Mystery Solved
Okay, so it was my family doctor who called and made the appointment with me about my test results. The twist: I have a new family doctor, Dr. Lombard. Apparently Dr. Booyens moved to Medicine Hat and my file was passed on to Dr. Lombard, and just nobody told me, as if doctors are some kind of interchangeable units, like lego bricks. Like maybe I wouldn't notice or something?

Anyway, the results: The "quiver" in my heart is the result of SLIGHT pulmonary and tricuspid regurgitation. I guess there's a leak in my heart that causes a tiny bit of blood to flow backwards. Lombard is pretty sure that this should make absolutely no difference in my day-to-day functioning whatsoever. It might make a difference if I have dental surgery, although I still don't understand exactly why (and I don't think he does either). Anyway, he's sending me to a cardiologist to find out exactly what it means and make absolutely sure that everything's okay.