Case:
A 64-year-old male presented with a 2-year history of palpitations and
light-headedness. Referral for electrophysiological assessment was
prompted by a Holter monitoring report of ‘frequent ventricular ectopic
beats (>21,000/24hr) with repetitive runs of atrial
fibrillation” (Fig 1A). Resting echocardiogram suggested low-normal
left ventricular function, and stress testing was normal.
Electrocardiogram (ECG) at baseline was normal. A 12-lead rhythm strip
was recorded during a brief burst of tachycardia in clinic (Fig 1B).
What are the differential diagnoses for the arrhythmia?