Percentage of fibrosis
We calculated a surrogate of fibrosis studying the percentage of LVA with 0.5 mV threshold. This percentage was calculated as the relationship between the area with voltage <0.5mV and the total area. We analysed it in both maps (AF and SR). In a newly created qualitative variable to assess fibrosis, we assigned a value of 1 when the percentage of LVA was greater than 5%.