@mplopez5 Thanks for your input. I've continued to search and I'm pretty sure the margin of error in the measurement is at least a couple of millimeters. Yet, I guess the surgeons have to work within this regardless. I found a YouTube video in which a vascular surgeon described his process for deciding when to intervene surgically. I should have bookmarked it.

I'm overthinking the reasons behind this meeting, but I am guessing he may be using what seems to be an increasingly used measure of risk: aortic cross-sectional area to height. (An overview is here: https://consultqd.clevelandclinic.org/improving-risk-stratification-dilated-aorta-trileaflet-aortic-valve/.) By that measure, I might be at non-trivial risk. We'll see. I can live with whatever is the outcome of the meeting. I don't think I'm at high absolute risk regardless and the wave of panic has subsided. 🙂