Dr Markides trained at Imperial College and qualified in 1992, having been awarded the University of London Gold Medal.
He trained in Cardiology and Cardiac Electrophysiology at a number of teaching hospitals in London and was appointed as Consultant Cardiologist with a special interest in arrhythmias, ablation, pacing and complex devices in 2003.
He led the development of the arrhythmia service at Royal Brompton and Harefield between 2006 and 2014, when he was appointed as Director of the Heart Division at the Royal Brompton Hospital.
Dr Markides visits East and North Herts NHS Trust on a weekly basis to see patients with arrhythmias and support the complex device service.