What happens during a stress test and what exactly is the doctor looking for?

See below: During any type of stress test, the heart rate is increased to a minimum level by exercise or medication. The goal is to see if there are any ekg changes indicating possible blockages or narrowing of the coronary arteries that may result in a heart attack in the future. Afterwards, images are taken of the heart motion to see if there is any past damage resulting in wall motion abnormalities.

ForAdvancedDisease: Brief intense exercise for detecting artery disease; misses most disease; arteries expand, not narrow. ~75%, or more, narrowing before stress tests, all forms, begin to detect any abnormalities. Nuclear (more expensive & person radiated) promoted as more sensitive; for all I have seen, a well done ekg exercise stress more sensitive & accurate. I quit doing stress tests 1995; better client options.