10. Echocardiographic evidence of severe pulmonary hypertension (PH): systolic pulmonary pressure ≥ 50 mm Hg or tricuspid regurgitation velocity ≥ 3.2 m/sec (unless severe PH is invalidated by a right heart catheterization). If the pulmonary pressure is not quantifiable, presence of significant right ventricular enlargement or hypertrophy or right ventricular dysfunction.