Key Clinical Summary: Rethink Pulmonary Arterial Hypertension - Optimize Escalation and Combination Therapy

This is a micro-learning module summary of a presentation by Dr. Sudarshan Rajagopal, which you can find here. Before participating, please read our CME and disclosure information which can be found here.

This program is supported by an independent educational grant from MSD. This online education program is designed solely for healthcare professionals in the USA. The content is not available for HCPs in any other country.

Myth 1: The Traditional Stepwise Approach Is Still Sufficient

Introduction
This summary examines contemporary strategies for the management of pulmonary arterial hypertension (PAH), emphasizing the mechanistic pathways that inform current therapeutic targets, the evidence supporting upfront combination therapy, and the evolving role of risk‑stratified treatment escalation. It outlines guideline‑directed approaches to initial and sequential therapy and highlights key clinical trial data that have reshaped expectations for disease modification in PAH. These principles are illustrated through a representative clinical case demonstrating therapeutic response.

Pathophysiologic Pathways Underlying PAH
PAH arises from dysregulation across four major molecular pathways central to vascular tone and remodeling:

• Endothelin‑1 pathway

  • Excessive vasoconstrictive and proliferative signaling
  • Therapeutically targeted with endothelin receptor antagonists (ERAs)

• Nitric oxide (NO) pathway

  • Impaired NO production and signaling reduce cyclic guanosine monophosphate–mediated vasodilation
  • Augmented through soluble guanylate cyclase stimulators or phosphodiesterase-5 inhibitors (PDE5i)

• Prostacyclin pathway

  • Reduced prostacyclin synthesis leads to diminished cyclic adenosine monophosphate signaling
  • Addressed with prostacyclin analogs and prostacyclin receptor agonists

• Activin/bone morphogenetic protein (BMP) signaling pathway

  • Overactive activin signaling and reduced BMP receptor type 2 activity promote smooth muscle proliferation
  • Activin signaling inhibitors such as sotatercept rebalance proliferative and antiproliferative signals

Case Illustration: Diagnostic and Risk Features

• 55-year-old man presenting with exertional dyspnea and chest discomfort
• Imaging and hemodynamics
  • Echocardiography showing right ventricular enlargement and Doppler notching
  • Right heart catheterization confirming precapillary pulmonary hypertension:
    • Mean pulmonary artery pressure 39 mmHg
    • Pulmonary capillary wedge pressure 7 mmHg
    • Pulmonary vascular resistance 6.2 Wood units
    • Preserved cardiac index (2.5 L/min/m²)
• Clinical markers
  • WHO functional class (FC) III symptoms
  • NT‑proBNP 551 pg/mL
  • 6‑minute walk distance (6MWD) 250 m
• Collectively consistent with intermediate‑risk PAH

Guideline‑directed Initial Therapy

• International guidelines (European Society of Cardiology/European Respiratory Society 2022; World Symposium on Pulmonary Hypertension consensus 2024) emphasize risk‑stratified initiation of therapy
• For non–high‑risk newly diagnosed PAH: Upfront dual oral therapy with an ERA + PDE5i is recommended
• For high‑risk patients: Initiation of triple therapy, including parenteral prostacyclin, is advised
• For patients with significant cardiopulmonary comorbidities: Initial monotherapy may be considered to assess tolerability
• Rationale:
  • Early combination therapy targets multiple dysregulated pathways simultaneously
  • Delays disease progression and improves functional and biomarker outcomes

Guideline‑directed Treatment Escalation and Risk‑Based Follow‑up

• Guidelines recommend reassessment at 3–4 months after therapy initiation
• Low‑risk achievement: No escalation required; continue current therapy
• Persistent intermediate or high risk: Add a prostacyclin pathway agent (oral, inhaled, or parenteral); consider addition of sotatercept based on emerging evidence
• Quadruple therapy (ERA + PDE5i + prostacyclin pathway agent + sotatercept): Increasingly used for patients not achieving low‑risk status
• Referral for lung transplantation: Recommended for patients who remain intermediate–high or high risk despite maximal therapy

Evidence Supporting Upfront Combination Therapy

• AMBITION Trial
  • Compared ambrisentan + tadalafil vs monotherapy in patients with FC II or III
  • Combination therapy demonstrated a 50% reduction in clinical failure events* (HR 0.50; 95% Cl, 0.35–0.72; p<0.001)
  • Benefits observed even in patients with left‑heart comorbidity risk factors
    *Death, hospitalization for worsening PAH, disease progression, unsatisfactory long-term clinical response

Clinical Application in the Case Example

• Patient initiated on tadalafil + macitentan
• At 3‑month follow‑up:
  • WHO functional class improved to II
  • NT‑proBNP decreased to 40 pg/mL
  • 6MWD increased to 401 m
  • Echocardiography showed improved right ventricular size and function
• Achieved low‑risk status, consistent with guideline targets
• No immediate need for therapy escalation, though continued monitoring is essential

Conclusions
Modern PAH management has shifted decisively away from a traditional stepwise approach toward early, pathway‑targeted combination therapy guided by structured risk assessment. Robust clinical trial evidence supports upfront dual therapy for most newly diagnosed patients and escalation to triple or quadruple therapy for those who do not achieve low‑risk status. The integration of emerging agents such as sotatercept further expands the therapeutic landscape, offering new opportunities to modify disease trajectory and improve long‑term outcomes.

Content is accurate as of the date of release on 13 February 2026.