My dad’s doctor said he should get one, Medicare denied it, but he paid out of pocket to get one anyway. He found out he was 95% blocked pretty much everywhere and had a quadruple bypass. It likely added many years to his life and avoided a heart attack.
If you’re under a certain age (I want to say somewhere in your 50s), there isn’t any guidance for what normal is. If you’re in your 20s or 30s, I wouldn’t run out and get one. But if you’re in your 40s with a family history, or up into your 50s and beyond, it’s worth thinking about. I’ve also heard you’re only supposed to get them every 2-3 years, it’s not a yearly thing, due to the radiation.
(I am not a doctor)
The time to take action is long before you have a CAC score. e.g. Start tracking ApoB regularly, see if you have genetic LPa exposure, and avoid the foods that increase your exposure while ignoring the grifters telling you it's a nonissue.
Emphasis on non-invasive diagnostic screening as invasive testing like angiogram need to be operated by specialist and can take months to be arranged, and only done after incidents e.g heart attack.
ECG is excellent for generic top level CVD anomaly conditions for examples arrhythmia and ischemia.