Mitral blood flow and insufficiency in patients with atrial fibrillation and restored sinus rhythm

Atrial fibrillation (AF) is the most common arrhythmia, affecting 1.5-2% of the general population. It is characterized by a loss of atrial contraction, which favors the formation of thrombi. Although thromboembolic events often occur immediately after cardioversion, such events have been described several days to weeks after it in patients who have apparently maintained sinus rhythm. Atrial mechanical contraction is reduced after cardioversion, despite normal atrial depolarization on ECG. Evaluation of mitral blood flow with pulse-Doppler echocardiography reflects the left atrial function. Several authors show that immediate peak A velocity and percent A-wave velocities are significantly lower in patients with AF of moderate (2-6 weeks) and prolonged (more than 6 weeks) duration compared to patients with AF of brief (less than 2 weeks) duration. Full recovery of atrial mechanical function is achieved within 24 hours for patients with brief duration, within 1 week for the moderate duration and within 1 month for prolonged duration AF. Transient depression and following improvement in atrial mechanical function are also demonstrated after ablation of pulmonary veins. Two months after maze procedure 40% of the patients have no transmitral A wave. It is found that the effective mechanical atrial function (EMAF) is likely to recover earlier in patients after pharmacological or spontaneous cardioversion than in those after electrical cardioversion (EC). The effect of the mode of cardioversion on recovery of EMAF is not statistically significant at 1 week after cardioversion, implying that the possible detrimental effect of electrical current on atrial function is an early phenomenon and wears off between 3 and 7 days after cardioversion. Cardiac stunning after EC is well known and could lead to the development of severe mitral regurgitation (MR), due to restrictive movement of leaflets. The transient character of the MR favors a functional origin with an alteration in the geometry of the mitral apparatus. Data on mitral flow and MR in 56 consecutive patients with restored sinus rhythm are presented.Key words: atrial fibrillation, cardioversion, mitral blood flow, mitral regurgitation