特発性拡張型心筋症による難治性心不全にPimobendanが著効した1例

A Case Report of Idiopathic Dilated Cardiomyopathy with Severe Congestive Heart Failure for which Pimobendan was Effective

要旨

　患者は64歳，男性．54歳時に心不全で当院入院．右室心内膜下心筋生検などで特発性拡張型心筋症(以下DCM)と診断．利尿剤，ジギタリス剤，酸素投与で軽快退院．55歳時，アンジオテンシン変換酵素阻害薬(以下ACE-I)，58歳時β遮断薬を加え，計10年間安定していた．64歳時に心不全が増悪し再入院．カテコラミンの点滴投与に反応なく，NYHAⅣ°となった．本人，家族よりBatista手術の打診があったが，ピモベンダン投与し3.75mg/日まで増量したところ心不全症状は改善を開始．BNPは2,000以上から446.1pg/mlとなり，現在外来でも同用量を30カ月以上にわたって継続し，NYHAⅠ°-Ⅱ°，BNP57pg/mlで，経時的に左室拡張末期径も縮小，心室性期外収縮の数も減少傾向で維持している．病理組織診断後，evidence based medicine(以下EBM)に基づいた内科治療で長期安定していたにもかかわらず，重症心不全に陥った終末期DCMにピモベンダンが著効した報告はなく，その詳細な内容経過報告は今後の本疾患治療戦略上に有益であると考え，若干の考案を加えて報告する．

Summary

　We treated a 64-year-old man who developed exertional dyspnea in 1992 (at age 54). He was admitted to our hospital after being diagnosed with heart failure. Echocardiography showed a left ventricular diastolic diameter (LVDd) of 58mm, a left ventricular ejection fraction (EF) of 34%, a left ventricular wall thickness of 7mm, and diffuse severe hypokinesis. Based on biopsy of the right ventricular subendocardial myocardium, the patient was diagnosed as having idiopathic dilated cardiomyopathy. He was discharged under treatment with a diuretic, a cardiotonic, and oxygen. An angiotensin-converting enzyme inhibitor (alacepril, 12.5mg/day) was added in 1993 (at age 55), as well as a β-blocker (carvedilol, 10 mg/day using dose escalation) in 1996 (at age 58). The patient was hospitalized again in 2001 (at age 64) due to worsening heart failure. He had cardiomegaly and deteriorated EF, for which intravenous infusion of catecholamines was ineffective. He was started on pimobendan (2.5mg/day) when his heart failure progressed to NYHA grade IV, and his symptoms began to improve when the dose was increased to 3.75mg/day. Echocardiography showed diminished LVDd from 58mm to 53mm, the left ventricular systolic diameter from 53mm to 48mm, the EF from 24% to 34%, and BNP from over 2,000pg/ml to 446.1pg/ml. The patient has since been monitored on an outpatient basis and is making satisfactory progress. We consider that the clinical course of this case in worth reporting in detail, because pimobendan is a recommendable drug even for patients with end-stage dilated cardiomyopathy which has been treated with ACE-I and β-blocker.