Treatment of Pulmonary Hypertension by WHO Classification Group
Treatment for pulmonary hypertension must be tailored to the specific WHO classification group, as therapies effective for Group 1 pulmonary arterial hypertension (PAH) are not recommended and may be harmful in Groups 2,3, and 5. 1
WHO Group 1: Pulmonary Arterial Hypertension (PAH)
Pharmacologic Treatment Options
For Group 1 PAH, multiple drug classes targeting three dysfunctional endothelial pathways are available 1, 2:
Approved medication classes include:
- Calcium channel blockers (amlodipine, diltiazem, nifedipine) - only for vasoreactive patients 1
- Prostacyclin derivatives (epoprostenol, treprostinil, iloprost) 1
- Endothelin receptor antagonists (bosentan, ambrisentan, macitentan) 1
- Phosphodiesterase-5 inhibitors (sildenafil, tadalafil) 1
- Soluble guanylate cyclase stimulator (riociguat) 1
- Selexipag (prostacyclin receptor agonist) 1
Vasoreactivity Testing - Critical for CCB Candidacy
Vasoreactivity testing is mandatory only in expert centers and only for patients with idiopathic PAH (IPAH), heritable PAH (HPAH), or drug-induced PAH to identify candidates for high-dose calcium channel blocker therapy. 1
- Positive response criteria: Reduction of mean PAP ≥10 mmHg to reach absolute mean PAP ≤40 mmHg with increased or unchanged cardiac output 1
- Preferred testing agents: Nitric oxide or intravenous epoprostenol 1
- Alternative agents: Adenosine (should be considered) or inhaled iloprost (may be considered) 1
- Contraindicated: Oral or intravenous CCBs during acute testing 1
- Not recommended: Vasoreactivity testing in PAH associated with other conditions or in WHO Groups 2,3,4, or 5 1
Treatment Strategy by Risk Level
For low or intermediate risk patients: Initial monotherapy or initial oral combination therapy 2
For high-risk patients: Initial combination therapy including intravenous prostacyclin analogues should be considered 2
For patients with inadequate response to maximum treatment (triple therapy with intravenous prostacyclin): Assessment for lung transplantation 2
Non-Pharmacologic Interventions
Supportive care measures include: 1
- Supplemental oxygen for chronic hypoxemia
- Diuretics for volume management
- Digoxin (may be considered)
- Anticoagulants (particularly for certain PAH subtypes)
Preventive care measures include: 1
- Influenza and pneumonia immunizations
- Contraception counseling
- High-risk pregnancy management
- Avoiding nonessential surgery with appropriate perioperative risk management
Cardiopulmonary rehabilitation may be considered as adjunctive therapy 1
Palliative care should be integrated into management 1
WHO Group 2: PH Due to Left Heart Disease
The optimal treatment of the underlying left heart disease is the cornerstone of management for Group 2 PH. 1
Critical Treatment Principle
PAH-specific drug therapy is NOT recommended in patients with PH due to left heart disease. 1
This represents a common pitfall - therapies approved for Group 1 PAH may be harmful in Group 2 PH patients 3. The distinction between Group 2 PH (particularly heart failure with preserved ejection fraction) and Group 1 PAH is challenging but vital, as treatment strategies differ completely 3.
When to Consider Research Protocols
Patients with "out of proportion" PH due to left heart disease should be enrolled in randomized controlled trials targeting PH-specific drugs. 1
"Out of proportion" typically refers to elevated transpulmonary gradient or pulmonary vascular resistance beyond what would be expected from left heart disease alone 4.
WHO Group 3: PH Due to Lung Disease and/or Hypoxia
The optimal treatment of the underlying lung disease, including long-term oxygen therapy in patients with chronic hypoxemia, is the recommended approach for Group 3 PH. 1
Critical Treatment Principle
PAH-specific drug therapy is NOT recommended in patients with PH due to lung diseases. 1
Current medications for treating PAH have not shown benefit in controlled trials of Group 3 PH, and their routine use is discouraged 5. Elevation of pulmonary arterial pressure is usually moderate and correlates with severity of lung disease 5.
When to Consider Research Protocols
Patients with "out of proportion" PH due to lung diseases should be enrolled in randomized controlled trials targeting PAH-specific drugs. 1
Patients with severe Group 3 PH should be considered for referral to expert centers or entry into clinical trials 5.
WHO Group 4: Chronic Thromboembolic Pulmonary Hypertension (CTEPH)
Surgical pulmonary endarterectomy (PEA) in deep hypothermia circulatory arrest is the recommended treatment for patients with CTEPH. 1
Mandatory Management Steps
Lifelong anticoagulation is required in all patients with CTEPH. 1
Assessment of operability and treatment decisions must be made by a multidisciplinary team of experts including at least one experienced PEA surgeon. 1
Medical Therapy for Inoperable or Persistent CTEPH
Riociguat is recommended in symptomatic patients classified as having persistent/recurrent CTEPH after surgical treatment or inoperable CTEPH by a CTEPH team. 1
Off-label use of drugs approved for PAH may be considered in symptomatic patients classified as having inoperable CTEPH by a CTEPH team. 1
Interventional Alternative
Balloon pulmonary angioplasty (BPA) may be considered in patients who are technically non-operable or carry an unfavorable risk:benefit ratio for PEA. 1
WHO Group 5: PH with Unclear/Multifactorial Mechanisms
Treatment focuses on the underlying causal disease, and PAH therapeutics are not recommended. 2
Common Pitfalls to Avoid
Never use PAH-specific therapies in Groups 2,3, or 5 PH outside of clinical trials - these may cause harm 1, 3
Do not prescribe high-dose calcium channel blockers without documented positive vasoreactivity testing - only 10-15% of IPAH patients are vasoreactive 1
Do not perform vasoreactivity testing outside expert centers - it is technically demanding and requires specific expertise 1
Do not delay referral to PEA-experienced centers for CTEPH patients - surgical candidacy assessment requires specialized expertise 1
Ensure all CTEPH patients receive lifelong anticoagulation regardless of other treatment decisions 1
Role of Specialized Centers
All patients with confirmed PAH or CTEPH should be managed at referral centers with multiprofessional teams including cardiology and respiratory medicine physicians, clinical nurse specialists, radiologists, and access to psychological and social work support. 1
Referral centers should follow at least 50 patients with PAH or CTEPH and receive at least two new referrals per month with documented PAH or CTEPH. 1