re: Calcium score CT

Yes, echoing what others have said.
I am mid 50s and have had 2 of these tests because my father, aunt, uncle and their father all had heart attacks and bypass or died at 49 or 50, so I have been proactive and why I have dug into the numbers.
The issue is that the numbers are categorized in broad terms as far as your risk for a future event. This test is what most people call a "cat scan", but performed in a way that is optimized to look at calcium deposits in your cardiac blood vessels and commonly these deposits are in the form of atherosclerotic plaques, which are made up calcium, cholesterol, and other stuff. They cause trouble because as they build up they restrict the flow of blood in that vessel or vessels and since that vessel feeds blood to heart, if it gets blocked abruptly, that is what is called a heart attack. the blockage can be from a blood clot and/or that plague breaking up.
My number went from ~30ish to right at 100, so I am still low risk but at the upper end so I think anything above 100 is more than just low risk. I have high blood pressure and mildly elevated "bad" cholesterol, and qualify for a statin. I only have one vessel involved, kind of like you, and suspect at some point in my future I will possibly need to get a stent to open that spot up if it continues to grow.
I would bet your cardiologist or someone will want to look and see if the calcium in that vessel is in one spot or spread along the length of the vessel (the score doesn't differentiate).
If you ever have symptoms of a heart attack, you probably should not delay getting to an ER. An older family friend and I were discussing our calcium scores at dinner a few months ago. His recent one was in 1300s and kid you not had symptoms of a heart attack a day or two later but fortunately got treated with a stent since one vessel disease when he had a heart cath. Doing well now, but he told me that he probably would have waited longer to call an ambulance if not for knowing he was at very high risk from his calcium score. Fortunately doesn't seem that his oxygen levels were low enough for long enough to do much if any long term harm to his heart muscle.

Good luck with this. I know I had to pay about $100 cash for my test. Did you get insurance to cover yours?