LAUSR

Abstract 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.