Abstract
OBJECTIVE: This study explores the risk factors for pulmonary embolism in patients with acute left lower extremity deep vein thrombosis and investigates the dual role of left iliac vein compression in the occurrence of pulmonary embolism. METHODS: In a single-center retrospective study, patients diagnosed with left iliac vein compression combined with acute left lower extremity deep vein thrombosis who completed pulmonary artery CT imaging examinations were consecutively enrolled from 2013 to 2023. The demographic characteristics, risk factors, comorbidities, onset time, degree of left iliac vein compression, and the relationship with the occurrence of pulmonary embolism were collected and analyzed. Logistic regression analysis was used to evaluate the odds ratios and 95% confidence intervals of pulmonary embolism across different levels of factors, and Restricted Cubic Spline were used to assess the association between pulmonary embolism and the degree of left iliac vein compression. RESULTS: A total of 120 patients were included, of which 48 were diagnosed with pulmonary embolism. Regression analysis found that left iliac vein compression was a protective factor against pulmonary embolism (B=-1.736, p < 0.001). Restricted Cubic Spline revealed a dual role of iliac vein compression in the occurrence of pulmonary embolism (p = 0.002): within the range of 0-46.7%, there was an increasing trend in the risk of pulmonary embolism as the degree of iliac vein compression increased; in the range of 46.7%-100%, as the degree of left iliac vein compression increased, the incidence of pulmonary embolism showed a decreasing trend; for patients with left iliac vein compression exceeding 62%, the incidence of pulmonary embolism was significantly reduced (OR < 1). CONCLUSIONS: In patients with acute left lower extremity deep vein thrombosis, the degree of left iliac vein compression may initially promote and subsequently inhibit the occurrence of pulmonary embolism. We should be vigilant about the risk of pulmonary embolism in patients with moderate degrees of left iliac vein compression.