Pulmonary arterial compliance as a long-term prognostic indicator in pulmonary arterial hypertension associated with adult congenital heart disease: results from a national multicenter prospective registry

Background Pulmonary arterial compliance (PAC) reflects the pulsatile load and predicts outcome in pulmonary arterial hypertension (PAH). The prognostic role of PAC in the heterogeneous patient population of PAH associated with congenital heart disease (PAH-CHD) is poorly defined. This study aimed to explore the prognostic value of PAC in patients with PAH-CHD. Methods Adult patients diagnosed with PAH-CHD were collected from a PAH multicenter prospective registry between August 2009 and December 2019. The primary endpoint was all-cause mortality. Multivariable Cox regression and restricted cubic spline (RCS) analysis were used to evaluate the association between PAC and the primary endpoint. Subgroup and interaction analysis between PAC and shunts or defect characteristics were explored. Incremental predictive performance was evaluated by calculating the C-index, continuous net reclassification improvement, and integrated discrimination improvement. Results A total of 434 adult PAH-CHD patients were enrolled. The median follow-up time was 52.2 months. The survival rate of patients in the lower PAC group was significantly worse than those in the higher PAC group (Log-rank P < 0.001). Multivariable Cox regression analysis showed that PAC independently predicted all-cause mortality after adjustment for other prognostic factors, whether as a continuous variable (HR = 0.665, 95%CI 0.503–0.878, P = 0.004) or a dichotomous variable (HR = 0.251, 95%CI 0.124–0.507, P < 0.001). A linear relationship between PAC and all-cause mortality was identified by RCS analysis. Subgroup analysis revealed that the impact of PAC might be affected by the presence of post-tricuspid shunt. Incorporating PAC into the validated risk models significantly improved the reclassification and discrimination ability for all-cause mortality. Conclusion PAC was significantly associated with all-cause mortality in patients with PAH-CHD and provided additional value on risk assessment. The role of PAC may vary across different clinical subgroups. Trial registration ClinicalTrials.gov (NCT01417338), registered 16th August 2011.