R on T phenomenon

Dear doctor.

Just wanted to ask a question about this mysterious phenomenon, as it's mentally bothersome for myself and several others suffering from cardiac neurosis. In the heart rhythm community here the question occur from time to time.

First, may the R on T phenomenon occur in a healthy heart (with no de/repolarization abnormalities on EKG and normal echo/stress test)? If it does, will it just be pure luck that determines if a PVC falls on the T wave?

Second, may this phenomenon, if it occur in healthy hearts, be dangerous and induce fibrillation or Torsades? I understand that this phenomenon is responsible for TdP in the setting of prolonged QT, but does this also apply to healthy hearts? Or can I (and other people with normal hearts) forget this entirely?

Last: I understand that a similar phenomenon is responsible for paroxysmal atrial fibrillation (PAC on atrial repolarization). Does this also apply only to people with structural heart disease like enlarged atria? The reason I ask is because I'm diagnosed with PACs and some of them are conducted with RBBB abberancy, so I think they are somewhat early in the cycle.

It is OK to use a somewhat technical terminology in your answer.

Thank you in advance.

[is_something_wrong]

I hope a physician may answer, not only because I'm anxious from time to time, but this question is common in the heart rhythm community and it would be great if we could refer to a professional answer.

[tickertock]

Most of the time, this a benign phenomenon, meaning no arrhythmia is triggered when it occurs, this is the answer I got from on this forum when I asked the question quite a few years back! Its not something to "dwell" on.

[is_something_wrong]

Thanks for your reply.

I understand, but I'm still hoping for a reply from a cardiologist concerning this. I remember your post by the way.

Thanks again.