Ananiev's nomination was backed by 121 MPs, as 85 voted against, parliament said in a statement posted on its website.
Prior to this appointment, Ananiev was deputy finance minister in the current government.
In October, local broadcaster BTV claimed there were irregularities in awarding procurement contracts, worth some 1.6 million levs ($951,500 /818,100 euro), by the Military Medical Academy in Sofia at the time when Petrov headed the hospital. In a written statement sent to the broadcaster, Petrov denied any unlawful action.
Petrov was chief of the Military Medical Academy between 2014 and 2017 before becoming healthcare minister in Boyko Borissov's government in May 2017.
(1 euro = 1.95583 levs)