[Kearns-Sayre syndrome. A rare indication for prophylactic cardiac pacing].

The authors report a case of Kearns-Sayre syndrome, a rare mitochondrial myopathy, diagnosed in a 19 year old man. Distal conduction defects are constant findings and are a dominant factor in the prognosis of this condition. Their early appearance and rapid progression pose the problem of prophylactic cardiac pacing despite the young age. In the case report, pacing was decided at the age of 23 in the absence of symptoms but with bifascicular block (right bundle branch block and left anterior hemiblock), without electrophysiological investigation. During follow-up, left bundle branch block was observed 3 years later and permanent complete atrioventricular block occurred 7 years after pacemaker implantation.