The session will review the importance of pulmonary hypertension (PH) complicating left heart disease (PH group 2) and lung disease (PH group 3). Attendees will learn potential and common diagnostic pitfalls. Clinical trial data on the use of targeted Pulmonary Arterial Hypertension (PAH) therapies in these populations will be reviewed, highlighting the absence of efficacy data and the potential for harmful effects. Case vignettes will be used to illustrate the challenges.