Professor Lee specialises in cardiac imaging with particular interest in echocardiography. His main research interests are heart valve disease, heart failure, advanced techniques in echocardiography and the application of cardiac imaging in guiding valvular surgery and structural heart intervention. In patients with dilated cardiomyopathy undergoing mitral valve repair, he established the importance of distal anterior leaflet tethering in the mechanism of recurrence of functional mitral regurgitation. The results of his work have been adopted by guidelines from the European Society of Cardiology, American Association for Thoracic Surgery, and American Society of Echocardiography. More recently, Prof. Lee and his group discovered the mechanistic link of mitral annular saddle shape with annular disjunction and progression of degenerative mitral regurgitation using 3D echocardiography.

Professor Lee has published over 200 articles in peer-reviewed journals including Circulation, European Heart Journal, Journal of American College of Cardiology, and Journal of American Society of Echocardiography. He has received important research awards including the ESC Young Investigator Award (2008), the Hong Kong College of Physicians Distinguished Research Awards for 3 times (2009, 2011, 2013), the State Ministry of Education First-Class Award in Technology Advancement (2012), the CUHK Research Excellence Award (2014), the Richard Yu Lectureship (2015), and the Distinguished Young Fellows of Hong Kong College of Physicians (2016).