A Concerned Runner

Hi Doctor,

Great service you guys provide here. I am rather new to running, having run about 2 years now. I was diagnosed some time ago with PAC's. When symptomatic they used to rattle me a bit but I have learned to live with them. I have recently begun training by heart rate and purchased a rather nifty heart rate monitor that's wirelessly picked up by the treadmill. Love technology!

The first time wearing the monitor, I noticed some minorly strange rhythms while still at rest and then during my run....without any symptoms in all occasions. I guess they could best be described as groups of 2 or 3 quick beats, never more than 3 beats. My symptomatic PAC's are just a pause with no physically (by pulse) detectable early beat, confirmed as PACs by my doctor on Holter.  Is what I experienced on my new heart rate monitor still PAC's? I know it wasn't just a faulty monitor reading because I took my pulse and was able to feel them.

Furthermore, a few months ago I had my first cardiologist visit ever. He put me on holter and recorded a total of 2 PAC's for an entire day. I've run into the hundreds on previous holters. So, I basically had a good heart day while wearing the monitor. He was quick to dismiss me and said I was perfectly fine. Now, if you had a patient who was complaining of numerous symptomatic PAC's during an extended period of time, would you have done another monitor or perhaps a 30 day event monitor to actually get some good hard evidence of what the patient was complaining of?

And finally, what is your view regarding electrolyte imbalances as related to heart issues? I was always just thrown on the monitor or given a stress test. Not once has any blood been taken except for a thyroid check. Do you check for things like magnesium levels with your patients?

[Michael J. McWilliams, M.D.]

The only way to know if it is a pac versus a pvc is to see it on a monitor.  You can't tell the difference by pulse or symptoms.

If you wanted the monitor, I would do it to put your mind at rest.  There isn't much that can be done to decrease them unless they are incredibly symptomatic.  I rarely use medications other than beta blockers or calcium channel blockers for PACs.  Besides, runners don't like beta blockers because it makes them feel tired.

I will rarely check magnesium levels in outpatients.  Only if I suspect that something is wrong.  I do not typically do this for patients with structurally normal hearts and pac/pvcs.  It is wrong to do it, I just haven't done it in the past.  Unless you are very deficient in magnesium, I doubt it plays much role in your extra beats.

I hope this helps.