Case report: Thrombus in transit—a cause of impending paradoxical embolism

BACKGROUND: A thrombus in transit (TIT) is a life-threatening condition associated with pulmonary embolism (PE). While TIT was once considered a rare diagnosis, its emergence has risen in recent years mainly through advancement in medical technology. Rare cases of a thrombus in transit crossing a patent foramen ovale in the context of pulmonary embolism have been reported. The appropriate treatment of patients in this setting remains unclear. CASE SUMMARY: We describe a 64-year-old man who presented with syncope to the emergency room secondary to acute pulmonary embolism. Initial transthoracic echocardiogram revealed a large intracardiac thrombus in transit across a patent foramen ovale, verified by transoesophageal echocardiogram. He underwent anticoagulation and urgent surgical thrombectomy with a favourable outcome. DISCUSSION: Risk stratification of patient with acute PE is mandatory for determining the appropriate therapeutic management. Initial risk stratification is based on clinical symptoms and signs of haemodynamic instability which indicate a high risk or early death associated massive PE. Thrombolytic therapy is indicated in high-risk patients (Grade 1B), while anticoagulation alone is recommended for intermediate-high- to low-risk patients. Assessment for intracardiac thrombi in PE modifies the treatment strategy in case of a thrombus in transit.