Abstract
BACKGROUND: Right heart thrombus in transit (RHTT) is a rare manifestation of venous thromboembolism with high mortality. Real-time sequential echocardiographic documentation of thrombus migration is exceptionally uncommon. CASE SUMMARY: A 41-year-old man presented after a minor vehicle accident, attributed to dozing off. He was asymptomatic and hemodynamically stable. Transthoracic echocardiography, prompted by electrocardiographic features suggestive of right ventricular strain after possible syncope, revealed a large RHTT. Continuous imaging captured sequential thrombus migration to the pulmonary artery. After computed tomography confirmation of pulmonary embolism, the patient rapidly deteriorated with hemodynamic collapse. Emergency thrombolysis achieved complete recovery. DISCUSSION: RHTT may be initially silent, presenting as syncope. Real-time echocardiography captured its migration to the pulmonary artery. Thrombolysis achieved complete recovery after hemodynamic collapse. The case underscores the abrupt transition to massive pulmonary embolism and the need for clinical vigilance and additional imaging when warranted. TAKE-HOME MESSAGES: Pulmonary embolism-related syncope can masquerade as unexplained accidents; heightened clinical suspicion in emergency settings is crucial. RHTT has an unpredictable course, and echocardiography can capture its real-time progression and guide timely intervention.