Percent Emphysema, Airflow Obstruction, and Impaired Left Ventricular Filling

Abstract

BACKGROUND: Very severe chronic obstructive pulmonary disease causescor pulmonale with elevated pulmonary vascular resistance and secondaryreductions in left ventricular filling, stroke volume, and cardiacoutput. We hypothesized that emphysema, as detected on computed tomography(CT), and airflow obstruction are inversely related to left ventricularend-diastolic volume, stroke volume, and cardiac output among personswithout very severe lung disease. METHODS: We measured left ventricularstructure and function with the use of magnetic resonance imagingin 2816 persons who were 45 to 84 years of age. The extent of emphysema(expressed as percent emphysema) was defined as the percentage ofvoxels below -910 Hounsfield units in the lung windows on cardiaccomputed tomographic scans. Spirometry was performed according toAmerican Thoracic Society guidelines. Generalized additive modelswere used to test for threshold effects. RESULTS: Of the study participants,13% were current smokers, 38% were former smokers, and 49% hadnever smoked. A 10-point increase in percent emphysema was linearlyrelated to reductions in left ventricular end-diastolic volume (-4.1ml; 95% confidence interval [CI], -3.3 to -4.9; P<0.001), strokevolume (-2.7 ml; 95% CI, -2.2 to -3.3; P<0.001), and cardiac output(-0.19 liters per minute; 95% CI, -0.14 to -0.23; P<0.001). Theseassociations were of greater magnitude among current smokers thanamong former smokers and those who had never smoked. The extent ofairflow obstruction was similarly associated with left ventricularstructure and function, and smoking status had similar modifyingeffects on these associations. Percent emphysema and airflow obstructionwere not associated with the left ventricular ejection fraction.CONCLUSIONS: In a population-based study, a greater extent of emphysemaon CT scanning and more severe airflow obstruction were linearlyrelated to impaired left ventricular filling, reduced stroke volume,and lower cardiac output without changes in the ejection fraction.