This 53-year-old woman is admitted to the neurology ward following an acute visual field loss. She gave a history of several episodes of near-syncope in the past year. This ECG is recorded:

• Marked sinus bradycardia (sinus rate 23/min)
• Junctional escape complexes with a pattern of bigeminy (“escape-capture bigeminy”)
• Ventricular rate 46/min.
• In view of the history of recurrent episodes of near-syncope and the ECG findings, a diagnosis of sick sinus node syndrome was made.
• Holter monitoring demonstrated several significant sinus pauses, the longest of 8.7 sec duration.

A therapeutic procedure is performed:

• AV sequential pacing, rate 65/min

Comment: CT scan and MRI demonstrated a lesion in the right occipital lobe compatible with an embolic stroke. Even though the patient had not experienced palpitation and Holter monitoring had demonstrated tachyarrhythmias, the possibility that she might have suffered from paroxysmal atrial fibrillation (tachy-brady-syndrome) could not be excluded. The patient was therefore started on Coumadin.