This 78-year-old man who had aorto-coronary bypass surgery ten years ago is in the cardiac clinic for a routine follow-up. He is stable and free of dyspnea or chest pain during moderate exertion. He denies any dizziness or syncope:

• Sinus rhythm with 2nd degree AV block and escape junctional complexes (escape-capture bigeminy)
• Ventricular rate 40/min
• Right bundle branch block
• Left anterior fascicular block

A commonly asked question when we review this ECG, is: “could this be a case of Mobitz I second degree AV block?”
However, the PR interval increases so dramatically and the long RR interval is so constant that we are most likely dealing with junctional escape (“escape-capture bigeminy”)

The patient remained symptom-free, and Holter monitoring demonstrated occasional second degree AV block with junctional escape during sleep. During an exercise test, the sinus rate increased appropriately without AV block. He  has been followed conservatively, and remains symptom-free.