Impact of left atrial fibrosis and left atrial size on the outcome of catheter ablation for atrial fibrillation

Background: Left atrial (LA) dilatation is an important risk factor for recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA). However, the clinical applications to select patients eligible for RFCA according to LA size is limited. Additional pre-procedural assessment of LA fibrosis might improve patient selection for RFCA. Objective: To investigate the impact of LA size and LA fibrosis on the outcome of RFCA for AF. Methods: One hundred and seventy consecutive patients undergoing RFCA for AF were studied. LA size was assessed by measuring maximum LA volume index on echocardiography. LA wall ultrasound reflectivity was assessed by measuring echocardiography-derived calibrated integrated backscatter (IBS) as a surrogate of LA fibrosis. Results: After 12±3 months' follow-up, 103 patients (61%) had maintained sinus rhythm and 67 patients (39%) had recurrence of AF. Univariate Cox analyses identified LA wall ultrasound reflectivity, as well as LA size and type of AF, as predictors of AF recurrence after RFCA. Importantly, multivariate analyses showed that LA wall ultrasound reflectivity remained a strong predictor after correction for LA size and type of AF. Moreover, LA wall ultrasound reflectivity provided an incremental value in predicting outcome of RFCA over LA size and type of AF (increment in global χ 2=61.6, p<0.001). Conclusion: Assessment of LA fibrosis using twodimensional echocardiography-derived calibrated IBS can be useful to predict AF recurrence after RFCA. Combined assessment of LA wall ultrasound reflectivity and LA size improves the identification of patients with a high likelihood for a successful ablation.