The 27-year-old Republic of Ireland international collapsed at half-time of the Foxes' Carling Cup clash with Nottingham Forest in August and had to be revived after suffering two heart attacks.
Clarke is now close to a return to training, despite a full diagnosis of his problem having not been reached.
He told the Daily Mail: "I'm just hoping to get back into it and get on to the training pitch, hopefully in the next couple of weeks, certainly in the New Year.
"It's been frustrating and I'm chomping at the bit to get back, but the doctors have been trying to get to the bottom of it and although they know what happened, they still don't know what brought it on.
"It could be hereditary but they think that is unlikely as they have found nothing to suggest it is. It's been a drawn-out process but now I just want to move forward.
"What happened was terrible and will stay with me, but I've got to get back out on to the pitch."