Huge Left Atrium Thrombus Presenting with Syncope and Sudden Death, Diagnosed by Point-of-care Ultrasound.

The left atrium (LA) thrombus is a life-threatening disease that can result in systemic embolization and sudden death if misdiagnosed. Point-of-care ultrasound (POCUS) is an efficient tool able to assist emergency physicians in accurately and promptly identifying patients with LA thrombus. We present a 72-year-old man who presented at the emergency department with out-of-hospital cardiac arrest. The patient received cardiopulmonary resuscitation and achieved spontaneous circulation upon arrival. The patient had a past history of mitral valve regurgitation and valve replacement, followed by warfarin treatment for 5 years. Clinical examination, including POCUS, resulted in a diagnosis of LA thrombus with systemic thromboembolism events affecting the brain, kidney, and lower limbs. Although an emergency thrombectomy was performed immediately, the patient eventually died. POCUS should be performed in patients with any prior history of structural heart disease, especially those who received valve replacement surgery, to identify life-threatening thromboembolism events and facilitate prompt treatment.