Increased main pulmonary artery diameter and main pulmonary artery to ascending aortic diameter ratio in smokers undergoing lung cancer screening.

OBJECTIVES

Pulmonary hypertension (PH) is a progressive, potentially fatal disease, difficult to diagnose early due to non-specific nature of symptoms. PH is associated with increased morbidity and death in many respiratory and cardiac disorders, and with all-cause mortality, independent of age and cardiopulmonary disease. The main pulmonary artery diameter (MPA), and ratio of MPA to adjacent ascending aorta (AA), MPA:AA, on Chest CT are strong indicators of suspected PH. Our goal was to determine the prevalence of abnormally high values of these indicators of PH in asymptomatic low-dose CT (LDCT) screening participants at risk of lung cancer, and determine the associated risk factors.

METHODS

We reviewed consecutive baseline LDCT scans of 1949 smokers in an IRB-approved study. We measured the MPA and AA diameter and calculated MPA:AA ratio. We defined abnormally high values as being more than two standard deviations above the average (MPA ≥ 34 mm and MPA:AA ≥ 1.0). Regression analyses were used to identify risk factors and CT findings of participants associated with high values.

RESULTS

The prevalence of MPA ≥ 34 mm and MPA:AA ≥ 1.0 was 4.2% and 6.9%, respectively. Multivariable regression demonstrated that BMI was a significant risk factor, both for MPA ≥ 34 mm (OR = 1.07, p < 0.0001) and MPA:AA ≥ 1.0 (OR = 1.04, p = 0.003). Emphysema was significant in the univariate but not in the multivariate analysis.

CONCLUSIONS

We determined that the possible prevalence of PH as defined by abnormally high values of MPA and of MPA:AA was greater than previously described in the general population and that pulmonary consultation be recommended for these participants, in view of the significance of PH.