As it has been just over one week I think you should discuss all new experiences with your doctor (or technical support).
A resting (you didn't say that) of 83 is fine, mine is there and is higher than in my pre-AFib days, but given you have a pacemaker to address a low night-time HR I wonder why it is that high. Is your pacemaker set to keep it that high? What was you HR when you "felt stronger"?
If it were me I'd want to discuss all question with my doctor, or the office support staff, until I became comfortable with what I was feeling.
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