Chronic thromboembolic pulmonary hypertension is classified in which group?

• A. Group 1
• B. Group 4
• C. Group 2
• D. Group 3

Answer: (B)

Chronic thromboembolic pulmonary hypertension is grouped with vascular obstruction from prior clots as Group 4. The defining issue here is persistent organized thrombi in the pulmonary arteries that block flow and raise pulmonary vascular resistance, causing hypertension. This is different from Group 1 (primary pulmonary arterial hypertension from small-artery disease), Group 2 (PH from left heart disease), or Group 3 (PH due to lung disease or hypoxia). In CTEPH, the central problem is mechanical obstruction from clots and their remodeling, which is why it sits in Group 4. Clinically, this distinction matters because treatment focuses on removing the obstructing material (e.g., pulmonary endarterectomy) rather than targeting parenchymal lung disease or left heart failure.