Abdominal obesity, and not general obesity, is associated with a lower 123I MIBG heart-to-mediastinum ratio in heart failure patients with preserved ejection fraction

Abstract

Background: The relationship between general obesity or abdominal obesity (abdominal circumference of ≥85 cm in men and ≥ 90 cm in women) and the heart-to-mediastinum ratio (HMR), a measure of cardiac sympathetic innervation, on cardiac iodine-123-metaiodobenzylguanidine scintigraphy (MIBG) in patients with heart failure with preserved ejection fraction (HFpEF) has not been clarified.

Methods: A total of 239 HFpEF patients with both MIBG and abdominal circumference data were examined. We divided these patients into those with abdominal obesity and those without it. In the cardiac MIBG study, early phase image was acquired 15-20 min after injection, and late phase image was acquired 3 h after the early phase. A HMR obtained from a low-energy type collimator was converted to that obtained by a medium-energy type collimator.

Results: Early and late HMRs were significantly lower in those with abdominal obesity, although washout rates were not significantly different. The incidence of patients with early and late HMRs <2.2 was significantly higher in those with abdominal obesity. Multivariate linear regression analysis revealed that abdominal obesity was independently associated with early HMR (standardized β = -0.253, P = 0.003) and late HMR (standardized β = -0.222, P = 0.010). Multivariate logistic regression analysis revealed that abdominal obesity was independently associated with early (odds ratio [OR] [95% confidence interval {CI}] = 4.25 [2.13, 8.47], P < 0.001) and late HMR < 2.2 (OR [95% CI] = 2.06 [1.11, 3.83], P = 0.022). Elevated BMI was not significantly associated with low early and late HMR. The presence of abdominal obesity was significantly associated with low early and late HMR even in patients without elevated BMI values.

Conclusion: Abdominal obesity, but not general obesity, in HFpEF patients was independently associated with low HMR, suggesting that visceral fat may contribute to decreased cardiac sympathetic activity in patients with HFpEF.

Trial registration: UMIN000021831.

Keywords: Abdominal circumference; Abdominal obesity; Heart failure; Heart to mediastinum ratio; Iodine-123-metaiodobenzylguanidine scintigraphy; Preserved ejection fraction.