Royal Antwerp sporting director Marc Overmars has suffered "irreparable" damage to his heart following a cardiac arrest last month.

The former Arsenal and Barcelona winger was admitted to hospital on December 29 after suffering a reported mild stroke.

However, De Telegraaf is reporting that Overmars' condition is worse than originally reported.

It's said that his heart is only able to pump blood at 30 per cent of its normal volume and that part of his heart muscle has died.

Upon his appointment at Antwerp this season, Overmars helped bring former Tottenham duo Toby Alderweireld and Vincent Janssen to the club.

The Reds are currently third in the Belgian Pro League, 13 points off leaders Genk, despite winning each of their first nine matches.