Resting heart rate measured 48 and he though 57-63 better
That is interesting. Is you doctor aware that some individuals who do regular cardiovascular exercise often have resting HR in the 40s? Are there any signs that you are having circulation issues?
Usually, a low HR is a good sign, indicating that the heart does not have to work as hard to distribute the blood your body needs to function.
I'll share an anecdote from my experience. Before my diagnosis in 2019, I was a cardio enthusiast and had not only a very low HR but it took a lot to get my HR high. As part of investigating my murmur, which would later turn out to be due to aortic stenosis and BAV, they had me do a treadmill stress test. The tech commented on how low my pulse was at 10-12 minutes in- I think I was barely over 100. She said that most people reach their HR max about then. I ended up going 19:20 before I had to stop and apparently set an office record for staying on the longest.
So, for the next 10 days I kept getting bad news, mostly about my valve, aortic stenosis, BAV, but also about having very high Lp(a), a very bad type of LDL cholesterol that is genetic. Well, I thought, at least I did good on the treadmill. Not so fast. I then get a call that my stress test result was irregular and I needed to come back to do another stress test with echo. Big shot to the gut; even my stress test was bad, at least irregular, whatever that meant.
When I had the follow up consult with my cardiologist I asked him what was irregular about my first stress test. He indicated, as best he could tell, the computer found it irregular because it took so long for my HR to reach max. But, he said that given the intense level of cardio training that I did it was not a surprise to him that my HR took that long to reach max. So, they made me jump through a bunch of extra hoops for nothing, lol.
Anyway, I would just be really cautious if they are planning to treat you to raise your HR. I would definitely get a second opinion from a cardiologist who specializes in athletes before taking anything to raise your HR.