Pulmonary artery enlargement predicts mortality on low-dose lung cancer screening CT

BACKGROUND: Although pulmonary artery (PA) enlargement on computed tomography (CT) has been linked to adverse cardiopulmonary outcomes, its prognostic significance in asymptomatic individuals undergoing low-dose lung cancer screening CT's remains unclear. PURPOSE: To evaluate the prognostic value of PA enlargement for predicting mortality in asymptomatic patients undergoing low-dose CT lung cancer screenings. MATERIALS AND METHODS: A total of 777 patients undergoing low-dose screening CT's at a tertiary academic center (2014-2018) were retrospectively identified. PA diameter and PA:AA ratio were measured. The primary endpoint was overall survival (OS), calculated from the date of reference CT to death or censoring at last follow-up. For survival analysis, patients with ≥3 years follow-up were included. Clinical and imaging variables were analyzed using univariate Cox proportional hazard model and statistically significant variables (P < 0.05) were entered into multivariable analysis to identify independent predictors of mortality. All statistical analyses were performed using Python (pandas, seaborn, lifelines). RESULTS: Sex-specific PA diameter thresholds (90th percentile: 29 mm men, 27 mm women) were applied. PA dilation was present in 179 patients (23%). On univariate analysis, age, underweight BMI, smoking status, diabetes, hypertension, coronary artery disease, PA dilation (absolute and PA:AA ratio), and emphysema severity (Goddard score) were associated with decreased survival. On multivariate analysis, PA dilation remained independently associated with increased mortality (HR = 1.83; 95% CI: 1.20-2.79; P = 0.005), along with age, underweight BMI, smoking status, hypertension, and higher Goddard scores. CONCLUSION: PA enlargement on low-dose CT independently predicts worse survival and may help risk-stratify asymptomatic patients undergoing lung cancer screening.