Do Patients With Low-Risk Pulmonary Arterial Hypertension Really Benefit From Upfront Combination Therapy?: Insight From the AMBITION Trial

PET/CT Imaging of the Right Heart Perfusion and Glucose Metabolism Depending on a Risk Status in Patients With Idiopathic Pulmonary Arterial Hypertension

Right ventricular heart failure (RV HF) is the leading cause of death in pulmonary arterial hypertension (PAH). Relevance of the low-risk status assessment using available diagnostic tools requires a reliable confirmation. The study aimed to evaluate right ventricular perfusion and glucose metabolism using positron emission tomography (PET)/computed tomography (CT) with [13N]-ammonia and [18F]-fluorodeoxyglucose ([18F]-FDG) in 30 IPAH patients (33.8 ± 9.4 years) according to ESC/ERS 2022 risk status. The ratio of SUVmaxRV/LV metabolism and SUVmaxRV/LV perfusion showed significant positive correlation with pulmonary artery pressure, right heart dilatation, NT-proBNP level and negative correlation with the RV ejection fraction. The SUVmaxRV/LV perfusion and SUVmaxRV/LV metabolism ratios differed significantly according to risk status. Low risk patients had a SUVmaxRV/LV metabolism comparable to the controls without PH. The SUVmaxRV/LV perfusion ratio was elevated in low-risk IPAH patients compared with controls. Increased SUVmaxRV/LV perfusion may be an early marker of coronary flow adaptation to RV pressure overload in low-risk IPAH patients and requires further evaluation. Further long-term studies are needed to determine the clinical relevance and cut-off values for the RV/LV PET/CT with [13N]-ammonia and [18F]-fluorodeoxyglucose ([18F]-FDG) uptake in different IPAH risk groups.