I'm still struggling with the same thing. I would ask for a referral to a cardiologist. I've done that, and will see them in two weeks. My rheumatologist said the cardiology dept. has much more in-depth tests they can do (a more thorough echocardiagram, for example) that may be able to tell more. It's a place to start. I'll tell you what I learn, and you can share what you learn. Maybe between the two of us we'll discover a workable approach. Best to you, Liame.
"If you trust Google more than you trust your doctor than maybe it's time to switch doctors."