Batum, 27, rolled his ankle in the fourth quarter when he stepped on the left foot of Heat rookie Justise Winslow while trying to post him up outside of the 3-point arc.
He was soon ruled out for the rest of the game.
Batum was not available after the game, but Hornets center Al Jefferson said that the injury looks bad enough that he doesn't expect him to return this series.
"It looked bad when it happened," Jefferson said. "Looking at his ankle now, it's pretty bad.
"That's part of the game. I feel like, me, personally, I don't think he will be able to come back."
When asked his level of concern about Batum's injury going forward, Hornets coach Steve Clifford responded, "Very."
"We won't know anything until tomorrow, but there was soreness, obviously," Clifford said. "And we'll just see."
Batum finished Game 2 with nine points on 3-for-11 shooting with seven rebounds and three assists in 34 minutes.
Batum missed the Hornets' regular-season finale with a sore left ankle. In his first year in Charlotte after an offseason trade from Portland, Batum averaged career highs in points (14.9) and assists (5.8) this regular season. He also averaged 6.1 rebounds, and his 1.68 real plus-minus ranked ninth among NBA shooting guards.
The Hornets head back to Charlotte trailing the series 0-2. The franchise has lost 12 straight playoff games, second in history to the New York Knicks from 2001-12.