Very Small Left Atrial Volume as a Marker for Mortality in Patients Undergoing Nongated Computed Tomography Pulmonary Angiography

Objectives: To evaluate the association between very small left atria (VSLA) on nongated computed tomography pulmonary angiography (CTPA) and mortality in patients without pulmonary embolism (PE). Methods: Patients who underwent nongated CTPA between 2011 and 2015 in order to rule out PE, and had an echocardiogram within 24 h of the CTPA, were retrospectively identified. The left atrial volume of nongated CTPA was calculated using automatic 4-chamber volumetric analysis software. The association between the lowest 5th percentile of the left atrial volume index, referred to as the VSLA group, and mortality was investigated after adjustment for age, gender, background diseases, and laboratory values. Results: The study cohort included 241 patients. Patients with VSLA had a left atrial volume index <24 mL/m² (n = 11). Demographics and background diseases did not differ between the study groups. The median follow-up was 22.7 months (IQR 0.03-54.3). VSLA was an independent predictor of mortality (HR_adj = 3.6; 95% CI 1.46-8.87; p = 0.005), along with malignancy (HR_adj = 2.28; 95% CI 1.32-3.93; p = 0.003) and lower hemoglobin (HR_adj = 0.86; 95% CI 0.76-0.99; p = 0.032). Conclusions: Our findings suggest that VSLA on nongated CTPA may serve as a marker for mortality. The use of CTPA volumetric analysis can help risk stratification in patients with dyspnea and no PE.