1. Clinic III for Internal Medicine (Cardiology) and Cologne Cardiovascular Research Center (CCRC), Heart Center at the University of Cologne, Germany (S.R.).
2. Center for Molecular Medicine Cologne (CMMC), University of Cologne, Germany (S.R.).
3. National Pulmonary Hypertension Service, Imperial College Healthcare NHS Trust, London, United Kingdom (L.S.H.).
4. Department of Medicine, George Washington University, Washington, DC (M.G.M.).
5. Department of Respiratory Medicine, Hannover Medical School, Germany (M.M.H.).
6. German Center for Lung Research (DZL), Hannover, Germany (M.M.H.).