Pulmonary Hypertension Classification
Definition
Pulmonary hypertension (PH) is classified into five clinical groups based on aetiology and haemodynamic mechanism. The 2022 ESC/ERS guidelines lowered the diagnostic mPAP threshold to >20 mmHg (from ≥25 mmHg). The five-group classification is the foundation of PH management since PAH-specific therapies are only appropriate for Group 1 pre-capillary disease and are contraindicated or ineffective in others.
Key Concepts
Haemodynamic Definitions (2022 ESC/ERS)
- PH (new threshold): mPAP >20 mmHg at rest — lowered from ≥25 mmHg based on upper-limit-of-normal studies and prognostic data. (sources/PHT-ESC-2022 — very high)
- Pre-capillary PH: mPAP >20 mmHg + PAWP ≤15 mmHg + PVR >2 WU — includes Groups 1, 3, 4, 5.
- Post-capillary PH: mPAP >20 mmHg + PAWP >15 mmHg — Group 2 (left heart disease):
- Isolated post-capillary PH (IpcPH): PVR ≤2 WU — passive venous congestion
- Combined post- and pre-capillary PH (CpcPH): PVR >2 WU — reactive pulmonary vasoconstriction superimposed
- Exercise PH (reintroduced 2022): mPAP/CO slope >3 mmHg/L/min between rest and exercise; not physiological in individuals <60 years. (sources/PHT-ESC-2022)
- 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 patients diagnosed under the new lower threshold. (sources/PHT-ESC-2022)
Five Clinical Groups
- Group 1 — PAH: Pre-capillary PH from intrinsic pulmonary vascular pathology. Subtypes: idiopathic (IPAH, 50–60%), heritable (HPAH — BMPR2 mutations in ~80%), drug/toxin-associated, connective tissue disease (SSc most common), portal hypertension, congenital heart disease, schistosomiasis. PVOD/PCH and persistent PH of the newborn (PPHN) were moved into Group 1 in 2022. (sources/PHT-ESC-2022 — very high)
- Group 2 — Left Heart Disease (PH-LHD): Post-capillary PH from HFrEF, HFpEF (≥50% of symptomatic HFpEF have PH), mitral or aortic valve disease. Most common cause of PH globally. PDE5i is Class III (not recommended) in isolated post-capillary PH. (sources/PHT-ESC-2022)
- Group 3 — Lung Disease/Hypoxia: PH from COPD, ILD, hypoventilation syndromes. Isolated OSA removed as a recognised cause (renamed from "sleep-disordered breathing"). Optimise underlying lung disease first; PAH-specific therapy reserved for severe PH at PH centres. (sources/PHT-ESC-2022)
- Group 4 — Pulmonary Artery Obstructions: CTEPH (chronic thromboembolic PH) + newly formalised CTEPD (chronic thromboembolic pulmonary disease without haemodynamic PH). Lifelong anticoagulation for all. PEA is treatment of choice; BPA upgraded to Class I (from IIb) for inoperable or residual CTEPH; riociguat Class I for inoperable/residual. (sources/PHT-ESC-2022)
- Group 5 — Unclear/Multifactorial: Haematological disorders, systemic/metabolic diseases, complex CHD, compressive lesions. No specific proven therapy; management is of underlying disease. (sources/PHT-ESC-2022)
Diagnostic Algorithm
- 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, right heart catheterisation).
- Echocardiography assigns PH probability (TRV threshold >2.8 m/s) but cannot confirm PH — RHC is mandatory before PAH therapy initiation. (sources/PHT-ESC-2022)
- V/Q scintigraphy: Class I for unexplained PH to screen for CTEPH. CT pulmonary angiography: Class I for suspected CTEPH.
PAH Genetics
- BMPR2 mutations: most common heritable PAH gene (~80% of HPAH); penetrance ~20% overall (42% female, 14% male). Annual multimodal screening recommended for carriers. (sources/PHT-ESC-2022)
- Other validated PAH genes: ATP13A3, AQP1, ABCC8, KCNK3, SMAD9, Sox17, CAV1, TBX4, EIF2AK4, ENG, ACVRL1 (HHT), GDF2.
Contradictions / Open Questions
- New mPAP >20 mmHg threshold — no drug trial evidence: No approved PAH drug has been tested in patients with mPAP 21–24 mmHg, PVR 2–3 WU. Treating this newly identified group with potent PAH vasodilators carries risk without evidence of benefit. (sources/PHT-ESC-2022)
- CTEPD management: CTEPD without PH is newly formalised but prevalence is unknown; BPA and PEA for symptomatic CTEPD are Class IIa with very limited supporting evidence. (sources/PHT-ESC-2022)
- Anticoagulation for IPAH/HPAH: Downgraded to Class IIb despite meta-analyses suggesting survival benefit — no RCT data exist. Potentially harmful in SSc-PAH. Recommendation reflects expert consensus more than evidence. (sources/PHT-ESC-2022)
Connections
- Related to entities/Pulmonary-Hypertension
- Related to entities/CTEPH
- Related to concepts/PAH-Risk-Stratification
- Related to concepts/Right-Heart-Catheterization
- Related to concepts/Balloon-Pulmonary-Angioplasty