Relation of left atrial volume from three-dimensional computed tomography to atrial fibrillation recurrence following ablation.

The effect of left atrial (LA) structural remodeling and dilatation on the outcome of ablation of atrial fibrillation (AF) remains unknown. We correlated potential prognostic markers of AF ablation, including LA volume from computed tomography, with AF recurrence after ablation. We studied 73 consecutive patients (52 with paroxysmal AF, 21 with persistent AF) undergoing AF ablation. LA volume was calculated by axial slice summation from 3-dimensional computed tomography. Follow-up was through 12 months, with success of ablation determined by electrocardiography and lack of symptoms (unless symptoms proved not AF by Holter monitor). Overall procedure success was 66% (including 15% repeat ablations, 12% on antiarrhythmics). Pulmonary vein isolation was performed, with additional linear ablation in 44 (60%). Mean LA volume (95% confidence interval) for those with recurrent AF was 119 ml (104 to 135) versus 98 ml (90 to 106) for no recurrence (p = 0.01, rank-sum test). Wide variation in LA volume occurred in the 2 groups, but, of the 15% of patients with very large LA volumes (>135 ml), 82% had recurrent AF. A cutpoint of 135 ml yields 36% sensitivity and 96% specificity for recurrence. In multivariable regression analysis, only LA volume and number of cardiovascular co-morbidities were associated with more recurrence (p = 0.02 and p = 0.03, respectively). In conclusion, LA volume varies greatly in those with and without successful AF ablations, mean LA volume is significantly larger in those with recurrence, and patients with LA volumes >135 ml are very likely to develop recurrent AF.