A multicentre randomized control study of atrial fibrillation in heart failure (CAMERA-MRI)

Arm 1 - Catheter Ablation Catheter ablation of AF is a minimally invasive procedure (involving the use of specialized instruments through the groin to make a small burn in the area of the heart that is responsible for irregular heart rates) which can eliminate AF in many patients. However in patients with AF and HF, it is currently difficult to identify those in whom the AF is causing or significantly contributing to the HF. Such patients may benefit from catheter ablation. Patients with HF display a unique pattern of scarring in the heart muscle capable of being detected by magnetic resonance imaging (MRI). The amount of scarring in the heart muscle appears proportional to the degree of reversibility of HF. Thus in patients with AF and HF, we propose that MRI may help identify those patients whose HF is most likely to improve, or even completely reverse, following catheter ablation. In this way, catheter ablation may become a useful tool in the treatment of patients with AF and HF. Catheter ablation will be guided using a 3D mapping system with integration of the left atriogram obtained at the time of MRI. Ablation is performed with an irrigated tip catheter to encircle the left and right sided pulmonary veins (PV) in pairs 1-2 cms from their ostia as defined by PV angiography and the 3D map. At the anterior aspect of the left PVs, ablation is performed along the ridge between the Left Atrial Appendage (LAA) and the PV ostia. The PVs are continuously assessed for electrical disconnection using the circular mapping catheter. If AF continues following PV electrical isolation further substrate modification is at the discretion of the operator and may include (i) linear ablation – a roof line joining the superior aspects of each wide encirclement ablation ring and an inferior LA line to achieve electrical isolation of the posterior LA wall or a mitral isthmus line and/or (ii) complex fractionated electrograms - left and right atria are mapped systematically for fractionated potentials which are then targeted for ablation. The procedure takes approximately 2-4 hours.