The 25-year-old has already made four appearances for the Bundesliga giants this season and featured for eight minutes of their Champions League victory over Barcelona on Tuesday night.
The France international is now facing a spell on the sidelines after undergoing a heart procedure, but he could potentially be back in first-team training over the next couple of weeks.
"'King' had an operation yesterday, he had a minor heart rhythm disturbance. I'll explain that with my little medical expertise," Nagelsmann told reporters.
"There are two strands that activate the sinus node. One of them was cut off so that there would be no additional blow. Sometimes he had less air for a short time and was less productive. That's why we did a long-term ECG (electrocardiogram) and found something that could be fixed quickly.
"He'll start cardio on Tuesday. It won't take much longer than a week and a half or two before he's back in team training."
Coman, who continues to be linked with a move away from the Allianz Arena, could potentially be available for Bayern's Bundesliga clash with Eintracht Frankfurt at the start of October. body check tags ::