拡張障害の進行により心不全悪化を来した慢性心筋炎の1剖検例

A Case of Chronic Myocarditis that Caused Heart Failure Exacerbation through a Progression of Diastolic Dysfunction

要旨　患者は42歳，男性．26歳時にうっ血性心不全で入院し，心筋生検を含む除外診断で拡張型心筋症と診断された．β遮断薬を含む至適薬物治療および心臓再同期療法が行われたが，心不全入院を繰り返し死亡した．約16年にわたり拡張型心筋症として経過観察されたが，剖検にて著明な炎症細胞浸潤を認め，初めて慢性心筋炎と判明した．本症例は，左室駆出率や左室拡張末期径は変化せず，左室収縮障害の進行はなく経過した．一方，左房拡大と左室流入血流速波形は経時的に悪化し，左室拡張障害が進行したことが心不全イベントの増加につながった．収縮障害でなく拡張障害が進行する慢性心筋炎病像があることから，拡張障害が進行する拡張型心筋症では慢性心筋炎の存在を検討する必要がある．

　A-42-year-old man died after repetitive hospitalization with heart failure exacerbation in spite of intensive treatment such as the use of beta-blockers and cardiac resynchronization therapy. The autopsy demonstrated severe myocardial inflammation for the first time, leading to the final diagnosis as chronic myocarditis. He had complained of dyspnea and had been diagnosed as dilated cardiomyopathy(DCM)16 years earlier through systematic evaluation including endmyocardial biopsy of the left ventricle(LV). Although the LV diastolic dimension/ejection fraction was 72mm/23%, respectively, upon the first symptoms of the disease, such echocardiographic parameters regarding LV systolic dysfunction had not altered over the entire clinical course. On the other hand, several indicators of LV diastolic dysfunction including left atrium expansion and a restrictive pattern of transmitral flow velocity had gradually increased. This is the first case report of chronic myocarditis with progressive LV diastolic dysfunction despite unaltered LV systolic properties. It is necessary to consider the possibility of chronic myocarditis in cases of DCM which progresses into LV diastolic dysfunction.