Coronary artery disease after bone marrow transplantation is rare in children and young adults. We report the case of a 21-year-old who developed coronary artery disease and acute myocardial infarction secondary to graft versus host disease following bone marrow transplantation. Physicians caring for young patients after bone marrow transplantation should be aware of the potential for coronary artery disease and evaluate appropriately.

Cardiac conduction disease affects patients with Kearns–Sayre syndrome. We report a young asymptomatic patient with Kearns–Sayre syndrome with abnormal conduction on electrocardiogram and Holter monitor, although not advanced atrioventricular block. She underwent prophylactic pacemaker placement, and rapidly developed complete atrioventricular block, which resulted in 100% ventricular pacing. It may be reasonable to consider prophylactic pacemaker implantation in patients with Kearns–Sayre syndrome with evidence of cardiac conduction disease even without overt atrioventricular block given its unpredictable progression to complete atrioventricular block.

A male neonate with d-transposition of the great arteries was diagnosed with the concomitant anomaly of left circumflex aortic arch and right-sided ductus arteriosus, which formed a vascular ring. Initial postnatal echocardiography had demonstrated an obscured aortic isthmus mimicking coarctation of the aorta, which could be a diagnostic clue to circumflex aortic arch.