Pure drivel. There are no "meridians" in the body, no channels through which "energy" flows. They're just a fuzzy construct used by various alternative practitioners for which there is no proof, and for which they don't seem to feel any is needed. Anatomy is well known however, so that kinda sorts that one out.
The battery of a watch does not have an "intense electromagnetic charge", and won't affect your heart no matter where you wear it.