Atrial Fibrillation (AF) is a common arrhythmia with a prevalence of 1.5-2%. This prevalence increases significantly after 80 years of age. After the appearance of first episode(s) some of the patients will present frequent arrhythmia recurrences moving from the paroxysmal status to the persistent and the permanent status of the continuous spectrum of the natural time course of AF. In contrast some other will not present further relapses. To study and predict the dynamic evolution of AF is clinically important, furthermore, the detection of different sub populations risk for AF relapses will determine and different therapeutic approaches.

Atrial Fibrillation (AF) is a common arrhythmia with a prevalence of 1.5-2%. This prevalence increases significantly after 80 years of age. In the presence of the Arrhythmia the risk of stroke increases five fold while the congestive heart failure and the mortality rates are increasing significantly also.After the appearance of first episode(s) some of the patients will present frequent arrhythmia recurrences moving from the paroxysmal status to the persistent and the permanent status of the continuous spectrum of the natural time course of AF. In contrast some other will not present further relapses. To study and predict the dynamic evolution of AF is clinically important, furthermore, the detection of different sub populations risk for AF relapses will determine and different therapeutic approaches. The study will include > 500 patients 30-80 years old. Inclusion criteria is one up to five paroxysmal AF (PAF) episodes during the last three years. Patients during screening must maintaining Sinus Rhythm. Exclusion criteria are substrate of severe valvular diseases, congenital heart disease, previous heart surgery, hyperthyroidism, severe diseases of the autonomic nervous system, alcoholism, diseases affecting seriously the survival and absence of adequate cooperation for the study. Screening will include 12 lead surface digital ECG, 30 min High Resolution (1000 Hz) ECG recording from 3 pseudo orthogonal x,y,z leads system, and complete ECHO study (2D, PWD, TDI, Strain).Among other indices will be analyzed: P duration, P index, P dispersion, P wave signal for Late potentials, for Wavelets, PQ/RR Dynamics, Heart Rate Dynamics and various markers for the autonomic nervous system status.Primary end point is one or more PAF relapse(s) during a period of 12 months after recruitment in study.Secondary end point is permanent AF during a period of 36 months after recruitment in study.

Inclusion Criteria:

• Inclusion criteria is one up to five paroxysmal AF (PAF) episodes during the last three years. Patients during screening must maintaining Sinus Rhythm.

Exclusion Criteria:

• previous heart surgery, hyperthyroidism, severe diseases of the autonomic nervous system, alcoholism, diseases affecting seriously the survival and absence of adequate cooperation for the study

The study will include > 500 patients 30-80 years old.