Very low resting heart rate - what could be wrong!

isadora 2021, while it doesn't seem that you have need for immediate help, you should be able to send a note to the doctor telling them that you would like to have Holter monitoring. If you experience the low rate every day 24 hours might capture it. Monitoring can be extended to 48 hours or more.
You shouldn't need another appointment with the PCP to have this ordered. Some PCP offices have the equipment. If your doctor's office doesn't, your primary should honor your request for a referral, maybe to a Cardiac electrophysiologist.

Isadora, congratulations on your successful cancer treatment!

Regarding your low HR- have you have a Holter monitor study done? Or a sleep study? Are you taking any medications or supplements? Do you monitor your BP?
I have a normal pulse usually in the 50's most of my life, although I am far from an elite athlete. I live in Colorado and as an RN, have taken care pf some elite athletes here with heart rates in the 30's. Without any symptoms.

@luvnursing52 Thank you for your comments. Apparently the lowest recorded average RHR of an athlete was 28 (and it wasn’t Usain Bolt)! Imagine.

It’s been almost 20 years since I was last an elite athlete. But having my heart learn to be effective helped in the years when I wasn’t active. My average resting heart rate stayed in the high 50’s. To suddenly have it drop so far recently with side effects of fatigue and dizziness has been a shock. Even at my fittest I didn’t go below 45.

I rechecked my smartwatch data last night and I’ve had a few days in November when my average RHR was 37!! Otherwise it’s mainly around 40-42. My doctor checked my smartwatch in real time against her equipment and it was accurate 🤷‍♀️

My BP reading in my GP appointment was normal. My bloods are good other than a Vitamin D deficiency due to malabsorption which I’m addressing with a supplement. My weight is fine.

I don’t think anything I’m doing has started this. No medications. No supplements (other than the recently started Vit D). No major exercise (walking 1 and a half hours a day with dogs who like to stop and sniff).

I’m going to ask for a Holter check and I’ve also just bought a BP monitor. I’ll start checking my weight more regularly (not just when having my PET-CT scans). I may have lost too much weight too quickly through walking and eating healthily 🤷‍♀️

@isadora2021 it’s pretty much general knowledge that fighting cancer with radiation and chemo can effect the heart. Personally I’m having an echo this February after completing my radiation and chemo treatments this past Aug. I’d keep pushing for more heart testing thru your cardiologist if nothing else than to give you peace of mind. Good luck DgA

@luvnursing52 Thank you for your comments. Apparently the lowest recorded average RHR of an athlete was 28 (and it wasn’t Usain Bolt)! Imagine.

It’s been almost 20 years since I was last an elite athlete. But having my heart learn to be effective helped in the years when I wasn’t active. My average resting heart rate stayed in the high 50’s. To suddenly have it drop so far recently with side effects of fatigue and dizziness has been a shock. Even at my fittest I didn’t go below 45.

I rechecked my smartwatch data last night and I’ve had a few days in November when my average RHR was 37!! Otherwise it’s mainly around 40-42. My doctor checked my smartwatch in real time against her equipment and it was accurate 🤷‍♀️

My BP reading in my GP appointment was normal. My bloods are good other than a Vitamin D deficiency due to malabsorption which I’m addressing with a supplement. My weight is fine.

I don’t think anything I’m doing has started this. No medications. No supplements (other than the recently started Vit D). No major exercise (walking 1 and a half hours a day with dogs who like to stop and sniff).

I’m going to ask for a Holter check and I’ve also just bought a BP monitor. I’ll start checking my weight more regularly (not just when having my PET-CT scans). I may have lost too much weight too quickly through walking and eating healthily 🤷‍♀️

Have you seen an EP? (electrophysiologist). Might be a help if the Cardio and GP are blowing you offf

@isadora2021 I think the main issue would be how your body reacts to having a low heart rate. If you're dizzy and falling, that's a problem. Some people have a low heart rate and feel just fine.
I think your conditioning when you were younger helped you as you aged. But don't get too thin! My husband is terribly thin & I struggle to put weight on him. If I make too many high calorie meals, then I gain the weight, not him. He still doesn't take in enough calories. ( Add to that, high fat meals KILL me since I don't have a gallbladder.)