PET/CT Assessment of Flow-Mediated Epicardial Vasodilation in Obesity and Severe Obesity
Ines Valenta, Anand Upadhyaya, Sudhir Jain, Thomas H. Schindler
Abstract
It is not known whether the transition from obesity and severe obesity, as 2 different metabolic disease entities, affect flow-mediated and, thus, endothelium-dependent epicardial vasodilation. The purpose of this study was to investigate the effect of obesity and severe obesity on flow-mediated epicardial vasomotion with positron emission tomography/computed tomography-determined longitudinal decrease in myocardial blood flow (MBF) from the base-to-apex direction of the left ventricle or gradient. 13N-ammonia positron emission tomography/computed tomography evaluated global MBF during pharmacologically induced hyperemia and at rest for assessment of coronary microvascular function. In addition, the Δ longitudinal MBF gradient (hyperemia minus rest) was determined. Patients were then grouped according to the body mass index (BMI) into normal weight (NW) (BMI 20.0-24.9 kg/m2, n = 27), overweight (OW) (BMI 25.0-29.9 kg/m2, n = 29), obesity (OB) (BMI 30.0-39.9 kg/m2, n = 53), and severe obesity (morbid obesity: BMI ≥40 kg/m2, n = 43). Compared to NW, left ventricular Δ longitudinal MBF gradient progressively declined in OW and OB (0.04 ± 0.09 mL/g/min vs −0.11 ± 0.14 mL/g/min and −0.15 ± 0.11 mL/g/min; P ≤ 0.001, respectively) but not significantly in SOB (−0.01 ± 0.11 mL/g/min, P = 0.066). Regadenoson-induced global hyperemic MBF was lower in OB than in NW (1.88 ± 0.40 mL/g/min vs 2.35 ± 0.32 mL/g/min; P ≤ 0.001), while comparable between NW and SOB (2.35 ± 0.32 mL/g/min vs 2.26 ± 0.40 mL/g/min; P = 0.302). The BMI of the study population was associated with the Δ longitudinal MBF gradient in a U-turn fashion (r = 0.362, standard error of the estimate = 0.124; P < 0.001) Increased body weight associates with abnormalities in coronary circulatory function that advances from an impairment flow-mediated, epicardial vasodilation in overweight and obesity to coronary microvascular dysfunction in obesity, not observed in severe obesity. The U-turn of flow-mediated epicardial vasomotion outlines obesity and severe obesity to affect epicardial endothelial function differently.