I-123 METAIODOBENZYLGUANIDINE IMAGES REFLECT INTENSE MYOCARDIAL ADRENERGIC NERVOUS ACTIVITY IN CONGESTIVE-HEART-FAILURE INDEPENDENT OF UNDERLYING CAUSE

Objectives. This study was undertaken to assess myocardial adrenergic activity using iodine-123 metaiodobenzylguanidine (MIBG) imaging in pa tients with heart failure. Background. In patients with congestive hea rt failure, adrenergic nerve activity is accelerated. However, whether myocardial adrenergic nerve activity reflects the severity of heart f ailure and its relation to the underlying cause have not yet been eluc idated. Methods. Planar MIBG images were obtained from 96 patients wit h heart failure and compared with images from 9 age-matched healthy su bjects. Groups 1 and 2 included 65 patients with heart failure related to impaired myocardial function and whose left ventricular ejection f raction was <40% (group 1 = 40 patients with dilated cardiomyopathy; g roup 2 = 25 patients with ischemic cardiomyopathy), Group 3 included 3 1 patients with heart failure related to a mechanical abnormality and whose left ventricular ejection fraction was >40% (mitral regurgitatio n in 16, aortic regurgitation in 9, aortic and mitral regurgitation in 4, ruptured aneurysm of Valsalva in 2). Myocardial uptake of MIBG was calculated as the heart/mediastinal activity ratio. Storage and relea se of MIBG were calculated as percent myocardial MIBG washout from 15 min to 4 h after isotope injection. Results. The heart/mediastinal act ivity ratio in the immediate images (15 min) showed a significant decr ease only in patients with severe heart failure (groups 1 and 2). The myocardial washout was accelerated in all three heart failure groups, The level of myocardial washout was related to severity of heart failu re and correlated well with New York Heart Association functional clas sification. Conclusions. In severe heart failure associated with cardi omyopathy, norepinephrine uptake is reduced, In addition, myocardial a drenergic nerve activity is accelerated in proportion to severity of h eart failure, independent of the underlying cause. (J Am Coll Cardiol 1995;26:1594-9)