Here is what to think about this test-
The calcium test shows calcified plaque. This is the most stable plaque you can have. The real issue is what about and how much of the non calcified plaque that is less stable and more prone to rupture do you have? How much and how many and in how many vessels do i have lesions with lipid rich plaque?
The answers can be had thru invasive and/or non invasive tests. Discuss with you cardiologist how to get these answers and what they mean to your risk profile.
Now, regarding your brother whose test came back much lower than yours. A low calcium score means that fewer lesions have "healed" and calcified. There could be a lot(or none) of non-calcified plaque-lurking sight unseen(as of now), the calcium test is not a measure of the truly dangerous plaque, it really only shows at what stage in the overall process your arteries are at.
It seems you do not have a cardiologist, that is the first action necessary.
I would anticipate you will be going to max dosage on your statin which is 80mg. I think if you research or discuss with your cardiologist which statin is the most effective you will be switching to 40mg of Rosuvastatin/Crestor.
Why? Your goal is to increase the rate at which your existing lesions continue to remodel/increase fibrous cap thickness and even reduce lipid content.
You have a family heart history. You must now be more diligent-and aggressive-in your acvsd management.
Good luck. You can ve sure that all of us who received a score like yours or higher all were in shock same as you. How you react now makes all the difference. Do not let any grass grow under your feet.