Abstract 12766: Cardiac Sympathetic Nerve System Activity Evaluated by Cardiac I-123 Metaiodobenzylguanidine Scintigraphy in Heart Failure Patients With Preserved or Reduced Ejection Fraction

Abstract

Introduction: Heart failure with preserved ejection fraction (HFpEF) is the predominant form of heart failure. However, there is no proven therapy for HFpEF. In contrast, significant benefits of beta-blockers that inhibit cardiac nerve system activity have been established in patients with heart failure with reduced ejection fraction (HFrEF). The purpose of this study is to compare cardiac sympathetic nerve system activity in patients with HFpEF versus HFrEF. Methods: The I-123 metaiodobenzylguanidine (MIBG) scintigraphy was performed to evaluate cardiac sympathetic nerve system activity in 48 heart failure patients (age 77.0±10.6 years; male 52.1%). We compared the early and delayed heart/mediastinum (H/M) ratio and the washout rate (WR) in patients with HFpEF (left ventricular ejection fraction; LVEF≥50%, n=20) and HFrEF (LVEF<50%, n=28). Results: There were no differences in age and sex between two groups. LVEF was significantly higher in patients with HFpEF than in those with HFrEF (62.5±11.7 vs 31.7±9.1%, p<0.001). Plasma BNP level was significantly lower in patients with HFpEF than in those with HFrEF (205.1 [IQR, 155.0-430.5] vs 369.0 [IQR, 196.6-662.1] pg/mL, p=0.04). Plasma norepinephrine level was not different between HFpEF patients and HFrEF patients (428.5 [IQR, 210.5-676.3] vs 392.5 [IQR, 307.2-535.8] pg/mL, p=0.93). No significant differences were found in the early H/M ratio (2.17±0.46 vs 2.10±0.32, p=0.53) and in the delayed H/M ratio (1.94±0.53 vs 1.80±0.35, p=0.91) between HFpEF patients and HFrEF patients. The WR was also similar in HFpEF patients and HFrEF patients (37.9±17.0 vs 46.3±16.4%, p=0.09). The use of beta-blockers was significantly lower in patients with HFpEF than in those with HFrEF (35.0 vs 71.4%, p=0.01). Conclusions: Although the use of beta-blockers was lower in patients with HFpEF as compared to in those with HFrEF, cardiac sympathetic nerve system activity was elevated to a similar extent between patients with HFpEF and HFrEF. These findings suggest that cardiac sympathetic nerve system is a promising therapeutic target in patients with HFpEF.