Toru Shirahata, MD
Pulmonary and Clinical Care Medicine
Toru Shirata, Badar Patel, Sirus J. Jesudasen,Pietro Nardelli, Ruben San José Estépar, Aaron B. Waxman, George R. Washko, Raúl San José Estépar, Sydney Montesi, Farbod N. Rahaghi
George R. Washko
Rationale: Pulmonary hypertension (PH) associated with lung disease is a heterogeneous process associated with pre and post capillary vasculopathy. Computed tomography (CT) is frequently obtained in lung disease and may enable improved phenotyping of lung disease associated PH. CT-derived left atrial (LA) size has been reported to distinguish patients with group 2 from group 1 PH. However, is not well known if it can detect elevated pulmonary capillary wedge pressure (PCWP) in patients with idiopathic pulmonary fibrosis (IPF). In this retrospective study we compared CT derived measures of LA size to PCWP in patients with IPF.
Methods: The study sample consisted of 164 patients with IPF who underwent both thin sectioned chest CT imaging and right heart catheterization (RHC) within two years. All measures were made in the axial view. The maximum distance of the anterior and posterior boundaries of the left atrium (AP diameter) and the distance between inner-most points of the inflow of either of the two left and right pulmonary veins along the traverse axis (Transverse diameter) was recorded.
Results: Both AP and transverse diameters were correlated with PCWP by RHC (r=0.24, p=0.002 and r=0.27, p=0.0005, respectively). When we divided patients into two groups: those who had enhanced CT(n=66) and non-enhanced CT (n=98), significant correlation in the transverse diameter with RHC was found in both groups (r=0.24, p=0.048 and r=0.28, p=0.006, respectively) while AP diameter had correlation with RHC in only enhanced CT group (r=0.29, p=0.018 and r=0.19, p=0.063, respectively). In addition, the product of the AP and transverse diameters showed the highest association with PCWP in each group.
Conclusion: Enlargement of CT-derived LA measurements in patients with IPF with thin sliced CT imaging correlated with elevated PCWP by RHC. This suggests that it could help in the phenotyping of PH in patients with IPF.
Although right heart catheterization remains the gold standard for diagnosis and classification of pulmonary hypertension, this procedure is invasive and risky. An approach based on identification of CT features of pre and post capillary PH in surveillance imaging obtained in this population will help with screening of IPF patients for PH and guide the clinician in identifying patients who likely have group 2 PH avoiding unnecessary right heart catheterizations for initiation of pulmonary vasodilators.