Cor Pulmonale Parvus in Chronic Obstructive Pulmonary Disease and Emphysema: The MESA COPD Study
What right ventricular (RV) changes are seen on cardiac magnetic resonance imaging (CMR) in individuals with chronic obstructive pulmonary disease (COPD) and emphysema?
The MESA (Multi-Ethnic Study of Atherosclerosis) COPD trial was a case-control study of RV morphology in COPD and emphysema in individuals ages 50-79 years with ≥10 pack-years of smoking and who were free of clinical cardiovascular disease; patients with clinically apparent heart failure were excluded. Participants were enrolled predominantly from a prospective population-based cohort study (MESA) and a lung cancer and emphysema progression study (Emphysema and Cancer Action Project [EMCAP]). CMR was used for the assessment of RV volumes and mass. Standard spirometric criteria were used to define COPD severity; emphysema was characterized by full-lung computed tomography (CT).
The analytic sample included 310 participants, of whom 47% had COPD. In fully adjusted models, RV end-diastolic volume (RVEDV) was lower in patients with COPD compared to controls (-7.8 ml; 95% confidence interval [CI], -15.0 to -0.5 ml; p = 0.04). Increasing severity of COPD was associated with smaller RVEDV. RV mass was similar between those with COPD and control subjects; right ventricular ejection fraction (RVEF) was not associated with the presence or severity of COPD. Although RVEDV was lower across increasing categories of percent emphysema on CT scan, percent emphysema was not associated with RV mass or RVEF.
In this multicenter study, patients with COPD and those with emphysema on CT scan had smaller RV volumes on CMR, compared to controls. There were no consistent relationships between COPD severity and percent emphysema with RVEF or RV mass.
This is an interesting study that provides insight on morphologic changes of the RV, as determined by CMR, in a contemporary cohort of patients with COPD. The findings of reduced RV volumes in COPD contradict the classical paradigm of increased RV mass and volume in COPD, as the authors acknowledge. The sample of COPD patients used in the analysis may have less severe COPD than patients from other studies with differing results; of note, only 7 of the 147 (4.7%) patients with COPD used long-term supplemental oxygen. Future studies should confirm findings from this multicenter analysis and provide insight into populations with more severe forms of COPD and other phenotypes of COPD (e.g., chronic bronchitis).
Keywords: Pulmonary Disease, Chronic Obstructive, Spirometry, Tomography, X-Ray Computed, Heart Failure, Stroke Volume, Confidence Intervals, Magnetic Resonance Imaging, Lung Neoplasms, Smoking, Pulmonary Emphysema
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