Exercise ventilatory reserve predicts survival in adult congenital heart disease associated pulmonary arterial hypertension with Eisenmenger physiology

Abstract

Impaired ventilatory responses during exercise significantly contribute to breathlessness in patients with pulmonary arterial hypertension (PAH). Breathing reserve (BR) at peak exercise during cardiopulmonary exercise testing (CPET), a measure of the reserve in the ventilatory capacity, and as a PAH prognostic marker has not received wide attention. We assessed the prognostic value of a reduced BR (≤30% predicted) on survival in patients with two forms of PAH: congenital heart disease-associated PAH and Eisenmenger physiology (EIS) and idiopathic PAH (IPAH). Propensity score matched cohorts of 50 EIS and 50 IPAH patients who underwent CPET in our institution were included. Overall transplant-free survival at 5 and 10 years was assessed. Twenty-five (50.0%) EIS and 15 (33.3%) IPAH patients had a BR ​≤ ​30% at peak exercise (p ​= ​0.047). Independent predictors of a BR ​≤ ​30% across all patients included cardiothoracic ratio on chest radiograph (HR 2.2, 95% CI 1.6–3.0, p ​= ​0.01) and moderate to severe restriction on resting spirometry (HR 1.9, 95% CI 1.1–2.8, p ​= ​0.03). A BR ​≤ ​30% was associated with a significantly higher risk of mortality in the EIS group at 10 years follow-up (HR 3.4, 95% CI 1.1 to 11.4, p ​= ​0.045). Neither a BR ​≤ ​30% or >30% offered prognostic discrimination in IPAH. In summary, a BR >30% at peak exercise is associated with better survival in patients with EIS. Lung parenchymal restriction inferred from larger cardiothoracic ratios may contribute to reduced BR along with increased ventilatory drive.