flutter

At 60, the sinewy Harbaugh is as fit as any head coach in the game, and his heart issues — diagnosed as atrial flutter — are not indisputably attributable to the stress of the game.

A cardiologist appointment Monday confirmed the 60-year-old experienced a third episode of atrial flutter, a heart rhythm disorder he first faced in 1999.

Coach Jim Harbaugh experienced his third episode of atrial flutter in his heart during the Chargers’ game at Denver but had not had an issue in 12 years.

But the arrhythmia — diagnosed as an atrial flutter — resurfaced in more dramatic fashion during pregame warmups, prompting him to briefly duck into the blue medical tent on the sideline then head for the locker room flanked by team medical personnel.

After his two previous episodes of atrial flutter, Harbaugh underwent ablations, which are minimally invasive procedures that treat irregular heartbeats by destroying heart tissue that causes abnormal electrical signals.