Heart or Thyroid Problem?

[donsabi]

History: MI, 14 years ago, CAD, and Hashimoto’s Thyroiditis. Age 61
Rx: Tenormin, Synthroid, Pravachol, Niaspan, and Asprin

In June I met with my new cardiologist. He did an EKG which looked good and said my heart sounded fine. He scheduled a stress test for July 12, he said everything looked OK so there was no rush.
As soon as the heat came on this year I felt fatigued with exertion. I wake up and feel great, but within four hours I am fatigued usually relieved with a nap. I also have some brain fog which comes and goes. I have no pain, chest pain or shortness of breath. BP and heart rate stay about normal for me, 140/80 @ 72bpm. Last year I had the same thing with the onset of summer heat. My symptoms were so severe I had a cardiac catherization which turned out OK, no need for intervention. At that time my symptoms were attributed to my hypothyroidism. Once the fall came with the cooler weather I began to feel better.
IMO, this is my hypothyroidism, but I wanted to hear some objective opinions.
I would appreciate your comments. Thanks.

[rc998]

i feel the same way in the heat, i get fast heart rate when i walk and its hot out, i guess some people handle the heat differently

[donsabi]

Today I went to the ER because lately I have be having extreme fatigue brought on by almost any exertion. They did all the cardiac tests and found nothing. They checked my thyroid and said that was normal. (I haven’t seen the test results yet). They attributed my symptoms to anxiety. If this is anxiety, why do I have the fatigue only in the heat. Or it is a symptom of CAD?
I think the hospital didn’t really know what is causing my fatigue and just blew it off as anxiety.
Comments appreciated. Thanks.