Eriksen, 29, collapsed on the grass in the first half of the Group B game and was quickly followed by medics who sprinted to his aid.
The Inter Milan playmaker was stretched off the pitch after receiving extensive treatment and taken to hospital, where his condition stabilized.
The Danish FA provided a promising update on Eriksen’s condition on Sunday morning, saying he had been in contact with his teammates and would be kept in hospital to be monitored.
And at a press conference on Sunday afternoon, they provided details on the causes of Parken’s terrifying incident in Copenhagen.
Danish sporting director Peter Moller, team doctor Morten Boesen and head coach Kasper Hjulmand were present at the press conference.
Boesen said: “We don’t have an explanation for what happened.
“I didn’t see it live, I saw it on screen after it happened. You saw the same as me, but there is no explanation so far.
“Well, he was gone. We did cardiac resuscitation. And it was cardiac arrest. How far were we [to losing him]? I do not know. We got it back after a defibrillation, so it’s pretty quick. “
Confirmation Eriksen suffered a heart attack confirms what many feared as the former Tottenham Hotspur star had to be revived on the pitch.
Despite Eriksen’s horrific ordeal, German team doctor Tim Meyer insists that current medical checks to look for underlying conditions are fit for purpose.
Meyer told reporters: “Basically we and other nations are following two strategies: 1. We regularly check our players for underlying health issues.
“The DFB does it comprehensively and I guess the Danish FA does it too.
“2. When such cases occur, it is essential that those affected are able to take appropriate action. Doctors and qualified medical staff are on standby.
“We still have two defibrillators, in case one fails. The chain of command and communication is clearly defined and functions well.
“Personally, I don’t think the DFB needs to take any further action. We can never completely rule out these cases, but we are well prepared. In fact, you could say that we are doing too much.
“We consider official recommendations to be basic requirements, and we do even more. “