When should ct angiography for heart be repeated?

It’ depends on what was the reason to order it in the first place. If it were to exclude certain abnormalities and the study turned out to be normal, it may not be repeated. If It’s done to detect a reversible condition and the study was abnormal, it will be repeated in a few weeks. If It’s to monitor a progressive condition it may be repeated every few years

That would depend on the reason for the CT angio as well as findings. One study found that if stenosis (narrowing) under 25%, no hx of diabetes and under 3 years since prior study. Chance of CT angio being significant (over 50% narrowing) was less than 5% and under 2% if prior study showed normal arteries. I would discuss risk factors with a cardiologist to see if further evaluations are needed