β遮断剤が著効し，123I-MIBG集積の改善を認めた拡張型心筋症の1例

A Case of Dilated Cardiomyopathy in which the Effect of β-blocker Therapy Was Clearly Demonstrated by 123I-MIBG Scintigraphy

　拡張型心筋症の¹²³I-MIBG心筋シンチグラム像の特徴として心臓全体の集積の低下，不均一な集積，wash out rateの増加などが知られているが，β遮断剤療法による¹²³I-MIBG心筋シンチグラム像の変化についての報告は少ない．われわれは左室拡張末期径74mm，駆出率25％という重症の拡張型心筋症患者にメトプロロールを漸増的に60mgまで投与し，拡張末期径68mm，駆出率48％と著しい拡張末期径の短縮，駆出率の改善を認めた．さらに，β遮断剤投与前に比べ前壁での¹²³I-MIBGの集積が改善し，planar像にて定量的に集積の改善を確認できた．β遮断剤投与による交感神経末端のノルエピネフリンの枯渇状態の改善が画像化されたものと考えられ，β遮断剤療法の治療効果判定にも有用と考えられた．

A 43-year old man was admitted to our hospital because of paroxysmal noctornal dyspnea. After treat-ment at our outpatient clinic for a month, he was admitted to our hospital for the purpose of further examination. Cardiac catheterization showed elevated LV enddiastolic pressure and LV enddiastolic volume and severely reduced ejection fraction. LV biopsy showed remarkable fibrosis in his myocardium. He was diagnosed as having dilated cardiomyopathy and was put on metprolol from 10mg/day incrementaly to 60mg/ day. His LV end diastolic dimension decreased remark-ably during administration of 60mg/day of metprolol.