[3] He serves as the chairman and managing director and chief cardiac surgeon of Medanta-The Medicity.

[4] In November 1969 he moved to USA and became a first-year resident at the Thomas Jefferson University Hospital in Philadelphia.

[4] Trehan was the founder, director and chief cardiovascular surgeon of Escorts Heart Institute and Research Center (EHIRC), which opened on Okhla Road, Delhi in 1988.

[5] Presently, Trehan is the Founder Chairman of Medanta - The Medicity one of the largest multi-specialty hospital at Gurgaon, Haryana established in 2009.

[7] His mother was a gynaecologist and father was an ENT specialist, both of them practised in Lyallpur until the partition of India his family belonged to Sri Hargobindapur, Batala.