You are confused. Let's just take the first result from a websearch:
https://ixquick.com/do/metasearch.pl...s+test+purpose
http://www.surgeryencyclopedia.com/S...ress-Test.html
"The stress test is particularly useful for detecting ischemia (inadequate supply of blood to the heart muscle) caused by blocked coronary arteries."
When you say imaging, that is particularly ambiguous, since an arteriogram in the cath lab is very different than say, a Calcium Artery Scoring or an IVUS. And nobody goes to the cath lab without a stress test first, except if an MI has already been well established and there exists a medical emergency.
Then what do you possibly think a stress test is done for?Especially since the autopsy provided no evidence of occlusion of any veins/arteries of the heart that would have been considered as causation of death, their cause of death is "cardiac arrhythmia" which in itself, can be adequate to cause death. There was nothing, either in their tests nor in the autopsy, that would suggest there was any real concern of a blockage.
I don't see how your statement is pertinent, since an simple EKG would have should any arrhythmia.
and I can assure you that angina is not the only cause for pain, either in the chest in general or specific to the heart. Some types of arrhythmia itself can be the cause of considerable pain.
I've already mentioned pericarditis. Causes such as chondritis, gastritis, pulmonary embolism etc are immaterial to this case.

