Lobectomy results in a greater increase in the pulmonary artery to aorta ratio compared to sublobar resection: a retrospective study

BACKGROUND: The pulmonary artery diameter-to-aortic diameter (PA/A) ratio on computed tomography correlates with PA pressure and is a simple tool for estimating the load on the right side of the heart. The purpose of this study was to investigate the change in the PA/A ratio in patients following lung resection according to the specific procedure used. METHODS: Patients with pathological stage 0-I lung cancer who underwent lobectomy or sublobar resection between 2018 and 2020 were included in this study. The PA/A ratios were measured pre-operatively and at 1 and 3 years post-operatively (POY1 and POY3). Changes over time and factors associated with an increased PA/A ratio were analysed. RESULTS: Of 301 eligible patients, 210 underwent lobectomy and 91 underwent sublobar resection (35 segmentectomies and 56 wedge resections). Age, sex, body mass index, and smoking status were similar between the groups. Cardiac comorbidity and pathological stage 0 disease were more common in the sublobar resection group versus the lobectomy group (20.9% vs. 11.0%, 29.7% vs. 6.2%). Compared with the sublobar resection group, the lobectomy group showed a significantly higher ratio at POY3 (0.823 ± 0.131 vs. 0.786 ± 0.128) and a greater mean increase from baseline to POY1 (difference between groups: 0.039, 95% confidence interval [CI] 0.023-0.05) and from baseline to POY3 (0.065, 95% CI 0.049-0.08). On multivariable analysis, lobectomy independently predicted a postoperative PA/A ratio increase (odds ratio 7.98, 95% CI 3.85-16.6). CONCLUSIONS: Compared with sublobar resection, lobectomy is associated with a significantly larger rise in the PA/A ratio, suggesting greater pulmonary-vascular loading after more extensive parenchymal removal. Surveillance of the PA/A ratios may help identify patients at risk of right-heart strain.