I have had similar types of symptoms for around 3 years. The doctors do not know what causes them, and can do little to nothing about them. If I were you skip the cardio doctor and go straight for the Electrophysiologist
I am guessing the risk factors for SCD are the same for getting a heart attack. Also throw in any family members who died suddenly at a young age (by young I mean under 45-50) Other risk factors like unusally BP or heart rate response to exercise or stress would show up on a complete cardiac workup.
what risk factors for SCD would you be talking about....? Or better..what are the risk factors?
I have experienced similar booming with my ectopic beats, feels like my heart is going to beat right through my ribcage and/or fly out of the base of my throat. I am not sure of all the other circumstances, as I am not a doc, but I have found that my dose of Toprol (a beta blocker) has helped sooth the booming a little... I still get it with the bigeminy, but not as severely. However, our other circumstances may be very different. Still, might be worth asking about...
If you have a structurally normal heart, normal EKG, and no other risk factors for sudden cardiac death, premature beats are not of clinical consequence. I know they cause symptoms but there is no good way to stop or decrease them in most cases. You are going to have to trust your doctors on this one. If you can't do that, consider a second opinion but understand that they will probably agree.