Diffusing Capacity of the Lungs for Carbon Monoxide and Echocardiographic Parameters in Identifying Mild Pulmonary Hypertension in the EUSTAR Cohort of Patients With Systemic Sclerosis.

Background: The 2022 European Society of Cardiology/European Respiratory Society guidelines define pulmonary hypertension (PH) as a resting mean pulmonary artery pressure (mPAP) > 20 mm Hg at right heart catheterization (RHC). Previously, patients with an mPAP between 21 and 24 mm Hg were classified in a "gray zone" of unclear clinical significance.
Research Question: What is the diagnostic performance of the main parameters used for PH screening in detecting patients with systemic sclerosis (SSc) with an mPAP of 21 to 24 mm Hg at RHC?
Study Design and Methods: Patients with SSc from the European Scleroderma Trials and Research (EUSTAR) database with available tricuspid annular plane systolic excursion (TAPSE), systolic PAP (sPAP), and mPAP data were included. Patients with mPAP 21 to 24 mm Hg and patients with mPAP ≤ 20 mm Hg were considered for the analysis. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated.
Results: TAPSE/sPAP was lower in the group of patients with SSc with mPAP 21 to 24 mm Hg than in the non-PH group (0.58 [0.46-0.72] vs 0.69 [0.57-0.81] mm/mm Hg, respectively; P < .01). No difference was found in other parameters between the two groups. Diffusing capacity of the lungs for carbon monoxide < 80% of the predicted value had the highest sensitivity (88.9%) and NPV (80%), but the lowest specificity (18.2%) and PPV (30.8%) in detecting patients with SSc with mPAP 21 to 24 mm Hg. TAPSE/sPAP < 0.55 mm/mm Hg had the highest specificity (78.9%), PPV (50%), and accuracy (68.1%); its NPV was 75.4%, and its sensitivity was 45.1%.
Interpretation: In this study, diffusing capacity of the lungs for carbon monoxide < 80% of the predicted value was the parameter with the highest sensitivity and NPV in detecting patients with SSc with mPAP 21 to 24 mm Hg. TAPSE/sPAP < 0.55 mm/mm Hg had the highest specificity, PPV, and accuracy and, therefore, can be a useful additional parameter to decrease the number of unnecessary RHCs.
Competing Interests: Financial/Nonfinancial Disclosures The authors have reported to CHEST the following: V. S. is senior clinical investigator of the Research Foundation—Flanders (Belgium): (FWO) (1.8.029.20N). This funding source had no role in the literature review and the synthesis and interpretation of the data; in the writing of the report; or in the decision to submit the paper for publication. C. B. received grants from Boehringer-Ingelheim, consulting fees from Janssen, honoraria for lectures from Novartis, and travel grants from Kyverna, which were not related to this project. E. Z. received speaking and lecture fees from Janssen and consulting fees from Janssen and GSK. F. I. received honoraria and speaking fees from AbbVie, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer, and UCB outside this work. C. P. S. A. received consulting fees and support for attending meetings from Janssen-Cilag SAS, Boehringer Ingelheim Ltd and MSD. None declared (A. C., E. H., C. P., G. R., J. H., D. L., A. M., A. M. G., M.-E. T., S. O., M. V., F. D. G., E. R.).
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