Thrombus in Transit: A Two-Case Series Highlighting Clinical Challenges and Outcomes.

Thrombus in transit (TIT), defined as mobile right atrial or right ventricular thrombi often associated with acute pulmonary embolism (PE), carries a high risk of morbidity and mortality. Optimal management remains controversial, with options including anticoagulation, systemic thrombolysis, surgical embolectomy, and percutaneous thrombectomy. We describe two elderly women with a history of thromboembolic disease who presented with acute decompensation in the setting of TIT and recurrent PE. The first case involved an 81-year-old female with massive bilateral PE and right atrial thrombus who underwent suction thrombectomy but died perioperatively. The second case involved a 74-year-old female with prior right atrial thrombectomy for TIT who presented with acute hypoxemic respiratory failure, large left pleural effusion, recurrent PE, and septic shock; despite anticoagulation with Argatroban and intensive care support, she developed cardiac arrest and died. These cases underscore the diagnostic and therapeutic challenges of TIT, particularly in elderly patients with multiple comorbidities. Early recognition, multidisciplinary coordination, and individualized management remain essential, but outcomes can be poor despite aggressive interventions.