心筋逸脱酵素の上昇を伴い重症心不全を呈した続発性心アミロイドーシスの1例

A Case of Cardiac Amyloidosis Secondary to Rheumatoid Arthritis Presenting with Severe Heart Failure and Creatine Kinase Elevation

要旨　患者は69歳女性．35歳より関節リウマチ(RA)として加療，65歳時血液透析を導入されていた．2004年6月，うっ血性心不全のため当院紹介受診．胸部X線写真上，心拡大と肺うっ血，心電図では前胸部誘導中心に広範にST低下を認めた．心臓超音波では左室壁運動のびまん性低下を認め，左室駆出分画(EF)は約20%であった．CPK1,422(CPK-MB223)の上昇を認めたため心筋梗塞を疑い心臓カテーテル検査を施行したが，冠動脈に有意狭窄は認めなかった．心筋炎も疑い，強心薬の投与および持続血液濾過(CHF)による除水を行い心不全を管理したが，心機能は改善せず第8病日死亡した．剖検では，全身へのAA型アミロイド沈着を認め，RAに合併した続発性アミロイドーシスと診断された．心臓には血管壁・間質ともにアミロイド沈着があり，広範に心筋の変性，壊死と線維化が認められた．本症は，冠動脈と微小血管へのアミロイド沈着が心筋虚血と広範な心筋壊死の引き金となり，重症心不全を発症したと考えられる貴重な症例であり報告する．

　The patient was a 69-year-old woman who had been suffering from rheumatoid arthritis(RA) for 35 years. She had been on regular hemodialysis due to chronic renal failure of unknown cause since 2000. She was referred to our hospital due to congestive heart failure(CHF) in June 2004. The chest X-ray film obtained on admission showed cardiomegaly and congestion in both lung fields, and the electrocardiogram disclosed extensive ST depression suggesting ischemic heart disease. Diffuse hypokinesis of the left ventricular wall was observed by echocardiography and her serum concentration of creatine kinase-MB increased with time. No significant coronary artery disease was detected by coronary angiography. She was treated with continuous hemofiltration in addition to conventional therapy for CHF. However, she died of severe heart failure on the 8th hospital day. The autopsy revealed systemic deposition of amyloid A associated with rheumatoid arthritis. Microscopic findings revealed microvascular occlusion with intramural deposition of amyloid A and necrosis of myocardial fibers.