This morning we called the doctor's office, and the receptionist immediately said, "Oh, your doctor wants to go over the results of your tests now." So Captain Midnight and I drove to another city, writing a long list of questions we'd like answered on the way.
Some of them were answered today, which was good. We still don't have a prognosis, but CM's doctor pointed out that CM is relatively asymptomatic -- in other words, there don't seem to be any attendant issues other than the racing heart -- and that this is a good sign. The echocardiogram didn't show any congenital structural issues or viral damage to his heart. In about a week he'll be undergoing a stress test so they can see what his heart is doing. In the meantime, he has officially been advised not to engage in any strenuous activity (no walking to work, for instance) and to lay off the caffeine. He has the OK to go back to work, since he has a desk job, but will probably use the elevators for a while.
I'm slightly relieved, but mostly I'm exhausted. There aren't really any physical reasons for me to be so tired... got enough sleep, haven't been doing anything particularly strenuous, and I still feel relatively calm (even though it didn't stop me from also feeling cheesed off yesterday). But I think all the not knowing and the concern for CM's health and well-being takes its toll after a while.