"He's his usual grumpy self," Johnson said jokingly. "Hopefully, he was watching the game. I was hoping that grand slam would shock him right out of that atrial fibrillation."
McCatty is in his fourth full season as the team's pitching coach and his 18th as a pitching coach at the professional level. A Michigan native, he planned on flying to Detroit before the rest of the team to spend Monday's off-day with his family, according to Johnson.
Instead, McCatty is expected to travel to Detroit on the team's flight Monday afternoon. The Nationals will begin a two-game series with the Tigers on Tuesday.
"They'll give him some medication, thin his blood, and something to slow his heart rate down," Johnson said, "and hopefully, he'll come out of the irregular beat."
Tom Schad is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.