So if you are on beta blockers and a Lion jumped into the room, my heart would get
to racing pace quicker than yours. Higher dosages do start
to lower the actual rate even at rest, so the right balance has to be found. I found it odd when I was on beta blockers. I lost that butterfly feeling in my stomach when I got anxious. So the answer to your question would really be, beta blockers can affect the heart rate, whether you have a pacemaker or not.