Pacemaker and Heartrate monitors

I am just coming up to 75 years of age and had a pacemaker fitted in 2004 due to borderline AV Block. It was and still is fine and I am absolutely delighted with it. I get no symptoms, can do anything I like including this year riding an event a month ago called the Classic Cols which is six of the famous Tour de France Alpine peaks in 3 days.
Since having it fitted though I have not until recently used a HRM because I could get nobody (either Polar, my Cardiologist or the manufacturer of the Pacemaker) to let me know if there was a problem of possible interference between the two devices. However I recently met another cyclist who had a pacemaker who used an HRM with no problems so decided to try it.
This coincided with me buying the Garmin Edge 800. On the Cols ride, the print out was amazing. For most of the ride it went up to 140 very quickly and stayed there for most of the ride never going higher and only dropping down when I stopped peddling. I assumed that this was due to my heart being paced because I have always had a slow heart beat even when racing and I had not seen it that high even for short periods let alone over several hours.
Last week I resurrected my old Polar device and amazingly the batteries on the strap still worked. However, the readings it gave me for the same effort were much closer to what I expected at about 100 and fluctuated down to about 80 in keeping with changes in effort.
Is it possible that the Garmin Edge is picking up some radiating frequency from the pacemaker so that the Edge is measuring the pacemaker not the HRM band?
Interestingly I know that my pacemaker is set on the top limit at 140bpm. Is this coincidental?