Inappropriate sinus tachycardia

I was told I have IST last week. Bisoprolol isn’t working for me so I’m being put on Ivabradine 7.5mg. 

I was told not to worry about my heart rate going up but I’m wondering, if my heart is beating fast is it being overworked and damaged in the process? 

What is ur bpm?

Resting is at 81 with bisoprolol