Exercise physiology in pulmonary hypertension patients with and without congenital heart disease

Background: Cardiopulmonary exercise testing allows the assessment of integrative cardiopulmonary response to exercise. Aims: The aim of the study was to better understand the exercise physiology in pulmonary arterial hypertension related to adult congenital heart disease compared to non-adult congenital heart disease patients by means of cardiopulmonary exercise testing parameters. Methods: The present is a multicentre retrospective study which includes pulmonary hypertension group 1 and group 4 patients. All subjects underwent full clinical and instrumental evaluation, including cardiopulmonary exercise testing and right heart catheterization. Results: One hundred and sixty-seven pulmonary hypertension patients (93 women and 74 men, 57 adult congenital heart disease and 110 non-adult congenital heart disease) were enrolled. Adult congenital heart disease patients had higher pulmonary pressure (mean pulmonary arterial pressure: 59.8 ± 19.5 mmHg vs 44.6 ± 16.5 mmHg, p < 0.001) and lower pulmonary blood flow (pulmonary blood flow: 3.3 (2.1–4.3) l/min vs 4.5 (3.8–5.4) l/min, p < 0.001). At cardiopulmonary exercise testing they had lower peak oxygen uptake/kg (12.8 ± 3.8 ml/kg/min vs 15.5 ± 4.2 ml/kg/min, p < 0.001) and higher ventilation/carbon dioxide elimination slope (53.2 (43.3–64.8) vs 44.0 (34.6–51.6), p < 0.001). When patients were paired for gender and peak oxygen uptake (± 1 ml/kg/min), obtaining 44 pairs, adult congenital heart disease patients had higher pulmonary pressure (mean pulmonary arterial pressure: 58.4 ± 20.2 mmHg vs 42.8 ± 16.8 mmHg, p < 0.001) and ventilation/carbon dioxide elimination slope (51.2 (43.4–63.6) vs 44.9 (35.4–55.1), p = 0.033). Conclusions: In pulmonary arterial hypertension-adult congenital heart disease patients, pulmonary pressure and ventilation/carbon dioxide elimination slope are higher compared to non-adult congenital heart disease pulmonary hypertension patients, while pulmonary blood flow and peak oxygen uptake are lower. After matching patients for gender and peak oxygen uptake, pulmonary pressure and ventilation/carbon dioxide elimination remain higher in adult congenital heart disease patients suggesting that the long-term adaptation to high pulmonary pressure, hypoxia and low pulmonary blood flow, as well as a persisting shunt has, at least partially, preserved exercise performance of pulmonary arterial hypertension-adult congenital heart disease patients.