Pulmonary vascular resistance is associated with two-year clinical outcomes in non-hypoxemic COPD with mild pulmonary hemodynamic abnormalities

BACKGROUND: Pulmonary hypertension (PH) complicates chronic obstructive pulmonary disease (COPD) and is associated with adverse outcomes. However, the clinical relevance of pulmonary vascular resistance (PVR) in non-hypoxemic COPD patients without severe PH remains unclear. METHODS: This pre-specified secondary analysis of a prospectively registered cohort (UMIN000042159) included non-hypoxemic COPD patients who underwent right heart catheterization and were managed without PH-targeted therapy. Patients were classified as having preliminary pulmonary vascular abnormality (resting mean pulmonary artery pressure [mPAP] ≤ 20 mmHg with exercise-related elevation during a study-specific exercise protocol) or mild-to-moderate PH (20 < resting mPAP <35 mmHg). The primary outcome was two-year overall survival. Secondary outcomes included home-stay survival and functional capacity assessed by 6-min walk distance (6MWD), metabolic equivalents (MET), and modified Medical Research Council (mMRC) dyspnea score. RESULTS: Thirty-seven patients were analyzed. During follow-up, 18 patients lost independent living and 11 died. Higher PVR and mPAP were associated with reduced home-stay survival and overall survival. PVR demonstrated the strongest association with mortality (hazard ratio 1.45, p = 0.0007). PVR was correlated with mMRC (ρ = 0.65), 6MWD (ρ = -0.62), and MET (ρ = -0.49). Spirometric indices were not predictive of survival. CONCLUSIONS: In non-hypoxemic COPD patients without severe PH, pulmonary vascular resistance was associated with functional limitation and two-year prognosis. suggesting that pulmonary vascular burden is an important determinant of near-term outcomes. CLINICAL TRIAL REGISTRATION: UMIN-CTR (UMIN000042159).