Hi thanks for your question
The increased heart rate
called as tacycardia usually occur due to stress
and anxiety(tension) and it could also cause pain in chest.
Relax,there is nothing to worry.
Medicine has controlled your heart rate,continue with medicine till you get your echocardiogram(scan of heart) done to rule out any organic cause of tacycardia.
Then you can discontinue medicine in consultation with your physicianm
Hope this answers your question