The Effect of Borderline Pulmonary Hypertension on Survival in Chronic Lung Disease

BACKGROUND: The impact of the new "borderline" hemodynamic class for pulmonary hypertension (PH) (mean pulmonary artery pressure [mPAP], 21-24 mm Hg and pulmonary vascular resistance, [PVR], ≥3 wood units, [WU]) in chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) is unclear. OBJECTIVES: The aim of this study was to assess the effect of borderline PH (BLPH) on survival in COPD and ILD patients. METHOD: Survival was analyzed from retrospective data from 317 patients in 12 centers (Italy, Spain, UK) comparing four hemodynamic groups: the absence of PH (NoPH; mPAP <21 mm Hg or 21-24 mm Hg and PVR <3 WU), BLPH (mPAP 21-24 mm Hg and PVR ≥3 WU), mild-moderate PH (MPH; mPAP 25-35 mm Hg and cardiac index [CI] ≥2 L/min/m2), and severe PH (SPH; mPAP ≥35 mm Hg or mPAP ≥25 mm Hg and CI <2 L/min/m2). RESULTS: BLPH affected 14% of patients; hemodynamic severity did not predict survival when COPD and ILD patients were analyzed together. However, survival in the ILD cohort for any PH level was worse than in NoPH (3-year survival: NoPH 58%, BLPH 32%, MPH 28%, SPH 33%, p = 0.002). In the COPD cohort, only SPH had reduced survival compared to the other groups (3-year survival: NoPH 82%, BLPH 86%, MPH 87%, SPH 57%, p = 0.005). The mortality risk correlated significantly with mPAP in ILD (hazard ratio [HR]: 2.776, 95% CI: 2.057-3.748, p < 0.001) and notably less in COPD patients (HR: 1.015, 95% CI: 1.003-1.027, p = 0.0146). CONCLUSIONS: In ILD, any level of PH portends worse survival, while in COPD, only SPH presents a worse outcome.