Iodine-123 mIBG Imaging for Predicting the Development of Atrial Fibrillation

OBJECTIVES We investigated whether cardiac sympathetic nervous system (SNS) activity measured by iodine-123 meta-iodobenzylguanidine (I-123-mIBG) imaging would be associated with both the occurrence of heart failure (HF) and the transit to permanent atrial fibrillation (AF) in patients with paroxysmal AF. BACKGROUND Atrial fibrillation occurs suddenly and transiently and can persist, and results in the occurrence of HF. An important feature of AF and HF is their propensity to coexist not only because they share antecedent risk factors, but also because the one may directly predispose the heart to the other. However, a useful modality for predicting the occurrences of both those has not been established in patients with paroxysmal AF. METHODS The I-123-mIBG scintigraphy was performed to evaluate cardiac SNS activity presented as the heart/mediastinum ratio in 98 consecutive patients (age 66 +/- 13 years, 63.3% male) with idiopathic paroxysmal AF and preserved left ventricular ejection fraction (>= 50%). RESULTS During 4 +/- 3.6 years of follow-up, the transit to permanent AF was associated with the occurrence of HF (34.3% in 12 of 35 patients with permanent AF vs. 6.3% in 4 of 63 patients without, p < 0.0001). Lower heart/mediastinum ratio and lower left ventricular ejection fraction were the independent predictors of the transit to permanent AF with adjusted hazard ratios of 3.44 (95% confidence interval [CI]: 1.9 to 6.2, p < 0.0001) and 1.04(95% CI: 1.01 to 1.08, p = 0.014). Further, these factors and higher plasma brain natriuretic peptide concentration were the independent predictors of the occurrence of HF with permanent AF, with adjusted hazard ratios of 5.08 (95% CI: 1.5 to 17.5, p = 0.011), 1.11 (95% CI: 1.03 to 1.19, p = 0.004), and 1.004 (95% CI: 1.001 to 1.008, p = 0.014). CONCLUSIONS Cardiac SNS abnormality was associated with the occurrence of both HF and permanent AF in paroxysmal AF patients, and I-123-mIBG imaging may be a useful modality for predicting the development of AF. (J Am Coll Cardiol Img 2011;4:78-86) (C) 2011 by the American College of Cardiology Foundation