Yes, I watched the medical press conference (and enjoyed when the ER supervising physician looked like he was going to tear the reporter a new one, toward the end.)
Let's cut to the chase: Whittington had an asymptomatic atrial fibrillation. They're keeping an eye on him, but don't see any permanent damage. They expect it to have no effect on his life in the future.
In a 78 year old man, this is still not as serious as if Whittington had broken an ankle.