What does a floating mass in a young patient's heart do?

A previously healthy 57-year-old male patient presented to our emergency department for palpitations, dry cough, and non-exertional chest pain. He denied lipothymia or syncope. Blood pressure was 160/90 mmHg, heart rate 76 beats/min, body temperature 36.4°C, respiratory rate was 14 breaths/min, and oxygen saturation 96% on room air. Physical examination revealed symmetrical air entry without wheezing or crackles, and a classical diastolic "tumor plop", not accompanied by another significant murmur at cardiac auscultation. Laboratory tests were all in the normal range, including troponin T (9.1 ng/mL, normal value <14) and C-reactive protein (2.2 mg/dL, normal value <6). An electrocardiogram showed a sinus rhythm and normal ventricular repolarization. Point-of-care ultrasound (POCUS) revealed a floating mass within the left atrium and a normal lung pattern without pleural effusion.