Jian-Guo He

Heterogeneity in Lung 18 FDG Uptake in Pulmonary Arterial Hypertension Potential of Dynamic 18 FDG Positron Emission Tomography With Kinetic Analysis as a Bridging Biomarker for Pulmonary Vascular Remodeling Targeted Treatments

Background— Pulmonary arterial hypertension (PAH) is a disease of progressive vascular remodeling, characterized by dysregulated growth of pulmonary vascular cells and inflammation. A prevailing view is that abnormal cellular metabolism, notably aerobic glycolysis that increases glucose demand, underlies the pathogenesis of PAH. Increased lung glucose uptake has been reported in animal models. Few data exist from patients with PAH. Methods and Results— Dynamic positron emission tomography imaging with fluorine-18–labeled 2-fluoro-2-deoxyglucose (18FDG) ligand with kinetic analysis demonstrated increased mean lung parenchymal uptake in 20 patients with PAH, 18 with idiopathic PAH (IPAH) (FDG score: 3.27±1.22), and 2 patients with connective tissue disease (5.07 and 7.11) compared with controls (2.02±0.71; P<0.05). Further compartment analysis confirmed increased lung glucose metabolism in IPAH. Lung 18FDG uptake and metabolism varied within the IPAH population and within the lungs of individual patients, consistent with the recognized heterogeneity of vascular pathology in this disease. The monocrotaline rat PAH model also showed increased lung 18FDG uptake, which was reduced along with improvements in vascular pathology after treatment with dicholoroacetate and 2 tyrosine kinase inhibitors, imatinib and sunitinib. Hyperproliferative pulmonary vascular fibroblasts isolated from IPAH patients exhibited upregulated glycolytic gene expression, along with increased cellular 18FDG uptake; both were reduced by dicholoroacetate and imatinib. Conclusions— Some patients with IPAH exhibit increased lung 18FDG uptake. 18FDG positron emission tomography imaging is a tool to investigate the molecular pathology of PAH and its response to treatment.

Comparison of 18F-FDG uptake by right ventricular myocardium in idiopathic pulmonary arterial hypertension and pulmonary arterial hypertension associated with congenital heart disease.

This study measured glucose uptake in the right ventricle (RV) of patients with pulmonary hypertension and investigated the relationship to hemodynamics and survival. Myocardial 18F-fluorodeoxy-glucose (FDG) uptake was measured using single-photon positron emission tomography (SPECT) in 24 patients with idiopathic pulmonary arterial hypertension (IPAH) and 43 patients with congenital heart disease (CHD). In both IPAH and CHD-PAH, RV FDG uptake (RV/LV ratio) was associated with pulmonary vascular resistance (PVR). A second SPECT scan was performed in nine patients after 6 months treatment with sildenafil. PVR decreased from 1683±426 to 1207±383 dyn s−1 cm−5 (P < 0.05) and cardiac index improved from 2.2±0.2 to 2.8±0.5 L/min/m2 (P < 0.01). RV/LV FDG uptake decreased from 1.28±0.32 before treatment to 0.99±0.23 (P < 0.05). Survival in the IPAH group with a baseline RV/LV FDG uptake greater than the median value of 1.20 was significantly lower than that of the group with RV/LV FDG uptake below 1.20 (log-rank test, P < 0.05). In contrast, baseline RV/LV FDG was of little informative value in CHD. FDG uptake by the RV reflects the severity of PVR in PAH. Increased RV FDG uptake is a marker of poor prognosis in IPAH and is reduced in patients receiving effective therapy. It could prove useful in the early clinical assessment of novel therapies for PAH.

Echocardiographic parameters in patients with pulmonary arterial hypertension: correlations with right ventricular ejection fraction derived from cardiac magnetic resonance and hemodynamics.

Background Echocardiography is the most convenient method used to evaluate right ventricular function, and several echocardiographic parameters were studied in previous studies. But the value of these parameters to assess the right ventricular function in patients with pulmonary arterial hypertension (PAH) has not been well defined. Methods Patients with PAH were observed prospectively. Right heart catheterization, echocardiography and cardiac magnetic resonance (CMR) were performed within 1 week interval. The correlations between echocardiographic parameters and right ventricular ejection fraction (RVEF) derived from CMR as well as hemodynamics were analyzed. Results Thirty patients were enrolled including 24 with idiopathic PAH, 5 with PAH associated with connective tissue diseases and 1 with hereditary PAH. All echocardiographic parameters except right ventricular myocardial performance index (RVMPI) correlated significantly with RVEF (tricuspid annual plane systolic excursion [TAPSE], r = 0.440, P = 0.015; tricuspid annular systolic excursion velocity [S’], r = 0.444, P = 0.016; isovolumic acceleration [IVA], r = 0.600, P = 0.001; right ventricular fraction area change [RVFAC], r = 0.416, P = 0.022; ratio of right ventricular transverse diameter to left ventricular transverse diameter [RVETD/LVETD], r = −0.649, P<0.001; RVMPI, r = −0.027, P = 0.888). After adjusted for mean right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance (PVR), only IVA and RVETD/LVETD could independently predict RVEF. Four echocardiographic parameters displayed significant correlations with PVR (TAPSE, r = −0.615, P<0.001; S’, r = −0.557, P = 0.002; RVFAC, r = −0.454, P = 0.012; RVETD/LVETD, r = 0.543, P = 0.002). Conclusions The echocardiographic parameters IVA and RVETD/LVETD can reflect RVEF independently regardless of hemodynamics in patients with PAH. In addition, TAPSE, S’, RVFAC and RVETD/LVETD can also reflect PVR in PAH patients.

Plasma Soluble ST2 Levels Correlate With Disease Severity and Predict Clinical Worsening in Patients With Pulmonary Arterial Hypertension

Soluble suppression of tumorigenicity (sST2) has been proposed to be a marker for biomechanical strain and a possible predictor of mortality in patients with chronic heart failure. The use of sST2 in pulmonary arterial hypertension (PAH) has not been well defined.

The Ratio of 18F-FDG Activity Uptake Between the Right and Left Ventricle in Patients With Pulmonary Hypertension Correlates With the Right Ventricular Function

Purpose It is known that patients with pulmonary hypertension (PH) can have elevated 18F-FDG uptake in the right ventricle (RV) on PET imaging. This study was designed to assess possible relationship between FDG uptake of ventricles and the function/hemodynamics of the RV in patients with PH. Patients and Methods Thirty-eight patients with PH underwent FDG PET imaging in both fasting and glucose-loading conditions. The standard uptake value (SUVs) corrected for partial volume effect in both RV and left ventricle (LV) were measured. The ratio of FDG uptake between RV to LV (SUVR/L) was calculated. Right heart catheterization and cardiac magnetic resonance (CMR) were performed in all patients within 1 week. The FDG uptake levels by the ventricles were compared with the result form the right heart catheterization and CMR. Results The SUV of RV (SUVR) and SUV of LV were significantly higher in glucose-loading condition than in fasting condition. In both fasting and glucose-loading conditions, SUVR and SUVR/L showed reverse correlation with right ventricular ejection fraction derived from CMR. In addition, in both fasting and glucose-loading conditions, SUVR and SUVR/L showed positive correlations with pulmonary vascular resistance. However, only SUVR/L in glucose-loading condition could independently predict right ventricular ejection fraction after adjusted for age, body mass index, sex, mean right atrial pressure, mean pulmonary arterial pressure, and pulmonary vascular resistance (P = 0.048). Conclusions The FDG uptake of RV increases with decreased right ventricular function in patients with PH. Increased FDG uptake ratio between RV and LV might be useful to assess the right ventricular function.

Increased levels of plasma CXC-Chemokine Ligand 10, 12 and 16 are associated with right ventricular function in patients with idiopathic pulmonary arterial hypertension.

OBJECTIVE To investigate plasma levels of CXC-Chemokine Ligand 10 (CXCL10), CXC-Chemokine Ligand 12 (CXCL12) and CXC-Chemokine Ligand 16 (CXCL16) in patients with idiopathic pulmonary arterial hypertension (IPAH). METHODS Plasma levels of biomarkers were measured by enzyme-linked immunosorbent assay in 61 patients with IPAH and 20 healthy volunteers. RESULTS Plasma CXCL10, CXCL12 and CXCL16 concentrations were increased significantly in IPAH patients compared with controls, and significantly correlated with N-terminal pro-brain natriuretic peptide, tricuspid annulus plane systolic excursion and right ventricular ejection fraction. CONCLUSIONS Increased levels of CXCL10, CXCL12 and CXCL16 are associated with right ventricular dysfunction in patients with IPAH.

Platelet Distribution Width and Mean Platelet Volume in Idiopathic Pulmonary Arterial Hypertension

BACKGROUND Previous studies have demonstrated that platelet activation occurs in patients with pulmonary arterial hypertension (PAH). Mean platelet volume (MPV) and platelet distribution width (PDW) are two markers of platelet activation, and have recently been recognised as risk predictors of cardiovascular diseases. This study aimed to investigate whether MPV and PDW would be useful to reflect disease severity and predict prognosis in idiopathic PAH (IPAH). METHODS MPV and PDW levels were measured in 82 IPAH patients without antiplatelet or anticoagulant treatment on admission and 82 healthy controls. Concurrent collected data included clinical, haemodynamic and biochemical variables. All patients were followed-up from the date of blood testing. The endpoint was all-cause mortality. RESULTS MPV and PDW were significantly higher in patients with IPAH than in age and sex-matched control subjects (11.4±0.9fl vs. 10.3±0.9fL and 14.3±2.9% vs. 11.9±1.9%, respectively; p=0.000). Pearsons correlation analysis revealed that MPV and PDW correlated positively with right ventricular systolic pressure, mean pulmonary arterial pressure and pulmonary vascular resistance. After a mean follow-up of 14±8 months, 12 patients died of right heart failure. Receiver operating characteristic analysis showed that MPV and PDW could not predict all-cause mortality. Multivariate Cox regression analysis suggested that right/left ventricular end-diastolic diameter ratio and NT-proBNP were independent predictive parameters of all-cause mortality. CONCLUSIONS Our results suggest that MPV and PDW were elevated in patients with IPAH. They could partly reflect disease severity, but did not predict prognosis.

Elevated plasma YKL‐40 as a prognostic indicator in patients with idiopathic pulmonary arterial hypertension

Pulmonary vascular remodelling and inflammation have been implicated in pulmonary arterial hypertension (PAH). YKL‐40, a marker of tissue remodelling and inflammation, has recently been recognized as a risk predictor of cardiovascular and inflammatory diseases. The study aimed to investigate a potential role of YKL‐40 in predicting prognosis in idiopathic PAH (IPAH).

Survival advantages of excess body mass index in patients with idiopathic pulmonary arterial hypertension.

Objective An obesity paradox, a “paradoxical” decrease in morbidity and mortality with increasing body mass index (BMI), has been shown in patients with heart failure. However, the impact of BMI in patients with idiopathic pulmonary arterial hypertension (IPAH) has not been studied. This study aims to find out whether BMI is a prognostic factor in IPAH. Methods and results We analysed 173 patients with IPAH. The patients were subclassified into categories of BMI defi ned as: underweight(< 18.5 kg/m2), normal weight (18.5 to 24.9 kg/m2), overweight and obese (25 to 34.9 kg/m2). The three BMI groups had similar profi les in terms of haemodynamic parameters assessed by right heart catheterization and level of NT-proBNP. The overweight and obese group had higher age, and lower WHO functional class, larger left ventricular end-diastolic dimensions (LVEDDs) than the other two groups. The Kaplan-Meier survival curves for the three BMI categories demonstrated that the overweight and obese group had a significantly higher survival rate than the normal weight and underweight groups (log-rank test, P= 0.027, P= 0.000, respectively). In a stepwise forward regression, lower BMI, higher WHO functional class, lower cardiac index, smaller LVEDDs and absence of targeted medication remained independent predictors of mortality. Conclusions Excess body mass is a protective factor for death in patients with IPAH.

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 (18)F-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-naïve 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.