London (CNN) -- Fabrice Muamba, the soccer player who collapsed during a game Saturday, may never return to professional football, according to a London heart specialist.
In an interview with CNN affiliate ITN, consultant cardiologist Dr. Iqbal Malik, from Hammersmith Hospital, said it was "very much in doubt" that he could resume his professional career.
The 23-year-old Bolton Wanderers player, originally from the Democratic Republic of Congo, is currently in a critical condition at the London Chest Hospital after collapsing during a match with Tottenham Hotspur.
Dr. Malik said the treatment he received on the pitch was crucial to his survival, and his chances of making a recovery better than someone who collapses in the street due to the medical facilities at the stadium.
"It's almost the ideal place because of course Premiership players are well looked after so he goes in with very good health and top of that he's being actively watched during the game," he said.
"The paramedics arrived immediately, the resuscitation attempt started immediately and the defibrillator -- which is the life-saving maneuver -- happened within a couple of minutes. Within the first three minutes if you can get the heart restarted, then you've got a good chance of survival."
The specialist who works at one of London's heart attack centers said there would now be concern about whether the young footballer had suffered brain damage.
"It may be that because he's young and fit he'll make a great recovery but the question is more about his brain than his heart. I think his heart will recover quickly from this, but has there been enough bloody supply going to his brain during the time of his cardiac arrest to make sure he's neurologically intact?
"We want to see that he wakes up and starts communicating -- that's the next step."
Dr. Malik believes the cardiac arrest was probably caused by an existing condition.
"Despite all of the screening, there is still an instance of about two in 100,000 of this sort of thing occurring. It's much rarer than in the general population because these are fit young guys, but you cannot pick up the subtle abnormalities."
He said the next 48 hours would be crucial.
"I'm more worried about [whether] he is going to wake up and be the person he was before."