心臓再同期療法により一過性左脚ブロックに伴う心不全増悪イベントの反復が回避できた1例

Clinical Benefit of Cardiac Resynchronization Therapy in a Patient with Repeated Heart Failure Exacerbation Coincident with Intermittent Left Bundle Branch Block

要旨　患者は73歳，女性．拡張型心筋症と診断され，心不全薬物治療にて管理されていた．心不全の急性増悪により入退院を繰り返したが，いずれの心不全増悪時にも一時的に完全左脚ブロックが出現し，重度の僧帽弁逆流に伴う高度肺うっ血を認めた．心不全が改善すると速やかに左脚ブロックは消失し，僧帽弁逆流が軽減した．一過性左脚ブロックが心不全増悪イベントの一要因と考え，心臓再同期療法を常時稼働させた．その後は，心不全増悪イベントが一切出現せず，左室逆リモデリングと僧帽弁逆流の軽減をみた．本例での心室再同期療法が奏功した事実は，心不全イベント時に付加される一時的な血行動態の変化がイベント露見に大きく寄与することを示唆し，新たな治療介入法として期待される．

　A 73-year-old woman, diagnosed as having dilated cardiomyopathy, was repeatedly hospitalized due to acute decompensation of heart failure(HF). On admission, she always demonstrated severe pulmonary congestion derived from worsened mitral valve regurgitation(MR)together with complete left bundle branch block(LBBB)and left ventricular(LV)dyssynchrony. As HF was relieved swiftly using pharmacological intervention and oxygen supplementation, MR was diminished and LBBB recovered to become narrow QRS intraventricular conduction. Since cardiac resynchronization therapy(CRT)was introduced, her clinical status has been stable without any cardiac events including HF hospitalization and, moreover, the enlarged and impaired LV has gradually reversed together with reduced MR.

　LV dyssynchrony by sudden onset of LBBB could induce not only a decrease in contraction of LV but also increased MR through interfering with the proper closure of the mitral valve, leading to exacerbation of HF. We conclude that CRT is a reliable therapeutic option in cases with intermittent LBBB coincident with acutely-decompensated HF.