High Washout Rate of Iodine-123-Metaiodobenzylguanidine Imaging Predicts the Outcome of Catheter Ablation of Atrial Fibrillation

INTRODUCTION: Excessive sympathetic nervous activity may contribute to atrial fibrillation (AF) recurrences after ablation, but its precise role remains controversial. The goals of this study were to assess the effects of AF on the iodine-123-metaiodobenzylguanidine ((123) I-MIBG) findings and to elucidate its impact on the procedural outcome in patients undergoing a first-time catheter ablation to treat AF. METHODS AND RESULTS: This study included 88 consecutive patients with paroxysmal (n = 48) or persistent (n = 40) AF who underwent radiofrequency catheter ablation and (123) I-MIBG scintigraphy. Five days after the ablation of AF, (123) I-MIBG scintigraphy was performed during sinus rhythm. Anterior planar imaging was obtained at 15 minutes and 180 minutes and the washout rate of the (123) I-MIBG was calculated. The (123) I-MIBG scintigraphy demonstrated an enhanced adrenergic nervous function (high washout rate) and decreased adrenergic nervous distribution (low heart to mediastinum ratios) in patients with both paroxysmal and persistent AF. During a mean follow-up period of 13.5 ± 2.2 months after the ablation, 25 (28%) patients had AF recurrences. The univariate predictors of an AF recurrence were the duration of the AF history, left atrial dimension, and washout rate of the (123) I-MIBG. Only the (123) I-MIBG washout rate was a multivariate predictor of an AF recurrence (hazard ratio: 1.6, 95% confidence interval: 1.004-1.125, P = 0.037). CONCLUSIONS: Excessive sympathetic nervous activation may be one of the mechanisms of AF recurrences. The evaluation of the cardiac nerve activity using (123) I-MIBG scintigraphy shortly after the AF ablation may be a promising tool to predict the patient's outcome.