Clinical significance of lung cross-sectional area measured by computed tomography in chronic thromboembolic pulmonary hypertension: The correlation with pulmonary hemodynamics and the limitations.

The percentage cross-sectional area of the lung under five (%CSA) is the percentage of pulmonary vessels with <5 mm area relative to the total lung area on computed tomography (CT). The extent that %CSA is related to pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension (CTEPH) is unclear, as is the effect of pulmonary endarterectomy (PEA) on %CSA. Therefore, we aimed to evaluate the clinical significance of %CSA in patients with CTEPH. We studied 98 patients (64 females, mean age 62.5 ± 11.9 years), who underwent CT with %CSA measurement and right heart catheterization (RHC). Patients were classified into groups based on eligibility for PEA. We compared the %CSA with pulmonary hemodynamics measured by RHC in various groups. In 38 patients who underwent PEA, the relationship between %CSA and pulmonary hemodynamics was also evaluated before and after PEA. Significant correlations between %CSA and pulmonary vascular resistance, and compliance, and pulmonary artery pulse pressure were observed in all patients. Pulmonary hemodynamics in the patients who underwent or were eligible for PEA showed a significant correlation with %CSA. Additionally, %CSA was significantly lower in the postoperative than in the preoperative group. There was no correlation between changes in %CSA and pulmonary hemodynamics before and after PEA. Furthermore, %CSA did not correlate significantly with prognosis. %CSA may reflect pulmonary hemodynamics in CTEPH with central thrombosis. Furthermore, %CSA was reduced by PEA postoperatively. However, %CSA is not a prognostic indicator, its clinical usefulness in CTEPH patients is limited, and further validation is required.