Prediction of Mortality in Pulmonary Embolism Based on Left Atrial Volume Measured on CT Pulmonary Angiography

BACKGROUND: Preliminary reports suggest that a small left atrium (LA) is associated with severe acute pulmonary embolism (PE). This study used data derived from volumetric analyses of computed tomographic pulmonary angiography (CTPA) to investigate whether a reduced LA volume can predict adverse outcome in a large series of patients with acute PE. METHODS: We retrospectively analyzed 756 consecutive patients who received a diagnosis of acute PE by nongated CTPA between January 2007 and December 2010. Each CTPA was investigated with volumetric analysis software that automatically provides the volumes of the LA, right atrium, right ventricle, and left ventricle. A classification tree divided the cardiac chamber volumes and ratios into categories according to mortality. Cox regression assessed the association between these categories and 30-day mortality after adjustment for age, sex, and clinical background. RESULTS: The final study group consisted of 636 patients who had successful volumetric segmentation and complete outcome data. Eighty-four patients (13.2%) died within 30 days of PE diagnosis. There was a higher mortality rate among patients with an LA volume <= 62 mL compared with those with an LA volume > 62 mL (19.6% vs 8.9%, respectively; HR, 2.44; P <.001), a left ventricle volume <= 67 mL (16.4% vs 8.3%; HR, 1.8; P = .024) and a right atrium/LA volume ratio > 1.2 (17% vs 9.4%; HR, 2.1; P = .002). A reduced LA volume was the best predictor of adverse outcome. CONCLUSIONS: Decreased LA volume is associated with higher mortality and is the first among the various cardiac compartments to predict mortality in patients with acute PE.