Original: He has served as music director of the La Scala opera house in Milan , principal conductor of the London Symphony Orchestra , principal guest conductor of the Chicago Symphony Orchestra , music director of the Vienna State Opera , and principal conductor of the Berlin Philharmonic orchestra from 1989 to 2002 , when he retired from the position for health reasons .
Simplified: Abbado stayed with them until 2002 when he left because of his bad health , although he returned in 2004 to make several recordings with them .