Comparison of Endothelin-1 Level in Group I Pulmonary Hypertension vs. Group II Pulmonary Hypertension Both at Rest and at Peak Exercise

Abstract

Purpose To assess Endothelin-1 (ET-1) level in patients with group I pulmonary hypertension (pulmonary arterial hypertension (PAH)) compared to patients with group II PH (due to heart failure with preserved ejection fraction (HFpEF)), both at rest and at peak exercise Methods We measured ET-1 level in patients with PAH , PH due to HFpEF and normal control both at rest and peak exercise. Right heart cath was done to confirm diagnosis and type of PH. This was followed by arm lifting exercise for 3 minutes (30 watts) and decrease of MVO2 by > 10% using different weights. Blood samples were collected to measure ET-1 level pre and post exercise using ET-1 ELISA . Results A total of 39 patients were included in this study. 18 patients had PH due to HFpEF with a mean ET-1 level of 2.58 fmol/ m +/- 1.12 at rest and 2.62 fmol/ m +/- 1.02 at peak exercise with p value of 0.43. In comparison, there was 16 patients who had PAH with a mean ET-1 level of 2.31 fmol/ m +/- 0.78 at rest and 2.38 fmol/ m +/- 0.87 at peak exercise with p value of 0.25. Higher levels of ET-1 is noted in patients with pulmonary hypertension (especially those due to HFpEF) was significantly higher than normal control. However, exercise didn't effect ET-1 level in the three groups (Figure 1) Conclusion This is the first study to show that ET-1 level is higher in pulmonary hypertension due to HFpEF compared to PAH. However, exercise has no effect on ET-1 level in the two groups