Pulmonary artery to aorta ratio is associated with cardiac structure and functional changes in mild-to-moderate COPD
Authors Cuttica MJ, Bhatt SP, Rosenberg SR, Beussink L, Shah SJ, Smith LJ, Dransfield MT, Kalhan R
Received 31 December 2016
Accepted for publication 9 March 2017
Published 12 May 2017 Volume 2017:12 Pages 1439—1446
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Editor who approved publication: Dr Richard Russell
Michael J Cuttica,1 Surya P Bhatt,2 Sharon R Rosenberg,1 Lauren Beussink,3 Sanjiv J Shah,3 Lewis J Smith,1 Mark T Dransfield,2 Ravi Kalhan1
1Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, 2Division of Pulmonary, Allergy & Critical Care Medicine, University of Alabama-Birmingham, Birmingham, AL, 3Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
Background: The ratio of the diameter of the pulmonary artery (PA) to the diameter of the aorta (PA:A) on computed tomography (CT) imaging is associated with both COPD exacerbation and pulmonary hypertension. The mechanisms of PA enlargement in COPD are poorly understood.
Methods: In this retrospective, single center study we evaluated pulmonary function, CT scans, right heart catheterizations, and echocardiography in 88 subjects with mild-to-moderately severe COPD. A sensitivity analysis was performed in 43 subjects in whom CT scan and echocardiogram were performed within 50 days of each other. To evaluate the association between PA:A ratio and echocardiographic parameters and hemodynamics, we performed simple correlations and multivariable linear regression analysis adjusting for lung function, age, sex, race, and diastolic function.
Results: All subjects had preserved left ventricular (LV) systolic function (LV ejection fraction 62.7%±5.5%). Among them, 56.8% had evidence of diastolic dysfunction. There was no association between PA:A ratio and the presence of diastolic dysfunction. In a multivariable model, PA:A ratio was associated with right ventricular (RV) chamber size (β=0.015; P<0.003), RV wall thickness (β=0.56; P<0.002), and RV function (–0.49; P=0.05). In the subgroup of subjects with testing within 50 days, the association with RV chamber size persisted (β=0.017; P=0.04), as did the lack of association with diastolic function. PA:A ratio was also associated with elevated PA systolic pressures (r=0.62; P=0.006) and pulmonary vascular resistance (r=0.46; P=0.05), but not pulmonary arterial wedge pressure (r=0.17; P=0.5) in a subset of patients undergoing right heart catheterization.
Conclusion: In patients with mild-to-moderately severe COPD and preserved LV function, increased PA:A ratio occurs independent of LV diastolic dysfunction. Furthermore, the PA:A ratio is associated with right heart structure and function changes, as well as pulmonary hemodynamics. These findings indicate that PA:A ratio is a marker of intrinsic pulmonary vascular changes rather than impaired LV filling.
Keywords: COPD, diastolic dysfunction, pulmonary artery