Treatment of pulmonary hypertension

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pulmonary hypertension classification diagnosis WHO groups management

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Based on the retrieved evidence and comprehensive medical knowledge, here is a thorough overview of pulmonary hypertension treatment:

Treatment of Pulmonary Hypertension

Definition and Classification

Pulmonary hypertension (PH) is defined as a mean pulmonary arterial pressure (mPAP) >20 mmHg on right heart catheterization. The WHO/ESC classification divides PH into 5 groups, each with distinct management strategies (GOLD 2025, p. 138):

Group	Etiology	Key Treatment Approach
1	Pulmonary Arterial Hypertension (PAH)	PAH-specific vasodilator therapies
2	Left heart disease	Treat underlying LHD; avoid PAH drugs
3	Lung disease / hypoxia	Treat underlying lung disease; O₂ therapy
4	CTEPH	Pulmonary endarterectomy (PEA); riociguat
5	Unclear/multifactorial	Treat underlying cause

PAH-specific drugs are approved and indicated primarily for Group 1. Using them inappropriately in Groups 2–5 can be harmful.

General (Supportive) Measures

Supplemental oxygen: Target SpO₂ >90–92%; corrects hypoxic vasoconstriction
Diuretics: Manage right heart failure and volume overload (furosemide ± spironolactone)
Anticoagulation: Recommended in idiopathic/heritable PAH (warfarin, target INR 1.5–2.5); individualized in other forms
Digoxin: May improve cardiac output acutely; limited long-term evidence
Exercise rehabilitation: Supervised cardiac/pulmonary rehab improves functional capacity
Avoid: Pregnancy (high mortality risk), high altitude, strenuous exertion, NSAIDs, certain drugs (amphetamines, dasatinib)

Group 1 PAH: Vasoreactivity Testing First

Before selecting PAH therapy, right heart catheterization with acute vasoreactivity testing (using inhaled nitric oxide, IV epoprostenol, or IV adenosine) is performed. (Harrison's, p. 7838)

Positive vasoreactivity (<5% of patients): Marked, sustained response → high-dose oral calcium channel blockers (CCBs) (amlodipine, diltiazem, nifedipine) with favorable prognosis
Negative vasoreactivity (majority): Must use targeted PAH drug classes

Targeted PAH Drug Therapy (Group 1)

Three major pathways are targeted:

1. Endothelin Receptor Antagonists (ERAs) — Oral

Drug	Notes
Ambrisentan	Selective ETA antagonist; once daily
Bosentan	Non-selective ETA/ETB; monitor LFTs monthly
Macitentan	Non-selective; shown to reduce morbidity/mortality (SERAPHIN trial)

2. Phosphodiesterase-5 Inhibitors (PDE5i) / sGC Stimulators — Oral

Drug	Class	Notes
Sildenafil	PDE5i	First-line; TID dosing
Tadalafil	PDE5i	Once daily; convenient
Riociguat	sGC stimulator	Also approved for CTEPH (Group 4); do NOT combine with PDE5i

3. Prostacyclin Pathway Agents

Drug	Route	Notes
Epoprostenol (IV)	Continuous IV	Gold standard for high-risk; improved survival in RCTs
Treprostinil	IV, SC, inhaled, oral	More stable than epoprostenol; SC route causes injection site pain
Iloprost	Inhaled	6–9 inhalations/day; short half-life
Selexipag	Oral	Prostacyclin receptor agonist (GRIPHON trial); reduces events

Risk Stratification and Treatment Algorithm

Per Harrison's Principles, 21st Ed. (p. 7838):

Newly diagnosed PAH
        ↓
Vasoreactivity testing at RHC
   ↓                    ↓
Positive (<5%)       Negative (majority)
   ↓                    ↓
High-dose CCB        Risk stratify
                    ↙           ↘
             Low/Intermediate     High risk
                    ↓                  ↓
        Dual oral combination    Triple combination therapy
        (ERA + PDE5i/tadalafil)  + IV prostacyclin (epoprostenol)

Risk Score Features (Low vs. High Risk)

Feature	Low Risk (Good)	High Risk (Poor)
WHO Functional Class	I–II	IV
6-minute walk distance	>440 m	<165 m
NT-proBNP	Low/normal	Markedly elevated
Hemodynamics (RAP, CI, SvO₂)	Normal	Abnormal
Imaging (RV size/function)	Normal	Significantly impaired

Group 4: Chronic Thromboembolic PH (CTEPH)

Pulmonary endarterectomy (PEA): Treatment of choice for operable disease; potentially curative
Balloon pulmonary angioplasty (BPA): For inoperable patients
Riociguat: Only PAH drug formally approved for inoperable/persistent CTEPH after PEA
Anticoagulation: Lifelong (warfarin preferred)

Groups 2 & 3: Left Heart Disease / Lung Disease

No PAH-specific therapies approved; focus is on treating the underlying cause
Group 2: Optimize HF therapy (ACE-I/ARB, beta-blockers, diuretics, cardiac interventions)
Group 3: Long-term O₂ therapy, treat COPD/ILD, consider lung transplant in advanced disease

Lung Transplantation

Reserved for patients who fail maximal medical therapy:

Bilateral lung transplant preferred
Indications: WHO FC III–IV despite combination therapy, rapidly progressive disease
Median post-transplant survival ~5–7 years

Emerging / Investigational Therapies

Sotatercept (activin receptor fusion protein): Phase 3 trial (STELLAR) showed significant improvement in 6MWD and hemodynamics in PAH; FDA-approved (2024) as add-on to background therapy
Inhaled treprostinil in ILD-associated PH (INCREASE trial): Improved 6MWD
Gene therapy and stem cell approaches: Under investigation

Summary of First-Line Recommendations (PAH, WHO FC II–III)

Dual oral combination therapy: ERA (ambrisentan or macitentan) + PDE5i (tadalafil or sildenafil)
- Supported by AMBITION trial (ambrisentan + tadalafil superior to monotherapy)
Escalate to triple therapy (add inhaled/SC/oral prostacyclin agent) if inadequate response
High-risk: Initiate with triple therapy including IV epoprostenol from the outset

Sources: Harrison's Principles of Internal Medicine, 21st Ed. (p. 7838); GOLD COPD 2025 Report (p. 138); ESC/ERS 2022 PH Guidelines; AMBITION, SERAPHIN, GRIPHON, STELLAR trials.

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