The symbiosis of contact force catheter use for hybrid ablation for atrial fibrillation

Hybrid ablation for atrial fibrillation: A systematic review and meta-analysis

Background

Both catheter and surgical ablation strategies offer effective treatments of atrial fibrillation (AF). The hybrid (joint surgical and catheter) ablation for AF is an emerging rhythm control strategy. We sought to determine the efficacy and safety of hybrid ablation of AF.

Methods

Systematic review and meta-analysis interrogating PubMed, EMBASE, and Cochrane databases from January 1, 1991, to November 30, 2017, using the following search terms: “Cox-maze,” “mini-maze,” “ablation methods (including radiofrequency, cryoablation, cryomaze),” and “surgery.” Included studies required ablation procedures to be hybrid and report rhythm follow-up.

Results

We included 925 patients with AF (38% persistent, 51% longstanding persistent) from 22 single-center studies (mean follow-up of 19 months). The surgical lesion set consisted of pulmonary vein isolation (n = 11) or box lesion (n = 11) with variable additional linear ablation. This was followed by sequential (n = 9), staged (n = 9), or combination (n = 4) catheter-based ablation to ensure isolation of pulmonary veins and to facilitate additional ablation or consolidation of surgically ablated lines. Overall, sinus rhythm maintenance was 79.4% (95% confidence interval [CI], 72.4-85.7] and 70.7% (95% CI, 62.2-78.7) with and without antiarrhythmic drugs, respectively at 19 ± 25 (range, 6-128) months. The use of the bipolar AtriCure Synergy system and left atrial appendage exclusion conferred superior rhythm outcome without antiarrhythmic drugs (P ≤ .01). The overall complication rate was 6.5% (95% CI, 3.4-10.2): mortality 0.2% (95% CI, 0-0.9); stroke 0.3% (95% CI, 0-1.1); reoperation for bleeding 1.6% (95% CI, 0.6-3.0); permanent pacing ~0% (95% CI, 0-0.5); conversion to sternotomy 0.3% (95% CI, 0-1.1); atrioesophageal fistula ~0% (95% CI, 0-0.5); and phrenic nerve injury 0.3% (95% CI, 0-1.1).

Conclusions

Hybrid ablation therapy for AF demonstrates favorable rhythm outcome with acceptable complication rates.

We Know What the Cardiac Surgeon Did During Last Hybrid Arrhythmia Procedure

Superior vena cava (SVC) is an important source of origin of atrial fibrillation (AF) triggers other than a pulmonary vein. Because of the proximity of SVC-aorta ganglionic plexi to the SVC and the extension of myocardium in the SVC from the right atrium, SVC frequently becomes an important source of ectopic beats initiating AF. The potential complications of SVC isolation may include sinus node injury. Sinus node isolation was observed in a patient who had undergone previous surgical isolation of SVC for AF, while attempting to ablate endocardially, near the superior part of interatrial septum for an atrial tachycardia.

Contact Force and Atrial Fibrillation Ablation

Catheters able to measure the force and vector of contact between the catheter tip and myocardium are now available. Pre-clinical work has established that the degree of contact between the radiofrequency ablation catheter and myocardium correlates with the size of the delivered lesion. Excess contact is associated with steam pops and perforation. Catheter contact varies within the left atrium secondary to factors including respiration, location, atrial rhythm and the trans-septal catheter delivery technology used. Compared with procedures performed without contact force (CF)-sensing, the use of this technology has, in some studies, been found to improve complication rates, procedure and fluoroscopy times, and success rates. However, for each of these parameters there are also studies suggesting a lack of difference from the availability of CF data. Nevertheless, CF-sensing technology has been adopted as a standard of care in many institutions. It is likely that use of CF-sensing technology will allow for the optimization of each individual radiofrequency application to maximize efficacy and procedural safety. Recent work has attempted to define what these optimal targets should be, and approaches to do this include assessing for sites of pulmonary vein reconnection after ablation, or comparing the impedance response to ablation. Based on such work, it is apparent that factors including mean CF, force time integral (the area under the force-time curve) and contact stability are important determinants of ablation efficacy. Multicenter prospective randomized data are lacking in this field and required to define the CF parameters required to produce optimal ablation.

Effective contact and outcome after pulmonary vein isolation in novel circular multi-electrode atrial fibrillation ablation

Introduction

Pulmonary vein (PV) reconnection is frequently the cause of recurrence of atrial fibrillation (AF) after ablation. The second-generation gold multi-electrode ablation (Gold-MEA) catheter has a new design possibly resulting in improved lesion formation compared with its predecessor. We aimed to determine the association between effective radiofrequency applications with the Gold-MEA catheter and outcome after AF ablation.

Methods

50 consecutive patients with paroxysmal AF underwent Gold-MEA (PVAC GOLD^TM, Medtronic Inc.) ablation. The Gold-MEA catheter was navigated to the PV ostium by fluoroscopy. Duty-cycled radiofrequency ablations were performed at all PV ostia. Lesions were considered transmural when electrode temperature was >50 °C and power >3 W for >30 seconds. After the ablation procedure, patients visited the outpatient clinic at 3‑month intervals including 24-hour Holter ECGs.

Results

Mean age was 56 years. All PVs were acutely isolated with the Gold-MEA catheter. Procedure time was 111 ± 22 minutes, ablation time was 24 ± 6.7 minutes and fluoroscopy time was 20 ± 8.1 minutes. No procedure-related complications were observed. One year after ablation, 60 % of patients were still free of arrhythmia recurrences after a single PV isolation attempt. The number of transmural lesions was associated with arrhythmia-free survival: 25.0 % in <72 transmural lesions, 64.3 % in 72–108 transmural lesions and 71.4 % in >108 transmural lesions (p = 0.029).

Conclusion

PV isolation can be performed successfully with the Gold-MEA catheter, with a favourable safety profile. Transmurality of lesions was associated with ablation success and may improve AF ablation success.

Hybrid ablation for atrial fibrillation: a systematic review

PURPOSE

Hybrid ablation for AF is performed in a growing number of centers. Due to absence of guidelines, operative approaches and perioperative care differ per center. In this review, an overview of findings from published studies on hybrid ablations is given, and related topics are discussed (e.g., one- and two-stage approaches, lesion sets, and patient management).

METHODS

A systematic literature search was performed in the PubMed and Embase databases. All identified articles were screened and checked for eligibility by the two authors.

RESULTS

Twelve studies describing a total of 563 patients were selected. Due to substantial differences in approaches (one-stage, two-stage, sequential), surgical techniques (bilateral or monolateral thoracoscopy, subxiphoideal, transabdominal), energy sources (unipolar, bipolar), lesion sets (applying left or right atrial lesions), periprocedural care and endpoints (monitoring, definition of recurrence), and success rates (sinus rhythm after a mean of 26 months) are difficult to compare and varied from 27 % (without antiarrhythmic drugs, AADs) to 94 % (with AADs). For studies using bipolar devices, success rates with the use of antiarrhythmic drugs were at least 71 %. Major complications such as bleeding, sternotomy, and death occurred in 7 % of the total population (of which ten complications, 16 %, occurred in the concomitant cardiac surgery hybrid group).

CONCLUSION

The field of AF ablation has dramatically changed over the past years, with one of the most recent developments the hybrid AF ablation. Lack of matching data hinders drawing conclusions and creating guidelines. Early results however are encouraging. More data are awaiting and needed.

Cryoablation in persistent atrial fibrillation - a critical appraisal

Ablation of atrial fibrillation is an established treatment for the management of patients with paroxysmal and persistent atrial fibrillation. The complex pathophysiology of persistent atrial fibrillation has fuelled the concept of adjunctive substrate modification on top of pulmonary vein isolation. However, recent studies have failed to demonstrate additive benefit from complex ablation approaches, thus supporting that standalone pulmonary vein isolation may prove sufficient, at least as the initial ablation strategy in persistent atrial fibrillation. In this premise, the new-generation cryoballoon is an attractive option in this demanding subgroup of patients due to its reliable efficacy in achieving pulmonary vein isolation combined with collateral debulking of the neighbouring atrial myocardium. In this review, we present a critical appraisal of the role of cryoablation in patients with persistent atrial fibrillation, discussing related technical considerations and existing scientific evidence.