It you heart rate is high > 100 but esp. greater than 125 you risk wearing your heart out IF you are in continuous A-fib.
If it is intermittent then you are at less risk. But stroke or PE(pulmonary embolism) are greater risk. That is the purpose of using anti-coagulants like eliquis.
I am at that point now 5 1/2 years out of my 1st ablation that I am having increasing intermittent A-fib. Within the last year I have been averaging A-fib events lasting 12-48 hours about on average every month or so. Cardiac mapping has improved significantly in the last 5 years as well as surgical procedures have improved. So I am scheduled for another ablation on Sept 25. I just had a 36 hour event this weekend and self converted on Sunday afternoon. So far I have not needed to be electro-cardioverted since my ablation 5 1/2 years ago. I have been fortunate enough to self-convert. Also my HR almost always stays below 90. But it still sucks and wears me down. I am 76 with a mild myopathy that weakens me. I have to continuously try to work out which includes gardening, walking and cutting firewood (love to heat my house with a wood stove). But every A-fib event knocks me back and I have to slowly rehab myself which slows me down. So I am hoping to get some better relief from an ablation.