A, B, Pulmonary arterial hypertension (PAH) clinical severity metrics are associated with NE, but not elafin. A, Box-and-whisker plots showing baseline NE and elafin (log-scale) stratified by heart failure symptom severity (with increasing NYHA functional class from I to IV). B, Lollipop plot summarizing median regression analyses that related NE and elafin to baseline PAH clinical metrics. Regression models were adjusted for age, sex, and BMI. The plot shows the direction and magnitude of clinical differences associated with each two-fold elevation of NE (red) and elafin (blue). Relationships achieving statistical significance (regression coefficient P < .05) are indicated as follows: ∗P < .05, ∗∗P < .01, or ∗∗∗P < .001. 6MWD = 6-min walk distance; Dlco = diffusion capacity of lung for carbon monoxide; mPAP = mean pulmonary arterial pressure; NE = neutrophil elastase; NT-proBNP = N-terminal pro-type brain natriuretic peptide; NYHA = New York Heart Association; PVR = pulmonary vascular resistance; TAPSE = tricuspid annular plane systolic excursion.