Thanks for posting your query.
Your stress test
appears to be invalid as exercise last for only six minutes and a stress test is called as valid if 85% heart rate
Rest part of your stress appears to be normal.
Your SPECT test and ejection fraction
is also normal.
So your all cardiac t\investigations are in normal limit.
Your chest heaviness and radiation
to left shoulder could be due to lung pathology with muscular ache in left shoulder.
You should consult with your treating doctor/ internal medicine specialist and should go for thorough check up.
You should also go for chest x ray and left shoulder x ray.
You should also go for spirometry
Meanwhile, you should take analgesics along with muscle relaxants.
For chest heaviness, you should use inhalational therapy with beta agonist and anticholinergics.
Dr. Mayank Bhargava