Low resting heart rate before taking Ivabradine?

[rainbowbrite9]

I have what seems like a "mild" version of Inappropriate Sinus Tachycardia (or a mild dysautonomia). I've been on 37.5mg of metoprolol for 3 years, so I have no idea what my actual resting heart rate is, but on the drug it's in the 50s/60s, so not high at all. The metoprolol definitely helps me feel less on edge all the time, but it doesn't prevent spikes (b/w 100-150) or my heart from getting "stuck" at a higher resting rate for hours on end (80s/90s). My cardiologist gave me a sample of Ivabradine to try. He said to lower my metoprolol to 25mg and take 2.5mg of Ivabradine twice daily. But I've been reading online that people whose resting rate is less than 70bmp shouldn't take Ivabradine. Again, I'm not sure what my resting rate is off Metoprolol, but it's not as high as someone with actual IST, which is >95 I believe, and again, on metoprolol it's in the 50s mostly. So I'm a little nervous to take the drug because I'm worried my resting heart rate will be too low. And I know I should be talking to my cardio about this, but twice now he has not responded to my emails. So I just thought I'd ask if anyone has successfully taken the drug who has sinus tachycardia, but who also has kind of a low resting heart rate, as opposed to a higher one you tend to see with people taking this drug?