A decrease of enlarged left atrium following cardioversion of atrial fibrillation predicts the long-term maintenance of sinus rhythm.

Background: Although increased left atrial size (LA) has been long regarded as one of the factors negatively influencing the long-term maintenance of sinus rhythm (SR) following cardioversion (CV) of atrial fibrillation (AF), some reports suggested that CV might be effective also in patients with large LA.Aim. We sought to determine the role of LA enlargement in long-term SR maintenance after CV of persistent AF.

Methods: 104 consecutive patients (33 females, 71 males, mean age 60.4+/-7.4 years) were assigned to SR restoration and maintenance with serial antiarrhythmic drugs. Transthoracic echocardiographic (TTE) variables were recorded prior to CV. Generalised additive logistic regression was used to investigate the impact of LA enlargement on the long-term SR maintenance.

Results: SR was present in 63.5% of patients after one year of follow-up. Increased LA area >28 cm (RR 1.72; 1.09-2.71; p<0.02) and increased fractional shortening values in ranges between 26-40% (1.2; 1.01-1.44; p<0.05) were significantly associated with SR maintenance after one year. In order to determine the influence of the LA diameter on the probability of SR maintenance, we analysed mean LA(ar) values prior to and after CV. Patients with large LA(ar) (28 cm(2)) presented a significant decrease of LA size (31.45+/-3.07 cm(2) vs 28.94+/-3.81 cm(2); p<0.008) during the first 30 days after SR restoration. In the group of patients with LA(ar) 28 cm(2) we noted decrease in LA size by 2.57+/-3.2 cm(2), whereas in patients with a smaller LA volume this decrease was significantly lower, being 0.47+/-2.9 cm(2) (p<0.004).

Conclusions: LA enlargement does not preclude a favourable outcome after CV of AF. The decrease in LA area occurring during 30 days following CV favours long term SR maintenance.