How do you approach the management of patients with mildly elevated mPAP (21-24 mmHg) and PVR (2-3 WU) who may be at risk of progression, given the recent changes in the hemodynamic definition of pulmonary hypertension?

The "new" definition of PH with a cutoff of 20 mmHg is a very sensible change, based on the study by Kovacs et al., PMID 19324955, which showed that a mean PAP of 20 mmHg is already two standard deviations above the mean PAP in normals. Thus, the cut off of 20 mmHg makes more sense than 25 mmHg.

To answer the question, note that two critical issues in determining therapy for PH are the CAUSE and the SEVERITY of the PH. If as above, it is MILD PH:

If group I PH (PAH), those with mild PH should be p...

The RHC numbers are one component of the REVEAL or REVEAL 2.0 score which should be ideally applied to decide whether/when one should treat. It includes nyha functional class, bnp/ntprobnp, 6 min walk, sbp, hr, gfr (Reference: Benza et al., PMID 32882243). I would also consider doing a VQ scan and ensuring that all etiologies of PH have been ruled out. The decision which medication to use (sildenafil/tadalafil or riociguat) may depend on it. Also, if vasodilator challenge has been performed duri...