Pre-capillary: Mean PA pressure ≥ 25 mm Hg with PCWP ≤ 15 mm Hg. This includes Group 1: Pulmonary arterial hypertension Group 3: Secondary to diseases of lungs and/or hypoxia Group 4: Chronic thromboembolic PH Group 5: Pulmonary hypertension due to multifactorial/unclear etiology. Post-capillary: Mean PA pressure ≥25 mm Hg with PCWP > 15mm Hg. This includes Group 2: Secondary to left heart disease

Table 2: Classification of PH based on the pulmonary capillary wedge pressure [5]: