Eur Respir Rev 2021; 30: 200178 [DOI: 10.1183/16000617.0178-2020].
This review summarises various applications of how ventilatory equivalent (ventilatory efficiency or better
still ventilatory inefficiency) and the minute ventilation (VʹE)/carbon dioxide production (VʹCO2) slope
obtained from cardiopulmonary exercise testing (CPET) can be used in the diagnostic or prognostic
workup of patients with congenital heart disease.
The field of congenital heart disease comprises not only a very heterogeneous patient group with various
heart diseases, but also various conditions in different stages of repair, as well as the different residuals
seen in long-term follow-up. As such, various physiologic disarrangements must be considered in the
analysis of increased VʹE/VʹCO2 slope from CPET in patients with congenital heart disease. In addition to
congestive heart failure (CHF), cyanosis, unilateral pulmonary stenosis and pulmonary hypertension (PH)
provide the background for this finding. The predictive value of increased VʹE/VʹCO2 slope on prognosis
seems to be more important in conditions where circulatory failure is associated with failure of the
systemic ventricle. In cyanotic patients, those with Fontan circulation, or those with substantial mortality
from arrhythmia, the impact of VʹE/VʹCO2 on prognosis is not that important.