4th May 2025

A 60-year-old female presents to ED with breathlessness and palpitations.

A 60-year-old female presents to ED with breathlessness and palpitations. Her past medical history includes transient ischaemic attacks, gout, type 2 diabetes. Her admission ECG shows a regular, narrow complex tachycardia consistent with AVNRT. Vagal manoeuvres fail to cardiovert her. The ED doctor then proceeds with an initial dose of 6mg of IV adenosine. Shortly, she loses consciousness and on the cardiac monitor there is a 9 second ventricular standstill before a slow return of sinus rhythm.

Which of the following medications that the patient is taking might be responsible for the ventricular pause?

Select the SINGLE most appropriate option from the list below. Select ONE option only.