Visual Summary.

Timeline of the Case

Time	Event
X	During routine outpatient follow-up after cardiac surgery, marked left ventricular dysfunction, left ventricular dilatation, and elevated levels of BNP levels were found.
X + 4 d	On re-evaluation, serum selenium levels were found to be below the detectable limit.
X + 10 d	The patient was admitted for further evaluation, including myocardial scintigraphy.
X + 3 wk	Endomyocardial biopsy was performed. Selenium supplementation and standard therapy for heart failure were initiated, after which the patient was discharged.
X + 1 mo∼	The clinical course was complicated by multiple episodes of heart failure exacerbation triggered by infections, requiring additional hospitalizations and treatment.
X + 2 y	Gradual improvement in echocardiographic findings and BNP levels was observed.
X + 2.5 y	BNP levels normalized, although septal asynergy remained evident on echocardiography.
X + 3 y	Subsequent imaging, including 123I-BMIPP myocardial scintigraphy, confirmed improvement.

“X” indicates the time point at which selenium deficiency–related cardiomyopathy was first recognized in this patient.

BNP = B-type natriuretic peptide.