Hi - what type of heart monitor are you referring to? PVCs and PACs are recorded exactly like any other heart beat, they are just premature. If you have PACs, they will not distort information, and if anything, having the PACs while wearing the monitor will provide valuable data to your doctor in terms of how your heart is functioning. An extremely rapid heart rate very early in exercise may be something your doctor wants to investigate. Have you had a stress test? Echocardiogram? If you have no other symptoms, such as shortness of breath, pain or dizziness, you are likely fine to continue working out. Many of us suffer from benign PVCs and PACs daily, sometimes several times a minute, and still lead very active lives. Make sure you speak with your doctor if the sensations change, and if you haven't done so already, having a full cardiac assessment would be a good next step to help give you peace of mind. Good luck.
I would not expect them to be accurate if you have odd rhythm. I'm not familiar w/ PACs. I had SVT...
Anyway, I have a Garmin and find that the reading get goofy if it's not strapped tight under the pecs. My advice would be listen to your body first.
Have you worn a Holter when exercising? If yes, and your Doc's not worried, I wouldn't worry. But regarding the HRM and accuracy with an irregular rhythm... prlly not accurate at all. Stop and take your pulse by hand and compare it to your HRM.
Keep truckin' though.
PACs doesn't make the heart rate rapid, unless you have lines of PACs; supraventricular tachycardia, and that's something completely different. PACs will make your heart rhythm irregular, with double beats and skipped beats.
Heart rate monitors don't always count the PACs if they produce a too low output to create a pulse wave. They may, and may not.
When I exercise, the monitor (the grips at the treadmill) often indicates skipped beats when there in fact aren't and they can't be completely trusted. The fact that you have PACs during exercise may indicate that your adrenaline levels are far too high (that exercise is stressing you, maybe because you are afraid of PACs?) and that itself may drive up the heart rate.
Ask your doctor for a stress test to get this phenomenon professionally evaluated, so you can get it out of your mind.