Impaired Exercise Capacity From PAH-CHD Most Prominent in Patients With Eisenmenger Syndrome

Although all patients with pulmonary arterial hypertension (PAH) show indications of impaired exercise capacity, those with Eisenmenger syndrome—characterized by irregular blood flow in the heart and lungs—have the most impairment, suggest study findings published in International Journal of Cardiology.

The study findings, coming from patients in China, offer insight into how exercise intolerance varies among subgroups of PAH associated with congenital heart disease (PAH-CHD), as previous data have characterized impaired exercise tolerance among PAH-CHD as a whole.

“Congenital heart defects, especially those allowing systemic-to-pulmonary shunts, can develop PAH,” explained the researchers. “Early surgical correction can reduce the development of PAH. However, the prevalence of PAH remains at 5% to 10% in European adults with CHD. In developing countries, surgical correction is less common, and PAH associated with CHD is an increasing health and socioeconomic challenge.”

The group retrospectively analyzed data from 171 patients with PAH-CHD who were classified into 1 of 4 subgroups:

• Eisenmenger syndrome
• PAH with systemic-to-pulmonary shunts
• PAH with small defects
• PAH after cardiac defect correction (PAH-CD)

The study also included 30 age- and sex-matched healthy controls.

Overall, despite being young and mostly in World Health Organization functional class I/II, patients with PAH-CHD had significantly impaired exercise capacity and ventilatory efficiency compared with healthy controls. Patients with the condition had a 45% reduced peak oxygen uptake (peak V_O2)and 70% higher slope of ventilatory equivalent for carbon dioxide (V_E/V_CO2). The median age of patients at study enrollment was 27.8 years, relatively younger than those with PAH in western countries.

“Also, the blood pressure and heart rate response during exercise were weaker than controls, indicating a worse cardiac reserve,” added the researchers. “This suggests the need for targeted therapy and additional medical care for better life quality in a wider undetected population of PAH-CHD, especially in developing countries like China.”

Across the subgroups, the 60 patients with Eisenmenger syndrome exhibited the worse capacity for exercise and ventilatory efficiency. These patients had the lowest peak V_O2 (P = .003) and the highest slope of V_E/V_CO2 (P = .012). The researchers noted that this finding was consistent with a previous study, which found that these patients had the shortest 6-minute walk distance compared with the other 3 subgroups of patients; however, this was with borderline significance.

Patients with PAH with systemic-to-pulmonary shunts showed the highest peak VO2 (P = .003) indicating the best capacity for exercise.

Reference

Zhang H, Yan Y, He Y, et al. Characteristics of exercise intolerance in different subgroups of pulmonary arterial hypertension associated with congenital heart disease. Int J Cardiol. Published online December 21, 2022. doi:10.1016/j.ijcard.2022.12.033