Iodine-123 metaiodobenzylguanidine scintigraphic analysis of myocardial sympathetic innervation in patients with AL (primary) amyloidosis.

Background Although a high incidence of myocardial adrenergic denervation has been reported in patients with familial amyloid polyneuropathy, assessment of cardiac sympathetic nerve function has not been available in patients with AL (primary) amyloidosis. Methods To test the hypothesis that myocardial sympathetic nerve innervation might be impaired and variable according to the presence or absence of clinical autonomic abnormalities and congestive heart failure in AL amyloidosis, we examined 25 patients by use of iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy. Results Ten of the 16 patients without autonomic symptoms and 5 of the 9 patients with autonomic neuropathy showed congestive heart failure. The heart/mediastinal activity (H/M) ratio (1.53 ± 0.06 vs 1.29 ± 0.05 at 3 hours, P <.001) and myocardial washout ratio (41.5% ± 4.8% vs 30.8% ± 4.0%, P <.001) of MIBG were significantly increased in patients without autonomic symptoms compared with patients showing autonomic neuropathy. In patient groups with and without autonomic dysfunction, patients demonstrating congestive heart failure exhibited a significantly decreased H/M ratio and increased washout compared with patients with no heart failure, and left ventricular fractional shortening was positively correlated with the H/M ratio and inversely correlated with the washout ratio. There were significant correlations between the low-frequency component of the heart rate variability and the H/M ratio and washout ratio in the entire patient population. Conclusions Patients with AL amyloidosis and no autonomic dysfunction showed variable degrees of enhanced cardiac adrenergic neuronal activity with presynaptic sympathetic dysfunction. In contrast, patients with AL amyloidosis and autonomic neuropathy exhibited prominent myocardial adrenergic denervation with normal or impaired sympathetic neural function of the heart. This study demonstrates that myocardial uptake and turnover of MIBG in patients with AL amyloidosis are heterogeneous and dependent on the presence or absence of congestive heart failure and cardiac autonomic dysfunction. (Am Heart J 2002;144:122-9.)