Professor McEwan was born and brought up in Glasgow and studied medicine at the University of Glasgow, undertaking postgraduate training in General Medicine there and in Nottingham.
She trained in Cardiology at the Hammersmith Hospital in West London, which at that time was the Royal Postgraduate Medical School, where she also undertook research and was awarded her PhD.
| Dates | Position | Institution |
| 2019-present | Consultant Cardiologist | University College London NHS Foundation Trust |
| 2014-2018 | Vice Dean, Education | University of Exeter Medical School |
| 2014-2018 | Honorary Consultant Cardiologist | Royal Devon and Exeter NHS Foundation Trust |
| 2010-2014 | Lead for Year 4 of the new curriculum, MBBS 2012 | University College London Medical School |
| 2006-2014 | Director of Undergraduate Education | University College London Hospitals |
| 1992-2014 | Honorary Consultant Cardiologist | University College London Hospitals |
| 2010-2014 | Lead for Year 4 of the new curriculum, MBBS 2012 | University College London Medical School |
| 2006-2014 | Director of Undergraduate Education | University College London Hospitals |
| 1992-present | Honorary Consultant Cardiologist | University College London Hospitals |
| 2012-2013 | Interim Dean, Faculty of Medical Sciences | University College London School of Life and Medical Sciences |
| 1998-2011 | Reader in Cardiology | University College London |
| 1992-1998 | Senior Lecturer | University College London |
| 1989-1992 | Lecturer in Cardiology and Clinical Pharmacology | Royal Postgraduate Medical School, Hammersmith Hospital, London |
| 1986-1989 | Medical Research Council Training Fellow | Dept. of Clinical Pharmacology Royal Postgraduate Medical School, Hammersmith Hospital, London |
| 1983-1986 | NHS Registrar in Cardiology and Clinical Pharmacology | Hammersmith Hospital, London |
| 1981-1983 | SHO rotation in Medicine | Nottingham City Hospital, Nottingham |
| 1980-1981 | Pre-registration House Officer | Glasgow Royal Infirmary and Glasgow Western Infirmary, Scotland |