The main findings were that CTEPH resulted in (i) RV hypertrophy, both at the global and the myocyte level; (ii) mild RV dysfunction, as indicated by decreased RV–PA coupling and elevated BNP expression, with trends towards an increased RV EDVi and a lower EF; (iii) a further decrease in RV–PA coupling during exercise that correlated with an increase in ROCK2, NOX1 and NOX4 expression; and (iv) increased VEGFA expression that was accompanied by an increased capillary density in the RV. Here, NOX1 is linked to chronic thromboembolic pulmonary hypertension.