Because of the high recurrence rates following electrical cardioversion and high morbidity in AF patients there is a need to explore prediction models for AF recurrence following ECV. Previous studies have primarily focused on high-sensitivity CRP (hsCRP), CRP, and IL-6, while other inflammatory indexes and gene scores might hold greater value. This prospective cohort study is planning to include 182 patients with persistent atrial fibrillation, planned for electrical cardioversion, and \>18 years at two medium-sized hospitals in Sweden. Blood samples will be collected prior to electrical cardioversion and at 7-, 30-, 90-, and 180-days follow-up. Atrial fibrillation recurrence will be evaluated at follow-up or upon patient request and diagnosed with 12-lead ECG. An interim analysis will be conducted after more than 80 patients have been included. If the results from univariate and/or multivariable logistic regression on inflammatory markers and genetic expression regarding atrial fibrillation recurrence are significant, the study will be concluded.