Increased right ventricular glucose metabolism in patients with pulmonary arterial hypertension

We aimed to assess the characteristics of glucose utilization in left and right ventricle (LV, RV) myocardium with F-18 fluorodeoxyglucose (FDG) on positron emission tomography in patients with pulmonary arterial hypertension (PAH), and to evaluate whether predominance of RV glucose metabolism as compared with that in LV relates to clinical, hemodynamic, echocardiographic, and neurohormonal parameters.

The study group comprised 23 patients with PAH and 16 healthy controls who underwent FDG positron emission tomography. The ratio of RV uptake (u) of FDG to those of LV was used as a marker for the glucose utilization by RV myocardium. Six-minute walking distance, plasma brain natriuretic peptide (BNP), planimetric echo measures of RV and LV areas, pulmonary arterial systolic pressure estimated by Doppler, Tei index, tricuspid annular excursion, and systolic tissue velocity (St) were used to assess the RV function.

The patients with PAH had significantly higher FDG SUV ratios as compared with controls. The RV to LV FDGu ratio showed a high correlation with PAPs (r=0.87, P<0.05), BNP (r=0.63, P<0.05), and planimetric echo measures of RV to LV area ratio (r=0.61, P<0.05); a mild correlation with Tei index (r=0.47, P<0.05); and a high and inverse correlation with tricuspid annular excursion (r=-0.80, P<0.05), 6-minute walking distance (r=-0.74, P<0.05), and St (r=-0.68, P<0.05).

Increased RV myocardium FDG accumulation indicates increased RV loading that correlates with prognostic markers in pulmonary hypertension including reduced exercise capacity, elevated BNP, and echo variables of tricuspid annular function. Moreover, identification of increased RV FDG accumulation predicts the presence but not the severity of elevated pulmonary systolic pressure.