ANT Forum

Garmin HRM's that use ANT technology cannot detect heart rate when the user has a Medtronic pacemaker installed. Any solutions?      

In fact this forum is not primariliy focussed on Garmin products.
And I strongly assume that not the ANT transmission HR strap -> display device is affected, but the picking up of the ECG waves.

Did you check other sources on the internet.
A simple google search with your buzzwords led me to http://www.pacemakerclub.com/public/jpage/1/p/story/a/storypage/sid/20401/content.do and many other hits.