Abstract
Carbon monoxide diffusion capacity (DLCO) is negatively associated with patient survival in idiopathic pulmonary hypertension (PH), but is not included in the risk stratification score proposed by the 2015 European guidelines. Since 2015, several new stratification scores based on a 3- or 4-severity scale have been explored. This retrospective cohort single-center study sought to investigate the association between DLCO and PH severity and survival. We included 85 treatment-naive patients with precapillary PH and DLCO measurement at diagnosis. DLCO status, based on lower and upper quartiles ranges, was added to a 3- and a 4-strata modified-risk assessment. DLCO was strongly associated with transplant-free survival (HR 0.939, 95% CI: 0.908–0.971, p < 0.001). In the intermediate and high-risk categories, DLCO was associated with transplant-free survival, irrespective of the risk category (HR 0.934, 95% CI: 0.880–0.980, p = 0.005). The correlation between modified-risk category and transplant-free survival was significant (HR 4.60, 95% CI: 1.294–16.352, p = 0.018). Based on the Akaike information criterion (AIC) levels, the 3- and 4-strata modified-risk stratification fits our results better than the conventional stratification. Low DLCO is associated with patient transplant-free survival, independently of the risk category. Inclusion of DLCO into a PH risk stratification score seems promising and needs further investigation.
Highlights
Pulmonary hypertension (PH) is a hemodynamic condition that results in high pulmonary arterial pressure (PAP) [1,2], as diagnosed by right heart catheterization (RHC), which is the established gold standard examination [3]
According to the 2015 European Society of Cardiology/European Respiratory Society (ESC/ERS) and 2018 World Symposium guidelines [2,5], PH is classified in five distinct diagnostic groups: Group 1 refers to pulmonary arterial hypertension (PAH), Group 2 to PH with left heart disease, Group 3 to PH with lung diseases or hypoxia, Group 4 to chronic thromboembolic PH (CTEPH) or other pulmonary artery obstructions, and Group 5 to PH with unclear or multifactorial mechanisms
The current study involving PH patients from 3 diagnostic groups clearly showed that: (1) DLCO is corrected using standard hemoglobin content (DLCOc) was at best loosely correlated with established prognostic parameters, such as the distance of the 6-min-walk test (6MWT) and NT‐proBNP levels, providing incremental inde‐ pendent information; (2) Baseline DLCOc and transplant‐free survival were strongly re‐ lated, independently of diagnostic group, NT‐proBNP, 6MWT distance, and cardiac index (CI); (3) DLCOc < 55% identified a sub‐group of 32 patients with more severe dyspnea, shorter
Summary
Pulmonary hypertension (PH) is a hemodynamic condition that results in high pulmonary arterial pressure (PAP) [1,2], as diagnosed by right heart catheterization (RHC), which is the established gold standard examination [3]. According to the 2015 European Society of Cardiology/European Respiratory Society (ESC/ERS) and 2018 World Symposium guidelines [2,5], PH is classified in five distinct diagnostic groups: Group 1 refers to pulmonary arterial hypertension (PAH), Group 2 to PH with left heart disease, Group 3 to PH with lung diseases or hypoxia, Group 4 to chronic thromboembolic PH (CTEPH) or other pulmonary artery obstructions, and Group 5 to PH with unclear or multifactorial mechanisms. The disease severity in PH patients comprising mainly those pertaining to Groups 1 and 4 is usually determined according to 2015 ESC/ERS risk assessment strategy. Regular comprehensive risk assessment involving multiple variables, notably clinical, functional, and laboratory parameters, is strongly recommended for optimal initial and follow-up evaluations, estimation of long-term prognosis, guidance of treatment strategy, and monitoring of treatment response in PH patients [6–8]
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