This 60-year-old man presents to the Emergency Department following an episode of syncope at home, lasting less than one minute. He reports having suffered from a myocardial infarction four years prior, from which he had made a good recovery and had been free of symptoms:

• Sinus rhythm with Mobitz I second degree AV block
• Junctional escape complexes
• Sinus rate 72/min, ventricular rate 54/min.
• Incomplete right bundle branch block (iRBBB)
• Inferior infarct, age undetermined

  Because of the ST elevation in III and aVF, the possibility of a recent infarction was considered. However, his troponin was normal.

Another ECG was recorded one day after admission:

• Sinus rhythm with complete heart block
• Junctional escape rhythm, 60/min
• Incomplete right bundle branch block (iRBBB)
• Inferior myocardial infarction, age undetermined