Thoracoscopic surgical ablation versus catheter ablation as first-line treatment for long-standing persistent atrial fibrillation: the CASA-AF RCT
Authors: Haldar Shouvik , Khan Habib R , Boyalla Vennela , Kralj-Hans Ines , Jones Simon , Lord Joanne , Onyimadu Oluchukwu , Sathishkumar Anitha , Bahrami Toufan , Clague Jonathan , De Souza Anthony , Francis Darrel , Hussain Wajid , Jarman Julian , Jones David G , Chen Zhong , Mediratta Neeraj , Hyde Jonathan , Lewis Michael , Mohiaddin Raad , Salukhe Tushar , Murphy Caroline , Kelly Joanna , Khattar Rajdeep , Toff William D , Markides Vias , McCready James , Gupta Dhiraj , Wong Tom 
Published: November 2021

Background
Standalone thoracoscopic surgical ablation may be more effective than catheter ablation in patients with long-standing persistent atrial fibrillation.

Objectives
To determine whether or not surgical ablation is clinically superior to catheter ablation as the first-line treatment strategy in long-standing persistent atrial fibrillation.

Design
This was a prospective, multicentre, randomised control trial.

Setting
Four NHS tertiary centres in England.

Participants
Adults with long-standing persistent atrial fibrillation, who had European Heart Rhythm Association symptom scores > 2 and who were naive to previous catheter ablation or thoracic/cardiac surgery.

Interventions
Minimally invasive thoracoscopic surgical ablation and conventional catheter ablation (control intervention).

Main outcome measures
The primary outcome was freedom from atrial fibrillation/tachycardia ≥ 30 seconds after a single procedure without antiarrhythmic drugs (class 1C/3) at 1 year, excluding a 3-month blanking period. The secondary outcomes include the intervention-related major complication rate; clinical success (≥ 75% reduction in arrhythmia burden); and changes in symptoms, quality of life and cost-effectiveness.

Methods
Patients (n = 120) were randomised to surgical ablation (n = 60) or catheter ablation (n = 60). An implanted loop recorder provided continuous cardiac monitoring following ablation. Follow-up visits were at 3, 6, 9 and 12 months. Loop recorder data were reviewed monthly by a physiologist who was blinded to the randomisation outcome.

Results
The study treatment was received by 55 patients in the surgical ablation arm and 60 patients in the catheter ablation arm; five patients withdrew from surgical ablation before treatment. Data from randomised and treated patients were analysed as per intention to treat. Patients had a mean age of 62.3 (standard deviation 9.6) years, were predominantly male (74%), had a mean left atrial diameter of 44.6 mm (standard deviation 6 mm) and were in continuous atrial fibrillation for 22 months (range 16–31 months). At 12 months, 26% of patients in the surgical ablation arm (14/54) and 28% of patients in the catheter ablation arm (17/60) were free from atrial arrhythmias after a single procedure without antiarrhythmic drugs (odds ratio 1.13, 95% confidence interval 0.46 to 2.83; p = 0.84). An arrhythmia burden reduction of ≥ 75% was seen in 36 out of 54 (67%) patients in the surgical ablation arm, compared with 46 out of 60 (77%) patients in the catheter ablation arm (odds ratio 1.64, 95% confidence interval 0.67 to 4.08; p = 0.3). Procedure-related serious complications within 30 days of the intervention occurred in 15% (8/55) of patients in the surgical ablation arm (including one death) compared with 10% (6/60) of patients in the catheter ablation arm (p = 0.46). Surgical ablation was associated with significantly higher costs (£23,221 vs. £18,186; p = 0.02) and fewer quality-adjusted life-years than catheter ablation (0.76 vs. 0.83; p = 0.02).

Limitations
This study was conducted in four highly specialised cardiology centres that have substantial experience in both treatment modalities; therefore, the results may not be widely generalisable. The study was not powered to detect small differences in efficacy.

Conclusions
We found no evidence to suggest that standalone thoracoscopic surgical ablation outcomes were superior to catheter ablation outcomes in achieving freedom from atrial arrhythmia after a single procedure without antiarrhythmic drugs. Moreover, surgical ablation is associated with a longer hospital stay, smaller improvements in quality of life and higher health-care costs than catheter ablation (standard care therapy).

Future work
Evaluation of the impact of ablation treatments on sinus rhythm maintenance and quality of life with extended follow-up to 3 years. Model-based economic analysis to estimate long-term benefits, harms and costs of surgical and catheter ablation compared with antiarrhythmic drug therapy in long-standing persistent atrial fibrillation patients.

Trial registration
Current Controlled Trials ISRCTN18250790 and ClinicalTrials.gov NCT02755688.

Funding
This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council (MRC) and National Institute for Health Research (NIHR) partnership. This study was supported by the UK Clinical Research Collaboration-registered King’s Clinical Trials Unit at King’s Health Partners, which is part funded by the NIHR Biomedical Research Centre for Mental Health at South London and Maudsley NHS Foundation Trust and King’s College London and the NIHR Evaluation, Trials and Studies Coordinating Centre. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 8, No. 18. See the NIHR Journals Library website for further project information.