CT-based pulmonary vascular pruning and emphysema: clinical correlations and prognostic impacts in COPD.

OBJECTIVES

Despite evidence of vascular remodeling in emphysematous lungs in chronic obstructive pulmonary disease (COPD), its natural history and clinical course across phenotypes are not fully understood. We aimed to determine the effect of pruning and emphysema co-occurrence on hemodynamics in the Keio COPD Comorbidity Research (K-CCR) and quality of life (QoL), airflow/diffusion decline, and mortality in the Hokkaido COPD Cohort Study.

MATERIALS AND

METHODS

Pruning was defined as a low blood vessel volume of < 5 mm2 in the lungs relative to total blood vessel volume (BV5/TBV). Within each cohort, participants were classified into four groups using cohort-specific median dichotomization of BV5/TBV and the percentage of low-attenuation volume. Hemodynamics were assessed using echocardiography-derived estimated systolic pulmonary artery pressure (eSPAP).

RESULTS

Participants from the K-CCR (N = 115) and Hokkaido COPD Cohort Study (N = 96) were evaluated. In the K-CCR, the pruning/severe-emphysema group was associated with poorer QoL and higher eSPAP. In the Hokkaido COPD Cohort Study, the pruning/severe-emphysema group had worse QoL, faster decline in forced expiratory volume in 1 s, and lower carbon monoxide transfer coefficient than the no-pruning/mild-emphysema group. Ten-year survival rates were 80%, 70%, 61%, and 36% for no-pruning/mild-emphysema, no-pruning/severe-emphysema, pruning/mild-emphysema, and pruning/severe-emphysema groups, respectively. In analyses using continuous variables, the percentage of low-attenuation volume was significantly associated with mortality, whereas BV5/TBV was not.

CONCLUSION

Pulmonary vascular pruning may be a CT-derived potential biomarker for subtyping patients with poor outcomes, such as impaired hemodynamics and accelerated airflow/diffusion decline, particularly in patients with severe emphysema, requiring further validation.

KEY POINTS: Question Does CT-based pulmonary vascular pruning provide additive prognostic information beyond emphysema severity for predicting pulmonary hemodynamics and longitudinal outcomes in COPD? Findings Categorical analyses suggested that low BV5/TBV was associated with poorer survival, worse hemodynamics, and greater ventilation/diffusion decline in patients with severe emphysema. Clinical relevance CT-derived BV5/TBV may help identify a vascular phenotype associated with worse pulmonary hemodynamics, impaired lung function, reduced quality of life, and adverse long-term outcomes, particularly in patients with severe emphysema, and may contribute to imaging-based phenotyping of COPD.