The ct scan 64/128 slice takes images of the anatomy of the vessels and reveals soft plaque, and soft plaque has the highest risk for heart attack (myocardial infarction) and sudden death. If and when soft plaque ruptures the lining of the vessel, it will form a clot that can break away totally blocking the vessel. The ct scan evaluates a prognosis based on calcium count in the 4 major arteries and a total count.
The stress test observes the lumen for any blockage and the degree of blockage that may cause angina (chest pain, etc.).