Barcelona have announced that Sergio Aguero will not play for three months after reaching a compromise at Alaves on Saturday.
The 33-year-old former Manchester City footballer underwent heart tests at the hospital after falling ill.
Aguero will receive care during medical tests.
The club said: “In the next three months, the effectiveness of the treatment will be evaluated to determine the recovery process.”
Aguero received a few minutes of treatment in the stadium before being taken to the hospital.
In a press release, Aguero said he was “positive and enthusiastic about the recovery process”
The former Manchester City forward is on his second starting start with Barcelona after suffering an injury in the preseason.
He joined the Spanish giant on a two-year contract in the summer after spending 10 years at City, during which time he became a full-time player with 260 points in 390 games.
Speaking ahead of the Barca Champions League controversy with Dynamo Kiev on Tuesday, manager Sergi Barjuan said: “I spoke to him and he was calm. He was in his room but, given the situation, calm.”