We also agree that besides pulmonary vasculopathy, a PAP increase during exercise may be triggered by other factors, such as a diastolic dysfunction of the left ventricle. This question is also discussed in our article. According to the unpublished data mentioned by Ciurzyński et al, an elevated pulmonary arterial wedge pressure was found in a very large proportion (75%) of their patients with scleroderma with manifest PAH or exercise-induced PAP increase. We found an elevated pulmonary arterial wedge pressure increase in “just”33%. This discrepancy may be caused by different methods, different definitions, different patient characteristics, or by chance. A larger prospective study would be necessary to answer the question of how frequently a left ventricular filling dysfunction occurs and on what it depends. The methods applied by Ciurzyński et al are similar to a previous article by Steen et al6 (positive response: increase of at least 20 mm Hg in the right ventricular systolic pressure with exercise), although the data here also show some differences (positive cases 44% in Steen et al vs 17% in Ciurzyński et al).