Borderline Mean Pulmonary Artery Pressure in Patients with Systemic Sclerosis: Transpulmonary Gradient Predicts Risk of Developing Pulmonary Hypertension

Objective: To determine whether patients with systemic sclerosis (SSc) and borderline mean pulmonary artery pressure (PAP) at cardiac catheterization are more likely to develop pulmonary hypertension (PH) than those in whom pulmonary pressure is normal.

Methods: Patients with SSc in whom PH and significant interstitial lung disease had been excluded at baseline were enrolled in our prospective cohort. Analysis of followup data identified patients who met prespecified criteria prompting repeat catheterization to reassess for possible PH. Using Kaplan-Meier, receiver operating characteristic, and Cox regression methods, we studied the development of PH and death.

Results: Of 228 patients in this study, 86 had borderline mean PAP (21-24 mm Hg) at baseline. Following prespecified criteria, 76 patients underwent repeat catheterization, and 29 of these developed PH. Two cases were related to disease of the left side of the heart. The average mean PAP increased from baseline (20.2 mm Hg) to followup (24.3 mm Hg) (P<0.05 by Student's t-test). Patients with borderline mean PAP were more likely to develop PH than patients with mean PAP≤20 mm Hg (P<0.001 by log rank test, hazard ratio [HR] 3.7). A transpulmonary gradient (TPG)≥11 mm Hg at baseline also predicted PH (P<0.001 by log rank test, HR 7.9). Incident development of pulmonary arterial hypertension (PAH) was not benign, with a mortality of 18% within 3 years.

Conclusion: Our findings indicate that borderline mean PAP and an elevated TPG in patients with SSc predict progression to PH. These patients should be monitored closely for the development of PH. Our findings indicate that catheterization data are useful in patients considered at risk of PAH.