There are controversies regarding the possibility of returning of A wave (mitral flow at left atrial contraction) after electroconversion (EC) in patients with persisting chronic atrial fibrillation in spite of successful surgical treatment of mitral valve disease. Twenty-four hours before successful EC, thereafter daily for 1 week and then on the 14th, 21st and 28th day and 6 months after EC, ECG, M-mode, two-dimensional and Doppler echocardiography were performed in 55 patients. A wave ( > 0.1 m/s) appeared on the 1st day in 31 patients, on the 2nd day in the next 6, on the 3rd in 5 patients, on the 4th and 5th days in 1 patient and on the 7th day in 4 patients. In 7 patients A wave did not restore. Maximum velocity of A wave increased from 0.48 ± 0.22 to 0.86 ± 0.28 m/s (p < 0.05) during the follow-up. In 92% of patiens with A wave 24 h after EC, significant increases in stroke index from 35 ± 12 to 47 ± 15 ml/m<sup>2</sup> (p < 0.04), ejection fraction from 46 ± 9 to 55 ± 8% (p < 0.01) and pulmonary acceleration time from 94 ± 26 to 107 ± 22 ms (p < 0.05) were observed. Sinus rhythm was still present on the 28th day in 34 patients (62%) and after 6 months in 31 patients (57%), all of them with A wave, observation shows the increase in pulmonary acceleration time, the decrease in the left atrial area and the increase in its systolic function in patients with A wave. Appearance of A wave determined the hemodynamic improvement, but we did not observe a correlation between maximal velocity of A wave and hemodynamic improvement. Appearance of A wave had a low predictive value for maintaining sinus rhythm (sensitivity 58% and specificity 45%). Relative increase in A wave velocity during the 1st week after EC correlated positively with long-term maintenance of sinus rhythm (r = 0.62; p < 0.001).