An interventional study of Catheter Ablation in Atrial Fibrillation (AF), sponsored by University College, London. Recruiting at 24 sites in 2 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-04.
Sponsored by University College, London · Not applicable, Interventional, and Prevention
Atrial fibrillation (AF) is a common heart rhythm disorder that causes an irregular heart beat and is a cause of heart failure (HF). Treatments include drugs to slow the heart rate, anti-arrhythmic drugs or ablation of the heart to help preserve normal rhythm. A number of trials have suggested that ablation may be superior to drug treatment to reduce hospitalisations or prevent early death. However, these studies have been small and the results not applicable to the general population with AF and heart failure in the UK. This international study will compare catheter ablation and optimal medical therapy versus optimal medical therapy alone to see if catheter ablation reduces unplanned heart failure hospitalisations and death rates and improves quality of life.
Atrial fibrillation (AF) increases the severity of, and death from, heart failure (HF). Several small studies have demonstrated that restoration of sinus rhythm by catheter ablation in patients with HF improves left ventricular (LV) function and exercise tolerance. What is unknown is whether or not AF ablation reduces all-cause death and urgent CV hospitalisations in populations with HF. The current trial will answer this outstanding question, which is faced by HF clinicians and electrophysiologists on a daily basis. AF ablation can be performed very effectively and efficiently using a cryo-balloon or radio-frequency ablation PVI technique. These techniques have evolved slowly and are unlikely to change substantially over the course of this trial. One small trial (n=363) in implantable cardioverter-defibrillator and CRT defibrillator recipients (CASTLE-AF) reported a death benefit of AF ablation but the patients were highly selected and the death reduction was far higher than real world expected differences. Recent studies have noted that the population randomised in CASTLE-AF was not representative of the general HF population with only 7% of patients in the "real world" setting meeting the trial entry criteria. CASTLE-AF is therefore provocative but inconclusive; it has made little change to clinical practice. As no studies have investigated the death benefit in a general HF population, the proposed trial is necessary and warranted. This study is designed as a randomised, open label multicentre clinical trial in which catheter ablation and medical therapy is compared to medical therapy alone in patients with HF with reduced ejection fraction (\<50%) and paroxysmal or persistent AF to determine if this reduces all-cause death and urgent CV hospitalisations as well as improving QoL. By utilising the clinical and research networks of the British Heart Failure Society and British Heart Rhythm Society (BHRS) we will recruit 1200 patients. The current trial will be almost three times the size of the only previous inconclusive trial which was reported in the New England Journal of Medicine.
3,870 studies on the registry are indexed under Atrial Fibrillation; 924 are open to participants now.
This study's planned enrollment of 1,200 is above the median of 144 across 2,380 interventional studies indexed under Atrial Fibrillation.
Browse Atrial Fibrillation studies →University College, London is the lead sponsor of 632 studies on the registry; 145 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 2 (33%) have results posted.
Counted across the registry records on this site, refreshed daily.
Patient with one of the following AF categories and at least one episode of AF documented (by any means eg ECG, Holter, Cardiac Implantable Electronic Device (CIED) interrogation or any other means):
LVEF \<50% (Cardiac imaging report of LVEF\<50% within 1 year (by echocardiography, cardiac magnetic resonance imaging or nuclear cardiology assessment)) AND after optimisation of medical therapy (see previous definition). Note - a LVEF of \<50% must be documented by any cardiac imaging performed after optimisation of medical therapy. Documentation of other baseline echocardiographic parameters (eg LA volume, E/E' etc can be obtained from any echocardiogram within 2.5 years). This allows a handheld or echocardiogram focused on LVEF assessment.
Exclusion criteria:
Participants randomised to the optimal medical therapy arm will receive optimal medical therapy according to the most contemporary ESC HF guidelines.
Catheter ablation is an established therapeutic strategy in patients without HF that aims to convert AF to sinus rhythm in symptomatic, drug-refractory AF in patients.
Procedure: Catheter Ablation
Participants randomised to the catheter ablation arm will undergo Pulmonary Vein Isolation (PVI) which is the essential ablation intervention. The technique used will be at the discretion of the treating physician but may include Cryoballoon (Medtronic/Boston Scientific), Radiofrequency: CARTO (Biosense), pulsed field radiofrequency ablation, or Precision (Abbott Medical) electro-anatomical mapping systems. Additional ablation lesions may be delivered as preferred by the operator and will be documented. Electro-anatomical voltage maps will be collected (in SR/AF) and stored for later analysis.
Time to first all-cause death and urgent CV hospitalisation
The primary outcome (time to first all-cause death and urgent CV hospitalisation) will be summarised by randomised group and analysed using a Cox proportional hazards regression model for time to first event, adjusting for factors used to balance the randomisation.
Time frame: 2 years minimum (range: 2-5.5 years)
Total (first and recurrent) all-cause death and urgent cardiovascular hospitalisations.
Total (first and recurrent) number of all-cause deaths and urgent cardiovascular-related hospitalisations. Joint frailty models will be used to analyse time to death and recurrent urgent CV hospitalisations simultaneously. Additionally, negative binomial regression will be used to analyse the number of recurrent urgent CV hospitalisations.
Time frame: 2 years minimum (range: 2-5.5 years)
QoL at 6 and 12 months assessed using the KCCQ-CSS.
Quality of Life (QoL) at 6 and 12 months assessed using the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS). Linear mixed effects regression models will be used to analyse repeated measurements of QoL. Scored from 0- 100, with a higher score indicating better health.
Time frame: 12 months
Time to all-cause death
Time to all-cause death will be analysed using Cox proportional hazards regression model for time to event, matching the primary outcome.
Time frame: 2 years minimum (range: 2-5.5 years)
Total (first and recurrent) all-cause death and urgent HF hospitalisations
Total (first and recurrent) number of all-cause deaths and urgent heart failure-related hospitalisations. Joint frailty models will be used to analyse time to death and recurrent urgent HF hospitalisations simultaneously. Additionally, negative binomial regression will be used to analyse the number of recurrent urgent HF hospitalisations.
Time frame: 2 years minimum (range: 2-5.5 years)
Cardiovascular death
Total number of cardiovascular-related deaths. Cox proportional hazards regression model for time to event, matching the primary outcome.
Time frame: 2 years minimum (range: 2-5.5 years)
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University College, London