MSRA-0154
A 32-year-old woman presents with dizziness to her General Practitioner. She reports a similar episode six months ago, which was also accompanied by some discomfort in her chest lasting for a short period. Upon further questioning, she admits to feeling her heart beating rapidly in her chest. She is currently stable, with a blood pressure of 120/80 mmHg, oxygen saturation of 99%, and a heart rate of 110 bpm. What is the best investigation to guide further management?