#pulmonary-hypertension #PAH #CTEPH #right-heart-failure #pulmonary-arterial-hypertension #haemodynamics #vascular-resistance #classification

Pulmonary Hypertension

Details

Pulmonary hypertension (PH) is a haemodynamic state defined by a mean pulmonary arterial pressure (mPAP) >20 mmHg at rest on right heart catheterization (RHC) — the 2022 ESC/ERS threshold, lowered from ≥25 mmHg. It affects ~1% of the global population across all age groups, with left heart disease (LHD) being the leading cause globally. PH is not a single disease but a haemodynamic consequence of diverse aetiologies classified into five clinical groups based on pathophysiology and aetiology: Group 1 (PAH), Group 2 (PH-LHD), Group 3 (PH-lung disease/hypoxia), Group 4 (PH-PA obstructions/CTEPH), and Group 5 (unclear/multifactorial). The five-group classification is the foundation of management since PAH-specific therapies are only appropriate for Group 1 pre-capillary disease and are contraindicated or ineffective in others. Irrespective of aetiology, developing PH is associated with worsening symptoms, RV dysfunction, and significantly increased mortality.

Key Facts

Haemodynamic Definitions (2022 ESC/ERS)

PH (new threshold): mPAP >20 mmHg at rest on RHC (lowered from prior ≥25 mmHg based on upper-limit-of-normal studies and prognostic data). (sources/PHT-ESC-2022, rating: very high)
Pre-capillary PH: mPAP >20 mmHg + PAWP ≤15 mmHg + PVR >2 WU — includes Groups 1, 3, 4, 5. (sources/PHT-ESC-2022, rating: very high)
Isolated post-capillary PH (IpcPH): mPAP >20 mmHg + PAWP >15 mmHg + PVR ≤2 WU — passive venous congestion. (sources/PHT-ESC-2022, rating: very high)
Combined post- and pre-capillary PH (CpcPH): mPAP >20 mmHg + PAWP >15 mmHg + PVR >2 WU — reactive pulmonary vasoconstriction superimposed on elevated venous pressure. (sources/PHT-ESC-2022, rating: very high)
Exercise PH (reintroduced 2022): mPAP/CO slope >3 mmHg/L/min between rest and exercise. Associated with impaired prognosis. Not physiological in subjects <60 years. (sources/PHT-ESC-2022, rating: very high)
Unclassified PH: mPAP >20 mmHg + PVR ≤2 WU + PAWP ≤15 mmHg — often from elevated pulmonary blood flow (CHD, liver disease, hyperthyroidism). (sources/PHT-ESC-2022, rating: very high)
Drug threshold caveat: All approved PAH drugs were studied only in patients with mPAP ≥25 mmHg and PVR >3 WU — no efficacy data exist for the lower-threshold zone (mPAP 21–24 mmHg, PVR 2–3 WU). (sources/PHT-ESC-2022, rating: very high)

PAWP normal range and zone of uncertainty

True physiological upper limit of normal PAWP: 13 mmHg (meta-analysis, n=940 healthy subjects; independent of BMI and age; women slightly higher than men). (sources/rhc-hf-ehj-2025, rating: high)
ESC PH guideline post-capillary PH threshold: PAWP >15 mmHg — this creates a diagnostic grey zone (13–15 mmHg) where early LHD may be under-recognised.
Zone of uncertainty (12–18 mmHg): PAWP in this range should be contextualised to individual clinical probability of left heart disease; provocative testing (exercise RHC, fluid challenge, passive leg raise) may be required. (sources/rhc-hf-ehj-2025, rating: high)
See concepts/Right-Heart-Catheterization for full PAWP methodology and pitfalls.

Pathophysiology

Pulmonary vascular resistance (PVR): The key haemodynamic driver in pre-capillary PH. Elevated PVR reflects pulmonary vascular remodelling (smooth muscle proliferation, endothelial dysfunction, in situ thrombosis, adventitial fibrosis) — not reversible by vasodilators alone in established disease. (sources/PHT-ESC-2022, rating: very high)
Right ventricular adaptation: RV adapts initially to elevated afterload via concentric hypertrophy with maintained contractility. Failure occurs when RV cannot maintain coupling with the pulmonary vasculature — RV–PA uncoupling → dilatation, tricuspid regurgitation, systemic venous congestion. RV failure is the proximate cause of death in advanced PH. See concepts/RV-PA-Coupling. (sources/rv-failure-aha-2026, rating: very high)
Vasoconstriction vs remodelling: In early PAH, vasoconstriction is partially reversible (acute vasoreactivity testing determines eligibility for CCBs in ~10% of patients); in established PAH, fixed structural remodelling dominates and vasoreactivity is absent in >90%. (sources/PHT-ESC-2022, rating: very high)
Post-capillary mechanisms (Group 2): Elevated PAWP from LHD raises pulmonary venous pressure passively (IpcPH). In some patients, compensatory pulmonary vasoconstriction develops → CpcPH with elevated PVR — this subset may benefit from PAH-targeted therapy at specialised centres. Reduction of LA pressure via GDMT optimisation is the primary strategy, not pulmonary vasodilators. (sources/PHT-ESC-2022, rating: very high; sources/rvfailure-nejm-2023, rating: very high)
Key drivers of maladaptive RV remodeling: inflammation (TNF-α/IL-6/IL-1β/NLRP3 inflammasome), metabolic reprogramming (Warburg effect, FAO → glycolysis shift), ECM fibrosis (TGF-β/MMP/integrin pathways). (sources/rv-failure-aha-2026, rating: very high)

Clinical Classification — 5 Groups

Group 1 — PAH: Includes IPAH, HPAH, drug/toxin-associated PAH, PAH associated with CTD/HIV/portal hypertension/CHD/schistosomiasis, PVOD/PCH (moved into Group 1 in 2022), and PPHN. Rare; prevalence 48–55/million adults. (sources/PHT-ESC-2022, rating: very high)
- Cancer therapy-associated PAH (drug/toxin Group 1): Bleomycin (lymphomas/testicular cancer) causes PAH via endothelial apoptosis and ↓ EC proliferation; cyclophosphamide also associated; dasatinib (BCR-ABL TKI) causes PAH in 5% vs. 0.4% with imatinib. (sources/cardio-oncology-vascular-metabolic-aha-2019, rating: very high; sources/Cardio-Oncology-ESC-2022, rating: very high)
Group 2 — Left Heart Disease (PH-LHD): Post-capillary PH from HFrEF, HFmrEF, HFpEF (≥50% of symptomatic HFpEF), or valvular disease. Most common cause of PH globally. (sources/PHT-ESC-2022, rating: very high)
Group 3 — PH-lung disease/hypoxia: Associated with COPD, ILD, hypoventilation syndromes; isolated OSA removed as a recognised cause. 1–5% of advanced COPD have mPAP >35–40 mmHg. (sources/PHT-ESC-2022, rating: very high)
Group 4 — PH-PA obstructions: Primarily CTEPH; prevalence 26–38/million adults. CTEPD (chronic thromboembolic pulmonary disease without haemodynamic PH) newly formalised as a related entity. Lifelong anticoagulation for all. (sources/PHT-ESC-2022, rating: very high)
Group 5 — Unclear/multifactorial: Haematological disorders, systemic/metabolic diseases (sarcoidosis, neurofibromatosis, fibrosing mediastinitis), complex CHD, compressive lesions. No specific proven therapy; management is of underlying disease. (sources/PHT-ESC-2022, rating: very high)

Epidemiology

Global prevalence: ~1% of the global population; prevalence higher in individuals >65 years. UK observed prevalence: 125 cases/million (doubled over 10 years). (sources/PHT-ESC-2022, rating: very high)
PAH (Group 1): Incidence ~6/million adults; prevalence 48–55/million adults. IPAH accounts for 50–60% of PAH; historically female-predominant but now increasingly older patients with equal sex distribution. (sources/PHT-ESC-2022, rating: very high)
CTEPH (Group 4): Incidence 2–6/million adults; prevalence 26–38/million adults. Cumulative incidence post-acute PE: 0.6% (all patients), 2.3% at 2 years in prospective data. (sources/PHT-ESC-2022, rating: very high)

Diagnosis

RHC: Required for PH confirmation; gold standard. Must be performed before initiating PAH therapy. Three-step pathway: Step 1 (GP suspicion — ECG, BNP/NT-proBNP, O₂ saturation); Step 2 (detection — echocardiography, PFTs, ABG); Step 3 (confirmation — referral to PH centre, RHC). (sources/PHT-ESC-2022, rating: very high)
Echocardiography: First-line non-invasive investigation (Class I/B); assigns echocardiographic probability of PH. TRV threshold >2.8 m/s maintained. Echocardiography alone insufficient to confirm PH — RHC is mandatory before PAH therapy initiation. (sources/PHT-ESC-2022, rating: very high)
V/Q scintigraphy: Class I for unexplained PH to screen for CTEPH. CT pulmonary angiography: Class I for suspected CTEPH. (sources/PHT-ESC-2022, rating: very high)
Warning signs for immediate hospitalization: Rapid WHO-FC III/IV progression, RV failure signs, syncope, low CO state, haemodynamic compromise. (sources/PHT-ESC-2022, rating: very high)

Screening

SSc: Annual PAH risk evaluation recommended (Class I/B); DETECT algorithm when disease duration >3 years + FVC ≥40% + DLCO <60% (Class I/B). Prevalence of PAH in SSc: 5–19%. (sources/PHT-ESC-2022, rating: very high)
BMPR2 carriers: Annual multimodal screening (ECG + NT-proBNP + DLCO + echo + CPET). Echocardiography alone insufficient. Lifetime PAH risk ~20% overall (42% female, 14% male). (sources/PHT-ESC-2022, rating: very high)
Post-PE: Evaluate for CTEPH/CTEPD in persistent/new dyspnoea after PE (Class I/C); refer to PH/CTEPH centre for mismatched perfusion defects persisting beyond 3 months (Class I/C). (sources/PHT-ESC-2022, rating: very high)

Genetics — Heritable PAH (HPAH)

BMPR2 (AD): Definitive — major genetic cause of HPAH; accounts for ~75–80% of familial PAH and ~20% of apparently idiopathic PAH. Lifetime penetrance ~20% (42% female, 14% male). (sources/clingen-summary-2026-05-09, rating: high; ClinGen classification date: 12/07/2020)
CAV1 (AD): Definitive — caveolin-1; established genetic cause of HPAH. (sources/clingen-summary-2026-05-09, rating: high; ClinGen classification date: 07/30/2025)
ATP13A3 (AD): Definitive — ATPase 13A3; established genetic cause of HPAH. (sources/clingen-summary-2026-05-09, rating: high; ClinGen classification date: 11/09/2021)
EIF2AK4 (AR): Definitive — established cause of PVOD/PCH (rare PAH subtype); biallelic loss-of-function variants diagnostic. (sources/clingen-summary-2026-05-09, rating: high; ClinGen classification date: 12/02/2022)
BMPR1A, BMPR1B (AD): Disputing — initial reports not confirmed with sufficient evidence; variants should not be classified as P/LP for HPAH without functional evidence. (sources/clingen-summary-2026-05-09, rating: high)
Additional genes reported in PAH literature (limited/disputed evidence): AQP1, ABCC8, KCNK3, SMAD9, Sox17, TBX4, ENG, ACVRL1 (HHT-associated), GDF2 — evidence not yet ClinGen-validated to definitive level. (sources/PHT-ESC-2022, rating: very high)
Genetic testing in PAH: 2022 ESC guidelines recommend genetic counselling and testing in all PAH patients (Class I/C). BMPR2, CAV1, ATP13A3, and EIF2AK4 (for PVOD/PCH) are the four genes with definitive ClinGen evidence. (sources/PHT-ESC-2022, rating: very high; sources/clingen-summary-2026-05-09, rating: high)

PAH General Measures

Supervised exercise training: Class I/A (upgraded from IIa) — large multicentre RCT showed +34.1 m 6MWD improvement in PAH/CTEPH on PAH drugs. (sources/PHT-ESC-2022, rating: very high)
Iron deficiency correction: Class I/C — i.v. iron for anaemia; repletion without anaemia is Class IIb. (sources/PHT-ESC-2022, rating: very high)
Anticoagulation: IIb (individual basis only) — not generally recommended; potentially harmful in SSc-PAH; conflicting evidence for IPAH. (sources/PHT-ESC-2022, rating: very high)
ACEi/ARB/ARNI/SGLT-2i/beta-blockers: Class III — not recommended in PAH unless required by comorbidities. (sources/PHT-ESC-2022, rating: very high)
Pregnancy: strongly discouraged — maternal mortality 11–25%; ERAs and riociguat contraindicated (Class III/B); CCBs/PDE5i/prostacyclins considered safe. (sources/PHT-ESC-2022, rating: very high)

PAH Drug Therapy

Low-risk treatment target (3-strata model): WHO-FC I/II, 6MWD >440 m, NT-proBNP in normal range, RAP <8 mmHg, CI ≥2.5 L/min/m², SVI ≥38 mL/m², mVO₂ >65% — the primary treatment goal. (sources/PHT-ESC-2022, rating: very high)
Acute vasoreactivity testing (AVT) — updated positive response definition: mPAP decrease ≥10 mmHg to absolute value ≤40 mmHg with maintained or increased CO; ~10% of PAH patients respond; predictive value only in idiopathic/heritable/drug-induced PAH. (sources/hemodynamic-hf-pht-aha-2026, rating: very high)
Preferred AVT agents: iNO and inhaled iloprost (Class I ESC 2022); IV epoprostenol (Class I ESC 2022); adenosine no longer recommended (ESC 2022) — AV block, bronchospasm, hypotension. (sources/hemodynamic-hf-pht-aha-2026, rating: very high)
Calcium channel blockers: Class I/C — only for vasoreactive patients with IPAH/HPAH/DPAH (<10% qualify). Adequate response: WHO-FC I/II + mPAP <30 mmHg + PVR <4 WU at 3–6 months. Class III in non-responders. (sources/PHT-ESC-2022, rating: very high; sources/hemodynamic-hf-pht-aha-2026, rating: very high)
Initial combination ERA + PDE5i: Class I/B for low-to-intermediate-risk IPAH/HPAH/DPAH. Ambrisentan + tadalafil (AMBITION): Class I. Macitentan + tadalafil: Class I (new in 2022). Other ERA + PDE5i: Class IIa. (sources/PHT-ESC-2022, rating: very high)
Bosentan + sildenafil: Class III (downgraded from IIb — no longer recommended). (sources/PHT-ESC-2022, rating: very high)
Escalation for intermediate-high/high risk: Parenteral prostacyclin addition or lung transplantation evaluation. (sources/PHT-ESC-2022, rating: very high)
See entities/CTEPH for CTEPH-specific therapy; see concepts/PAH-Risk-Stratification for treatment targets.

PH-LHD (Group 2)

RHC: Class I — for suspected PH-LHD when results aid management; also for severe tricuspid regurgitation before valve intervention. (sources/PHT-ESC-2022, rating: very high)
PDE5i in HFpEF + isolated post-capillary PH: Class III — not recommended. SIOVAC trial demonstrated worsened outcomes with sildenafil in persistent PH after left-sided valvular disease correction. 77% of US centres continue to use PAH-approved therapies in non-Group 1 PH despite evidence of harm. (sources/PHT-ESC-2022, rating: very high; sources/rvfailure-nejm-2023, rating: very high)
Borderline PAWP (13–15 mmHg) with HFpEF features: Exercise or fluid challenge may unmask post-capillary PH (Class IIb). (sources/PHT-ESC-2022, rating: very high)
CpcPH with PVR >5 WU: Individualized approach; referral to PH centre (Class I). (sources/PHT-ESC-2022, rating: very high)

PH-Lung Disease (Group 3)

Optimize underlying lung disease treatment: Class I. (sources/PHT-ESC-2022, rating: very high)
Inhaled treprostinil: Class IIb — may be considered in PH-ILD. (sources/PHT-ESC-2022, rating: very high)
Ambrisentan: Class III — not recommended in PH-IPF. (sources/PHT-ESC-2022, rating: very high)
Riociguat: Class III — not recommended in PH-IIP. (sources/PHT-ESC-2022, rating: very high)

PAH Associated with ASD (CHD-PAH) — Closure Decision Thresholds

ASD-associated PAH is Group 1 pre-capillary PAH (CHD-PAH). Key distinguishing feature: the presence of the ASD shunt means haemodynamic decision-making requires PVR measurement to determine whether closure is safe, beneficial, or contraindicated.

PVR <5 WU: ASD closure safe and associated with reduced PAP and symptom improvement (extent inversely related to PVR). (sources/asd-ehj-2022 — high)
PVR ≥5 WU: Closure likely harmful; patients unlikely to improve and may worsen → initiate PAH pharmacotherapy (oral ERA ± PDE5i), then re-evaluate. (sources/asd-ehj-2022 — high)
PVR ≥5 WU + Qp/Qs >1.5 on PAH therapy: Fenestrated closure may be considered (long-term evidence lacking). (sources/asd-ehj-2022 — high)
PVR ≥5 WU despite PAH treatment: ASD closure contraindicated. (sources/asd-ehj-2022 — high)
Vasoreactivity testing with inhaled NO: NOT recommended when deciding whether to close an ASD in PAH. (sources/asd-ehj-2022 — high)
LV impairment + ASD: Invasive haemodynamic assessment mandatory before closure; balloon test occlusion helps guide complete vs fenestrated vs no closure (elevated PCWP after balloon occlusion = worse HF risk). (sources/asd-ehj-2022 — high)
Eisenmenger syndrome (ASD with reversed or bidirectional shunt): Closure absolutely contraindicated; proactive advanced PAH therapy with prostacyclins; subcutaneous/inhaled preferred over parenteral. (sources/asd-ehj-2022 — high)
Contemporary series: prevalence of PH in closed ASD patients <3% — reflects earlier diagnosis and proactive closure approach. (sources/asd-ehj-2022 — high)
See concepts/Atrial-Septal-Defect for full ASD management framework.

RV Failure in PH — Mechanisms and Assessment

RV–PA uncoupling is the haemodynamic hallmark of right heart failure in PH: Ees/Ea <≈0.7 = uncoupling threshold; optimal coupling 1.5–2.0. See concepts/RV-PA-Coupling. (sources/rv-failure-aha-2026, rating: very high)
Progression: chronic pressure overload → RV hypertrophy (adaptive) → RV dilation, fibrosis, diastolic stiffness → RV–PA uncoupling (maladaptive) → right heart failure — primary cause of death in advanced PH. (sources/rv-failure-aha-2026, rating: very high)
RV afterload is multifactorial: PVR + PA compliance + pulsatile load — PVR alone insufficient to characterise haemodynamic burden. (sources/rv-failure-aha-2026, rating: very high)
Noninvasive RV–PA coupling surrogates: TAPSE/sPAP (widely used; prognostic); RV free wall strain/sPAP (superior for PAH outcomes prediction); RVEF change with therapy. (sources/rv-failure-aha-2026, rating: very high)
CMR: Gold standard for RV volumes/function; LGE and T1/T2 mapping detect fibrosis in maladaptive remodeling; 4D flow predicts PH vs RHC. (sources/rv-failure-aha-2026, rating: very high)
BMPR2 mutation carriers: More severe RV dysfunction independent of afterload; higher mortality/transplantation risk vs non-carriers. (sources/rv-failure-aha-2026, rating: very high)

Sotatercept — Activin-Signaling Inhibitor for PAH

Sotatercept (ACTRIIA-Fc fusion protein; activin signaling inhibitor): FDA-approved for PAH; first-in-class mechanism targeting pulmonary vascular remodeling via activin/BMP pathway rebalancing rather than vasodilation. Complementary to ERAs, PDE5i, sGC stimulators, and prostacyclins; used as add-on therapy. See entities/Sotatercept. (sources/rv-failure-aha-2026, rating: very high)
STELLAR trial (Phase 3, WHO FC II/III, n=323): Improved 6MWD (+34.4 m), PVR, PA compliance, PA–RV coupling, and RV function; 84% reduction in clinical worsening events. (sources/rv-failure-aha-2026, rating: very high)
SPECTRA trial (Phase 2b): Decreased RV mass; increased haemoglobin and peak VO₂ without changes in resting cardiac output; potential direct cardioprotective effect on cardiomyocytes. (sources/rv-failure-aha-2026, rating: very high)
ZENITH trial (Phase 3, WHO FC III/IV, REVEAL Lite 2 ≥9 on maximum double/triple therapy, n=172): Stopped early for overwhelming efficacy. Primary composite (all-cause death/lung transplant/PAH hospitalization ≥24h): HR 0.24 (95% CI 0.13–0.43, P<0.001); 17.4% vs 54.7%. PAH hospitalization: 9.3% vs 50.0%. All-cause death: 8.1% vs 15.1% (HR 0.42; technically NS due to hierarchical testing after early stopping). (sources/sotatercept-zenith-nejm-2025, rating: very high)
HYPERION trial (Phase 3, WHO FC II/III, diagnosed <1 year, REVEAL Lite 2 ≥6 or COMPERA 2.0 ≥2, double/triple background therapy, n=320): Stopped early for loss of clinical equipoise (ZENITH results). Primary composite (clinical worsening): HR 0.24 (95% CI 0.14–0.41, P<0.001); 10.6% vs 36.9%; NNT=5 at 12 months. Exercise testing deterioration dominant driver (5% vs 29%); all-cause death balanced (4.4% vs 3.8%). Population older and more comorbid than prior trials — representative of real-world registries. (sources/sotatercept-hyperion-nejm-2025, rating: very high)
Long-term consequences of sotatercept's direct RV myocardial effects remain under investigation (SOTERIA open-label extension ongoing). (sources/rv-failure-aha-2026, rating: very high)

Lung Transplantation in PAH — Referral and Listing Criteria

See concepts/Lung-Transplantation-PAH for full details on procedure, perioperative strategy, and outcomes.
Referral when (any): ESC/ERS intermediate/high risk or REVEAL >7 on appropriate PAH medication; progressive disease or recent hospitalisation; need for IV/SC prostacyclin; high-risk variants (PVOD, PCH, scleroderma-PAH); secondary liver/kidney dysfunction due to PAH; recurrent haemoptysis (sources/PHT-RVsupport-WSPH-2019, rating: high)
Listing when: ESC/ERS high risk or REVEAL ≥10 on optimised PAH therapy (usually IV/SC prostacyclin); expected 1-year medical-therapy mortality (>20%) exceeds expected 1-year post-Tx mortality (~10%) (sources/PHT-RVsupport-WSPH-2019, rating: high)
No degree of RV dysfunction precludes bilateral lung transplantation in PAH — RV recovers within weeks post-transplant regardless of pre-operative severity (sources/PHT-RVsupport-WSPH-2019, rating: high)
Bilateral lung transplantation is the procedure of choice; perioperative and prolonged postoperative ECMO is standard of care in expert centres — prevents early graft dysfunction from LV diastolic dysfunction; 1-year survival >90% (sources/PHT-RVsupport-WSPH-2019, rating: high)
ICU management of acute RV failure in PH: avoid intubation, avoid fluid loading, use IV prostacyclins for afterload reduction, consider dobutamine/milrinone, use vasopressin/norepinephrine for vasopressor support — see concepts/ECLS-in-PH (sources/PHT-RVsupport-WSPH-2019, rating: high)

Perioperative Management of PH

Continue all PAH-targeted therapy perioperatively (COR 1): Abrupt discontinuation of ERA, PDE5i, or prostacyclins causes acute haemodynamic decompensation and death — must be maintained without interruption including on the day of surgery. (sources/periop-aha-2024, rating: very high)
Specialist centre referral (COR 2a): Severe PH patients undergoing elevated-risk NCS should be managed at centres with PAH expertise — multidisciplinary team including PH cardiologist, anaesthesiologist, and intensivist. (sources/periop-aha-2024, rating: very high)
Perioperative risk: PH confers 43% increased odds of postoperative death, MI, or stroke. Group 1 PAH specifically: 2.5× increased MACE risk and 5× increased cardiogenic shock risk vs patients without PH. (sources/periop-aha-2024, rating: very high)
Invasive haemodynamic monitoring (COR 2a): Recommended for elevated-risk NCS; avoid fluid overload and agents that increase RV afterload. (sources/periop-aha-2024, rating: very high)
Inhaled pulmonary vasodilators (COR 2a): Inhaled NO or epoprostenol available for perioperative pulmonary hypertensive crises; vasopressors (norepinephrine, vasopressin) preferred to maintain RV perfusion pressure. (sources/periop-aha-2024, rating: very high)

Contradictions / Open Questions

Lower haemodynamic threshold not yet backed by drug trial evidence: The 2022 definition extends PH diagnosis to mPAP 21–24 mmHg + PVR 2–3 WU, but all approved PAH drugs were studied only in patients with mPAP ≥25 mmHg and PVR >3 WU. No efficacy data exist for this lower-threshold zone — clinicians may face diagnostic labelling without actionable treatment options. (sources/PHT-ESC-2022, rating: very high)
Exercise PH thresholds require further validation: mPAP/CO slope >3 mmHg/L/min is age-dependent; reproducibility across centres and prognostic implications require prospective validation before routine clinical use. (sources/PHT-ESC-2022, rating: very high)
Anticoagulation in IPAH remains unresolved: Downgraded to Class IIb despite meta-analyses suggesting survival benefit; no RCT data; potentially harmful in SSc-PAH; recommendation driven by expert opinion. (sources/PHT-ESC-2022, rating: very high)
Normal PAWP vs PH classification threshold: True physiological PAWP upper limit is 13 mmHg (meta-analysis), but ESC guidelines use 15 mmHg as the post-capillary PH threshold. The grey zone (13–15 mmHg) may lead to under-recognition of early LHD-related PH. (sources/rhc-hf-ehj-2025, rating: high)
CTEPD management evidence gap: CTEPD without haemodynamic PH is newly formalised but prevalence is unknown; BPA and PEA for symptomatic CTEPD without PH are Class IIa with very limited supporting evidence. (sources/PHT-ESC-2022, rating: very high)
RV–PA uncoupling transition point remains elusive: The adaptive-to-maladaptive remodeling transition cannot be reliably identified prospectively; no validated serial monitoring algorithm integrates Ees/Ea surrogates into clinical practice. (sources/rv-failure-aha-2026, rating: very high)
ESC/ERS guidelines lack comprehensive ongoing risk assessment incorporating advanced RV imaging: Current guidelines use imaging metrics for initial diagnosis only; no validated multiparametric model for serial RV monitoring in PH. (sources/rv-failure-aha-2026, rating: very high)
Sotatercept survival benefit clinically evident but statistically unproven in ZENITH: HR 0.42 for all-cause death (8.1% vs 15.1%) strongly favors sotatercept in high-risk PAH, but early trial stopping constrained follow-up and hierarchical testing did not reach pre-specified alpha for overall survival (SOTERIA will inform). (sources/sotatercept-zenith-nejm-2025, rating: very high)
Sotatercept early-disease benefit is functional, not survival-based: HYPERION (FC II/III, <1 year) shows HR 0.24 for clinical worsening composite but deaths were balanced (4.4% vs 3.8%). ZENITH (FC III/IV, high-risk) showed mortality trend favoring sotatercept (HR 0.42). The nature of benefit differs by disease stage; longer follow-up needed. (sources/sotatercept-hyperion-nejm-2025, rating: very high)
Sotatercept first-line therapy question unresolved: All STELLAR, ZENITH, and HYPERION trials required pre-established stable background therapy; whether sotatercept can be initiated as first-line therapy is unanswered. (sources/sotatercept-hyperion-nejm-2025, rating: very high)
ClinGen disputes BMPR1A and BMPR1B in HPAH (2026): ClinGen classification is "Disputing" — insufficient evidence to establish gene-disease causality. Variants in BMPR1A and BMPR1B should not be labelled P/LP for HPAH without strong functional validation. (sources/clingen-summary-2026-05-09, rating: high)

Connections

Related to concepts/Atrial-Septal-Defect — ASD-PAH is Group 1 CHD-PAH; PVR thresholds determine closure safety
Related to entities/CTEPH
Related to concepts/PAH-Risk-Stratification
Related to entities/Heart-Failure
Related to entities/HFpEF
Related to concepts/Right-Heart-Catheterization
Related to concepts/RV-PA-Coupling
Related to concepts/Right-Ventricular-Failure
Related to concepts/Balloon-Pulmonary-Angioplasty
Related to concepts/Perioperative-Cardiovascular-Assessment
Related to concepts/Cancer-Therapy-Related-CV-Toxicity
Related to concepts/ClinGen-Gene-Disease-Validity
Related to entities/Sotatercept — activin-signaling inhibitor; STELLAR + ZENITH + HYPERION trial evidence; mechanism complementary to vasodilators
Related to concepts/ECLS-in-PH — VA-ECMO/PA-LA for refractory RV failure in PH; awake ECMO bridge to transplant
Related to concepts/Lung-Transplantation-PAH — referral/listing criteria; bilateral Tx; perioperative ECMO; 1-year survival >90%
Related to sources/PHT-ESC-2022
Related to sources/rhc-hf-ehj-2025
Related to sources/rv-failure-aha-2026
Related to sources/periop-aha-2024
Related to sources/cardio-oncology-vascular-metabolic-aha-2019
Related to sources/clingen-summary-2026-05-09