IMPAIRMENT OF CARDIAC NEURONAL FUNCTION IN ACUTE MYOCARDITIS - IODINE-123-MIBG SCINTIGRAPHY STUDY

Abnormalities of norepinephrine uptake have been found to reflect impa irment in adrenergic nerve function that has influenced the cardiac ou tcome of patients with heart failure. The aim of this study was to exp lore the cardiac neuronal function by using I-123-metaiodobenzylguanid ine (MIBG) scintigraphy in patients with acute myocarditis. Methods: W e studied 15 patients (age range 42 +/- 10 yr) with clinical, biologic al, electrocardiographic and radionuclide left ventricular ejection fr action (LVEF) (41% +/- 7%) data indicating myocarditis and 10 normal s ubjects (age range 36 +/- 7 yr, mean radionuclide LVEF 69% +/- 8%, p < 0.05). Fourteen patients had positive histologic findings of myocardi tis and 1 had nonspecific histological data. All patients underwent pl anar cardiac imaging after intravenous injection of 185 MBq I-123-MIBG and right ventricular biopsy within 7 days. A chest anterior view was acquired 4 hr later. Heart-to-mediastinum ratio activity was measured , as previously described in our laboratory. Results: Significant impa irment of cardiac neuronal uptake of MIBG was observed and based on a reduction of heart-to-mediastinum ratio (148% +/- 16% versus 234% +/- 36%, p < 0.05). A significant correlation was observed between LVEF an d MIBG uptake in patients (y = 1.58x + 83.7, r = 0.72, p < 0.01). Conc lusion: Acute myocarditis is associated with an injury of the cardiac adrenergic neuronal function. In addition to the inflammatory injury o f the myocytes, the impairment of adrenergic function may be involved in the cardiac pump failure induced by myocarditis.