I have had 4 previous mi's. at night exper. chest heaviness but no pain? some wheezing. minor discomfort taking deep breaths. is this another mi?

Unable to say: Heart attacks can cause many different symptoms. In any given person it is impossible to diagnose a problem without a true evaluation. Because of your history you should be under the care of a physician with experience in cardiovascular disease and should call with any new or unusual symptoms.

Diabetes?Smoking?: In patients with diabetes, chest heaviness may be your unstable anginal equivalent or even sometimes that is all you may feel while having a heart attack. This is obviously a serious matter and i think you should insist to your cardiologist that your symptoms are serious enough and want a coronary angiogram. Coronary stents do close specially in diabetics. If you have coronary stents, r/orestenosis.