Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic Inc Background The progression of atrial fibrillation (AF) after the first clinical AF episode is not well known. AF burden is of clinical significance as it may have clinical implications concerning the long-term management of the arrhythmia and the decision-making on AF patients. Continuous rhythm monitoring via implantable loop recorders (ILRs) can precisely evaluate the AF recurrence profile. Purpose To observe the AF progression and AF burden in patients after their first clinical AF episode. Methods Thirty consecutive patients (age 66.9 ± 10 years; 14 men) received an ILR after their first clinical AF episode. We recorded the AF recurrences and burden during a follow-up period of three years. We excluded patients with persistent or permanent AF and patients with an episode of AF attributed to reversible or transient causes. Results Three patients (10%) had no AF recurrence, whereas 4 patients (13.3%) presented only one episode. Almost half of the patients (46.7%) had a low recurrence rate (<5 episodes/year), whereas the majority of patients (19/30) suffered from episodes with maximum duration ≤24 hours. Eleven patients (36.7%) presented either no episode or a low recurrence rate with episodes lasting ≤24 hours. In 16 patients (53.3%) the AF burden was increased during the second year of follow-up period while in 9 patients (30%) the AF burden was decreased. During the third year of follow-up period the AF burden was increased in 19 patients (63.3%), decreased in 7 patients (23.3%) and remained almost the same in 4 patients (13.3%). Five patients (16.6%) presented at least one episode of persistent AF during the follow-up period. Seven patients (23.3%) suffered only from symptomatic AF episodes, while in nine patients (30%) only asymptomatic AF episodes were recorded. Eleven patients (36.7%) had both types of AF episodes (symptomatic and asymptomatic). Conclusions The AF recurrences and burden increased in most AF patients. However, a significant percentage of patients either suffer no AF recurrence after their first symptomatic episode or show a low recurrence rate. Most patients present episodes of short duration. Paroxysmal AF clinical profile differed significantly among the patients. If these findings are confirmed in larger studies, they could have clinical implications ensuring individualized management of the arrhythmia in the future in newly diagnosed AF patients.