My doctor said my normal ct scans means i have no blocked arteries. is this true?

Likely insignificant: If this was a ct angiogram, probably low risk of significant disease. If a ct calcium score, less likely, but still encouraging news.

Partially: It depends on the type of ct scan, the location, and the arteries in question. A ct angio is a good test to see blockages in arteries, but a regular ct scan is less helpful, and a ct scan with no IV contrast cannot diagnose this at all. Certain larger arteries are seen better than smaller ones. Also, ct scan is better at diagnosing a complete blockage. Small or partial blockages can be missed.

Seek clarification : It's always best to seek clarification from the doctor who gave you the information. If you are not satisfied, ask for a copy of the images on cd and take to a second doctor for another opinion.