Adult congenital heart disease (ACHD) often leads to increased blood flow in the pulmonary circulation resulting in pulmonary arterial hypertension (PAH), which is associated with increased patient morbidity and mortality. According to the 2020 European Society of Cardiology (ESC)/European Respiratory Society (ERS) guidelines, PAH is present when the mPAP is greater than 20 mmHg and PVR is greater than 3 WU (pre-capillary pulmonary hypertension). The most common classification of ACHD-PAH patients is in four groups depending on the defect type, shunt direction, and history of congenital heart disease surgical correction. The Bosentan Randomized Trial of Endothelin Antagonist Therapy-5 (BREATHE-5) showed that bosentan is effective in treating patients with Eisenmenger Syndrome, whereas the more recent Macitentan in Eisenmenger Syndrome to Restore Exercise Capacity (MAESTRO) Study concluded that Macitentan has a neutral effect on the same population. Treatment of patients with ACHD-PAH should be individualized and carried out in specialized centers.
Adult Congenital Heart Disease; Pulmonary Arterial Hypertension; Therapeutic Trends
Adult congenital heart disease (ACHD) often leads to increased blood flow in the pulmonary circulation due to a blood shunt from an intracardiac defect or extracardiac communication. As a result, pulmonary arterial hypertension (PAH) often occurs in this setting increasing patient morbidity and mortality.
ACHD-related PAH (ACHD-PAH) has been traditionally characterized by increased mean pulmonary artery pressure (mPAP) combined with increased pulmonary vascular resistance (PVR). According to the 2020 European Society of Cardiology (ESC)/European Respiratory Society (ERS) guidelines, PAH is present when the mPAP is greater than 20 mmHg (> 25mmHg in the 2015 ESC/ERS guidelines) and PVR is greater than 3 WU (pre-capillary pulmonary hypertension) [1,2]. This PVR cut-off has been chosen to differentiate patients with ACHD and PAH from those with ACHD and post-capillary pulmonary hypertension (PPH) which is usually due to systemic valve regurgitation. Patients with PAH are expected to improve with PAHtargeted treatments while this is not the case for patients with PPH. It is anticipated that due to the new PAH definition, more patients with ACHD and PAH will benefit from the earlier institution of PAHspecific medications.
The most common classification of ACHD-PAH patients is in four groups depending on the defect type, shunt direction, and history of congenital heart disease (CHD) surgical correction. Group A includes patients with Eisenmenger syndrome (ES) severely elevated PVR, right to left shunt, and cyanosis at rest. Group B consists of patients with large defects, moderately elevated PVR, and mainly left to right shunt. Group C includes patients with PAH and small cardiac defects that do not participate in the pathophysiology of PAH. Group D encompasses patients who display PAH after CHD surgical correction .
The survival of ACHD-PAH patients varies greatly and depends on PAH-specific therapy and the underlying structural heart disease. The COMPERA-CHD registry  confirmed previous observations that survival of ACHD-PAH patients is significantly better than those with primary PAH (76% vs. 54%) but also considerably reduced compared to congenital heart disease patients who do not have PAH despite the use of PAH-specific treatments.