Quantitative assessment of right ventricular glucose metabolism in idiopathic pulmonary arterial hypertension patients: a longitudinal study

Aims Right ventricular (RV) glucose metabolism disorder in pulmonary arterial hypertension (PAH) has been studied using 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging with inconsistent results. We aimed to quantitatively assess RV glucose metabolism and further identify its role of monitoring RV function in idiopathic PAH (IPAH) patients in a longitudinal study. Methods and results Twenty-seven treatment-naive IPAH patients and 21 healthy control subjects performed FDG-PET dynamic scan for quantification of the rate of myocardium glucose utilization (rMGU) and echocardiography for assessment of cardiac function. Right heart catheterization was conducted for IPAH patients for haemodynamic measurement. A subgroup of 14 patients repeated FDG-PET and echocardiography after 6-month treatment. RV rMGU was significantly increased compared with controls; while the rMGU in left ventricle showed no difference. RV rMGU was significantly correlated with pulmonary artery pressure, pulmonary vascular resistance, RV Tei index, and right atrial area, and negatively correlated with RV ejection fraction (RVEF) and tricuspid annular plane systolic excursion. Six of 14 patients with increased RV rMGU after 6-month treatment showed no change in RVEF, 6-min walk distance (6MWD), and RV Tei index; however, the other 8 patients with decreased RV rMGU demonstrated significantly increased RVEF and 6MWD and decreased RV Tei index. Notably, the change in RV rMGU of 14 patients was significantly correlated with the change in 6MWD and RV Tei index. Conclusion Increased RV rMGU of IPAH correlates with RV dysfunction and RV pressure overload. The change in RV glucose metabolism may help monitor RV function after treatment.