NPPB and Hypertension: According to the results in Additional file 5: Table S2 and clinical significance, we adjusted for the confounders, including sex, body mass index, right ventricular diameter, creatinine, and hypertension, to demonstrate the real association between TMAO levels and disease severity assessed by WHO-FC, NT-proBNP, TAPSE, mixed venous oxygen saturation, risk stratification, CI, and PVR.