I believe that a blood clot anywhere in the body can effect the heart. Being anxious is one of the first signs of heart being affected--as in heart attack.
I had 22 episodes in 5 days 2 emergency trips to the hospital before they found miocardial ifartion--heart attack. I was too young (at 41 mind you)
first time sent me home with more antiacids!!!
You could also be just paranoid, I don't know how much you know about your condition--which could be the cause of the paranoiah(however you spell it)
what do the dr's say about the blood clot, blood thinners!!??
Please update me

Oh and by the way, if you are getting that anxious your prolly raising your blood pressure, although dr's haven't found it when you go in.
That can also affect the heart, not saying heart attack, I just know it affects it.
You are pretty young--how you get blood clot? Do they know?
There are many heart conditions that are "not" life threatening, and it could be you might have one of them, you only notice when your anxious, raising your blood pressures or your heart rate. Or could be noticing it when the clot might slow your blood flow.
Watch for things like hot burning, then cold spots in the leg, that won't go away. Watch for numbness more than usual, if you have numbness with the clot, also watch for numbness tingling pains in left arm. And always pains in the chest or back just near the heart.

I hope this helps
and try not to worry--see another dr if you think he's not doing a right job for you