Fig. 1From: Late outcome of surgical radiofrequency ablation for persistent valvular atrial fibrillation in China: a single-center studyKaplan-Meier survival curves showing freedom from AF recurrence by (a) AF duration, (b) Pre-op B-type natriuretic peptide, (c) Pre-op heart rate and (d) Pre-op left atrial diameter. CI, confidence intervalsBack to article page