Professor Tandon is one of the foremost cardiologists in India and has contributed significantly in the fields of pediatric cardiology and preventive cardiology. He received his cardiology training in india and at Harvard Medical School USA. He subsequently joined the faculty of the Cardiology Department at the All India Institute of Medical Science, New Delhi, from where he retired as the Head of the Department in 1991 Since then he has been a Consultant of Cardiology at the Sitaram Bhartia Institute of Science & Research, Centre for Health Care.

He has had several scientific publications and books to his credit and has received many awards and honours. He is an Emeritus Professor of cardiology at the All India Institute and a visiting faculty at many other institutions. He has been very active in the field of cardiovascular disease prevention and tobacco cessation through research and advocacy.