How is pulmonary arterial hypertension classified and what are treatment options for WHO Group 1 PAH?

1 Answer

WHO Classification of Pulmonary Hypertension (5 Groups): Group 1 - PAH (Idiopathic/Heritable/Drug-induced/Associated with connective tissue disease, HIV, portal hypertension, congenital heart disease) Group 2 - Left heart disease (most common cause of PH) Group 3 - Lung disease or hypoxia (COPD, ILD, OSA) Group 4 - Chronic thromboembolic PH (CTEPH) Group 5 - Unclear/multifactorial mechanisms Diagnostic Criteria for PAH: - mPAP ≥20 mmHg at rest on right heart catheterization (updated 2022) - PAWP ≤15 mmHg (to exclude left heart cause) - PVR >2 Wood units Your patient: mPAP 45 mmHg, no secondary cause = GROUP 1 PAH confirmed Treatment of WHO Group 1 PAH: Background therapy: O2 (if hypoxic), diuretics, anticoagulation (selected cases) Vasoreactivity Testing: (inhaled NO or adenosine) - Positive (rare): Long-term CCB (Nifedipine, Diltiazem, Amlodipine) at high dose - Negative: PAH-specific therapy PAH-Specific Therapy by Risk Stratification: Low/Intermediate Risk: - PDE5 inhibitor (Sildenafil, Tadalafil) + ERA (Ambrisentan, Macitentan) - Dual oral therapy preferred (AMBITION trial) High Risk (WHO FC III-IV, rapidly deteriorating): - IV Prostacyclin (Epoprostenol) - gold standard - Or oral Selexipag (prostacyclin receptor agonist) - Triple combination therapy For your patient (mPAP 45, idiopathic PAH): Vasoreactivity test, if negative start dual oral therapy (ERA + PDE5i), refer to specialized PH center