Lexapro may cause a rapid heart rate which is one of the signs of serotonin syndrome.
I would like to suggest you discuss this phenomenon with your physician if you have concerns about a fast heart rate.
Re Ativan, anytime you are going to stop a medication it is wise to set up a weaning plan with your physician.
*~* https://www.healingwell.com/donate *~*
"When you find peace within yourself, you become the kind of person who can live at peace with others."
Not a mental health professional of any kind
Clickable Link: Anxiety-Panic Resources