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Training on flecainide

I am 41 years old and have mild mitral stenosis. I had some membrane removed from my aortic valve when I was 15. So my heart is not normal, but healthy enough not to get in my way as long as I don't try compete in running or riding races, or field sports.

In April I had atrial fibrillation. I was electro-cardioverted and returned to normal rhythm and was taken off all meds except blood thinners. In September the A-fib came back and I was electro cardioverted again and have now being put on CR 200mg Flecainide (1 pill a day). I have no side effects except how it holds me back when my heart rate increases to about 145 bpm.

Sustaining the level of exertion at a higher HR than that (which I need to do when I am jogging on anything but the flatest of flat smooth roads) becomes really hard work. I usually can't sustain that level of effort for more than a few minutes which is when I need to take a break and let my HR return to 130 and then I can start again .. and repeat if the HR goes up that high again.

I have seen elsewhere that this is quite a normal effect of flecainide so I am not concerned about it. I am also accepting that I can't run at the speeds i did in the days before flecainide (not that i was breaking any records). But I am interested to hear from others that have tried to stay fit, and/or get fitter, on flecainide.

Whats the best approach? Is it best just to go for long slow runs on flat roads or is there benefit in exerting oneself to the point where you have to stop (effectively doing low intensity interval training!)?

BTW I also mountain bike, but haven't done that much recently (the reason has nothing to do with the A-fib) - when I ride, my heart rate is lower so the flecainide doesn't get in the way nearly as much.

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Not a reply to your question but I'm pleased to meet someone else who had a subaortic membrane. I didn't have mine removed until age 58 (long story). There don't seem to be many with congenital cardiac conditions in this group.

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After 2 catheter ablutions for AF and on flecainide my instruction was not to exercise to a heart rate of over 150. My advice would be to ask your cardiac nurse or doctor as different patients with different reasons for taking flecainide might be given different answers.


Thanks, when i was put on the flec i asked him what my limits were and specifically asked about high intensity training and he said: go for it, do want ever you want


Hi Jonathan

Whatever exercise you do you need to warm up slowly so that your heart rate gradually increases, otherwise the internal alarm bells start ringing and the Flecainide will want to get it back down. It's also really important to warm down afterwards.

If you read about exercise and AF, the advice seems to be to avoid endurance training or anything that causes great rushes of adrenaline (first-time bungee jumping or parachuting!) and that exercise should be moderately hard i.e. you can still hold a conversation but are not ending up in an exhausted heap.

You mention that you are taking your flecainide as 1x200 mg tablet - have you been given a particular time that you need to take it? It may help if you could split the 200mg between morning and evening. I tend to exercise early in the morning and then take the morning Flecainide (before breakfast) and have a second dose in the evening. I started on 100mg morning and evening but found that I was getting side effects on my eyesight. The EP dropped it to 50mg morning, 100mg evening when it didn't matter that my sight was slightly blurred as I was asleep! I'm currently on 50mg morning and evening.

You'll get to know what works for you with AF and exercise. Some days you'll feel great, other days it may be that all you can do is a gentle walk and stretch. Best advice is listen to your body.



Thanks Caroline. I take a capsule (so wouldn't want to split in half) and it is slow release (so the timing only makes a small difference, if any).

The warm up advice may be spot on as the times I have really struggled have been after starting a bit quicker than usual (even though i tried not to)


Oh...a fellow mountain biker! If you go back to it, you will likely need to walk up longer, steeper, rockier hills. Your fitness training will need to change, but that doesn't mean you are any less healthy. You will probably have a lower anaerobic threshold, but unless a competitive athlete, who cares. That is only really relevant near the upper ranges of your maximum heart rate. Since there is more and more evidence linking long term endurance athletes with arrhythmias, there are some of us who are going to need to chose...healthy hearts or high end exercise.

Here is a link about flutter but things can be applied to A fib...read near the end about reasons not to elevate you heart rate a lot while taking flecainide. It can make things worse. He doesn't say how high is too high, but I'm guessing above 70% MHR.


I really like this guy because he is also an athlete, and has personal experience with his own arrhythmias.

I am 4 weeks out from an ablation (right side only, mostly for flutter, and from scarring due to exercise induced over stretching of the atrial wall) and am on Flecainide and will be for the entire 3 month blanking period. I hope and pray that this ablation works, and plan to probably go back to lower intensity aerobic exercise for life.

Good luck!

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thanks, good luck for the ablation


Hello Jonathan, and Canyonsister who I've chatted to previously - hope your recuperation is going well!! I run and started Flecanide approx 2 months ago 2 x 50mg per day. I have recently started running again after a long break whilst going through tests etc. And feeling down/scared. A week ago I ran a hilly half marathon course in my own time which made me very happy. It wasn't fast (approx 2hrs) but I did it. In fact it was bloody hard!! I have never measured my HR when running so still don't know if I'm currently struggling due to natural deconditioning and/or weight gain or, if as you suggest, the Flec is stopping me! I don't know. All I can say is that my EP, Cardiologist and GP have told me that Flec should not affect my HR as do beta blockers like bisopropol etc. I have also not been told to stop running, or pushing myself, just to 'be sensible' as I could risk the AF breaking through. Well there you go. That's my story for now! Keep in touch!


I met someone through twitter who is taking the same dose as you and he said he doesn't feel any effect of the flecainide.

I think (based on the guy mentioned above and your experience) that the difference between 100 mg vs 200mg is the difference between feeling the strain at 150bpm and feeling it at 170bpm... (rough estimation).

...so I think that if you are pushing yourself to 160 bpm then you won't feel the flecainide if you are only taking 100mg... (this is my personal theory, i take no responsibility if its completely wrong!)

so I am really hoping my cardioligist drops my dose to 100mg when i see him in 5 months time


I've heard worse theories! Also I've never heard of anyone taking 200mg in one go. 2 x 100mg yes but not 1 tab. 5mnths is a long time to wait though. Can you not perhaps speak to your GP or even write/call your cardiologist? I've written twice to my cardiologist and he's replied both times!


i may give him a call. its actually still early days as I haven't jogged that many times since being on the flec.

Also I got a big fright when the a-fib re-occurred so quickly so there is some comfort taking a big dose of flecainide that almost guarantees the a-fib will stay away.

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Just heed the warnings in the link guys...there is concern about flecainide and a higher heart rate. It slows conduction of the electrical impulse and at a high HR, that can cause mischief. I think I made that mistake right before my ablation (but was on propafenone..similar effect tho). Know too that many cardiologists aren't athletes so "be sensiblele" to them means something entirely different for us! I would think that 70 to 75 % MHR is ok. I'm sure hoping so. I believe post ablation, HR is elevated by 10 to 15 BPM even at rest. Poor hearts take a beating in ablations, just not on the surface where we can see them. I'm trying to be patient and not worry about the twitchy feelings I'm getting at this stage of the game...grateful to be walking about three miles a day and teaching yoga.


To allay your concerns I think I am being sensible... I promise. I don't try push it and stop for rests when I feel strained rather than try push through it.

Also can you point me to the section of the article you are referring to? Is it #11?


Yes, number 11. Rhythm control drugs like flecainide are great but they do mess up electrical conduction (that's how they work). I think I was thinking "ok the arrhythmia is controlled so I can get my HR up more" and that may have been a mistake. I think a HR monitor is probably a good idea, as well as your perceived level of exertion. I hate stopping on my bike...that was the problem!


Another perspective: I was very specific when I asked my cardiologist about training and about the fact that I mountain bike and like to ride up single track and steep hills and how that often blows the heart rate sky high. I asked this question after he wrote my script for flecainide. Without any hesitation he told me to do whatever I wanted to do.


One other question I have realised I need to ask to those using flecainide is: when you do a hard session of exercise do you find your body takes longer to recover than in the days before flecainide?

I haven't mountain biked for a while and did a pretty decent 40km ride and my body seemed to hurt more than usual. On Saturday I did an 11km trail run (a lot of it is spent walking) and am sure I am feeling it more than I used to (I have done the route a few times).

I only have this when doing something tougher than the usual - for instance I jogged 7km last week and was totally fine.

Perhaps this is the med's way of telling me I must take it easy on the endurance side of things?


My Cardio was quite clear do not go mad on HR when exercising when on Flec so as usual I guess there are different advices out there.


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