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Iodine-123 mIBG imaging found beneficial in predicting AF, HF
Akutsu Y. J Am Coll Cardiol Img. 2011;4:78-86.
Crawford M.
J Am Coll Cardiol Img. 2011;4:87-88.
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Cardiac sympathetic nervous system abnormality measured by iodine-123 meta-iodobenzylguanidine imaging in patients with paroxysmal atrial fibrillation was associated with the occurrence of HF and permanent atrial fibrillation in a new study.
Researchers from Tokyo performed iodine-123 meta-iodobenzylguanidine (123I-mIBG) scintigraphy on 98 consecutive patients with idiopathic paroxysmal AF and preserved left ventricular ejection fraction of at least 50%. They determined sympathetic nervous system activity as the heart-to-mediastinum ratio.
During a median follow-up of 4 ± 3.6 years, 35 patients with paroxysmal AF transited to permanent AF. Overall, HF occurred in 16 patients, with 12 of the cases diagnosed in patients with permanent AF (34.3%) and four cases in patients without permanent AF (6.3%; trend P<.0001).
Independent predictors of transit to permanent AF included lower heart-to-mediastinum ratio (adjusted HR=3.44; 95% CI, 1.9-6.2) and lower LVEF (adjusted HR=1.04; 95% CI, 1.01-1.08). Furthermore, these factors, as well as a higher brain natriuretic peptide, were independent predictors of occurrence of HF with permanent AF (P≤.014 for all three).
“Our major finding is that [sympathetic nervous system] abnormality was an independently powerful factor for predicting not only the transit to permanent AF but also the occurrence of HF with permanent AF in patients with paroxysmal AF and preserved cardiac function,” the researchers concluded. “Our findings may have important implications for the management of patients with paroxysmal AF before the occurrence of remarkable structural remodeling of atria and subsequent cardiac dysfunction of the left ventricle caused by AF.”
Michael H. Crawford, MD, of the University of California San Francisco, commented in an accompanying editorial on the implications of these findings.
“The results … suggest that a low heart/mediastinum ratio in a paroxysmal AF patient should encourage prophylactic therapy, perhaps with at least beta-blockers to try to prevent the development of permanent AF,” Crawford said, adding, however, that a randomized trial is needed to establish such a strategy.
Disclosure: Dr. Crawford has no relevant financial disclosures.
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