Since her appointment at St George’s she has undertaken extensive research and teaching with an emphasis on sudden cardiac death. She has been appointed as national trainer for cardiac pathology for forensic and general pathology  trainees in UK. She has published 160 peer reviewed papers, 71 case reports, 24 book chapters, 36 reviews/letters/articles, 9 international guidelines/government reports. In addition she has co-edited one book, co authored four books including cardiac pathology and imaging, pulmonary pathology and cardiac valve disease and has completed the second edition of her book on Cardiovascular Pathology.

She is the Cardiovascular Pathology representative on the specialist advisory committee of Royal College of Pathologists. She is a member of the Editorial Board and subeditor (cardiac pathology) for Histopathology and Editorial board member of Cardiovascular Pathology. She is President of the Pathology Section of the Royal Society of Medicine. She is also an advisor to governmental bodies in relation to cardiovascular pathology and on national cardiovascular steering group developing a database on sudden cardiac death. She is also on committee developing international guidelines in training in cardiovascular pathology. She has also written the guidelines on the investigation of sudden cardiac death issued by Royal College of pathologists.

Professor Sheppard was awarded the Stokes Medal for her work by the Irish Cardiovascualar Society in 2009 and gave Phillip Poole Wilson memorial lecture in London in October 2014.