For a study, the normal mean pulmonary arterial pressure (mPAP) was 14.0 ± 3.3 mm Hg (mean ± SD). The prognostic significance of mildly raised mPAP that does not meet the criterion of pulmonary hypertension (PH; mPAP 25 mm Hg) had a pending investigation in a real-world scenario. In a retrospective and prospective cohort of individuals with unexplained dyspnea and at risk of PH, the link of resting mPAP with all-cause death was investigated by researchers. Classification of mPAP as lower-normal (mean + 1 SD), upper-normal (between mean + 1 SD and mean + 2 SD), borderline (between mean + 2 SD and 25 mm Hg), and manifest PH (25 mm Hg) using 1) classification and regression tree (CART) analysis without any preset thresholds, and 2) preset thresholds based on literature data defining mPAP as lower-normal (mean + 1 SD), upper-normal (between mean + 1 SD).

Researchers used univariate and multivariate survival analyses, with age and comorbidities considered. They enrolled 547 individuals with lower-normal, upper-normal, or borderline mPAP and apparent PH in 137, 56, 64, and 290 patients. The CART analysis of mPAP found three prognostic groups: mPAP less than 17 mm Hg, 17 to 26 mm Hg, and greater than 26 mm Hg, all of which had significantly lower survival rates. When comparing lower-normal mPAP to upper-normal mPAP, borderline mPAP, and evident PH, univariate analysis using preset criteria revealed that upper-normal mPAP, borderline mPAP, and manifest PH were all substantially linked with poor survival. Only borderline mPAP (hazard ratio, 2.37; 95% CI, 1.14–4.97; P=0.022) and manifest PH (hazard ratio, 5.05; 95% CI, 2.79–9.12; P<0.001) were significantly associated with poor survival in the multivariate model, which took age and comorbidities into account. CART analysis identifies prognostic thresholds at a resting mPAP of 17 mm Hg and 26 mm Hg in patients at risk for PH and with unexplained dyspnea, and values between 20 mm Hg and 25 mm Hg indicate an independent predictor of poor survival in patients at risk for PH and with unexplained dyspnea.