@mrspudhead
I was going to recommend a Electrophysilogist (EP) but you mentioned it yourself.

I had tons of PVCs and I see a EP who treated one in my RV with ablation and fixed it. I have them in LV but prefers he treats it with medications. The medications cut my PVCs in half.

You mentioned your cardiologist does not know where they come from. Have you had a holter monitor test? That will tell you cardiologist where the PVCs are coming from. That test would reveal where coming from.

I first saw a EP back in 2006 when my local cardiologist was treating me and wanted me to see a local electrophysiologist. I wanted to get a second opinion on my diagnosis and treatments and went to Mayo Jacksonville to see a EP. I have been treated there every since. I had a ICD/pacemaker inplanted in 2006 and also was referred to heart failure doctor by my Mayo EP who is excellent also.

From my experience with PVCs and my treatments my suggestion is to see a electrophysiologist. I have had several holter monitor tests and they were used to find the source of PVCs and decide the burden on heart.