The value of extensive catheter linear ablation on persistent atrial fibrillation (the CLEAR-AF Study)
Introduction
Catheter ablation for persistent atrial fibrillation (PerAF) is still challenging due to its high recurrence rate. A recently published meta-analysis analyzed one hundred and thirteen studies including 18 657 patients who underwent various ablation approaches for the treatment of PerAF and found out that the efficacy of a single AF ablation procedure for PerAF or long-standing PerAF was just 43% [1]. Previously published STAR AF II trial indicated that additional linear ablation or ablation of complex fractionated electrograms is not superior to pulmonary vein isolation (PVI) alone [2]. Therefore, the ablation strategy for PerAF is currently at a bottleneck stage and deserves further exploration.
Cox maze III approach with extensive additional linear scar creation in atria resulted in nearly 90% maintenance of sinus rhythm (SR) 10 years after surgery and thus had been recognized as the most effective strategy for PerAF [3]. Additional linear ablation strategy for PerAF patients was rooted in such surgical approach. Unlike surgical incision, incomplete transmural lesions and post-ablational reconnection result in poorer outcomes of radiofrequency ablation compared with the Cox maze procedure. Our team performed additional linear ablation of the anterior wall (LAAW) in previous studies to increase the chances of blocking the roof and isthmus of left atrium (LA) and achieved a good short-term and medium-term maintenance of SR in atrial fibrillation (AF) patients [4,5]. This study was aimed to evaluate the efficacy and safety of the approach with PVI plus extensive linear ablation (Supplementary Fig. 1) combined with contact force sensing techniques for PerAF. Base on the insufficiency of PVI alone and the brilliant clinical outcome of surgical procedure for the PerAF patients, this study was also designed to clarify “more lesions” or “fewer lesions” would be a reasonable option for PerAF ablation strategy.
Section snippets
Study design
The CLEAR AF trial was designed as a prospective, randomized, multicenter trial (NCT02892162). It was approved by the respective ethics committees at each center. The written informed consent was obtained from all patients. Patients with PerAF or long-standing PerAF were recruited from five experienced centers. Patients were prospectively and randomly assigned to two groups according to the strategies of radiofrequency catheter ablation:
Group I (n=107): PVI + LA roof linear ablation + LAAW
Patients characteristics
In this multiple center study, 214 patients were consecutively enrolled. A total of 209 (97.7%) patients (104 in Group I and 105 in Group II) completed the 24 months follow-up. The clinical characteristics are shown in Table 1. There were no significant differences in any of the assessed baseline characteristics.
Procedural parameters
The procedural parameters are summarized in Supplementary Table 1. Mitral isthmus linear ablation was performed in 72 patients in Group I and 83 patients in Group II respectively.
Discussion
In this multicenter randomized trial, we observed the value of extensive linear ablation in PerAF patients. Compared with control group, extensive linear ablation increased the acute success rate of AF termination during ablation, although it did not reduce the recurrence rate of AF/AT in 24 months follow up. However, the recurrence in the group with extensive lines was more often as AT, which can be precisely mapped during repeat procedure. Furthermore, extensive linear ablation had a higher
Limitations
There are some limitations to this study. Firstly, different pacing is the best method to check the bidirectional block across the linear lesions. However, the judgment of this technique would be affected by three linear lesions created in the LA, and also considering the feasible application in five EP centers, we did not evaluate bidirectional block of each linear lesion due to technical concerns. However, we performed high output pacing at each lesion to confirm transmurality and delivered
Conclusions
This trial demonstrated that extensive linear ablation with contact force monitoring did not improve the long-term outcomes for PerAF patients. Repeat ablation procedure showed a possible higher chance of sinus rhythm restoration during follow-up.
Sources of funding
This work was supported by the Investigator-Initiated Study Program of Biosense Webster, Inc.
Disclosures
Dr. Yao, Dr. He, Dr. Shi, Dr. Zhang, and Dr. Cai received research grants from Biosense Webster. The other authors report no conflicts.
Acknowledgements
The authors acknowledge Xiaomang Wang and Yongming Huang for their technical support in electrophysiological mapping.
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These authors contributed equally to this work.