Istrățescu has had significant achievements in his career, including winning multiple major tournaments and championships. He won the 2005 and 2007 French Chess Championships. He also won the 1997 Romanian Chess Championship. He has won numerous international tournaments, such as the Paris Championship in 2004 and 2005, and the Bucharest International in 1996 and 2001.
He has also won several open tournaments including the 2006, 2008 and 2011 Cannes tournament, and the 2003 and 2005 Béthune Open. Other major victories include the Geneva Open in 2004, 2009 and 2013, and the Andorra Open in 2009 and 2016.
In team chess, Istrățescu has successfully represented both France and Romania on multiple occasions, including the World and European Team Chess Championships. He was also a part of the team winning the French Team Championship in 2004 and 2005.