Survival in pulmonary arterial hypertension (PAH) related to systemic sclerosis (PAH-SSc) is worse than idiopathic PAH (IPAH) for unclear reasons, but is potentially related to differential neurohormonal responses to cardiac stressors. N-terminal pro-brain natriuretic peptide (NT-proBNP) is a marker of neurohormonal activation that is useful in the diagnosis and prognosis of various forms of PAH. We sought to characterize and compare NT-proBNP in a cohort of PAH-SSc and IPAH patients.
NT-proBNP samples were collected within one week of right heart catheterization from PAH-SSc and IPAH patients who were followed prospectively; levels were compared and correlated with hemodynamic variables. Cox proportional hazard models were created to assess the predictive value of NT-proBNP.
Ninety-eight patients (55 PAH-SSc, 43 IPAH) were followed for a median of 722 days (range 90–1389). Nearly half were on specific PAH-therapy at enrollment (45/98). Hemodynamics were similar between groups, except for lower mPAP in the PAH-SSc group. NT-proBNP levels were significantly higher in PAH-SSc (3419 ± 3784 vs. 1393 ± 1633 pg/mL, p < 0.01), and were more closely related to hemodynamic variables in PAH-SSc than IPAH. Twenty-eight patients (20 PAH-SSc, 8 IPAH) died. NT-proBNP strongly predicted survival (HR 3.18; p < 0.01) in the overall cohort; however when stratified by group, predicted survival only in PAH-SSc (HR 3.07, p < 0.01 vs. 2.02, p = 0.29 in IPAH).
NT-proBNP levels are significantly higher in PAH-SSc than IPAH despite less severe hemodynamic perturbations. In this cohort, NT-proBNP was a strong predictor of survival only in PAH-SSc, suggesting that neurohormonal regulation may differ between PAH-SSc and IPAH.
Elevations in NT-proBNP levels in PAH-SSc compared to IPAH despite less severe hemodynamic pertubations suggest differential neurohormonal responses to cardiac stressors. Future studies are needed to confirm these finding and to elucidate underlying mechanisms.
Stephen Mathai, No Financial Disclosure Information; No Product/Research Disclosure Information