Clinical benefit of cardiac resynchronization therapy in a patient with repeated heart failure exacerbation coincident with intermittent left bundle branch block

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.