Cather ablation of non-paroxysmal atrial fibrillation is less effective compared to paroxysmal atrial fibrillation. Therefore, new techniques have been developed, such as high-density mapping to determine areas of focal and rotational activities. The aim is to assess the clinical efficacy of ablation focal and rotational activities, and to assess the relation between the areas of focal and rotational activities with fibrosis of both atria assessed using magnetic resonance.