Title: Catheter Ablation Versus Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation (CASA-AF)
Funder: Medical Research Council

Abstract: INTRODUCTION Atrial fibrillation (AF) is the commonest arrhythmia worldwide. Its sequelae, especially stroke and heart failure, cause significant morbidity and mortality, resulting in an increasing public health burden for an ageing population. Long-standing persistent AF (LSPAF) is the most difficult type of AF to treat. For those with highly symptomatic LSPAF successful restoration of sinus rhythm (SR) is highly preferred, but unfortunately, very difficult to achieve with anti-arrhythmic drug therapy (AAD). There are two potential routes to cure. First, percutaneous catheter ablation (CA), which has been well studied. Second, surgical ablation, which comparatively has received less attention. CA applies radiofrequency (RF) ablation to critical areas of the heart to restore normal SR. For early stage AF ('paroxysmal AF') this procedure can deliver 78% success at a single procedure but in later stages, such as LSPAF, the single procedure success for CA is ~ 40% in most studies conducted [1]. Multiple procedures are often required to improve the clinical outcome which is expensive, unpleasant and confers additional risk. There was a historical surgical approach to ablation consisting of multiple surgical incisions (‘surgical maze’) to compartmentalise the atrial tissue to restore SR. Long term results from this approach are excellent (>90% success at 5 years), but it was a technically difficult open heart procedure with significant morbidity and mortality and therefore seldom used. Advances in surgery has led to thoracoscopic surgical techniques (closed heart or keyhole surgery) which allows the application of RF ablation (to recreate the surgical incision effect) to be conducted under direct vision without opening the chest. This recently developed technique offers clear advantages for patients with greater safety and less discomfort compared to traditional surgical ablation, but with the potential of recreating its excellent results. As CA is less invasive and very effective in paroxysmal AF, thoracoscopic surgical ablation is unlikely to play a major role in treating this group of patients. It is in the persistent forms of AF where it may have a role which has informed our choice of study population. To date, data on the clinical success of thoracoscopic surgical ablation in treating LSPAF is limited. A non-randomised study in persistent AF demonstrated an 80% single procedure success rate at 1 year (without AAD) [2]. There has one key randomised control trial (RCT) comparing CA with thoracoscopic surgical ablation which unfortunately recruited a mixture of paroxysmal and persistent AF patients (predominantly paroxysmal). Although the results were favourable towards surgical ablation, the procedural methods are heterogenous making the results difficult to interpret [3]. In our pilot study, 21 patients with LSPAF have undergone thoracoscopic surgical ablation and 17 patients have completed 6 months' follow-up with 76% were free from atrial arrhythmia after a single procedure compared with 44% in the catheter ablation group. There were no operative deaths.The preliminary results suggest that the procedure is safe and superior to CA. There is, therefore, a pressing need for a careful, unbiased, prospective evaluation taking into account patient quality of life assessments and a comprehensive health economic evaluation.There are no RCTs comparing these two modalities of treatment specifically in LSPAF. HYPOTHESIS Thoracoscopic surgical ablation has superior single procedure efficacy than catheter ablation in restoring sinus rhythm at one year. AIMS 1. To identify the most effective ablation strategy in treating patients with LSPAF. 2. To relate the effectiveness of the ablation techniques to quality of life. 3. To compare the cost-effectiveness of the two ablation techniques in treating AF. DESIGN A multi-centre, prospective, randomised controlled trial.


Research activity codes: 6.5 RADIOTHERAPY AND OTHER NON-INVASIVE THERAPIES
Health categories: CARDIOVASCULAR