Smaller Left Ventricle Size at Noncontrast CT Is Associated with Lower Mortality in COPDGene Participants

Abstract

Background Smokers with chronic obstructive pulmonary disease (COPD) have smaller left ventricles (LVs) due to reduced preload. Skeletal muscle wasting is also common in COPD, but less is known about its contribution to LV size. Purpose To explore the relationships between CT metrics of emphysema, venous vascular volume, and sarcopenia with the LV epicardial volume (LVEV) (myocardium and chamber) estimated from chest CT images in participants with COPD and then to determine the clinical relevance of the LVEV in multivariable models, including sex and anthropomorphic metrics. Materials and Methods The COPDGene study (ClinicalTrials.gov identifier: NCT00608764) is an ongoing prospective longitudinal observational investigation that began in 2006. LVEV, distal pulmonary venous blood volume for vessels smaller than 5 mm2 in cross section (BV5), CT emphysema, and pectoralis muscle area were retrospectively extracted from 3318 nongated, unenhanced COPDGene CT scans. Multivariable linear and Cox regression models were used to explore the association between emphysema, venous BV5, pectoralis muscle area, and LVEV as well as the association of LVEV with health status using the St George's Respiratory Questionnaire, 6-minute walk distance, and all-cause mortality. Results The median age of the cohort was 64 years (interquartile range, 57-70 years). Of the 2423 participants, 1806 were men and 617 were African American. The median LVEV between Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 and GOLD 4 COPD was reduced by 13.9% in women and 17.7% in men (P < .001 for both). In fully adjusted models, higher emphysema percentage (β = -4.2; 95% confidence interval [CI]: -5.0, -3.4; P < .001), venous BV5 (β = 7.0; 95% CI: 5.7, 8.2; P < .001), and pectoralis muscle area (β = 2.7; 95% CI: 1.2, 4.1; P < .001) were independently associated with reduced LVEV. Reductions in LVEV were associated with improved health status (β = 0.3; 95% CI: 0.1, 0.4) and 6-minute walk distance (β = -12.2; 95% CI: -15.2, -9.3). These effects were greater in women than in men. The effect of reduced LVEV on mortality (hazard ratio: 1.07; 95% CI: 1.05, 1.09) did not vary by sex. Conclusion In women more than men with chronic obstructive pulmonary disease, a reduction in the estimated left ventricle epicardial volume correlated with a loss of pulmonary venous vasculature, greater pectoralis muscle sarcopenia, and lower all-cause mortality. © RSNA, 2020 Online supplemental material is available for this article.

Figures

Graphical abstract

Figure 1:

Consort diagram for ever-smokers with chronic obstructive pulmonary disease (COPD). GOLD = Global Initiative for Chronic Obstructive Lung Disease.

Figure 2:

Images in a 57-year-old man with body mass index of 28.3 kg/m2 and forced expiratory lung volume in 1 second expressed as a percentage of predicted values of 58.5% from the COPDGene cohort with the different reconstructions for the left ventricle, pulmonary veins, and pectoralis muscles. A, Coronal view of the inspiratory CT scan at the level of the trachea. Upper lobe shows predominant advanced centrilobular emphysema (emphysema percentage = 29.0%). B, Segmentation of the pectoralis major (blue) and minor (green) at the level of the aortic arch used to compute the pectoralis muscle area. The pectoralis muscle area was 25.9 cm2. C, Lateral view of the left ventricle epicardium model used to calculate the estimated left ventricle epicardial volume (159.6 mL). D, Display of the venous phase of the pulmonary vascular tree extracted with the scale-space particles approach and segmented by an artery-vein deep learning method used to compute the venous blood volume of vessels smaller than 5 mm2 in cross section (62.9 mL). Color shading of the vessels represents vessel caliber.