OBJECTIVES: Clot in transit represents a life-threatening manifestation of venous thromboembolism of which we have limited understanding. This study was designed to describe the risk factors, clinical characteristics and outcomes associated with the development of a clot in transit as well as death within clot in transit patients. METHODS: We enrolled 1,093 consecutive patients into our single-center Pulmonary Embolism Response Team Registry. We compared 76 patients who had a clot in transit to 589 pulmonary embolism patients who did not have a clot in transit. RESULTS: Clot in transit was present in 11.4% of patients who received an echocardiogram to look for it. Multivariate analysis showed congestive heart failure (OR 2.954, 95% CI 1.349 – 6.467, P = 0.0068), a pre-existing inferior vena cava filter (OR 2.777, 95% CI 1.204 – 6.407, P = 0.0167), and hemodynamic collapse (OR 3.495, 95% CI 1.129 – 10.823, P = 0.0300) to be independent predictors of clot in transit. All-cause mortality by 30 days was higher in clot in transit patients (24.3% vs 9.7%, P < 0.001). All-cause mortality by 7 days within clot in transit patients was associated with hemodynamic collapse (45.5% vs 12.3%, P = 0.018) and mental status change (63.6% vs 21.5%, P = 0.008). CONCLUSIONS: The presence of congestive heart failure, a pre-existing inferior vena cava filter, and hemodynamic collapse are independent predictors of clot in transit and should alert physicians to patients who may require an echocardiogram. The mortality for clot in transit is high even when compared to a more severe pulmonary embolism population. Clot in transit represents a high-risk finding that may require more aggressive interventions. / 2020-06-14T00:00:00Z