For the past few weeks I've seen sudden and high spikes in my HR of 200+ while riding, even on the flats. (I ride with the Garmin Edge 800 which includes a HR monitor and chest strap.) I have a slow resting HR (typically mid-40s immediately after waking up in the morning). Several years ago I had a treadmill stress test which showed no problems but the doctor reported "benign PACs" but was otherwise VERY impressed with my fitness.
I have been under stress for several months. I drink 1 large mug of coffee early in the morning but I am slowly weaning off to see if it helps. I am prone to anxiety (just free-floating, no attacks). Sometimes when I see these spikes I also feel a surge of excitement or an adrenaline rush; other times I feel nothing at all, or I feel that surge/rush but no spike in the HR. I've also seen higher-than-normal numbers in the lower ranges (150 when I usually see 130, 130 when I usually see 100-teens, etc.). We already replaced the battery in the chest strap but it hasn't improved.
I have not uploaded the data to my computer to view it there but I am assuming I'll see whatever my Garmin displays.
Has anyone seen such high spikes with no symptoms? Could this be due to interference?