Successful catheter ablation of atrial fibrillation improves but not reverses the abnormalities of left atrial mechanics and energy loss.

Background: Dissipative energy loss (EL), a new index to quantify the inefficient blood flow, has not been explored within left atrium (LA) in patients with atrial fibrillation (AF). We aimed to study the intra-atrial flow and mechanics in patients with AF before and after successful catheter ablation by evaluating EL and LA global longitudinal strain (LAS).

Methods: In our study, there were 53 patients undergoing catheter ablation for AF at baseline (AF group) and 33 age- and sex-matched controls. They were both assessed of LA EL using vector flow mapping (VFM) and of LAS using two-dimensional tracking (2DTT) during systole (sys), early diastole (ed), and atrial contraction phase (ac). Out of 53 patients, 37 patients who sustained sinus rhythm and carried out the echocardiographic examination at 3 and 6 months follow-up were evaluated of change in EL and LAS. The independent predictors of EL during three phases in AF group were performed using stepwise multivariate linear regression analyses.

Results: Left atrium EL and LAS among all phases in AF group were significantly lower than controls (all P < 0.01). During follow-up, LASsys and LASac both significantly improved at 3 and 6 months (both P < 0.01), and ELac significantly increased after 6 months (P < 0.05); ELsys, ELed and LASed were no significant change; EL and LAS among all phases were no normalized during follow-up. The independent predictors of EL were: for ELsys, BSA (P = 0.004) and LASac (P = 0.025); for ELed, E (P = 0.001) and A (P = 0.014); for ELac, E/A (P < 0.001).

Conclusion: Vector flow mapping and 2DTT revealed impaired intra-atrial flow and mechanics. Successful catheter ablation for AF slightly improves but not reverses the aforementioned impairment, indicating the continuous LA dysfunction.