Left atrial size measured on CT pulmonary angiography: another parameter of pulmonary embolism severity? A systematic review

We systematically review the potential role of left atrial (LA) size, evaluated at computed tomography angiography (CTA) in patients with acute pulmonary embolism (PE), as a new parameter of PE severity. A literature search based on PubMed (MEDLINE), Scopus, Cochrane library and Google Scholar databases was performed to locate previous published investigations reporting data on the severity of acute PE based on the evaluation of LA size (either volume, diameter or area). Six studies, corresponding to a total of 990 patients, published between 2012 and 2019 were included into the analysis. The severity of acute PE, in terms of hemodynamic impairment, increases with the reduction of the LA volume and a significant negative correlation was observed between the pulmonary artery obstruction index (PAOI) and the LA area. Similarly, the longest left-to-right as well as the anteroposterior diameters of the LA had a significant positive correlation with the PAOI index for both the measurement. The LA volume significantly decreased with the increasing of the PAOI index. Moreover, a lower LA volume was observed in those subjects with a saddle PE appearing as the best single parameter able to discriminate between patients having or not a saddle acute PE. Intriguingly, PE patients died within 30 days from the acute event had a significant small LA volume compared to survivors. Data obtained from the current medical literature seem to suggest that the evaluation of LA size evaluation could be a new parameter of PE severity. Further and larger prospective studies are needed to confirm preliminary findings.