CT Emphysema Subtypes and Cardiac Hemodynamics Estimated on Magnetic Resonance Imaging: The MESA COPD Study.

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is traditionally associated with pulmonary hypertension, but treatments targeting elevated pulmonary artery pressure (PAP) in COPD have largely failed, possibly due to an incomplete understanding of subphenotypes of disease.

Research questions: Are novel, machine-learned computed tomography (CT) emphysema subtypes associated with specific cardiac hemodynamic profiles?

Study design and methods: The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited participants with and without COPD aged 50-79 years with ≥10 pack-years smoking and without clinical cardiovascular disease predominantly from MESA and a lung cancer screening cohort. COPD and COPD severity were defined by standard spirometric criteria. CT emphysema subtypes were defined by unsupervised machine learning in an independent study and labeled on chest CTs. Hemodynamics were estimated on cardiac magnetic resonance imaging using validated equations. Linear regression models were weighted by the inverse probability of sampling and adjusted for potential confounders.

Results: The mean age of the 300 participants was 68±7 years, 60% were male, 28% currently smoked and 47% had COPD, 45% of mild and 41% of moderate severity. More severe COPD was associated with lower estimated pulmonary arterial wedge pressure (ePAWP; p-trend=0.02) and greater estimated pulmonary vascular resistance (ePVR; p-trend=0.03) but not estimated PAP (ePAP; p-trend=0.83). Only the combined bronchitic-apical emphysema subtype was associated with greater ePAP (1.08 mmHg/10%, 95% CI 0.40, 1.75). The diffuse emphysema subtype was associated with lower ePAWP (-0.49 mmHg/10%, 95% CI -0.75, -0.24) and greater ePVR (0.36 Wood units/10%, 95% CI: 0.10, 0.61).

Interpretation: In this case-control study of predominantly mild-moderate COPD, greater ePAP was specific to the combined bronchitic-apical emphysema subtype while the diffuse emphysema subtype, and COPD severity, were associated with lower ePAWP and greater ePVR. The CT emphysema subtype findings suggest more precise avenues to therapeutic interventions in cardiopulmonary dysfunction.