1 Department of Management, Information and Production Engineering, University of Bergamo, Dalmine BG, Italy; Dyspnea and Pulmonary Hypertension Center, Department of Cardiology, Ospedale San Luca IRCCS Istituto Auxologico Italiano, Milano, Italy.
2 Dyspnea and Pulmonary Hypertension Center, Department of Cardiology, Ospedale San Luca IRCCS Istituto Auxologico Italiano, Milano, Italy.
3 Duke Clinical Research Institute, Durham, NC, USA; Department of Medicine, Duke University Medical Center, Durham, NC, USA. Electronic address: marat.fudim@duke.edu.