Group 3 PH: Clinical Features and Treatment

Group 3 pulmonary hypertension (PH) is a broad category of PH caused by chronic lung diseases (CLD) including chronic obstructive pulmonary disease (COPD), diffuse parenchymal lung diseases (DPLD), sleep disordered breathing, chronic exposure to high altitudes and developmental abnormalities. It is the second most common type after group 2 PH which is secondary to left heart disease or pulmonary venous hypertension. Clinical features of group 3 PH are often difficult to discern from the signs and symptoms of the primary lung disease and most of the time, symptoms out of proportion to the severity of lung disease prompts evaluation for group 3 PH. In most patients with group 3 PH, the mean pulmonary artery pressure (mPAP) is usually mildly elevated. However, it is invariably associated with reduced functional ability, impaired quality of life, greater oxygen requirements and an increased risk of mortality. Transthoracic echocardiography is the best screening test to evaluate for underlying PH. Right heart catheterization (RHC) is the gold standard test for confirmation and is performed when significant PH is suspected and the patient's management will likely be influenced by the RHC results. Treatment of group 3 PH can be divided into four major categories- primary, adjunctive, PH-specific and treatment of refractory disease. Treatment of the primary lung disease is the most important aspect but supportive therapy including supplemental oxygen and pulmonary rehabilitation are also very essential. The role of pulmonary vasodilators in group 3 PH is still unclear and large, randomized controlled trials are in dire need.