The aim of our study was to verify the effi ciency of catheter ablation of atrial fi brillation (CA AF) according to the "atrial fi brillation (AF) burden"(time spent in AF) and symptoms related to AF. METHODS: We retrospectively analysed a selected set of 133 patients with atrial fi brillation (81% men, 19% women) who underwent an invasive therapy in the form of CA AF and at the same time had an implanted longterm ECG loop recorder (Reveal XT) in a period of eight years. We investigated AF burden and objective symptoms of AF by data obtained from a long-term implantable ECG loop recorder. Subjective symptoms related to AF were identifi ed during outpatient controls. RESULTS: Firstly, our results demonstrate for the fi rst time a clinically relevant increase in the occurrence of asymptomatic episodes of AF after CA AF. Secondly, when analysing AF symptoms and AF burden at the same time, CA AF in terms of reduction of symptoms and shortening the time in AF had a better effect in patients undergoing 1 procedure (CA AF) compared to patients undergoing repeated procedures (re CA AF). CONCLUSION: The increase in the occurrence of asymptomatic episodes of AF is of considerable importance both for the clinical evaluation of ablation effi cacy and for individualized clinical management of patients, especially with respect to antithrombotic therapy (Fig. 10, Ref. 19). Text in PDF www.elis.sk. KEY WORDS:atrial fi brillation, symptoms of atrial fi brillation, atrial fi brillation burden, catheter ablation of atrial fi brillation, continuous ECG monitoring.