Is There a Significant Post-Operative H.L. Fibrillation?

Is it fair to say that significant post-operative H.L. fibrillation or ICU related AFib is that that might last more than 48 hours? I've seen that number being used in the literature and I'm just curious is that the threshold that you would be there significant or is it not as clear a clear cut? To be honest, there is no cut off. The only guideline that made this the timing, like a time cut off is the Canadian cardiovascular guidelines back,. They used a 72 hour as a cut off. But to be honest, it's arbitrary because what if someone had three 24 hour episodes? Is it cumulative or it's continuous? I think generally speaking