When should you suspect TR related to pacemaker lead placement as a cause of RV dysfunction rather than pulmonary HTN or other etiologies for RV failure associated with tricuspid regurgitation?

It would be patient-specific but would need to include RHC to rule out pHTN (of any group). That should point you in the right direction. I suspect this would be pretty rare and would have to have very severe TR.

We know there is a magic amount of slack to put in the RV lead to minimize TR, but this is very difficult to do reliably with the type of anesthesia and likely more important body position. I am not aware of any specific strategies beyond estimating appropriate slack to give.

This scenario comes up not infrequently. Sometimes intracardiac echo or TEE could be helpful to see if the RV pacing lead is going through the tricuspid valve leaflet or tethering the valve open. The best way to prevent perforating the tricuspid valve leaflet is to prolapse the lead across the valve during placement. This ensures the tip of the lead will not go through the valve itself. However, despite all precautionary measures, sometimes chronic heavier leads such as ICD leads can get adheren...