Aim: Atrial fibrillation (AF) is accompanied by the lack of contractile function and successive progression of atrial volumes. Endoscopic microwave pulmonary isolation represents a new technique of AF ablation (the isolation of pulmonary veins by epicardial approach). The aim of the study was to assess the function and size of left atrium (LA) after successful proceduře. Methods: 11 patients with symptomatic paroxysmal or persistent AF were prospectively studied. All of them underwent an ablation proceduře. The efficacy of the proceduře was assessed by 48 h. Holter recordings 1 and 3 months after the proceduře, only 9 patients with full restoration and maintenance of sinus rhythm were analyzed. Echocardiography was performed before (baseline), then 1 and 3 months following the proceduře. Parameters studied were: left LA diameter (DS), maximal volume of LA during ventricular systole (ESV), minimal volume of LA during ventricular diastole (EDV), and ejection fraction of LA (LAEF). Peak velocity of atrial contraction (A velocity), velocity time integrál of the A wave (AVTI) and peak velocity of mitral annular motion in latě diastole (Aa) were measured by Doppler or tissue Doppler respectively. Results: Compared with baseline values, EDV volume decreased significantly 3 months after the proceduře (EDV 53,9±14,9 ml vs. 47,4±16,2 ml, p<0.05). Furthermore, transient decrease of LA mechanical function (LAEF, Aa, A velocity) was observed one month after proceduře with the recovery at 3 m. (LA EF 35,3±5,2 % vs. 32,4±7,8 %, Aa 6,52±0,83 cm/s vs. 6,5511,16 cm/s, Avel: 0,55±0,04 m/s vs. 0,55±0,l m/s, all p=n.s.). Conclusion: The successful restoration and maintenance of sinus rhythm by EndoMaze proceduře is associated with progressive decrease of EDV. However, the contractile function of LA is transiently decreased shortly after procedure.

        Key words: atrial fibrillation, ablation, pulmonary vein isolation, left atrium, mechanical function of left atrium.