methacholine challenge safe for someone with an arrhythmia?

My Electrophysiologist insisted that I see a Pulmonoloist when I started wheezing after I failed a cardiac stress test a little over a month ago. I have a history of childhood asthma, but now at the age of 25, had thought I'd pretty much outgrown it. I was on 50mg of Toprol at the time (now cut down to 12.5mg), and her thoughts were that the medication might be aggravating the asthma that might not be quite as gone as I thought it was. Since I'd been coughing a lot more than normal for me in addition, I thought maybe she had a point (since I believe beta blockers are contradicted in people with asthma?). I cut down on the Toprol, and while it did nothing for my cardiac symptoms, it did seem to help with the asthmatic symptoms. We'd also come a lot closer to diagnosing the cardiac problems, and are now setting out the plans to try to fix them.

Cut to today, when I finally got to see the pulmonologist. He performed a basic pulmonary function test, which basically came back normal (but for some reason my function dropped a little with the bronchodilator?). However, during the test, I could feel my arrhythmias being set off, and got very light headed- which just confirms to me that this is a cardiac problem, and not a pulmonary one. I asked if this could effect the results, but was assured that it didn't, since they were essentially within the normal range. Because of this, the doctor decided he wants to send me for a methacholine challenge to see once and for all if the asthma is gone. I know this is the "gold standard" in testing for asthma, but I'm concerned about whether or not this will trigger my arrhythmias to go off. I'm dealing with AFib, IST, atrial tach and possible POTS. If the basic pulmonary function test set off runs of the arrhythmia, what will a test that's much more aggravating by design going to do? I asked the doctor, but he assures me everything is fine. (just as he assures me albuterol won't make me tachy, but I know that's not true).  I'm pretty sure the asthma is gone (at least it's not bothering me any more), so I'm not even sure it's worth it to do the test.

Has anyone ever dealt with this before? Do you know if it's safe to have a methacholine challenge if you have an underlying unstable arrhythmia?

[itdood]

I don't know the specific answer myself.  I would bring the question up with the doctor if it's tough to find any patient feedback on this one, as it seems like a legit concern.

[RedAngel84]

Thanks for the reply!

I figured might be a difficult question for anyone here to answer, but I thought it was worth a shot. I've asked my pulmonologist and the place where I'm having the test done about it, and they both said the reactions vary from person to person, so there's no way tell how I'll react. I take that to mean they have no idea.

I'm starting to wonder if it's even worth having the test done at this point, since it's been scheduled for two weeks after my EP study/ possible ablation, and I have no idea how I'll be recovery wise then. Probably fine, but if my heart may be throwing strange rhythms in the healing process anyway, this may be a bad idea. The asthma hasn't bothered me in a very long time, and obviously the heart issues are what's most important.

Is it even worth the potential risk to my heart of doing this test to know once and for all if the asthma is gone?