INS and metabolic syndrome: Many studies have linked insulin resistance and the metabolic syndrome to PAH [27, 40–43], the lack of data in our study on insulin levels, fasting blood glucose and hemoglobin A1C level and other lipoproteins could suggest that the observed finding of association between HDL-C in CTEPH with larger decrease in PVR post PTE and decreased prevalence of right ventricular dilation on echocardiography could be related to insulin resistance.