Clinical characterization and survival of patients with borderline elevation in pulmonary artery pressure

Normal resting mean pulmonary artery pressure (PAP) is 8-20 mmHg. Pulmonary hypertension is defined as mean PAP of ≥25 mmHg. Borderline PAP levels of 21-24 mmHg are of unclear significance. We sought to determine the clinical characteristics and survival of subjects with mean PAP of 21-24 mmHg. We examined 1,491 patients enrolled in the Cleveland Clinic Pulmonary Hypertension Registry between February 1990 and May 2012 with baseline right heart catheterization. The relationship between PAP and all-cause mortality was assessed by Cox models and a tree-based analysis. Sixty-three patients had borderline PAP (underlying conditions: 12 left heart disease, 20 respiratory disease, 17 connective-tissue disease, 4 others, and 10 none). We then compared 3 groups: borderline PAP without heart or lung disease ([Formula: see text]), normal PAP without heart or lung disease ([Formula: see text]), and category 1 pulmonary arterial hypertension (PAH; [Formula: see text]). Borderline-PAP patients had levels of hemodynamic and functional compromise between those for normal-PAP patients and those for patients with PAH. Borderline PAP was associated with increased mortality compared to normal PAP (hazard ratio: 4.03 [95% confidence interval: 0.78-20.80], [Formula: see text]). A tree-based analysis demonstrated almost identical cut points in mean PAP (≤20, 21-26, and ≥27 mmHg) associated with differential survival ([Formula: see text]). Connective-tissue disease and an elevated transpulmonary gradient were predictors of worse survival in the borderline-PAP population. Borderline PAP elevation is associated with decreased survival, particularly in the context of connective-tissue disease and an elevated transpulmonary gradient.