One-line viva summary:
Diagnose pre-capillary PH on RHC at mPAP >20 and PVR >2.0 with PAWP ≤15. Echo screens; it does not treat.
Risk-stratify, escalate until low-risk.
New PAH is upfront dual oral therapy.
Sotatercept is disease modification, not another vasodilator.
Group 3 PH-ILD: inhaled treprostinil — not a systemic vasodilator.
I. Investigations and the New Hemodynamic Definition
Right-heart catheterisation — Class I gold standard
RHC remains mandatory to diagnose PAH and to start PAH-specific drugs. The hemodynamic threshold has been permanently lowered.
Risk stratification — treatment is driven by risk, not by a single number
Baseline: 3-strata model — low / intermediate / high.
Follow-up: 4-strata model — low / intermediate-low / intermediate-high / high (COMPERA 2.0 or French Registry criteria).
Escalation rule: treat until the patient is low-risk, and escalate whenever low-risk is not achieved or not maintained.
Echocardiography
Echo is the screening tool (estimated RVSP, RV size and function, pericardial effusion). It is not sufficient to diagnose PAH or to prescribe advanced PAH-specific therapy. Confirmatory RHC is required.
II. Disease Modification: STELLAR (2023–2024)
Core concept
Move from pulmonary vasodilation alone to targeting vascular remodeling — endothelial and smooth-muscle hyperproliferation.
Trial
Phase III add-on to stable background PAH therapy.
Sotatercept: first-in-class activin-signaling inhibitor (fusion protein / ligand trap for TGF-β superfamily members).
Subcutaneous every 3 weeks.
Key findings
Large improvement in 6-minute walk distance.
84% reduction in clinical worsening or death versus placebo.
Marked fall in PVR and improved RV function.
Paradigm
Pure vasodilation → disease modification. Sotatercept induces reverse remodeling. Approved Class IIa/I role for patients who remain symptomatic on maximal background therapy.
III. Fixed-Dose Dual Therapy: A DUE (2023)
Core concept
Upfront dual oral therapy is Class I in newly diagnosed low-to-intermediate risk PAH, but pill burden wrecks adherence.
Trial
Single-pill fixed-dose combination: macitentan (ERA) + tadalafil (PDE-5 inhibitor).
Compared with monotherapy with either agent.
Key findings
Superior PVR reduction versus either monotherapy.
Safety consistent with the known profiles of the two parent drugs.
Paradigm
Keep the Class I upfront dual-therapy mandate, but deliver it as a single pill so early risk reduction actually happens.
IV. High-Dose ERA: UNISUS (2024–2025)
Core concept
Historical ERA doses may have under-blocked the endothelin pathway.
Trial
Phase III: macitentan 75 mg versus the approved 10 mg dose.
Key findings
75 mg superior for time to clinical worsening (morbidity/mortality endpoint).
Paradigm
A higher oral efficacy ceiling before stepping to parenteral prostacyclin. Do not quote 10 mg as the only “full” ERA dose in a 2026 viva.
V. Group 3 PH (PH-ILD): INCREASE OLE and BREEZE (2023–2025)
Core concept
PH due to interstitial lung disease previously had no approved targeted drug. Systemic vasodilators worsen V/Q mismatch in fibrotic lung.
Trials
Long-term INCREASE open-label extension and BREEZE: inhaled treprostinil, including dry-powder inhaler delivery.
Key findings
Improved 6MWD.
Fewer exacerbations of the underlying lung disease.
Did not worsen oxygenation.
DPI is far more usable than nebulizer systems.
Paradigm
Inhaled treprostinil is first-line targeted therapy for PH-ILD. Drug is deposited in ventilated alveoli, avoiding the V/Q penalty of oral or intravenous vasodilators. This ends therapeutic nihilism in Group 3 PH.
VI. Summary Table (2023–2026)
VII. Exam Traps
mPAP ≥25 or PVR ≥3 is the old definition. Current pre-capillary cut-offs are >20 and >2.0.
Echo is not a licence to start PAH drugs. RHC first.
Sotatercept is not “another vasodilator.” Activin / TGF-β ligand trap; reverse remodeling.
New low–intermediate risk PAH: upfront dual oral therapy, not sequential monotherapy “to see how they do.”
Do not give systemic vasodilators as first-line in PH-ILD. Inhaled treprostinil.
Treatment target is low-risk status, not a single 6MWD or a single PAP number.
Follow-up risk is 4-strata, not the same 3-strata used at diagnosis.
VIII. Quick Viva Cards
Teaching summary drawn from the source note on 2023–2026 PH trials and current hemodynamic definitions. Confirm exact COR/LOE in the parent ESC/ERS document before quoting in a protocol.
meritmedscript.blogspot.com · Clinical exam notes · September 2026
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