The purpose of this study was to explore the role of structural and functional characteristics of the myocardium, heart rate variability (HRV) and electrophysiological data on the frequency and duration of paroxysms of atrial fibrillation (AF). The study included 343 pts with paroxysmal AF of non-valvular genesis. These subjects were divided into groups according to frequency and duration of paroxysms: group 1a – 263 pts with frequent paroxysms of AF (≤ 1/week), group 1b group – 80 pts with rare (< 1/week) paroxysms; group 2a – 291 pts with duration of paroxysms ≤ 48 hours, group 2b – 52 pts with duration of paroxysms > 48 hours. The following methods were used in the study: two-dimensional and Doppler echocardiography, Holter ECG monitoring and HRV analysis. The function of the heart conducting system and atrium vulnerability were explored by
transesophageal electrophysiological examination. Atrium vulnerability was evaluated by AV frequency point and ff med interval duration. Significant differences have been revealed in two groups based on the size of left atrium (LA) and LA index. Atrium vulnerability increase in patients with frequent paroxysms of AF was associated with significant decrease in atrioventricular frequency point, ff medium interval duration and diminished
parasympathetic tone. Our study revealed correlation between LA index and threshold of AF inducibility (r1=0.612; P<0.05) in patients with frequent AF paroxysms. In patients with AF paroxysms duration > 48 hours
LA index correlated with ff medium interval (r2=–0.772; P<0.005). Our findings implay relationship between LA dilatation, AF paroxysm onset and duration.