Sad news, I knew he was around that age.
His sublime recording of Bruckner's Second Symphony with the Saarbrucken RSO on Arte Nova is absolutely my favourite of that wonderful piece, ahead of other fine versions by Giulini, Karajan, Stein, Chailly et al. His Bruckner 9 is also good.
Wikipedia informs me he was principal conductor of the Cologne Radio Symphony Orchestra from 1977 to 1983, and general music director of the Deutsche Oper am Rhein, Düsseldorf from 1981 to 1986. He was artistic director and principal conductor of the Tonhalle Orchestra Zürich, Switzerland from 1987 to 1991. From 1982 to 1991, he was also a permanent conductor at the Semperoper Dresden and Staatskapelle Dresden.
Not sure how much Mahler he conducted or if he pursued a career in the US.