HR variation during exercise

Dear wise friends,

Apologies for this detailed message. I am an otherwise healthy 52-year-old female with a PM installed three years ago (12/17) for bradycardia and heart block. A month ago I developed AFib and had a successful cardioversion earlier this week. There is some thought that I may have hypertrophic cardiomyopathy (MRI in 2017 showed asymmetric septal hypertrophy and mild enlargement of both ventricles and left atrium) and I have an appointment with a specialist in this disorder in a few weeks. 

My main (only) complaint has been chronotropic incompetence with exercise, which continued to plague me even after the PM installation. After the cardioversion this week, my EP tweaked my settings this week, keeping my resting HR at 50bpm and raising my maximum bpm from 150 to ... something higher (he did not specify a number).

I have cautiously begun to exercise again — walking, mainly, and short, light jogs — and though I feel mostly fine, my HR monitor is showing HR accelerations that don't correlate with exercise intensity. So that while my HR might accelerate normally during a job over .3 miles, say, when I then pause and begin to walk, my HR might continue to accelerate, hitting 170 bpm after a couple of minutes and then dropping into the 80s a minute or so later and then rising a couple minutes later to 140 bpm, etc. The resulting HR graph on my app shows a series of spikes and troughs.

Should I avoid exercise until I can see a specialist? Or is a HR monitor not 100% reliable for people with PMs? I'm trying not to be alarmed, but the pattern I'm seeing disturbs me. 

Thanks for any advice,




Exercise with caution based on “how you feel”

by Gemita - 2020-10-04 16:59:31

Dear Emily,

Personally I wouldn't push yourself until you have seen the specialist.  An arrhythmia like AF can certainly cause spikes and falls in heart rate as well as blood pressure and some heart rate monitors may struggle to keep up with such sudden changes.  I appreciate you have had a cardioversion but I wonder if you are still getting episodes of AF?

Hopefully your specialist will give you good advice and treatment so that you can safely exercise again in the near future. In the meantime, I would let your EP know what is happening with your heart rate.  He may wish to check your settings again or monitor you for AF.

Those massive swings in heart rate are common for me when I am in AF.  I certainly wouldn't feel comfortable or safe exerting myself during an AF episode which is why I would advise caution until you have discussed your condition with your specialist and EP.  

For your information I do use a good digital blood pressure monitor which can confirm an irregular rhythm like AF and indicate with accuracy a heart rate up to around 150 bpm but anything higher or a sudden drop from these levels will definitely cause my monitor to "error" and AF being so "irregular" in nature is the reason why home monitoring can be hit and miss.  Many have used the Apple Watch with success too and the Kardia Mobile.  The pacemaker may cause some interference but a good monitor should provide a fair assessment of your heart rate.   Otherwise I check manually neck pulse.

I wish you the very best of luck

thank you

by heartbeat26 - 2020-10-04 22:26:12


Thanks for your thoughtful and supportive comments; much appreciated. It had occurred to me to wonder whether I might be returning to AFib when I walk/jog, though I'm told that if I do go into AFib for 10 seconds or more my PM will revert to a steady rate of 70bpm as a safety measure (this happened during my original AFib episode), and since my cardioversion my HR has been all over the place (though my resting rate is in the 50s). I wish I had a better understanding of chronotropic incompetence. Maybe if I can obtain a primary diagnosis I will have a better grasp of this phenomenon and why it is occurring. In the meantime, I will stick to walking. 

Thanks so much!



by AgentX86 - 2020-10-04 23:38:24

No, heart rate monitors are not accurate for those without arrhythmias and much more so  for those with.  A pacemaker complicates things further.

Chronotropic incompetence should be corrected with your pacemaker's rate response but it may take some time to get it dialed in.  Count your heart rate yourself, though.  Do not trust any monitor.

Cardiomyopathy and Afib go together, though not a 100% correlation.  Cardiomyopathy is thought to cause fibrosis in the heart which in turn causes errant electrical pathways.  On the other hand, untreated Afib and the associated tachycardia tends to cause cardiomyopathy.  The two then feed on each other.  It's critical to keep the resting heart rate below 100bpm. 


A cardioversion is just a patch.  It may last for some time or 30 seconds.  I've been on both sides.  After the first DCCV I went seven years without another Afib breakout.  After that time I had a chemical (ameoderone) cardioversion that got me ut of Afib, though with antiarrhythmics, until I had a CABG a few months later.  After a couple of days I was in Aflutter and the DCCV didn't last long enough to get back to my room. 


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