial diameter ≤40 mm (n = 43), freedom from atrial tachyarrhythmias without AADs was 81.4%, 74.3% and 74.3% at 12, 36 and 60 months, respectively.

CONCLUSIONS

In patients with paroxysmal AF and left atrial diameter ≤40 mm, 5-year freedom from atrial tachyarrhythmias without AADs was 74.3%, which was better than that in patients with left atrial diameter >40 mm. A larger sample size and improved study design are needed to confirm our conclusions.

Clamping versus nonclamping thoracoscopic box ablation in long-standing persistent atrial fibrillation

OBJECTIVE

To compare clinical outcomes of clamping devices and linear nonclamping devices for isolation of the posterior left atrium (box) in thoracoscopic ablation of long-standing persistent atrial fibrillation.

METHODS

Eighty patients who underwent thoracoscopic pulmonary vein and box isolation using a bipolar clamping device (42 patients) or bipolar nonclamping device (38 patients) to create the roof/inferior lesions for box isolation were included from 2 centers. Follow-up consisted of 24-hour Holter at regular intervals. Freedom from AF during 1-year follow-up and catheter repeat interventions were compared between groups.

RESULTS

Acute intraoperative electrical isolation of the box compartment was significantly higher in the clamping group than in the nonclamping group (100% and 79%, respectively, P < .01). At 1-year follow-up, 91% of the clamping group and 79% of the nonclamping group were in sinus rhythm. During 1-year follow-up, recurrence rates did not significantly differ between the 2 groups (P = .08). Repeat catheter interventions were required in 10% of the clamping group and 21% of the nonclamping group (P = .15). Conduction gaps in the roof or inferior lesions were found in 1 patient (2%) in the clamping group versus 4 patients (11%) in the nonclamping group (P = .13).

CONCLUSIONS

Thoracoscopic pulmonary vein and box isolation are highly effective in restoring sinus rhythm in long-standing persistent atrial fibrillation on short-term follow-up. Comparison of clamping and nonclamping devices revealed lower rates of intraoperative exit block of the box in the nonclamping group. However, this did not translate into a significant difference in atrial fibrillation freedom at short-term (1-year) follow-up.

Impact of left atrial box surface ratio on the recurrence after ablation for persistent atrial fibrillation

Background

The posterior wall of the left atrium (LA) is a well‐known substrate for atrial fibrillation (AF) maintenance. Isolation of the posterior wall between the pulmonary veins (box lesion) may improve ablation success. Box lesion surface area size varies depending on the individual anatomy. This retrospective study evaluates the influence of box lesion surface area as a ratio of total LA surface area (box surface ratio) on arrhythmia recurrence.

Methods

Seventy consecutive patients with persistent AF (63 ± 11 years, 53 men) undergoing computed tomography (CT) imaging and ablation procedure consisting of a first box lesion were included in this study. Box lesion surface area was measured on electroanatomical maps and total LA surface area was derived from CT. Patients were followed with 24‐h electrocardiography and exercise tests at 3, 6, and 12 months after AF ablation. Arrhythmia recurrence was defined as any AF/atrial tachycardia (AT) beyond 3 months without antiarrhythmic drugs.

Results

During a median follow‐up of 13 (interquartile range = 10‐17) months, 42 (60%) patients had AF/AT recurrence. Multivariate Cox proportional regression analysis showed that a larger box surface ratio protected against recurrence (hazard ratio [HR] = 0.81; 95% confidence interval [CI] = 0.690‐0.955; P = 0.012). Left atrial volume index (HR = 1.01 [0.990‐1.024, P = 0.427] and a history of mitral valve surgery (HR = 2.90; 95% CI = 0.970‐8.693; P = 0.057) were not associated with AF recurrence in multivariate analysis.

Conclusion

A larger box lesion surface area as a ratio of total LA surface area is protective for AF/AT recurrence after ablation for persistent AF.

The future of hybrid ablation: an emerging need for an anticoagulation protocol for thoracoscopic ablation

The midterm efficacy of hybrid ablation of atrial fibrillation (AF) reported in recent papers is about 70% in terms of sinus rhythm maintenance without antiarrhythmic drugs. Bearing in mind that the majority of patients enrolled are patients with persistent and long-standing persistent AF, the reported efficacies seem to be very good. Despite the high efficacies, safety remains a critical issue in hybrid, and especially thoracoscopic ablations. The frequency of complications during thoracoscopic ablations is more than 10% in the majority of reports. Most are short-term with no sequelae (such as pneumothorax or pneumonia); however, life-threatening complications have also been described, e.g., a sternotomy in response to a laceration of the left atrium (LA). One of the most serious ablation complications is stroke. The rate of strokes, which has been reported during or shortly after thoracoscopic ablation, seems to be higher than the rate reported after catheter ablation. This is especially true in papers describing thoracoscopic ablations that were not immediately followed by a catheter ablation. A possible explanation is differences in anticoagulation management during the two procedures. During catheter endocardial procedures, a standard anticoagulation protocol exists and is routinely applied; however, there is no such set of recommendations for anticoagulation during the thoracoscopic-phase of an ablation. It seems probable that, in many cases, no anticoagulation is used during thoracoscopic ablations. Moreover, whatever anticoagulation protocol is used during thoracoscopic ablations often goes unreported. A discussion about the best anticoagulation strategy during thoracoscopic ablation is urgently needed. In the future, standards of anticoagulation during thoracoscopic ablation should be clearly reported, just as they are now for catheter ablations.