Doctors say they know why the Chicago Symphony Orchestra’s music director collapsed during rehearsals.

A common heart rhythm disturbance caused Riccardo Muti’s fainting spell, according to a joint statement by the CSO and cardiologists at Northwestern Memorial Hospital.  The hospital gave Muti a pacemaker to prevent “possible future episodes of slow heart rate.” Doctors said Muti otherwise has “superb” heart function.

Muti fainted and fell during rehearsal last week. He underwent surgery to repair facial fractures from the fall.

Muti said he was grateful for all the support, and disappointed he couldn’t make music with the CSO.

“A music director’s relationship with his orchestra is like a marriage,” Muti said in the statement. “Together, we are a family, and we bond in times of joy and in times of challenge.  I think it was destiny that I came to Chicago, and I think what has happened is also destiny because now I understand and feel more comfortable than ever about returning to my work.” 

The chair of the CSO association, William A. Osborn, reaffirmed the board’s support for Muti.

“I can say with certainty that the relationship between the CSOA and Maestro Muti is strong. He is an important part of our family,” Osborn said.

Muti continues his recovery at Northwestern Memorial Hospital.

The CSO has found guest conductors to fill in for Muti this month. Muti missed his entire winter residency with the CSO, as well as half of last fall’s scheduled performances due to extreme exhaustion.