Professor Ivan Mitev Ivanov (Bulgarian: Иван Митев Иванов) (4 October 1924 – 15 April 2006) was a Bulgarian pediatrician and cardio rheumatologist who discovered the sixth heart tone,[1] called the tone of Mitev.
He was awarded by Todor Zhivkov (leader of the People’s Republic of Bulgaria from 1954 until 1989) at a grand ceremony and dedicated to Mitev’s discovery was issued a special postage stamp – the first stamp dedicated to cardiology.