This 23-year-old man has complained of palpitation since his early teens. His exercise tolerance is normal. He has been followed in the cardiac clinic:

• Sinus rhythm with Mobitz I second degree AV block and junctional escape complexes
• ST elevation compatible with early repolarization

Comment: Congenital second degree AV block was diagnosed when the patient was 22 year old. There was no evidence of structural heart disease. A dual chamber pacemaker was inserted and programmed in DDI mode, with minimum rate 30/min.