Jim Harbaugh didn’t have the heart to tell Chargers quarterback Justin Herbert that he had left Sunday’s game.

“He hid it very well because I wasn’t aware of it,” the Bolts QB said after Los Angeles stopped the Broncos, 23-16, on Sunday at Empower Field. “They did a good job of staying calm and I hope he is doing well.”

With that, Herbert, who threw for 237 yards against a Broncos defense that lost Pro Bowl cornerback Pat Surtain II to a concussion in the first quarter, cast a look of genuine concern.

“Is he okay?” Herbert asked reporters in the visiting team’s press conference room.

“He’s doing well,” a reporter replied.

“He’s had it before…” another added.

Evoke a second concerned look.

“Yeah, I don’t know,” the quarterback said. “‘Calm down. Let’s clear that up.'”

Harbaugh, 60, left the visiting sideline in the first quarter and was escorted to the Chargers’ blue medical tent. Shortly thereafter, the longtime coach was escorted to the Bolts’ locker room, where he remained for much of the first eight or nine minutes of the game. Defensive coordinator Jesse Minter officiated the game while Harbaugh was treated for what he called an atrial flutter, which causes the upper chambers of the heart to beat 250 to 350 times per minute.

The coach returned to the sideline later in the first quarter and completed the game without incident.

“Everything turned out to be fine,” Harbaugh later recalled. “The doctors checked me and it came back into sinus rhythm – a normal rhythm.”

Harbaugh said he had ablations for cardiac arrhythmias in 2012 and 1999, and that he could tell his heart rate was out of whack during pre-game warmups on Sunday.

“I’m not good at taking my own pulse,” the coach continued, “so (an employee) just took the pulse and it was within (the range of) the arrhythmia. But I felt like we were good. And then they said, ‘No, we need to do an ECG.’ So, trust the doctors, you know? If you don’t trust your doctors, who are you going to trust?

Harbaugh said he was given an IV and that Marco Zucconi, the team’s director of player health, wellness and performance, “gave me some kind of magnesium drug.”

Paramedics at Empower treated the Chargers coach in the locker room and checked his heart to make sure it returned to sinus rhythm, the coach recalled.

“And I said, ‘I feel good,’” Harbaugh continued, “so I went back on the field.”

As Harbaugh was taken to the locker room, the Chargers had taken the ball from the Broncos via a Bo Nix interception 1:23 into the game. The Bolts drove 39 yards in nine plays, but got stoned in the red zone when the Broncos defense forced a fourth-and-goal at the 2. Minter opted to kick a field goal from 20 yards, giving the visitors a quick 3 got a -0 lead.

In November 2012, while Harbaugh was coaching the 49ers, he reportedly experienced a palpitation on a Wednesday night in their week of preparation for a Monday night battle against the Chicago Bears. Harbaugh missed practice on Thursday for what was described as “a minor procedure” but returned to work the next day. The Niners went on to defeat the Bears, 32-7.