This is an excerpt re beta-blockers in the question dated December 20, 2003:-
Propranolol is a beta-blocker, and it’s a highly effective antidote to thyroid hormone. It’s so effective that many patients who are overstimulated by thyroid hormone (as in Graves' disease) use it. Propranolol relieves these patients’ overstimulation by indirectly blocking the cellular effects of thyroid hormone.
I'm always baffled when a doctor prescribes propranolol for a hypothyroid patient. If the patient isn’t taking thyroid hormone, propranolol is likely to worsen her hypothyroid symptoms. If she is taking thyroid hormone, the drug will nullify most benefits the patient would otherwise get from the hormone. Hence, there’s no sense whatever in a hypothyroid patient taking propranolol, and I suggest you ask your doctor about using another type of drug for your high blood pressure.
There’s something else, however, you and your doctor should consider. When you’re no long blocking the effects of the Armour with propranolol, your blood pressure may come down to normal without any other medication. Of course, you and your doctor would need to work closely together to make sure your blood pressure does come down.
All my palpitations, tachycardia, missed beats etc. stopped once I switched from levothyroxine altogether. A 5 day heart monitor showed heart is fine.