Cardiac resynchronization induces favorable neurohumoral changes

Aim: The aim of this article is to examine whether cardiac resynchronization therapy (CRT) induces improvements in the neurohumoral system. Methods and Results: Thirteen patients with HF (left ventricular (LV) ejection fraction < 35%) were included. Before and after 6 months of CRT, myocardial I-123-metaiodobenzylguanidine (I-123-MIBG) uptake indices, used as an index of neural norepinephrine reuptake and retention, and brain natriuretic peptide (BNP) levels, used as an index of LV end-diastolic pressure, NYHA classification and echocardiographic indices were assessed. Six months of CRT resulted in significant improvement in (1) NYHA classification and reduction in QRS width (P < 0.001), (2) decrease of LV end-diastolic diameter (P = 0.005), LV end-systolic diameter (P = 0.005), septal to lateral delay (P = 0.01) and mitral regurgitation (MR, P = 0.04), (3) delayed I-123-MIBG heart/mediastinum ratios improved (P = 0.03) and I-123-MIBG washout decreased (P = 0.001), and (4) BNP levels decreased (P = 0.001). Conclusions: Parallel to significant functional improvement and echocardiographic reverse remodeling and resynchronization, our data indicate that CRT induces favorable changes in the neurohumoral system.