Quadruple-Chamber Clot in Transit Traversing a Patent Foramen Ovale

BACKGROUND: Clot in transit (CIT) is a rare, life-threatening manifestation of venous thromboembolism. When a thrombus traverses a patent foramen ovale, the risk of systemic embolization increases, and optimal management remains undefined. CASE SUMMARY: A 73-year-old woman presented with dyspnea and saddle pulmonary embolism with right heart strain. Echocardiography revealed a serpentine thrombus extending from the right atrium across the tricuspid valve, traversing a patent foramen ovale into the left atrium, and prolapsing through the mitral valve. After multidisciplinary discussion, she underwent mechanical thrombectomy with removal of a 14 cm intracardiac thrombus and pulmonary emboli. She recovered without clinically apparent systemic embolization. DISCUSSION: Quadruple-chamber CIT with transseptal extension is exceedingly rare and carries high embolic risk. This case highlights mechanical thrombectomy as an alternative to surgery in selected patients. TAKE-HOME MESSAGE: Mechanical thrombectomy may represent an effective and less invasive option for complex biatrial and biventricular CIT with pulmonary embolism.