The Met says:
On the advice of his doctors, James Levine will reduce his conducting dates at the Met for the rest of the current season while he continues to recover from recent procedures to alleviate back pain. His planned performances of Das Rheingold on March 30 and April 2 will be conducted by Fabio Luisi, while those of Il Trovatore on April 20, 23, 27, and 30 will be conducted by Marco Armiliato.
Levine will conduct upcoming performances of Wozzeck (April 6, 9, 13. and 16), the new production of Die Walküre (April 22, 25, 28, May 2, 5, 9, and 14), and two concerts with the MET Orchestra at Carnegie Hall (April 10 and May 15) as scheduled.
Fabio Luisi, the Met's principal guest conductor, is already scheduled to conduct Rigoletto (April 26, 30, May 3, 6, 12) and Ariadne auf Naxos (May 7 mat., 10, 13).
Marco Armiliato conducted Il Trovatore earlier this season. He is also conducting Tosca this season, having led the first run in January and returning on March 25 for a second run of performances.