The Impact of ERA Switching on Risk Stratification in Pulmonary Arterial Hypertension

Condition(s) studied

Investigational drug(s) / intervention(s)

Switch from Ambrisentan to Bosentan: This intervention refers to a therapeutic switch from ambrisentan (10 mg once daily) to bosentan (125 mg twice daily) in adult patients with pulmonary arterial hypertension (PAH), performed as part of routine clinical care. The switch was not assigned by the investigators but was made based on clinical indications prior to study enrollment. Patients are followed prospectively for up to 6 months to assess changes in risk stratification, functional status, laboratory parameters, and safety outcomes.

Maintenance of Ambrisentan Therapy: Continued treatment with ambrisentan 10 mg once daily without transition to bosentan, as part of routine clinical care. Treatment was not assigned by the investigators. Clinical, functional, laboratory, and safety outcomes are assessed over a 3- to 6-month period.

Study summary

Pulmonary arterial hypertension (PAH) is a rare, progressive, and potentially life-threatening disease characterized by pulmonary vascular remodeling, increased pulmonary vascular resistance, and right ventricular dysfunction. The endothelin pathway plays a central role in its pathophysiology and is targeted by endothelin receptor antagonists (ERAs), including ambrisentan and bosentan.

Ambrisentan is a selective ETA receptor antagonist, whereas bosentan blocks both ETA and ETB receptors. Although transitions between ERAs occur in clinical practice, evidence regarding the clinical impact of switching from ambrisentan to bosentan remains limited.

ACTION is a retrospective, observational, single-center cohort study evaluating adult patients with pulmonary arterial hypertension (World Health Organization Group 1) and/or chronic thromboembolic pulmonary hypertension (World Health Organization Group 4) confirmed by right heart catheterization. Patients who switched from ambrisentan to bosentan because of a national ambrisentan shortage will be compared with clinically similar patients who remained on ambrisentan.

Clinical, functional, and laboratory data recorded at baseline and at 3 to 6 months of follow-up will be assessed. The primary outcome is the proportion of patients with worsening risk stratification after switching from ambrisentan to bosentan compared with patients who continued ambrisentan. Risk will be evaluated using the COMPERA 2.0 and REVEAL Lite 2 assessment tools.

Secondary outcomes include changes in World Health Organization/New York Heart Association functional class, 6-minute walk distance, BNP levels, individual risk-assessment components, hepatic enzymes, hemoglobin levels, and clinically relevant events such as hospitalization, emergency department visits, initiation of supplemental oxygen, and right heart failure decompensation.

Eligibility

Primary outcome measure(s)

• Change in risk category according to used scores — From 3 to 6 months
  Proportion of participants with worsening clinical risk category from baseline to follow-up, comparing patients who switched from ambrisentan to bosentan with patients who remained on ambrisentan..

Trial sites (1)

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