Inga,
Thanks for the post, and Gutentag (I hope I got that right?).
The long-term outcomes after sinus node modification or ablation largely depend on why the procedure was done in the first place.
Innapropriate Sinus Tach (IST) can often be successfully treated with an ablation procedure provided a firm diagnosis of IST has been established. POTS patients, as an example, frequently derive little benefit from a sinus node modification.
Developing AVNRT or aflutter after an ablation of the sinus node would be uncommon. It is more likely that these arrhythmias were always present, but just masked by the IST.
Lastly, in specific answer to your question about long-term studies, the Mayo clinic has published several smallish series. Most of their published work shows benefit for very specifically treated/targeted patients.
We still do 2 or 3 IST ablations per month at the CCF. I can't speak to other hospitals' patterns.
Hope that helps.