PURPOSE: Pulmonary Arterial Hypertension (PAH) evaluation includes computed axial tomography of chest (CT chest) and right heart catheterization (RHC). An increasing number of patients referred for PAH evaluation belong to the WHO diagnostic Group II classification i.e., pulmonary hypertension with left heart disease. This study was undertaken to correlate LA appearance on CT chest with the RHC evidence of left heart disease (pulmonary capillary wedge pressure).
METHODS: CT chest was reviewed in patients had RHC evidence of elevated pulmonary artery pressures at the Pulmonary Hypertension Center at Baylor College of Medicine. Left atrial size was measured in the mediastinal window at the point where left atrium (LA) appeared the largest. Length and width of the LA was determined and LA area was calculated (area=length × width). In addition, the LA area was corrected for patient size by dividing length (L) and width (w) of the LA with intrathoracic chest wall length (Lcw) (LxW/Lcw). These measurements were done at the same plane. The pulmonary artery wedge pressure (PCWP) data was obtained from the RHC. Patients were divided into two groups based on the National Institute of Health Registry guidelines, normal PCWP defined as < 15 mm Hg and elevated as > 15 mmHg.
RESULTS: Preliminary data from eight patients was analyzed. In normal PCWP group the mean value was 11.3±2 (mean±SD) mm Hg and in the elevated PCWP group the mean value was 28.5±6 mm Hg (p<0.05). In four patients with normal PCWP, the LA area was 19±6 cm2 and in the high PCWP group, the LA area was 41±11 cm2. The corrected LA area for the chest wall length (LxW/Lcw) was 0.80±0.24 and 1.59±0.45 cm respectively (p<0.05). There was no significant difference in the mean pulmonary artery pressures in the two groups.
CONCLUSION: In this pilot study, enlarged LA area on the CT chest predicted an elevated PCWP on RHC.
CLINICAL IMPLICATIONS: Increased LA area on CT chest could suggest the presence of left heart dysfunction in pulmonary arterial hypertension.
DISCLOSURE: Zeenat Safdar, None.