Researchers investigating pulmonary artery size in idiopathic pulmonary fibrosis (IPF) patients have found that the pulmonary artery:ascending aorta diameter (PA:A) ratio could predict IPF clinical outcome, representing a potential new tool for stratifying patients to identify those most at risk. The study, “Pulmonary artery size as a predictor of outcomes in idiopathic pulmonary fibrosis,” was published in the European Respiratory Journal.
IPF prognosis has mostly been based on pulmonary function tests, but personal characteristics such as age, sex, and body mass index (BMI) may also play important roles in the clinical outcome, leading to the development of more accurate indexes for patient evaluation.
Because IPF patients are at an increased risk for pulmonary hypertension, its early detection is of significant importance for risk-stratification and listing for treatments such as lung transplantation. Research has focused on the development of non-invasive screening tools, like chest computed tomography (CT), to predict pulmonary hypertension. In these studies, parameters such as pulmonary artery diameter and PA:A ratio were evaluated, but their association with IPF clinical outcome was not assessed.
Researchers in this new study investigated the possibility of an independent correlation between pulmonary artery size assessed through CT and clinical outcome in IPF patients. The study included analysis of the medical records of all IPF patients evaluated at a tertiary care center between 2008 and 2013. Pulmonary artery and ascending aorta diameters were measured in 98 patients with available high-resolution CT (HRCT) scans, followed by the calculation of pulmonary artery: ascending aorta diameter ratios, and assessment of clinical outcomes, including death or lung transplant.
Results showed that IPF patients had a mean pulmonary artery diameter and PA:A ratio of 32.8 mm and 0.94 mm, respectively. Results showed that patients with a PA:A ratio greater than 1 had an increased risk for death or lung transplant compared to patients with a PA:A ratio less than or equal to 1, demonstrating that a PA:A ratio greater than 1 is associated with worse clinical outcomes.
The team emphasized that the PA:A ratio can be easily measured using non-invasive tools and concluded, “Evaluation of this readily available ratio may facilitate prognostication and counselling of patients with IPF. In addition, it may prove to have a role in stratifying patients within clinical studies as well as prioritization for lung transplantation. Future studies are encouraged to further evaluate this ratio. Such studies might include correlating the ratio with contemporaneous invasive hemodynamic measurements as well as looking at the significance of change in the pulmonary artery diameter and PA:A ratio over time.”
IPF is a chronic interstitial lung disease associated with significant mortality and morbidity. It is characterized by the inflammation or accumulation of scar tissue (fibrosis), leading to progressive loss of elasticity, failure of proper lung activity, and insufficient oxygenation of the blood and organs. IPF’s clinical course and progression is highly variable among patients, and the trajectory and rate of decline are difficult to predict at diagnosis.