The winger was diagnosed with a heart arrhythmia – an irregular heartbeat – and the club decided to carry out the surgery quickly.
Speaking in his Friday press conference, Bayern boss Nagelsmann gave details of Coman’s condition and operation.
‘Kingsley Coman underwent surgery yesterday,’ he said.
‘His heartbeat rhythm had a slight disturbance with a minor added beat. At times, he had a slight shortage of breath.
‘That’s why we opted for long-term ECG monitoring and went ahead with this procedure.’
The German boss expects the Frenchman back in training in a few days and the starting XI not long after.
‘He will be doing cardio training again on Tuesday and won’t be out of action for any more than one and a half to two weeks,’ Nagelsmann revealed.
The 25-year-old is an integral part of the Bayern Munich set-up and is a highly decorated player with spells with Bayern, Juventus and Paris Saint-Germain.