RECOVERY OF I-123 METAIODOBENZYLGUANIDINE UPTAKE ASSOCIATED WITH LEFT-VENTRICULAR FUNCTIONAL RECOVERY IN A PATIENT WITH DILATED CARDIOMYOPATHY - ENDOMYOCARDIAL HISTOLOGICAL-FINDINGS BEFORE AND AFTER THE IMPROVEMENT OF UPTAKE

A 58-year-old man with idiopathic dilated cardiomyopathy was treated w ith incremental administration of a beta-blocker (metoprolol) and an a ngiotensin converting enzyme inhibitor (enarapril). The left ventricul ar end-diastolic dimension and ejection fraction improved in 8 months from 83.3 mm and 17.3% to 46 mm and 69%, respectively. The washout rat io and heart-to-mediastinum ratio depicted on the delayed image for io dine-123 metaiodobenzylguanidine (I-123-MIBG) uptake improved from 61. 7% and 1.34 to 23.1% and 1.85, respectively, in association with impro vement of left ventricular indices. Successive endomyocardial biopsy s pecimens disclosed reduction of the degrees of vacuolation, staining i rregularity, and deformity of myocyte cytoplasm and nucleus compared t o the findings before therapy. In this patient with dilated cardiomyop athy I-123-MIBG scintigraphy was useful for the evaluation of the effe cts of therapy. We conclude that it may be informative in the estimati on of the histopathological abnormalities of the myocardium.