NPPB and pulmonary arterial hypertension: PH: pulmonary hypertension; BMI: body mass index; WHO FC: world health organization function class; NT-proBNP: N-terminal pro-brain natriuretic peptide; ALT: alanine aminotransferase; AST: aspartate aminotransferase; 6MWD: 6-minute walk distance; mRAP: mean right atrial pressure; RVDP: right ventricular diastolic pressure; mPAP: mean pulmonary atrial pressure; ERA: endothelium-Receptor Antagonist; NO: nitric oxide