Table 5.

Variables used in clinical practice to determine response to therapy and prognosis in patients with PAH

Variables	Good response to therapy and better prognosis
WHO functional class	Class I or II
Echocardiography/CMR	Normal/near normal RV size and function
Hemodynamics	Normalization of RV function (RAP <8 mmHg and CI >2.5–3.0 L/minute/m2)
6-minute walking distance	>380–440 m; may not be aggressive enough in young individuals
Cardiopulmonary exercise testing	Peak VO2 >15 mL/minute/kg and EqCO2 <45 L/minute/L/minute
B-type natriuretic peptide level	Normal

Abbreviations: PAH, pulmonary arterial hypertension; WHO, World Health Organization; CMR, cardiac magnetic resonance; RV, right ventricular; RAP, right atrial pressure; CI, cardiac index; VO₂, oxygen consumption; EqCO₂, ventilatory equivalent for carbon dioxide.