Hi theusen2000,
First off, it's going to be very difficult for me to say anything about what is going on with you without seeing, examining you, and having the information already gathered in front of me. However, I'll give you some thoughts.
First off, I'm not sure if your left ventricular hypertrophy (which is thickening of the muscle of the heart) is from long-standing blood pressure (the usual cause). You are on blood pressure medication so that may be a possibility. I don't think that in and of itself would explain your symptoms. From a cardiac perspective, if people are feeling like they are going to pass out, we worry about: the electrical system of the heart, the structure of the heart (muscles, valves), and blood flow to the heart (blood vessels feeding the heart).
If you were having symptoms while the loop recorder was on and they didn't pick anything up, it is unlikely to be the electrical system of the heart. If you did not have symptoms, you would need another one to ensure that you're being recorded during one of these episodes. As long as the PVCs are not causing weakening of the heart muscle (which doesn't seem to be the case in you), that probably is not the cause either.
If you've had an echocardiogram, it would pick up problems with weakening of your heart muscle or a problem with your valves. That doesn't seem to be the case in you. Sometimes, echocardiograms will not pick up the subtle findings that can be seen on MRI. If there is worry that this is your heart, that could be considered. I'm assuming you have had a stress test which would rule out any disease of the blood vessels of your heart. If not, a stress test would also be reasonable in you.
If none of the above have revealed anything, then we start to think about things that are not related to the heart. You should have your thyroid checked (particularly since you are on what sounds like amiodarone), your calcium levels checked, and other labs to ensure this is not a metabolic problem. Also, patients with panic attacks/anxiety disorder can often have exactly the sensations you described. They can come on for no reason and can often be relieved with medication. There are also rheumatologic conditions (conditions that can cause inflammation) that can sometimes cause such vague symptoms.
As a side note, amiodarone is probably not the best drug for you long-term given its side effects. I would discuss this with your cardiologist. You should also discuss diet and exercise with him or her. Activity and diet modification can sometimes do wonders for people.
Hope this helps!
CCFHeartMD20
four years ago a cardio put me on amiodarone and let 15 months go by without tests for thyroid. It steadied my heart but by that time my TSH was 38 instead of the approved maximum of 4 and I'm still taking levothroxine to keep the levels normal. For the rest of my life I have to take the meds at 6a.m. and wait 30 mins before thinkng of a coffee. A new cardio then put me on propafenol, that too, kept it steady for a year. Now I take Coreg. Whatever my bad luck, be assured that there are meds that will help you.