snugglepuss, according to my pdoc and many studies, hypothyroidism and MI are directly related. In fact low thyroid can actually mimic MI. Some people have actually been misdiagnosed as MI when it was indeed just thyroid issues.
I just started on T3 (not sure the medical name for it) recently and I feel TONS better. My TSH levels were within normal range but my pdoc wanted to see higher/lower levels (I don't remember which, sometimes I don't pay close enough attention at my appts).
Of course you are entitled to your opinion as to if the two are related in your circumstance, but if you are interested there is plenty of information out there if you choose to research it.