Pulmonary Vascular Pruning on CT and Estimated Pulmonary Artery Pressures on Doppler Echocardiography

Rationale: Vascular pruning refers to the relative loss of the small pulmonary vessels and can be quantified from computed tomography (CT) scans. More severe CT pruning has been associated with pulmonary hypertension (PH) on right heart catheterization, but it is not known whether CT pruning is associated with estimated pulmonary arterial systolic pressure (PASP) on the noninvasive standard of Doppler echocardiography (TTE). Methods: We collected clinical, echocardiographic, and CT data from 102 patients from our institution who underwent wedge resection or lobectomy for early-stage lung adenocarcinoma. PH-related echocardiographic measures included PASP and presence/absence of right ventricular (RV) dysfunction and dilation on clinical TTE reports. CT pruning was defined as the ratio of small pulmonary vessel volume (BV5) to total pulmonary vascular volume (TBV), with lower BV5/TBV values indicating greater pruning. We used multivariable linear and logistic regression models to investigate the association of CT measured pruning with PASP (both continuous and dichotomized as >25 or ≤25 mmHg), RV dilation, and RV dysfunction on TTE. All models were adjusted for age, gender, height, weight, smoking status, and total pack-years. In secondary analyses, we additionally adjusted for forced expiratory volume in 1-second (FEV1), diffusing capacity, and left ventricular ejection fraction (LVEF). Results: The mean age of participants was 70.2±8.7 years; 60 (58.8%) were women and 20 (19.6%) were current smokers, while 62 (60.8%) and 20 (19.6%) were former and never-smokers, respectively. Only 7% and 5% had RV dilation and RV dysfunction, respectively, and 28.4% had un-estimable PASP. The mean BV5/TBV was 44.9±10.6%. There was a pattern of higher PASP with more severe CT pruning: per standard deviation (SD) lower BV5/TBV, PASP was 2.1mmHg higher (95% CI: -0.4, 4.6, p=0.096) (Figure) and the odds of elevated PASP (>25 mmHg) on TTE increased per SD lower BV5/TBV (OR=1.7, 95% CI: 0.9, 3.2, p=0.128). There was no association of CT pruning with RV dilation or with RV dysfunction. In secondary analyses additionally adjusting for FEV1, diffusing capacity, and LVEF, the magnitude of the association between BV5/TBV and PASP was similar. results