Study limitations:
An important limitation of our study is its single-center design and relatively small study group. In addition, this is not a prospective clinical study indicating the relationship between ECG parameter and long term prognosis. As our measurement method using the electrophysiological recording system is extremely precise we are aware, that our results could not be comparable directly to the results of other authors. We’ve already mentioned, the duration of persistent form of the arrhythmia could not be exactly estimated. Because our hypothesis is the prolongation of the duration of the P wave is mainly related to atrial fibrillation itself, it should be assumed as the main limitation of our study, even if the literature data contradict the correlation between the arrhythmia duration and P wave prolongation [16].