This 64-year-old woman is seen in the cardiac clinic for a yearly follow-up. She had an anterior infarction 5 years ago and has made a good recovery. No cardiac symptoms during normal activity. Occasional brief episodes of dizziness. No history of syncope:  

• Sinus rhythm with type II 3:2 sino-atrial block (rate 38/min)
• The longer P-P is twice the shorter P-P interval
• Previous anterior infarction