Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with significant morbidity and mortality. Historically, anti-arrhythmic drug (AAD) therapy achieves sub-optimal efficacy. The last two decades have seen major advances in cardiac electrophysiology, with catheter ablation now becoming the treatment of choice for AF. However, although outcomes for paroxysmal AF are excellent, the optimal interventional strategy for patients with long-standing persistent atrial fibrillation (LSPAF) has yet to be determined. Catheter ablation in LSPAF can achieve a modest degree of success, but the majority of patients require more than one procedure. Thoracoscopic surgical ablation, a relatively new technique, with the potential to improve clinical outcomes in AF, has yet to be evaluated in a head-to-head trial in LSPAF.
The Catheter Ablation Versus Thoracoscopic Surgical Ablation in Persistent Atrial Fibrillation (CASA-AF) was a prospective, non-randomised clinical trial, designed to investigate de novo patients with LSPAF and left ventricular ejection fraction (LVEF) of ≥ 40%. Patients underwent either thoracoscopic surgical ablation or catheter ablation. The primary end-point was freedom from atrial arrhythmias after a single procedure without AADs. Secondary end-points included: clinical success (defined as 75% or greater reduction in AF burden), multi-procedure success, change in atrial anatomy and function, and change in AF symptom score (EHRA score) and quality of life assessments (SF-36).
This thesis aims to investigate the interventional techniques used in the management of AF, with the main focus on the CASA-AF study. In addition, the Complex Fractionated Atrial Electrogram sub-study assesses the atrial substrate and its role in AF, whilst the Cardiac Magnetic Resonance sub-study investigates the changes in atrial and ventricular chambers pre- and post-ablation. The final study presented in this thesis concerns the effects of using exciting new Contact Force technology on the acute efficacy of pulmonary vein isolation in AF ablation.