It might depend on what caused your AF in the first place. A history of chronic endurance training is a significant risk factor for developing AF, and even then, some athletic/active people with AF can continue exercise, others can't. You need to be seeing an electrophysiologist for arrhythmia though, cardiologists are not the experts. My electrophysiologist told me he has several Olympic athletes among his patients.
I developed AF as a result of 30 years of overtraining, and whilst I've tried and tried to maintain/resume exercise over the last 10 years, it hasn't worked out well. The NHS have always insisted that AF is no reason to stop exercise, but they have an agenda: the years of overtraining were at the behest of doctors who told me to ignore symptoms and exercise more, so they're not going to admit that my AF has anything to do with training. In fact they went further than that, at first they tried lying, and denied that I had ever been diagnosed with AF at all.
Initially I tried resuming training, but each time I did so I ended back on an ambulance. An ablation improved things to some extent, but in 10 years of trying to re-train
very carefully I have never succeeded, any apparent initial improvement always ends in relapse. Of course, in my case I can't be sure how much of this failure is due to the AF, and how much to the years of overtraining previously. The upshot though is that I have lost all my fitness over the last 10 years, and as my fitness has declined it takes less and less exercise to precipitate another relapse.
It's noticeable on the AF forum that there are two categories of patient: those who feel lousy, and those who seem to shrug off the AF with relative ease. When I was diagnosed, a heart rate of 250 didn't really bother me, it all seemed a bit of a giggle and a lark, but not so now. These days the AF makes me feel absolutely lousy, which has reinforced my long held suspicion that those who are bothered least by it are those who are the fittest.
All this led me to reflect on the way I'd been trying to re-train carefully, failed, lost all my fitness, and been left worse off, so I decided that perhaps my best option was to forget trying to be careful, go back to 'overtraining', and see if I could regain any fitness, or at least prevent any further decline. Well that was a howling success. As usual, it seemed ok at first, but it led to another major relapse that I've never really recovered from, and I now can't do even the minimal exercise that I was able to do as recently as 2019.
We're all different, so I don't know how much help this is to you, but it's just my experience of developing AF, and trying to continue cycling with it. Another thing to consider is that Class 1c sodium channel blockers like Flecainide can promote atrial flutter, as they do in me, so they need to be used in conjunction with a rate control drug such as Diltiazem, or a betablocker if you're exercising. I have a long reading list which you're welcome to, but most of it relates to overtraining and its role of in the development of AF, rather than the ability to continue training afterwards.
Hoogsteen observed that 41% of subjects had to cease all sporting activities.
From Heidbuchel:
"Apart from the initial evaluation, regular follow-up should be performed in patients/athletes with arrhythmias. They should also be advised to present for immediate re evaluation in the case of symptoms, certainly if these are exercise related. The importance of unspecific symptoms such as sudden exertional fatigue or dyspnoea needs to be discussed with them." Which doesn't sit well with the NHS instructions to go away and get on with it.
And:
"It needs to be stressed, however, that there is no clear division between recreational and (semi)- competitive sports. Some patients may engage in high intensity exercise during leisure-time activities."
This is an interesting comment from Zipes:
"it is often difficult to establish the importance of a cardiac rhythm disturbance in assessing an athlete’s eligibility for competition. Few data exist that have been obtained prospectively from well-designed, scientifically acceptable studies to determine whether a particular rhythm disturbance predisposes an athlete to sudden death or to symptoms.......Many of our conclusions result from data obtained in non-athletes, from general perceptions, or experience and from a heavy input of 'what seems reasonable.'"
2004 Hoogsteen, Schep, van Hemel, van der Wall:
Paroxysmal atrial fibrillation in male endurance athletes. A 9 year follow up.
Europace (2004) 6 222-228
https://academic.oup.com/europace/a...oxysmal-atrial-fibrillation-in-male-endurance
2006 Heidbüchel, et al: Recommendations for participation in leisure-time physical activity and competitive sports in patients with arrhythmias and potentially arrhythmogenic conditions Part I: Supraventricular arrhythmias and pacemakers.
European Journal of Cardiovascular Prevention & Rehabilitation 2006 13: 475
http://cpr.sagepub.com/content/13/5/676.short
2005 Zipes, et al: Eligibility Recommendations for Competitive Athletes With Cardiovascular Abnormalities
Task Force 7: Arrhythmias, 36th Bethesda Conference
JACC Vol. 45, No. 8, 2005 April 19, 2005:1354–63
http://content.onlinejacc.org/article.aspx?articleid=1136518