1. Department of Internal Medicine, University of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany, member of the German Center of Lung Research (DZL)
2. Department of Pneumology, Kerckhoff Heart and Thoracic Center, Bad Nauheim, Germany
3. Center for Pulmonary Hypertension, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4. Department of Medicine, Imperial College London, London, UK