Relationship Between Left Ventricular Dyssynchrony and Reverse Remodeling After Cardiac Resynchronization Therapy

Background: Cardiac resynchronization therapy (CRT) is recommended for patients with advanced chronic heart failure. The presence of left ventricular (LV) dyssynchrony before CRT is an important predictor of response to the therapy. We aimed to investigate time course of LV dyssynchrony after CRT and the relationship between LV dyssynchrony improvement and reverse remodeling (RR). Hypothesis: The relationship between the improvement of LV dyssynchrony and RR may differ according to criteria used to determine RR. Methods: Thirty patients with advanced heart failure, wide QRS complex, and LVEF <= 35% were included. Echocardiography coupled with tissue Doppler imaging was performed at baseline, and repeated at 1 and 6 months in follow-up. Patients were divided into RR and no-remodeling groups according to 10% decrease in left ventricular end-systolic volume (LVESV) and/or 25% increase in LVEF. Results: Left ventricular dyssynchrony improvement was significant at the first month in both the RR and no-remodeling groups according to LVESV decrease. Left ventricular dyssynchrony improvement was continued in the RR group; however, it did not improve significantly in the no-remodeling group. Left ventricular dyssynchrony improvement was significant at the first and sixth month in the RR and no-remodeling groups according to LVEF increase. Conclusions: Our study suggests that LV dyssynchrony improvement plays an important role in the development of RR according to decrease in LVESV. Reverse remodeling according to the increase in LVEF was developed independently from LV dyssynchrony improvement. The improvement in LV dyssynchrony is a necessary but not sufficient explanation for improvement in LVEF and LVESV.