answering your question would require a thorough and time consuming analysis of his complete medical history. It sounds very complex. PVCs can have many different causes.
I had a very high load back in 2009 and we never figured out why.
I think it may have been a viral infection.
I hated it when people/doctors would tell me it was stress. Yea I'm stressed, I'm getting all these PVCs! They subsided when I was still very stressed so explain that to me!! ugh, it was depressing.
I tried beta blockers and calcium channel blockers which I swore made it worse and quickly went off them. glad I did because the condition ended up settling on its own, and I would still be on those meds thinking that's what fixed it.
Does he know where they are originating from? what part of the heart has the ectopy? are they coming from the same spot (unifocal)? are they coming from different spots (multi focal)? how old is he? any other conditions? Where did he have the ablations done? what type of catheter was used?
Sorry to hear that your dad is having a hard time with PVCs. For the doctor to try ablation and then amiodarone means he considers your dad's condition relatively serious. Around 80% of PVCs are right ventricular outflow tract related and ablation should be able to help. Sometimes though, the problem area maybe hard to get to. The vast majority of centers (95%) do less than 25 of these procedures per year as the simpler bread and butter procedures are SVT, implants and AF, while VT/PVC takes several hours to do and taxing in other ways. So you have to be selective as far as the center skill, experience and VT/PVC procedural volume.
There are been a number of studies just published by the top VT experts recently about the need to do ablations for patients like your dad whether they end up with ICDs or not. The ones that are successfully ablated don't need the ICD implant and have a significantly better quality of life for the patients that got ICD implants without ablation mainly because the ICD patients were getting many more shocks and go downhill quickly after the first shock whether the shock was appropriate or not.